From aabb81ecb58208e7c9151bea6ebc19f6060e7515 Mon Sep 17 00:00:00 2001
From: Lakshman Annadorai <lakshmana@google.com>
Date: Tue, 31 Jan 2023 17:01:27 -0800
Subject: [PATCH 1/4] Update CpuInfoReader to compute normalized available CPU
 frequency.

- Guard against reading CpuInfos too frequently.
- Implement dump logic in CpuInfoReader.
- Guard against zero time value in the time_in_state file.

Test: atest CpuInfoReaderTest
Bug: 242722241
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:67bc88121775785907a3aebd87db7c4bdef5fff9)
Merged-In: I9fc109c43fe0bd5f1d16135ad3167325ae502e15
Change-Id: I9fc109c43fe0bd5f1d16135ad3167325ae502e15
---
 .../com/android/server/cpu/CpuInfoReader.java | 159 ++++++++++++++++--
 .../android/server/cpu/CpuInfoReaderTest.java |  79 +++++----
 2 files changed, 190 insertions(+), 48 deletions(-)

diff --git a/services/core/java/com/android/server/cpu/CpuInfoReader.java b/services/core/java/com/android/server/cpu/CpuInfoReader.java
index ca97a9847b39b..ce68edbb9fa1f 100644
--- a/services/core/java/com/android/server/cpu/CpuInfoReader.java
+++ b/services/core/java/com/android/server/cpu/CpuInfoReader.java
@@ -21,8 +21,10 @@ import static com.android.server.cpu.CpuMonitorService.TAG;
 
 import android.annotation.IntDef;
 import android.annotation.Nullable;
+import android.os.SystemClock;
 import android.system.Os;
 import android.system.OsConstants;
+import android.util.IndentingPrintWriter;
 import android.util.IntArray;
 import android.util.LongSparseLongArray;
 import android.util.SparseArray;
@@ -50,6 +52,9 @@ public final class CpuInfoReader {
     private static final String POLICY_DIR_PREFIX = "policy";
     private static final String RELATED_CPUS_FILE = "related_cpus";
     private static final String AFFECTED_CPUS_FILE = "affected_cpus";
+    // TODO(b/263154344): Avoid reading from cpuinfo_cur_freq because non-root users don't have
+    //  read permission for this file. The file permissions are set by the Kernel. Instead, read
+    //  the current frequency only from scaling_cur_freq.
     private static final String CUR_CPUFREQ_FILE = "cpuinfo_cur_freq";
     private static final String MAX_CPUFREQ_FILE = "cpuinfo_max_freq";
     private static final String CUR_SCALING_FREQ_FILE = "scaling_cur_freq";
@@ -70,16 +75,18 @@ public final class CpuInfoReader {
     private static final Pattern TIME_IN_STATE_PATTERN =
             Pattern.compile("(?<freqKHz>[0-9]+)\\s(?<time>[0-9]+)");
     private static final long MILLIS_PER_CLOCK_TICK = 1000L / Os.sysconf(OsConstants._SC_CLK_TCK);
+    private static final long MIN_READ_INTERVAL_MILLISECONDS = 500;
 
     @Retention(RetentionPolicy.SOURCE)
     @IntDef(prefix = {"FLAG_CPUSET_CATEGORY_"}, flag = true, value = {
             FLAG_CPUSET_CATEGORY_TOP_APP,
             FLAG_CPUSET_CATEGORY_BACKGROUND
     })
-    private @interface CpusetCategory{}
+    /** package **/ @interface CpusetCategory{}
 
     // TODO(b/242722241): Protect updatable variables with a local lock.
     private final File mCpusetDir;
+    private final long mMinReadIntervalMillis;
     private final SparseIntArray mCpusetCategoriesByCpus = new SparseIntArray();
     private final SparseArray<File> mCpuFreqPolicyDirsById = new SparseArray<>();
     private final SparseArray<StaticPolicyInfo> mStaticPolicyInfoById = new SparseArray<>();
@@ -90,16 +97,20 @@ public final class CpuInfoReader {
     private SparseArray<CpuUsageStats> mCumulativeCpuUsageStats = new SparseArray<>();
     private boolean mIsEnabled;
     private boolean mHasTimeInStateFile;
+    private long mLastReadUptimeMillis;
+    private SparseArray<CpuInfo> mLastReadCpuInfos;
 
     public CpuInfoReader() {
-        this(new File(CPUSET_DIR_PATH), new File(CPUFREQ_DIR_PATH), new File(PROC_STAT_FILE_PATH));
+        this(new File(CPUSET_DIR_PATH), new File(CPUFREQ_DIR_PATH), new File(PROC_STAT_FILE_PATH),
+                MIN_READ_INTERVAL_MILLISECONDS);
     }
 
     @VisibleForTesting
-    CpuInfoReader(File cpusetDir, File cpuFreqDir, File procStatFile) {
+    CpuInfoReader(File cpusetDir, File cpuFreqDir, File procStatFile, long minReadIntervalMillis) {
         mCpusetDir = cpusetDir;
         mCpuFreqDir = cpuFreqDir;
         mProcStatFile = procStatFile;
+        mMinReadIntervalMillis = minReadIntervalMillis;
     }
 
     /**
@@ -167,6 +178,16 @@ public final class CpuInfoReader {
         if (!mIsEnabled) {
             return null;
         }
+        long uptimeMillis = SystemClock.uptimeMillis();
+        if (mLastReadUptimeMillis > 0
+                && uptimeMillis - mLastReadUptimeMillis < mMinReadIntervalMillis) {
+            Slogf.w(TAG, "Skipping reading from device and returning the last read CpuInfos. "
+                    + "Last read was %d ms ago, min read interval is %d ms",
+                    uptimeMillis - mLastReadUptimeMillis, mMinReadIntervalMillis);
+            return mLastReadCpuInfos;
+        }
+        mLastReadUptimeMillis = uptimeMillis;
+        mLastReadCpuInfos = null;
         SparseArray<CpuUsageStats> cpuUsageStatsByCpus = readLatestCpuUsageStats();
         if (cpuUsageStatsByCpus == null || cpuUsageStatsByCpus.size() == 0) {
             Slogf.e(TAG, "Failed to read latest CPU usage stats");
@@ -202,6 +223,12 @@ public final class CpuInfoReader {
                         + " policy ID %d", policyId);
                 continue;
             }
+            if (curFreqKHz > maxFreqKHz) {
+                Slogf.w(TAG, "Current CPU frequency (%d) is greater than maximum CPU frequency"
+                        + " (%d) for policy ID (%d). Skipping CPU frequency policy", curFreqKHz,
+                        maxFreqKHz, policyId);
+                continue;
+            }
             for (int coreIdx = 0; coreIdx < staticPolicyInfo.relatedCpuCores.size(); coreIdx++) {
                 int relatedCpuCore = staticPolicyInfo.relatedCpuCores.get(coreIdx);
                 CpuInfo prevCpuInfo = cpuInfoByCpus.get(relatedCpuCore);
@@ -241,9 +268,73 @@ public final class CpuInfoReader {
                 }
             }
         }
+        mLastReadCpuInfos = cpuInfoByCpus;
         return cpuInfoByCpus;
     }
 
+    /** Dumps the current state. */
+    public void dump(IndentingPrintWriter writer) {
+        writer.printf("*%s*\n", getClass().getSimpleName());
+        writer.increaseIndent();    // Add intend for the outermost block.
+
+        writer.printf("mCpusetDir = %s\n", mCpusetDir.getAbsolutePath());
+        writer.printf("mCpuFreqDir = %s\n", mCpuFreqDir.getAbsolutePath());
+        writer.printf("mProcStatFile = %s\n", mProcStatFile.getAbsolutePath());
+        writer.printf("mIsEnabled = %s\n", mIsEnabled);
+        writer.printf("mHasTimeInStateFile = %s\n", mHasTimeInStateFile);
+        writer.printf("mLastReadUptimeMillis = %d\n", mLastReadUptimeMillis);
+        writer.printf("mMinReadIntervalMillis = %d\n", mMinReadIntervalMillis);
+
+        writer.printf("Cpuset categories by CPU core:\n");
+        writer.increaseIndent();
+        for (int i = 0; i < mCpusetCategoriesByCpus.size(); i++) {
+            writer.printf("CPU core id = %d, %s\n", mCpusetCategoriesByCpus.keyAt(i),
+                    toCpusetCategoriesStr(mCpusetCategoriesByCpus.valueAt(i)));
+        }
+        writer.decreaseIndent();
+
+        writer.println("Cpu frequency policy directories by policy id:");
+        writer.increaseIndent();
+        for (int i = 0; i < mCpuFreqPolicyDirsById.size(); i++) {
+            writer.printf("Policy id = %d, Dir = %s\n", mCpuFreqPolicyDirsById.keyAt(i),
+                    mCpuFreqPolicyDirsById.valueAt(i));
+        }
+        writer.decreaseIndent();
+
+        writer.println("Static cpu frequency policy infos by policy id:");
+        writer.increaseIndent();
+        for (int i = 0; i < mStaticPolicyInfoById.size(); i++) {
+            writer.printf("Policy id = %d, %s\n", mStaticPolicyInfoById.keyAt(i),
+                    mStaticPolicyInfoById.valueAt(i));
+        }
+        writer.decreaseIndent();
+
+        writer.println("Cpu time in frequency state by policy id:");
+        writer.increaseIndent();
+        for (int i = 0; i < mTimeInStateByPolicyId.size(); i++) {
+            writer.printf("Policy id = %d, Time(millis) in state by CPU frequency(KHz) = %s\n",
+                    mTimeInStateByPolicyId.keyAt(i), mTimeInStateByPolicyId.valueAt(i));
+        }
+        writer.decreaseIndent();
+
+        writer.println("Last read CPU infos:");
+        writer.increaseIndent();
+        for (int i = 0; i < mLastReadCpuInfos.size(); i++) {
+            writer.printf("%s\n", mLastReadCpuInfos.valueAt(i));
+        }
+        writer.decreaseIndent();
+
+        writer.println("Latest cumulative CPU usage stats by CPU core:");
+        writer.increaseIndent();
+        for (int i = 0; i < mCumulativeCpuUsageStats.size(); i++) {
+            writer.printf("CPU core id = %d, %s\n", mCumulativeCpuUsageStats.keyAt(i),
+                    mCumulativeCpuUsageStats.valueAt(i));
+        }
+        writer.decreaseIndent();
+
+        writer.decreaseIndent();    // Remove intend for the outermost block.
+    }
+
     /**
      * Sets the CPU frequency for testing.
      *
@@ -496,6 +587,9 @@ public final class CpuInfoReader {
         for (int i = 0; i < timeInState.size(); i++) {
             totalTimeInState += timeInState.valueAt(i);
         }
+        if (totalTimeInState == 0) {
+            return CpuInfo.MISSING_FREQUENCY;
+        }
         double avgFreqKHz = 0;
         for (int i = 0; i < timeInState.size(); i++) {
             avgFreqKHz += (timeInState.keyAt(i) * timeInState.valueAt(i)) / totalTimeInState;
@@ -624,16 +718,29 @@ public final class CpuInfoReader {
         @CpusetCategory
         public final int cpusetCategories;
         public final boolean isOnline;
+        public final long maxCpuFreqKHz;
         // Values in the below fields may be missing when a CPU core is offline.
         public final long curCpuFreqKHz;
-        public final long maxCpuFreqKHz;
         public final long avgTimeInStateCpuFreqKHz;
         @Nullable
         public final CpuUsageStats latestCpuUsageStats;
 
+        private long mNormalizedAvailableCpuFreqKHz;
+
         CpuInfo(int cpuCore, @CpusetCategory int cpusetCategories, boolean isOnline,
                 long curCpuFreqKHz, long maxCpuFreqKHz, long avgTimeInStateCpuFreqKHz,
                 CpuUsageStats latestCpuUsageStats) {
+            this(cpuCore, cpusetCategories, isOnline, curCpuFreqKHz, maxCpuFreqKHz,
+                    avgTimeInStateCpuFreqKHz, /* normalizedAvailableCpuFreqKHz= */ 0,
+                    latestCpuUsageStats);
+            this.mNormalizedAvailableCpuFreqKHz = computeNormalizedAvailableCpuFreqKHz();
+        }
+
+        // Should be used only for testing.
+        @VisibleForTesting
+        CpuInfo(int cpuCore, @CpusetCategory int cpusetCategories, boolean isOnline,
+                long curCpuFreqKHz, long maxCpuFreqKHz, long avgTimeInStateCpuFreqKHz,
+                long normalizedAvailableCpuFreqKHz, CpuUsageStats latestCpuUsageStats) {
             this.cpuCore = cpuCore;
             this.cpusetCategories = cpusetCategories;
             this.isOnline = isOnline;
@@ -641,6 +748,11 @@ public final class CpuInfoReader {
             this.maxCpuFreqKHz = maxCpuFreqKHz;
             this.avgTimeInStateCpuFreqKHz = avgTimeInStateCpuFreqKHz;
             this.latestCpuUsageStats = latestCpuUsageStats;
+            this.mNormalizedAvailableCpuFreqKHz = normalizedAvailableCpuFreqKHz;
+        }
+
+        public long getNormalizedAvailableCpuFreqKHz() {
+            return mNormalizedAvailableCpuFreqKHz;
         }
 
         @Override
@@ -657,6 +769,8 @@ public final class CpuInfoReader {
                     .append(avgTimeInStateCpuFreqKHz == MISSING_FREQUENCY ? "missing"
                             : avgTimeInStateCpuFreqKHz)
                     .append(", latestCpuUsageStats = ").append(latestCpuUsageStats)
+                    .append(", mNormalizedAvailableCpuFreqKHz = ")
+                    .append(mNormalizedAvailableCpuFreqKHz)
                     .append(" }").toString();
         }
 
@@ -673,13 +787,32 @@ public final class CpuInfoReader {
                     && isOnline == other.isOnline  && curCpuFreqKHz == other.curCpuFreqKHz
                     && maxCpuFreqKHz == other.maxCpuFreqKHz
                     && avgTimeInStateCpuFreqKHz == other.avgTimeInStateCpuFreqKHz
-                    && latestCpuUsageStats.equals(other.latestCpuUsageStats);
+                    && latestCpuUsageStats.equals(other.latestCpuUsageStats)
+                    && mNormalizedAvailableCpuFreqKHz == other.mNormalizedAvailableCpuFreqKHz;
         }
 
         @Override
         public int hashCode() {
             return Objects.hash(cpuCore, cpusetCategories, isOnline, curCpuFreqKHz, maxCpuFreqKHz,
-                    avgTimeInStateCpuFreqKHz, latestCpuUsageStats);
+                    avgTimeInStateCpuFreqKHz, latestCpuUsageStats, mNormalizedAvailableCpuFreqKHz);
+        }
+
+        private long computeNormalizedAvailableCpuFreqKHz() {
+            if (!isOnline) {
+                return MISSING_FREQUENCY;
+            }
+            long totalTimeMillis = latestCpuUsageStats.getTotalTimeMillis();
+            if (totalTimeMillis == 0) {
+                Slogf.wtf(TAG, "Total CPU time millis is 0. This shouldn't happen unless stats are"
+                        + " polled too frequently");
+                return MISSING_FREQUENCY;
+            }
+            double nonIdlePercent = 100.0 * (totalTimeMillis
+                    - (double) latestCpuUsageStats.idleTimeMillis) / totalTimeMillis;
+            long curFreqKHz = avgTimeInStateCpuFreqKHz == MISSING_FREQUENCY
+                    ? curCpuFreqKHz : avgTimeInStateCpuFreqKHz;
+            double availablePercent = 100.0 - (nonIdlePercent * curFreqKHz / maxCpuFreqKHz);
+            return (long) ((availablePercent * maxCpuFreqKHz) / 100.0);
         }
     }
 
@@ -712,7 +845,7 @@ public final class CpuInfoReader {
             this.guestNiceTimeMillis = guestNiceTimeMillis;
         }
 
-        public long getTotalTime() {
+        public long getTotalTimeMillis() {
             return userTimeMillis + niceTimeMillis + systemTimeMillis + idleTimeMillis
                     + iowaitTimeMillis + irqTimeMillis + softirqTimeMillis + stealTimeMillis
                     + guestTimeMillis + guestNiceTimeMillis;
@@ -796,8 +929,8 @@ public final class CpuInfoReader {
 
         @Override
         public String toString() {
-            return "FrequencyPair{cpuFreqKHz=" + cpuFreqKHz + ", scalingFreqKHz=" + scalingFreqKHz
-                    + '}';
+            return "FrequencyPair{cpuFreqKHz = " + cpuFreqKHz + ", scalingFreqKHz = "
+                    + scalingFreqKHz + '}';
         }
     }
 
@@ -812,7 +945,7 @@ public final class CpuInfoReader {
 
         @Override
         public String toString() {
-            return "StaticPolicyInfo{maxCpuFreqPair=" + maxCpuFreqPair + ", relatedCpuCores="
+            return "StaticPolicyInfo{maxCpuFreqPair = " + maxCpuFreqPair + ", relatedCpuCores = "
                     + relatedCpuCores + '}';
         }
     }
@@ -831,9 +964,9 @@ public final class CpuInfoReader {
 
         @Override
         public String toString() {
-            return "DynamicPolicyInfo{curCpuFreqPair=" + curCpuFreqPair
-                    + ", avgTimeInStateCpuFreqKHz=" + avgTimeInStateCpuFreqKHz
-                    + ", affectedCpuCores=" + affectedCpuCores + '}';
+            return "DynamicPolicyInfo{curCpuFreqPair = " + curCpuFreqPair
+                    + ", avgTimeInStateCpuFreqKHz = " + avgTimeInStateCpuFreqKHz
+                    + ", affectedCpuCores = " + affectedCpuCores + '}';
         }
     }
 }
diff --git a/services/tests/mockingservicestests/src/com/android/server/cpu/CpuInfoReaderTest.java b/services/tests/mockingservicestests/src/com/android/server/cpu/CpuInfoReaderTest.java
index b214787533010..04f6f8b2e9f0b 100644
--- a/services/tests/mockingservicestests/src/com/android/server/cpu/CpuInfoReaderTest.java
+++ b/services/tests/mockingservicestests/src/com/android/server/cpu/CpuInfoReaderTest.java
@@ -92,6 +92,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(0, new CpuInfoReader.CpuInfo(/* cpuCore= */ 0,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_230_000,
                 /* maxCpuFreqKHz= */ 2_500_000, /* avgTimeInStateCpuFreqKHz= */ 488_095,
+                /* normalizedAvailableCpuFreqKHz= */ 2_402_267,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 32_249_610,
                         /* niceTimeMillis= */ 7_950_930, /* systemTimeMillis= */ 52_227_050,
                         /* idleTimeMillis= */ 409_036_950, /* iowaitTimeMillis= */ 1_322_810,
@@ -101,6 +102,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(1, new CpuInfoReader.CpuInfo(/* cpuCore= */ 1,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_450_000,
                 /* maxCpuFreqKHz= */ 2_800_000, /* avgTimeInStateCpuFreqKHz= */ 502_380,
+                /* normalizedAvailableCpuFreqKHz= */ 2_693_525,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_949_280,
                         /* niceTimeMillis= */ 7_799_450, /* systemTimeMillis= */ 54_004_020,
                         /* idleTimeMillis= */ 402_707_120, /* iowaitTimeMillis= */ 1_186_960,
@@ -111,6 +113,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 1_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ 464_285,
+                /* normalizedAvailableCpuFreqKHz= */ 1_901_608,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_959_280,
                         /* niceTimeMillis= */ 7_789_450, /* systemTimeMillis= */ 54_014_020,
                         /* idleTimeMillis= */ 402_717_120, /* iowaitTimeMillis= */ 1_166_960,
@@ -121,6 +124,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 1_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ 464_285,
+                /* normalizedAvailableCpuFreqKHz= */ 1_907_125,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 32_349_610,
                         /* niceTimeMillis= */ 7_850_930, /* systemTimeMillis= */ 52_127_050,
                         /* idleTimeMillis= */ 409_136_950, /* iowaitTimeMillis= */ 1_332_810,
@@ -139,6 +143,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(0, new CpuInfoReader.CpuInfo(/* cpuCore= */ 0,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_000_000,
                 /* maxCpuFreqKHz= */ 2_500_000, /* avgTimeInStateCpuFreqKHz= */ 419_354,
+                /* normalizedAvailableCpuFreqKHz= */ 2_425_919,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 10_000_000,
                         /* niceTimeMillis= */ 1_000_000, /* systemTimeMillis= */ 10_000_000,
                         /* idleTimeMillis= */ 110_000_000, /* iowaitTimeMillis= */ 1_100_000,
@@ -148,6 +153,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(1, new CpuInfoReader.CpuInfo(/* cpuCore= */ 1,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 2_800_000,
                 /* maxCpuFreqKHz= */ 2_800_000, /* avgTimeInStateCpuFreqKHz= */ 429_032,
+                /* normalizedAvailableCpuFreqKHz= */ 2_403_009,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 900_000,
                         /* niceTimeMillis= */ 1_000_000, /* systemTimeMillis= */ 10_000_000,
                         /* idleTimeMillis= */ 1_000_000, /* iowaitTimeMillis= */ 90_000,
@@ -158,6 +164,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 2_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ 403_225,
+                /* normalizedAvailableCpuFreqKHz= */ 1_688_209,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 10_000_000,
                         /* niceTimeMillis= */ 2_000_000, /* systemTimeMillis= */ 0,
                         /* idleTimeMillis= */ 10_000_000, /* iowaitTimeMillis= */ 1_000_000,
@@ -168,6 +175,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ false, /* curCpuFreqKHz= */ MISSING_FREQUENCY,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ MISSING_FREQUENCY,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 2_000_000,
                         /* niceTimeMillis= */ 1_000_000, /* systemTimeMillis= */ 1_000_000,
                         /* idleTimeMillis= */ 100_000, /* iowaitTimeMillis= */ 100_000,
@@ -189,6 +197,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(0, new CpuInfoReader.CpuInfo(/* cpuCore= */ 0,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_230_000,
                 /* maxCpuFreqKHz= */ 2_500_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 2_253_713,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 32_249_610,
                         /* niceTimeMillis= */ 7_950_930, /* systemTimeMillis= */ 52_227_050,
                         /* idleTimeMillis= */ 409_036_950, /* iowaitTimeMillis= */ 1_322_810,
@@ -198,6 +207,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(1, new CpuInfoReader.CpuInfo(/* cpuCore= */ 1,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_450_000,
                 /* maxCpuFreqKHz= */ 2_800_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 2_492_687,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_949_280,
                         /* niceTimeMillis= */ 7_799_450, /* systemTimeMillis= */ 54_004_020,
                         /* idleTimeMillis= */ 402_707_120, /* iowaitTimeMillis= */ 1_186_960,
@@ -208,6 +218,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 1_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 1_788_079,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_959_280,
                         /* niceTimeMillis= */ 7_789_450, /* systemTimeMillis= */ 54_014_020,
                         /* idleTimeMillis= */ 402_717_120, /* iowaitTimeMillis= */ 1_166_960,
@@ -218,6 +229,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 1_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 1_799_962,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 32_349_610,
                         /* niceTimeMillis= */ 7_850_930, /* systemTimeMillis= */ 52_127_050,
                         /* idleTimeMillis= */ 409_136_950, /* iowaitTimeMillis= */ 1_332_810,
@@ -237,6 +249,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(0, new CpuInfoReader.CpuInfo(/* cpuCore= */ 0,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_000_000,
                 /* maxCpuFreqKHz= */ 2_500_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 2323347,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 10_000_000,
                         /* niceTimeMillis= */ 1_000_000, /* systemTimeMillis= */ 10_000_000,
                         /* idleTimeMillis= */ 110_000_000, /* iowaitTimeMillis= */ 1_100_000,
@@ -246,6 +259,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(1, new CpuInfoReader.CpuInfo(/* cpuCore= */ 1,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 2_800_000,
                 /* maxCpuFreqKHz= */ 2_800_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 209111,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 900_000,
                         /* niceTimeMillis= */ 1_000_000, /* systemTimeMillis= */ 10_000_000,
                         /* idleTimeMillis= */ 1_000_000, /* iowaitTimeMillis= */ 90_000,
@@ -256,6 +270,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 2_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 453514,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 10_000_000,
                         /* niceTimeMillis= */ 2_000_000, /* systemTimeMillis= */ 0,
                         /* idleTimeMillis= */ 10_000_000, /* iowaitTimeMillis= */ 1_000_000,
@@ -266,6 +281,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
                 FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
                 /* isOnline= */ true, /* curCpuFreqKHz= */ 2_000_000,
                 /* maxCpuFreqKHz= */ 2_000_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                /* normalizedAvailableCpuFreqKHz= */ 37728,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 2_000_000,
                         /* niceTimeMillis= */ 1_000_000, /* systemTimeMillis= */ 1_000_000,
                         /* idleTimeMillis= */ 100_000, /* iowaitTimeMillis= */ 100_000,
@@ -323,38 +339,8 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
 
         SparseArray<CpuInfoReader.CpuInfo> actualCpuInfos = cpuInfoReader.readCpuInfos();
         SparseArray<CpuInfoReader.CpuInfo> expectedCpuInfos = new SparseArray<>();
-        expectedCpuInfos.append(1, new CpuInfoReader.CpuInfo(/* cpuCore= */ 1,
-                FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 3_000_000,
-                /* maxCpuFreqKHz= */ 1_000_000, /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
-                new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_949_280,
-                        /* niceTimeMillis= */ 7_799_450, /* systemTimeMillis= */ 54_004_020,
-                        /* idleTimeMillis= */ 402_707_120, /* iowaitTimeMillis= */ 1_186_960,
-                        /* irqTimeMillis= */ 14_786_940, /* softirqTimeMillis= */ 1_498_130,
-                        /* stealTimeMillis= */ 78_780, /* guestTimeMillis= */ 0,
-                        /* guestNiceTimeMillis= */ 0)));
-        expectedCpuInfos.append(2, new CpuInfoReader.CpuInfo(/* cpuCore= */ 2,
-                FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
-                /* isOnline= */ true, /* curCpuFreqKHz= */ 9, /* maxCpuFreqKHz= */ 2,
-                /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
-                new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_959_280,
-                        /* niceTimeMillis= */ 7_789_450, /* systemTimeMillis= */ 54_014_020,
-                        /* idleTimeMillis= */ 402_717_120, /* iowaitTimeMillis= */ 1_166_960,
-                        /* irqTimeMillis= */ 14_796_940, /* softirqTimeMillis= */ 1_478_130,
-                        /* stealTimeMillis= */ 88_780, /* guestTimeMillis= */ 0,
-                        /* guestNiceTimeMillis= */ 0)));
-        expectedCpuInfos.append(3, new CpuInfoReader.CpuInfo(/* cpuCore= */ 3,
-                FLAG_CPUSET_CATEGORY_TOP_APP | FLAG_CPUSET_CATEGORY_BACKGROUND,
-                /* isOnline= */ true, /* curCpuFreqKHz= */ 9, /* maxCpuFreqKHz= */ 2,
-                /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
-                new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 32_349_610,
-                        /* niceTimeMillis= */ 7_850_930, /* systemTimeMillis= */ 52_127_050,
-                        /* idleTimeMillis= */ 409_136_950, /* iowaitTimeMillis= */ 1_332_810,
-                        /* irqTimeMillis= */ 8_136_740, /* softirqTimeMillis= */ 438_970,
-                        /* stealTimeMillis= */ 71_950, /* guestTimeMillis= */ 0,
-                        /* guestNiceTimeMillis= */ 0)));
 
-        compareCpuInfos("CPU infos with corrupted CPU frequency", expectedCpuInfos,
-                actualCpuInfos);
+        compareCpuInfos("CPU infos with corrupted CPU frequency", expectedCpuInfos, actualCpuInfos);
     }
 
     @Test
@@ -368,6 +354,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(0, new CpuInfoReader.CpuInfo(/* cpuCore= */ 0,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_230_000,
                 /* maxCpuFreqKHz= */ 2_500_000, /* avgTimeInStateCpuFreqKHz= */ 488_095,
+                /* normalizedAvailableCpuFreqKHz= */ 2_402_267,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 32_249_610,
                         /* niceTimeMillis= */ 7_950_930, /* systemTimeMillis= */ 52_227_050,
                         /* idleTimeMillis= */ 409_036_950, /* iowaitTimeMillis= */ 1_322_810,
@@ -377,6 +364,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         expectedCpuInfos.append(1, new CpuInfoReader.CpuInfo(/* cpuCore= */ 1,
                 FLAG_CPUSET_CATEGORY_TOP_APP, /* isOnline= */ true, /* curCpuFreqKHz= */ 1_450_000,
                 /* maxCpuFreqKHz= */ 2_800_000, /* avgTimeInStateCpuFreqKHz= */ 502_380,
+                /* normalizedAvailableCpuFreqKHz= */ 2_693_525,
                 new CpuInfoReader.CpuUsageStats(/* userTimeMillis= */ 28_949_280,
                         /* niceTimeMillis= */ 7_799_450, /* systemTimeMillis= */ 54_004_020,
                         /* idleTimeMillis= */ 402_707_120, /* iowaitTimeMillis= */ 1_186_960,
@@ -393,7 +381,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         assertWithMessage("Make empty dir %s", emptyDir).that(emptyDir.mkdir()).isTrue();
         CpuInfoReader cpuInfoReader = new CpuInfoReader(emptyDir, getCacheFile(
                 VALID_CPUFREQ_WITH_TIME_IN_STATE_DIR),
-                getCacheFile(VALID_PROC_STAT));
+                getCacheFile(VALID_PROC_STAT), /* minReadIntervalMillis= */0);
 
         assertWithMessage("Init CPU reader info").that(cpuInfoReader.init()).isFalse();
 
@@ -406,7 +394,7 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         File emptyDir = getCacheFile(EMPTY_DIR);
         assertWithMessage("Make empty dir %s", emptyDir).that(emptyDir.mkdir()).isTrue();
         CpuInfoReader cpuInfoReader = new CpuInfoReader(getCacheFile(VALID_CPUSET_DIR), emptyDir,
-                getCacheFile(VALID_PROC_STAT));
+                getCacheFile(VALID_PROC_STAT), /* minReadIntervalMillis= */0);
 
         assertWithMessage("Init CPU reader info").that(cpuInfoReader.init()).isFalse();
 
@@ -420,12 +408,32 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
         assertWithMessage("Create empty file %s", emptyFile).that(emptyFile.createNewFile())
                 .isTrue();
         CpuInfoReader cpuInfoReader = new CpuInfoReader(getCacheFile(VALID_CPUSET_DIR),
-                getCacheFile(VALID_CPUFREQ_WITH_TIME_IN_STATE_DIR), getCacheFile(EMPTY_FILE));
+                getCacheFile(VALID_CPUFREQ_WITH_TIME_IN_STATE_DIR), getCacheFile(EMPTY_FILE),
+                /* minReadIntervalMillis= */0);
 
         assertWithMessage("Cpu infos with empty proc stat").that(cpuInfoReader.readCpuInfos())
                 .isNull();
     }
 
+    @Test
+    public void testReadingTooFrequentlyReturnsLastReadCpuInfos() throws Exception {
+        CpuInfoReader cpuInfoReader = new CpuInfoReader(getCacheFile(VALID_CPUSET_DIR),
+                getCacheFile(VALID_CPUFREQ_WITH_TIME_IN_STATE_DIR), getCacheFile(VALID_PROC_STAT),
+                /* minReadIntervalMillis= */ 60_000);
+        assertWithMessage("Initialize CPU info reader").that(cpuInfoReader.init()).isTrue();
+
+        SparseArray<CpuInfoReader.CpuInfo> firstCpuInfos = cpuInfoReader.readCpuInfos();
+        assertWithMessage("CPU infos first snapshot").that(firstCpuInfos).isNotNull();
+        assertWithMessage("CPU infos first snapshot size").that(firstCpuInfos.size())
+                .isGreaterThan(0);
+
+        SparseArray<CpuInfoReader.CpuInfo> secondCpuInfos = cpuInfoReader.readCpuInfos();
+        compareCpuInfos("CPU infos second snapshot", firstCpuInfos, secondCpuInfos);
+
+        SparseArray<CpuInfoReader.CpuInfo> thirdCpuInfos = cpuInfoReader.readCpuInfos();
+        compareCpuInfos("CPU infos third snapshot", firstCpuInfos, thirdCpuInfos);
+    }
+
     private void compareCpuInfos(String message,
             SparseArray<CpuInfoReader.CpuInfo> expected,
             SparseArray<CpuInfoReader.CpuInfo> actual) {
@@ -462,7 +470,8 @@ public final class CpuInfoReaderTest extends ExpectableTestCase {
 
     private static CpuInfoReader newCpuInfoReader(File cpusetDir, File cpuFreqDir,
             File procStatFile) {
-        CpuInfoReader cpuInfoReader = new CpuInfoReader(cpusetDir, cpuFreqDir, procStatFile);
+        CpuInfoReader cpuInfoReader = new CpuInfoReader(cpusetDir, cpuFreqDir, procStatFile,
+                /* minReadIntervalMillis= */ 0);
         assertWithMessage("Initialize CPU info reader").that(cpuInfoReader.init()).isTrue();
         return cpuInfoReader;
     }

From ceab3a6e8aa8e9d0fb622692bcb35b8b67b1c20f Mon Sep 17 00:00:00 2001
From: Lakshman Annadorai <lakshmana@google.com>
Date: Wed, 1 Feb 2023 11:38:57 -0800
Subject: [PATCH 2/4] Monitor CPU availability using CPU frequency stats.

- Implement the core CPU availability monitoring logic by reading
  the CPU infos with CpuInfoReader.
- Start debug monitoring on user-debug and eng builds when no
  callbacks are registered.
- Update CpuAvailabilityInfo to cache the uptime of the cached data.
- Update CpuAvailabilityMonitoringConfig to return cpuset string.

Test: atest CpuMonitorServiceTest
Bug: 242722241
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:1a18fd0962728468830cc2f2752c1ede3e0c1473)
Merged-In: I6e12c11f243966914079f54df4430d69b797ec1f
Change-Id: I6e12c11f243966914079f54df4430d69b797ec1f
---
 .../server/cpu/CpuAvailabilityInfo.java       |  63 ++-
 .../cpu/CpuAvailabilityMonitoringConfig.java  |  15 +-
 .../android/server/cpu/CpuMonitorService.java | 393 ++++++++++++++++--
 3 files changed, 417 insertions(+), 54 deletions(-)

diff --git a/services/core/java/com/android/server/cpu/CpuAvailabilityInfo.java b/services/core/java/com/android/server/cpu/CpuAvailabilityInfo.java
index 06b45bf0fb4b8..97507be96d84d 100644
--- a/services/core/java/com/android/server/cpu/CpuAvailabilityInfo.java
+++ b/services/core/java/com/android/server/cpu/CpuAvailabilityInfo.java
@@ -21,6 +21,8 @@ import static com.android.server.cpu.CpuAvailabilityMonitoringConfig.CPUSET_BACK
 
 import com.android.internal.util.Preconditions;
 
+import java.util.Objects;
+
 /** CPU availability information. */
 public final class CpuAvailabilityInfo {
     /** Constant to indicate missing CPU availability percent. */
@@ -35,29 +37,64 @@ public final class CpuAvailabilityInfo {
     @CpuAvailabilityMonitoringConfig.Cpuset
     public final int cpuset;
 
+    /** Uptime (in milliseconds) when the data in this object was captured. */
+    public final long dataTimestampUptimeMillis;
+
     /** The latest average CPU availability percent. */
     public final int latestAvgAvailabilityPercent;
 
-    /** The past N-second average CPU availability percent. */
-    public final int pastNSecAvgAvailabilityPercent;
+    /**
+     * The past N-millisecond average CPU availability percent.
+     *
+     * <p>When there is not enough data to calculate the past N-millisecond average, this field will
+     * contain the value {@link MISSING_CPU_AVAILABILITY_PERCENT}.
+     */
+    public final int pastNMillisAvgAvailabilityPercent;
 
-    /** The duration over which the {@link pastNSecAvgAvailabilityPercent} was calculated. */
-    public final int avgAvailabilityDurationSec;
+    /** The duration over which the {@link pastNMillisAvgAvailabilityPercent} was calculated. */
+    public final long pastNMillisDuration;
 
     @Override
     public String toString() {
-        return "CpuAvailabilityInfo{" + "cpuset=" + cpuset + ", latestAvgAvailabilityPercent="
-                + latestAvgAvailabilityPercent + ", pastNSecAvgAvailabilityPercent="
-                + pastNSecAvgAvailabilityPercent + ", avgAvailabilityDurationSec="
-                + avgAvailabilityDurationSec + '}';
+        return "CpuAvailabilityInfo{" + "cpuset = " + cpuset + ", dataTimestampUptimeMillis = "
+                + dataTimestampUptimeMillis + ", latestAvgAvailabilityPercent = "
+                + latestAvgAvailabilityPercent + ", pastNMillisAvgAvailabilityPercent = "
+                + pastNMillisAvgAvailabilityPercent + ", pastNMillisDuration = "
+                + pastNMillisDuration + '}';
     }
 
-    CpuAvailabilityInfo(int cpuset, int latestAvgAvailabilityPercent,
-            int pastNSecAvgAvailabilityPercent, int avgAvailabilityDurationSec) {
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof CpuAvailabilityInfo)) {
+            return false;
+        }
+        CpuAvailabilityInfo info = (CpuAvailabilityInfo) obj;
+        return cpuset == info.cpuset && dataTimestampUptimeMillis == info.dataTimestampUptimeMillis
+                && latestAvgAvailabilityPercent == info.latestAvgAvailabilityPercent
+                && pastNMillisAvgAvailabilityPercent == info.pastNMillisAvgAvailabilityPercent
+                && pastNMillisDuration == info.pastNMillisDuration;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(cpuset, dataTimestampUptimeMillis, latestAvgAvailabilityPercent,
+                pastNMillisAvgAvailabilityPercent, pastNMillisDuration);
+    }
+
+    CpuAvailabilityInfo(int cpuset, long dataTimestampUptimeMillis,
+            int latestAvgAvailabilityPercent, int pastNMillisAvgAvailabilityPercent,
+            long pastNMillisDuration) {
         this.cpuset = Preconditions.checkArgumentInRange(cpuset, CPUSET_ALL, CPUSET_BACKGROUND,
                 "cpuset");
-        this.latestAvgAvailabilityPercent = latestAvgAvailabilityPercent;
-        this.pastNSecAvgAvailabilityPercent = pastNSecAvgAvailabilityPercent;
-        this.avgAvailabilityDurationSec = avgAvailabilityDurationSec;
+        this.dataTimestampUptimeMillis =
+                Preconditions.checkArgumentNonnegative(dataTimestampUptimeMillis);
+        this.latestAvgAvailabilityPercent = Preconditions.checkArgumentNonnegative(
+                latestAvgAvailabilityPercent);
+        this.pastNMillisAvgAvailabilityPercent = pastNMillisAvgAvailabilityPercent;
+        this.pastNMillisDuration = Preconditions.checkArgumentNonnegative(
+                pastNMillisDuration);
     }
 }
diff --git a/services/core/java/com/android/server/cpu/CpuAvailabilityMonitoringConfig.java b/services/core/java/com/android/server/cpu/CpuAvailabilityMonitoringConfig.java
index a3c4c9e828b4f..cbe02fc09d84c 100644
--- a/services/core/java/com/android/server/cpu/CpuAvailabilityMonitoringConfig.java
+++ b/services/core/java/com/android/server/cpu/CpuAvailabilityMonitoringConfig.java
@@ -90,8 +90,19 @@ public final class CpuAvailabilityMonitoringConfig {
 
     @Override
     public String toString() {
-        return "CpuAvailabilityMonitoringConfig{cpuset=" + cpuset + ", mThresholds=" + mThresholds
-                + ')';
+        return "CpuAvailabilityMonitoringConfig{cpuset=" + toCpusetString(cpuset) + ", mThresholds="
+                + mThresholds + ')';
+    }
+
+    /** Returns the string equivalent of the provided cpuset. */
+    public static String toCpusetString(int cpuset) {
+        switch (cpuset) {
+            case CPUSET_ALL:
+                return "CPUSET_ALL";
+            case CPUSET_BACKGROUND:
+                return "CPUSET_BACKGROUND";
+        }
+        return "Invalid cpuset: " + cpuset;
     }
 
     private CpuAvailabilityMonitoringConfig(Builder builder) {
diff --git a/services/core/java/com/android/server/cpu/CpuMonitorService.java b/services/core/java/com/android/server/cpu/CpuMonitorService.java
index 4eefe5c8cad5c..fac8a2f7b1681 100644
--- a/services/core/java/com/android/server/cpu/CpuMonitorService.java
+++ b/services/core/java/com/android/server/cpu/CpuMonitorService.java
@@ -18,15 +18,31 @@ package com.android.server.cpu;
 
 import static android.os.IServiceManager.DUMP_FLAG_PRIORITY_CRITICAL;
 
+import static com.android.server.cpu.CpuAvailabilityMonitoringConfig.CPUSET_ALL;
+import static com.android.server.cpu.CpuAvailabilityMonitoringConfig.CPUSET_BACKGROUND;
+import static com.android.server.cpu.CpuInfoReader.FLAG_CPUSET_CATEGORY_BACKGROUND;
+import static com.android.server.cpu.CpuInfoReader.FLAG_CPUSET_CATEGORY_TOP_APP;
+
+import android.annotation.Nullable;
 import android.content.Context;
 import android.os.Binder;
-import android.util.ArrayMap;
+import android.os.Build;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Process;
+import android.os.SystemClock;
 import android.util.IndentingPrintWriter;
 import android.util.Log;
+import android.util.LongSparseArray;
+import android.util.SparseArray;
+import android.util.SparseArrayMap;
 
 import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.DumpUtils;
+import com.android.server.ServiceThread;
 import com.android.server.SystemService;
+import com.android.server.Watchdog;
 import com.android.server.utils.PriorityDump;
 import com.android.server.utils.Slogf;
 
@@ -34,28 +50,52 @@ import java.io.FileDescriptor;
 import java.io.PrintWriter;
 import java.util.Objects;
 import java.util.concurrent.Executor;
+import java.util.concurrent.TimeUnit;
 
 /** Service to monitor CPU availability and usage. */
 public final class CpuMonitorService extends SystemService {
     static final String TAG = CpuMonitorService.class.getSimpleName();
-    static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
-    // TODO(b/242722241): Make this a resource overlay property.
-    //  Maintain 3 monitoring intervals:
-    //  * One to poll very frequently when mCpuAvailabilityCallbackInfoByCallbacks are available and
-    //    CPU availability is above a threshold (such as at least 10% of CPU is available).
-    //  * One to poll less frequently when mCpuAvailabilityCallbackInfoByCallbacks are available
-    //    and CPU availability is below a threshold (such as less than 10% of CPU is available).
-    //  * One to poll very less frequently when no callbacks are available and the build is either
-    //    user-debug or eng. This will be useful for debugging in development environment.
-    static final int DEFAULT_CPU_MONITORING_INTERVAL_MILLISECONDS = 5_000;
+    static final boolean DEBUG =  Log.isLoggable(TAG, Log.DEBUG);
+    // TODO(b/267500110): Make these constants resource overlay properties.
+    /** Default monitoring interval when no monitoring is in progress. */
+    static final long DEFAULT_MONITORING_INTERVAL_MILLISECONDS = -1;
+    // TODO(b/242722241): Add a constant for normal monitoring interval when callbacks are
+    //  registered.
+    /**
+     * Monitoring interval when no registered callbacks and the build is either user-debug or eng.
+     */
+    private static final long DEBUG_MONITORING_INTERVAL_MILLISECONDS = TimeUnit.MINUTES.toMillis(1);
+    /**
+     * Size of the in-memory cache relative to the current uptime.
+     *
+     * On user-debug or eng builds, continuously cache stats with a bigger cache size for debugging
+     * purposes.
+     */
+    private static final long CACHE_DURATION_MILLISECONDS = Build.IS_USERDEBUG || Build.IS_ENG
+            ? TimeUnit.MINUTES.toMillis(30) : TimeUnit.MINUTES.toMillis(10);
+    // TODO(b/267500110): Investigate whether this duration should change when the monitoring
+    //  interval is updated. When the CPU is under heavy load, the monitoring will happen less
+    //  frequently. Should this duration be increased as well when this happens?
+    private static final long LATEST_AVAILABILITY_DURATION_MILLISECONDS =
+            TimeUnit.SECONDS.toMillis(30);
 
     private final Context mContext;
+    private final HandlerThread mHandlerThread;
+    private final CpuInfoReader mCpuInfoReader;
+    private final boolean mShouldDebugMonitor;
+    private final long mDebugMonitoringIntervalMillis;
+    private final long mLatestAvailabilityDurationMillis;
     private final Object mLock = new Object();
     @GuardedBy("mLock")
-    private final ArrayMap<CpuMonitorInternal.CpuAvailabilityCallback, CpuAvailabilityCallbackInfo>
-            mCpuAvailabilityCallbackInfoByCallbacks = new ArrayMap<>();
+    private final SparseArrayMap<CpuMonitorInternal.CpuAvailabilityCallback,
+            CpuAvailabilityCallbackInfo> mAvailabilityCallbackInfosByCallbacksByCpuset;
     @GuardedBy("mLock")
-    private long mMonitoringIntervalMilliseconds = DEFAULT_CPU_MONITORING_INTERVAL_MILLISECONDS;
+    private final SparseArray<CpusetInfo> mCpusetInfosByCpuset;
+    private final Runnable mMonitorCpuStats = this::monitorCpuStats;
+
+    @GuardedBy("mLock")
+    private long mCurrentMonitoringIntervalMillis = DEFAULT_MONITORING_INTERVAL_MILLISECONDS;
+    private Handler mHandler;
 
     private final CpuMonitorInternal mLocalService = new CpuMonitorInternal() {
         @Override
@@ -64,17 +104,22 @@ public final class CpuMonitorService extends SystemService {
             Objects.requireNonNull(callback, "Callback must be non-null");
             Objects.requireNonNull(config, "Config must be non-null");
             synchronized (mLock) {
-                if (mCpuAvailabilityCallbackInfoByCallbacks.containsKey(callback)) {
-                    Slogf.i(TAG, "Overwriting the existing CpuAvailabilityCallback %s",
-                            mCpuAvailabilityCallbackInfoByCallbacks.get(callback));
-                    // TODO(b/242722241): Overwrite any internal cache (will be added in future CLs)
-                    //  that maps callbacks based on the CPU availability thresholds.
+                // Verify all CPUSET entries before adding the callback because this will help
+                // delete any previously added callback for a different CPUSET.
+                for (int i = 0; i < mAvailabilityCallbackInfosByCallbacksByCpuset.numMaps(); i++) {
+                    int cpuset = mAvailabilityCallbackInfosByCallbacksByCpuset.keyAt(i);
+                    CpuAvailabilityCallbackInfo callbackInfo =
+                            mAvailabilityCallbackInfosByCallbacksByCpuset.delete(cpuset, callback);
+                    if (callbackInfo != null) {
+                        Slogf.i(TAG, "Overwriting the existing %s", callbackInfo);
+                    }
                 }
-                CpuAvailabilityCallbackInfo info = new CpuAvailabilityCallbackInfo(config,
+                CpuAvailabilityCallbackInfo callbackInfo = new CpuAvailabilityCallbackInfo(config,
                         executor);
-                mCpuAvailabilityCallbackInfoByCallbacks.put(callback, info);
+                mAvailabilityCallbackInfosByCallbacksByCpuset.add(config.cpuset, callback,
+                        callbackInfo);
                 if (DEBUG) {
-                    Slogf.d(TAG, "Added a CPU availability callback: %s", info);
+                    Slogf.d(TAG, "Added a CPU availability callback: %s", callbackInfo);
                 }
             }
             // TODO(b/242722241):
@@ -86,58 +131,188 @@ public final class CpuMonitorService extends SystemService {
         @Override
         public void removeCpuAvailabilityCallback(CpuAvailabilityCallback callback) {
             synchronized (mLock) {
-                if (!mCpuAvailabilityCallbackInfoByCallbacks.containsKey(callback)) {
-                    Slogf.i(TAG, "CpuAvailabilityCallback was not previously added."
-                            + " Ignoring the remove request");
-                    return;
-                }
-                CpuAvailabilityCallbackInfo info =
-                        mCpuAvailabilityCallbackInfoByCallbacks.remove(callback);
-                if (DEBUG) {
-                    Slogf.d(TAG, "Removed a CPU availability callback: %s", info);
+                for (int i = 0; i < mAvailabilityCallbackInfosByCallbacksByCpuset.numMaps(); i++) {
+                    int cpuset = mAvailabilityCallbackInfosByCallbacksByCpuset.keyAt(i);
+                    CpuAvailabilityCallbackInfo callbackInfo =
+                            mAvailabilityCallbackInfosByCallbacksByCpuset.delete(cpuset, callback);
+                    if (callbackInfo != null) {
+                        if (DEBUG) {
+                            Slogf.d(TAG, "Successfully removed %s", callbackInfo);
+                        }
+                        return;
+                    }
                 }
+                Slogf.w(TAG, "CpuAvailabilityCallback was not previously added. Ignoring the remove"
+                        + " request");
             }
-            // TODO(b/242722241): Increase CPU monitoring interval when all callbacks are removed.
         }
     };
 
     public CpuMonitorService(Context context) {
+        this(context, new CpuInfoReader(), new ServiceThread(TAG,
+                Process.THREAD_PRIORITY_BACKGROUND, /* allowIo= */ true),
+                Build.IS_USERDEBUG || Build.IS_ENG, DEBUG_MONITORING_INTERVAL_MILLISECONDS,
+                LATEST_AVAILABILITY_DURATION_MILLISECONDS);
+    }
+
+    @VisibleForTesting
+    CpuMonitorService(Context context, CpuInfoReader cpuInfoReader, HandlerThread handlerThread,
+            boolean shouldDebugMonitor, long debugMonitoringIntervalMillis,
+            long latestAvailabilityDurationMillis) {
         super(context);
         mContext = context;
+        mHandlerThread = handlerThread;
+        mShouldDebugMonitor = shouldDebugMonitor;
+        mDebugMonitoringIntervalMillis = debugMonitoringIntervalMillis;
+        mLatestAvailabilityDurationMillis = latestAvailabilityDurationMillis;
+        mCpuInfoReader = cpuInfoReader;
+        mCpusetInfosByCpuset = new SparseArray<>(2);
+        mCpusetInfosByCpuset.append(CPUSET_ALL, new CpusetInfo(CPUSET_ALL));
+        mCpusetInfosByCpuset.append(CPUSET_BACKGROUND, new CpusetInfo(CPUSET_BACKGROUND));
+        mAvailabilityCallbackInfosByCallbacksByCpuset = new SparseArrayMap<>();
     }
 
     @Override
     public void onStart() {
+        // Initialize CPU info reader and perform the first read to make sure the CPU stats are
+        // readable without any issues.
+        if (!mCpuInfoReader.init() || mCpuInfoReader.readCpuInfos() == null) {
+            Slogf.wtf(TAG, "Failed to initialize CPU info reader. This happens when the CPU "
+                    + "frequency stats are not available or the sysfs interface has changed in "
+                    + "the Kernel. Cannot monitor CPU without these stats. Terminating CPU monitor "
+                    + "service");
+            return;
+        }
+        mHandlerThread.start();
+        mHandler = new Handler(mHandlerThread.getLooper());
         publishLocalService(CpuMonitorInternal.class, mLocalService);
         publishBinderService("cpu_monitor", new CpuMonitorBinder(), /* allowIsolated= */ false,
                 DUMP_FLAG_PRIORITY_CRITICAL);
+        Watchdog.getInstance().addThread(mHandler);
+        synchronized (mLock) {
+            if (mShouldDebugMonitor && !mHandler.hasCallbacks(mMonitorCpuStats)) {
+                mCurrentMonitoringIntervalMillis = mDebugMonitoringIntervalMillis;
+                Slogf.i(TAG, "Starting debug monitoring");
+                mHandler.post(mMonitorCpuStats);
+            }
+        }
     }
 
     private void doDump(IndentingPrintWriter writer) {
         writer.printf("*%s*\n", getClass().getSimpleName());
         writer.increaseIndent();
+        mCpuInfoReader.dump(writer);
         synchronized (mLock) {
-            writer.printf("CPU monitoring interval: %d ms\n", mMonitoringIntervalMilliseconds);
-            if (!mCpuAvailabilityCallbackInfoByCallbacks.isEmpty()) {
+            writer.printf("Current CPU monitoring interval: %d ms\n",
+                    mCurrentMonitoringIntervalMillis);
+            if (hasClientCallbacksLocked()) {
                 writer.println("CPU availability change callbacks:");
                 writer.increaseIndent();
-                for (int i = 0; i < mCpuAvailabilityCallbackInfoByCallbacks.size(); i++) {
-                    writer.printf("%s: %s\n", mCpuAvailabilityCallbackInfoByCallbacks.keyAt(i),
-                            mCpuAvailabilityCallbackInfoByCallbacks.valueAt(i));
+                mAvailabilityCallbackInfosByCallbacksByCpuset.forEach(
+                        (callbackInfo) -> writer.printf("%s\n", callbackInfo));
+                writer.decreaseIndent();
+            }
+            if (mCpusetInfosByCpuset.size() > 0) {
+                writer.println("Cpuset infos:");
+                writer.increaseIndent();
+                for (int i = 0; i < mCpusetInfosByCpuset.size(); i++) {
+                    writer.printf("%s\n", mCpusetInfosByCpuset.valueAt(i));
                 }
                 writer.decreaseIndent();
             }
         }
-        // TODO(b/242722241): Print the recent past CPU stats.
         writer.decreaseIndent();
     }
 
+    private void monitorCpuStats() {
+        long uptimeMillis = SystemClock.uptimeMillis();
+        SparseArray<CpuInfoReader.CpuInfo> cpuInfosByCoreId = mCpuInfoReader.readCpuInfos();
+        if (cpuInfosByCoreId == null) {
+            // This shouldn't happen because the CPU infos are read & verified during
+            // the {@link onStart} call.
+            Slogf.wtf(TAG, "Failed to read CPU info from device");
+            synchronized (mLock) {
+                stopMonitoringCpuStatsLocked();
+            }
+            // Monitoring is stopped but no client callback is removed.
+            // TODO(b/267500110): Identify whether the clients should be notified about this state.
+            return;
+        }
+
+        synchronized (mLock) {
+            // 1. Populate the {@link mCpusetInfosByCpuset} with the latest cpuInfo.
+            for (int i = 0; i < cpuInfosByCoreId.size(); i++) {
+                CpuInfoReader.CpuInfo cpuInfo = cpuInfosByCoreId.valueAt(i);
+                for (int j = 0; j < mCpusetInfosByCpuset.size(); j++) {
+                    mCpusetInfosByCpuset.valueAt(j).appendCpuInfo(uptimeMillis, cpuInfo);
+                }
+            }
+
+            // 2. Verify whether any monitoring thresholds are crossed and notify the corresponding
+            // clients.
+            for (int i = 0; i < mCpusetInfosByCpuset.size(); i++) {
+                CpusetInfo cpusetInfo = mCpusetInfosByCpuset.valueAt(i);
+                cpusetInfo.populateLatestCpuAvailabilityInfo(uptimeMillis,
+                        mLatestAvailabilityDurationMillis);
+                // TODO(b/242722241): Check CPU availability against thresholds and notify clients.
+            }
+
+            // TODO(b/267500110): Detect heavy CPU load. On detecting heavy CPU load, increase
+            //  the monitoring interval and notify the clients.
+
+            // 3. Continue monitoring only when either there is at least one registered client
+            // callback or debug monitoring is enabled.
+            if (mCurrentMonitoringIntervalMillis > 0
+                    && (hasClientCallbacksLocked() || mShouldDebugMonitor)) {
+                mHandler.postAtTime(mMonitorCpuStats,
+                        uptimeMillis + mCurrentMonitoringIntervalMillis);
+            } else {
+                stopMonitoringCpuStatsLocked();
+            }
+        }
+    }
+
+    @GuardedBy("mLock")
+    private boolean hasClientCallbacksLocked() {
+        for (int i = 0; i < mAvailabilityCallbackInfosByCallbacksByCpuset.numMaps(); i++) {
+            if (mAvailabilityCallbackInfosByCallbacksByCpuset.numElementsForKeyAt(i) > 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @GuardedBy("mLock")
+    private void stopMonitoringCpuStatsLocked() {
+        mHandler.removeCallbacks(mMonitorCpuStats);
+        mCurrentMonitoringIntervalMillis = DEFAULT_MONITORING_INTERVAL_MILLISECONDS;
+        // When the monitoring is stopped, the latest CPU availability info and the snapshots in
+        // {@code mCpusetInfosByCpuset} will become obsolete soon. So, remove them.
+        for (int i = 0; i < mCpusetInfosByCpuset.size(); i++) {
+            mCpusetInfosByCpuset.valueAt(i).clear();
+        }
+    }
+
+    private static boolean containsCpuset(@CpuInfoReader.CpusetCategory int cpusetCategories,
+            @CpuAvailabilityMonitoringConfig.Cpuset int expectedCpuset) {
+        switch (expectedCpuset) {
+            case CPUSET_ALL:
+                return (cpusetCategories & FLAG_CPUSET_CATEGORY_TOP_APP) != 0;
+            case CPUSET_BACKGROUND:
+                return (cpusetCategories & FLAG_CPUSET_CATEGORY_BACKGROUND) != 0;
+            default:
+                Slogf.wtf(TAG, "Provided invalid expectedCpuset %d", expectedCpuset);
+        }
+        return false;
+    }
+
     private static final class CpuAvailabilityCallbackInfo {
         public final CpuAvailabilityMonitoringConfig config;
+        @Nullable
         public final Executor executor;
 
         CpuAvailabilityCallbackInfo(CpuAvailabilityMonitoringConfig config,
-                Executor executor) {
+                @Nullable Executor executor) {
             this.config = config;
             this.executor = executor;
         }
@@ -170,4 +345,144 @@ public final class CpuMonitorService extends SystemService {
             PriorityDump.dump(mPriorityDumper, fd, pw, args);
         }
     }
+
+    private static final class CpusetInfo {
+        @CpuAvailabilityMonitoringConfig.Cpuset
+        public final int cpuset;
+        private final LongSparseArray<Snapshot> mSnapshotsByUptime;
+        @Nullable
+        private CpuAvailabilityInfo mLatestCpuAvailabilityInfo;
+
+        CpusetInfo(int cpuset) {
+            this.cpuset = cpuset;
+            mSnapshotsByUptime = new LongSparseArray<>();
+        }
+
+        public void appendCpuInfo(long uptimeMillis, CpuInfoReader.CpuInfo cpuInfo) {
+            if (!containsCpuset(cpuInfo.cpusetCategories, cpuset)) {
+                return;
+            }
+            Snapshot currentSnapshot = mSnapshotsByUptime.get(uptimeMillis);
+            if (currentSnapshot == null) {
+                currentSnapshot = new Snapshot(uptimeMillis);
+                mSnapshotsByUptime.append(uptimeMillis, currentSnapshot);
+                if (mSnapshotsByUptime.size() > 0
+                        && (uptimeMillis - mSnapshotsByUptime.valueAt(0).uptimeMillis)
+                        > CACHE_DURATION_MILLISECONDS) {
+                    mSnapshotsByUptime.removeAt(0);
+                }
+            }
+            currentSnapshot.appendCpuInfo(cpuInfo);
+        }
+
+        public void populateLatestCpuAvailabilityInfo(long currentUptimeMillis,
+                long latestAvailabilityDurationMillis) {
+            int numSnapshots = mSnapshotsByUptime.size();
+            if (numSnapshots == 0) {
+                mLatestCpuAvailabilityInfo = null;
+                return;
+            }
+            Snapshot latestSnapshot = mSnapshotsByUptime.valueAt(numSnapshots - 1);
+            if (latestSnapshot.uptimeMillis != currentUptimeMillis) {
+                // When the cpuset has no stats available for the current polling, the uptime will
+                // mismatch. When this happens, return {@code null} to avoid returning stale
+                // information.
+                if (DEBUG) {
+                    Slogf.d(TAG, "Skipping stale CPU availability information for cpuset %s",
+                            CpuAvailabilityMonitoringConfig.toCpusetString(cpuset));
+                }
+                mLatestCpuAvailabilityInfo = null;
+                return;
+            }
+            // Avoid constructing {@link mLatestCpuAvailabilityInfo} if the uptime hasn't changed.
+            if (mLatestCpuAvailabilityInfo != null
+                    && mLatestCpuAvailabilityInfo.dataTimestampUptimeMillis
+                    == latestSnapshot.uptimeMillis) {
+                return;
+            }
+            long earliestUptimeMillis = currentUptimeMillis - latestAvailabilityDurationMillis;
+            mLatestCpuAvailabilityInfo = new CpuAvailabilityInfo(cpuset,
+                    latestSnapshot.uptimeMillis, latestSnapshot.getAverageAvailableCpuFreqPercent(),
+                    getCumulativeAvgAvailabilityPercent(earliestUptimeMillis),
+                    latestAvailabilityDurationMillis);
+        }
+
+        private int getCumulativeAvgAvailabilityPercent(long earliestUptimeMillis) {
+            long totalAvailableCpuFreqKHz = 0;
+            long totalOnlineMaxCpuFreqKHz = 0;
+            int totalAccountedSnapshots = 0;
+            long earliestSeenUptimeMillis = Long.MAX_VALUE;
+            for (int i = mSnapshotsByUptime.size() - 1; i >= 0; i--) {
+                Snapshot snapshot = mSnapshotsByUptime.valueAt(i);
+                earliestSeenUptimeMillis = snapshot.uptimeMillis;
+                if (snapshot.uptimeMillis <= earliestUptimeMillis) {
+                    break;
+                }
+                totalAccountedSnapshots++;
+                totalAvailableCpuFreqKHz += snapshot.totalNormalizedAvailableCpuFreqKHz;
+                totalOnlineMaxCpuFreqKHz += snapshot.totalOnlineMaxCpuFreqKHz;
+            }
+            // The cache must have at least 2 snapshots within the given duration and
+            // the {@link earliestSeenUptimeMillis} must be earlier than (i,e., less than) the given
+            // {@link earliestUptimeMillis}. Otherwise, the cache doesn't have enough data to
+            // calculate the cumulative average for the given duration.
+            // TODO(b/267500110): Investigate whether the cumulative average duration should be
+            //  shrunk when not enough data points are available.
+            if (earliestSeenUptimeMillis > earliestUptimeMillis || totalAccountedSnapshots < 2) {
+                return CpuAvailabilityInfo.MISSING_CPU_AVAILABILITY_PERCENT;
+            }
+            return (int) ((totalAvailableCpuFreqKHz * 100.0) / totalOnlineMaxCpuFreqKHz);
+        }
+
+        public void clear() {
+            mLatestCpuAvailabilityInfo = null;
+            mSnapshotsByUptime.clear();
+        }
+
+        @Override
+        public String toString() {
+            return "CpusetInfo{cpuset = " + CpuAvailabilityMonitoringConfig.toCpusetString(cpuset)
+                    + ", mSnapshotsByUptime = " + mSnapshotsByUptime
+                    + ", mLatestCpuAvailabilityInfo = " + mLatestCpuAvailabilityInfo + '}';
+        }
+
+        private static final class Snapshot {
+            public final long uptimeMillis;
+            public int totalOnlineCpus;
+            public int totalOfflineCpus;
+            public long totalNormalizedAvailableCpuFreqKHz;
+            public long totalOnlineMaxCpuFreqKHz;
+            public long totalOfflineMaxCpuFreqKHz;
+
+            Snapshot(long uptimeMillis) {
+                this.uptimeMillis = uptimeMillis;
+            }
+
+            public void appendCpuInfo(CpuInfoReader.CpuInfo cpuInfo) {
+                if (!cpuInfo.isOnline) {
+                    totalOfflineCpus++;
+                    totalOfflineMaxCpuFreqKHz += cpuInfo.maxCpuFreqKHz;
+                    return;
+                }
+                ++totalOnlineCpus;
+                totalNormalizedAvailableCpuFreqKHz += cpuInfo.getNormalizedAvailableCpuFreqKHz();
+                totalOnlineMaxCpuFreqKHz += cpuInfo.maxCpuFreqKHz;
+            }
+
+            public int getAverageAvailableCpuFreqPercent() {
+                return (int) ((totalNormalizedAvailableCpuFreqKHz * 100.0)
+                        / totalOnlineMaxCpuFreqKHz);
+            }
+
+            @Override
+            public String toString() {
+                return "Snapshot{uptimeMillis = " + uptimeMillis + ", totalOnlineCpus = "
+                        + totalOnlineCpus + ", totalOfflineCpus = " + totalOfflineCpus
+                        + ", totalNormalizedAvailableCpuFreqKHz = "
+                        + totalNormalizedAvailableCpuFreqKHz
+                        + ", totalOnlineMaxCpuFreqKHz = " + totalOnlineMaxCpuFreqKHz
+                        + ", totalOfflineMaxCpuFreqKHz = " + totalOfflineMaxCpuFreqKHz + '}';
+            }
+        }
+    }
 }

From 17a7c61a4353901e07523efa46c327f5e3d00e4e Mon Sep 17 00:00:00 2001
From: Lakshman Annadorai <lakshmana@google.com>
Date: Wed, 1 Feb 2023 13:00:05 -0800
Subject: [PATCH 3/4] Verify CPU availability against client thresholds and
 notify the clients.

Test: atest CpuMonitorServiceTest
Bug: 242722241
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:741709bf4a7d6087b34efd4bda82df5dba717f13)
Merged-In: I6c189b6880bf9fb5cd73e7cd31419d915bbaff61
Change-Id: I6c189b6880bf9fb5cd73e7cd31419d915bbaff61
---
 .../android/server/cpu/CpuMonitorService.java | 97 ++++++++++++++++++-
 1 file changed, 92 insertions(+), 5 deletions(-)

diff --git a/services/core/java/com/android/server/cpu/CpuMonitorService.java b/services/core/java/com/android/server/cpu/CpuMonitorService.java
index fac8a2f7b1681..7e930b4a1ef52 100644
--- a/services/core/java/com/android/server/cpu/CpuMonitorService.java
+++ b/services/core/java/com/android/server/cpu/CpuMonitorService.java
@@ -32,6 +32,7 @@ import android.os.HandlerThread;
 import android.os.Process;
 import android.os.SystemClock;
 import android.util.IndentingPrintWriter;
+import android.util.IntArray;
 import android.util.Log;
 import android.util.LongSparseArray;
 import android.util.SparseArray;
@@ -51,6 +52,7 @@ import java.io.PrintWriter;
 import java.util.Objects;
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
+import java.util.function.BiConsumer;
 
 /** Service to monitor CPU availability and usage. */
 public final class CpuMonitorService extends SystemService {
@@ -92,6 +94,8 @@ public final class CpuMonitorService extends SystemService {
     @GuardedBy("mLock")
     private final SparseArray<CpusetInfo> mCpusetInfosByCpuset;
     private final Runnable mMonitorCpuStats = this::monitorCpuStats;
+    private final NotifyCpuAvailabilityFunctor mNotifyCpuAvailabilityFunctor =
+            new NotifyCpuAvailabilityFunctor();
 
     @GuardedBy("mLock")
     private long mCurrentMonitoringIntervalMillis = DEFAULT_MONITORING_INTERVAL_MILLISECONDS;
@@ -115,7 +119,7 @@ public final class CpuMonitorService extends SystemService {
                     }
                 }
                 CpuAvailabilityCallbackInfo callbackInfo = new CpuAvailabilityCallbackInfo(config,
-                        executor);
+                        callback, executor);
                 mAvailabilityCallbackInfosByCallbacksByCpuset.add(config.cpuset, callback,
                         callbackInfo);
                 if (DEBUG) {
@@ -254,7 +258,7 @@ public final class CpuMonitorService extends SystemService {
                 CpusetInfo cpusetInfo = mCpusetInfosByCpuset.valueAt(i);
                 cpusetInfo.populateLatestCpuAvailabilityInfo(uptimeMillis,
                         mLatestAvailabilityDurationMillis);
-                // TODO(b/242722241): Check CPU availability against thresholds and notify clients.
+                checkClientThresholdsAndNotifyLocked(cpusetInfo);
             }
 
             // TODO(b/267500110): Detect heavy CPU load. On detecting heavy CPU load, increase
@@ -272,6 +276,41 @@ public final class CpuMonitorService extends SystemService {
         }
     }
 
+    @GuardedBy("mLock")
+    private void checkClientThresholdsAndNotifyLocked(CpusetInfo cpusetInfo) {
+        int prevAvailabilityPercent = cpusetInfo.getPrevCpuAvailabilityPercent();
+        CpuAvailabilityInfo latestAvailabilityInfo = cpusetInfo.getLatestCpuAvailabilityInfo();
+        ArrayMap<CpuMonitorInternal.CpuAvailabilityCallback,
+                CpuAvailabilityCallbackInfo> callbackMap =
+                mAvailabilityCallbackInfosByCallbacksByCpuset.get(cpusetInfo.cpuset);
+        if (latestAvailabilityInfo == null || prevAvailabilityPercent < 0
+                || callbackMap.isEmpty()) {
+            // When either the current or the previous CPU availability percents are
+            // missing, skip the current cpuset as there is not enough data to verify
+            // whether the CPU availability has crossed any monitoring threshold.
+            return;
+        }
+        for (int i = 0; i < callbackMap.size(); i++) {
+            CpuAvailabilityCallbackInfo callbackInfo = callbackMap.valueAt(i);
+            if (didCrossAnyThreshold(prevAvailabilityPercent,
+                    latestAvailabilityInfo.latestAvgAvailabilityPercent,
+                    callbackInfo.config.getThresholds())) {
+                asyncNotifyCpuAvailabilityToClient(latestAvailabilityInfo, callbackInfo);
+            }
+        }
+    }
+
+    private void asyncNotifyCpuAvailabilityToClient(CpuAvailabilityInfo availabilityInfo,
+            CpuAvailabilityCallbackInfo callbackInfo) {
+        if (callbackInfo.executor == null) {
+            mHandler.post(() -> mNotifyCpuAvailabilityFunctor.accept(callbackInfo.callback,
+                    availabilityInfo));
+        } else {
+            callbackInfo.executor.execute(() -> mNotifyCpuAvailabilityFunctor.accept(
+                    callbackInfo.callback, availabilityInfo));
+        }
+    }
+
     @GuardedBy("mLock")
     private boolean hasClientCallbacksLocked() {
         for (int i = 0; i < mAvailabilityCallbackInfosByCallbacksByCpuset.numMaps(); i++) {
@@ -306,21 +345,47 @@ public final class CpuMonitorService extends SystemService {
         return false;
     }
 
+    private static boolean didCrossAnyThreshold(int prevAvailabilityPercent,
+            int curAvailabilityPercent, IntArray thresholds) {
+        if (prevAvailabilityPercent == curAvailabilityPercent) {
+            return false;
+        }
+        for (int i = 0; i < thresholds.size(); i++) {
+            int threshold = thresholds.get(i);
+            // TODO(b/267500110): Identify whether or not the clients need to be notified when
+            //  the CPU availability jumps too frequently around the provided thresholds.
+            //  A. Should the client be notified twice - once when the availability reaches
+            //     the threshold and once when it moves away (increase/decrease) from the threshold
+            //     immediately?
+            //  B. Should there be some sort of rate-limiting to avoid notifying the client too
+            //     frequently? Should the client be able to config the rate-limit?
+            if (prevAvailabilityPercent < threshold && curAvailabilityPercent >= threshold) {
+                return true;
+            }
+            if (prevAvailabilityPercent >= threshold && curAvailabilityPercent < threshold) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private static final class CpuAvailabilityCallbackInfo {
         public final CpuAvailabilityMonitoringConfig config;
+        public final CpuMonitorInternal.CpuAvailabilityCallback callback;
         @Nullable
         public final Executor executor;
 
         CpuAvailabilityCallbackInfo(CpuAvailabilityMonitoringConfig config,
-                @Nullable Executor executor) {
+                CpuMonitorInternal.CpuAvailabilityCallback callback, @Nullable Executor executor) {
             this.config = config;
+            this.callback = callback;
             this.executor = executor;
         }
 
         @Override
         public String toString() {
-            return "CpuAvailabilityCallbackInfo{" + "config=" + config + ", mExecutor=" + executor
-                    + '}';
+            return "CpuAvailabilityCallbackInfo{config = " + config + ", callback = " + callback
+                    + ", mExecutor = " + executor + '}';
         }
     }
 
@@ -375,6 +440,11 @@ public final class CpuMonitorService extends SystemService {
             currentSnapshot.appendCpuInfo(cpuInfo);
         }
 
+        @Nullable
+        public CpuAvailabilityInfo getLatestCpuAvailabilityInfo() {
+            return mLatestCpuAvailabilityInfo;
+        }
+
         public void populateLatestCpuAvailabilityInfo(long currentUptimeMillis,
                 long latestAvailabilityDurationMillis) {
             int numSnapshots = mSnapshotsByUptime.size();
@@ -407,6 +477,14 @@ public final class CpuMonitorService extends SystemService {
                     latestAvailabilityDurationMillis);
         }
 
+        public int getPrevCpuAvailabilityPercent() {
+            int numSnapshots = mSnapshotsByUptime.size();
+            if (numSnapshots < 2) {
+                return -1;
+            }
+            return mSnapshotsByUptime.valueAt(numSnapshots - 2).getAverageAvailableCpuFreqPercent();
+        }
+
         private int getCumulativeAvgAvailabilityPercent(long earliestUptimeMillis) {
             long totalAvailableCpuFreqKHz = 0;
             long totalOnlineMaxCpuFreqKHz = 0;
@@ -485,4 +563,13 @@ public final class CpuMonitorService extends SystemService {
             }
         }
     }
+
+    private static final class NotifyCpuAvailabilityFunctor implements
+            BiConsumer<CpuMonitorInternal.CpuAvailabilityCallback, CpuAvailabilityInfo> {
+        @Override
+        public void accept(CpuMonitorInternal.CpuAvailabilityCallback callback,
+                CpuAvailabilityInfo availabilityInfo) {
+            callback.onAvailabilityChanged(availabilityInfo);
+        }
+    }
 }

From b9e7f3dd8798e45e9da08d6f78801ac03fcd8e3d Mon Sep 17 00:00:00 2001
From: Lakshman Annadorai <lakshmana@google.com>
Date: Wed, 1 Feb 2023 13:00:05 -0800
Subject: [PATCH 4/4] Start/Stop CPU monitoring based on the client callback
 addition/removal.

- Start CPU monitoring when the first client callback is added.
- Stop CPU monitoring when the last client callback is removed.
- When on client callbacks are available, perform debug monitoring only
  user-debug and eng builds.
- When a client callback is added, notify the client of the latest CPU
  availability and the current monitoring interval.

Test: atest CpuMonitorServiceTest
Bug: 242722241
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:5182a35f25e43edd5e979432ad76bbde989c8a1d)
Merged-In: I6d423ee165ad6e0623f6078e3c68cc4fd1871371
Change-Id: I6d423ee165ad6e0623f6078e3c68cc4fd1871371
---
 .../android/server/cpu/CpuMonitorService.java | 196 ++++--
 .../server/cpu/CpuMonitorServiceTest.java     | 642 ++++++++++++++++--
 2 files changed, 744 insertions(+), 94 deletions(-)

diff --git a/services/core/java/com/android/server/cpu/CpuMonitorService.java b/services/core/java/com/android/server/cpu/CpuMonitorService.java
index 7e930b4a1ef52..df8cfad4ab03e 100644
--- a/services/core/java/com/android/server/cpu/CpuMonitorService.java
+++ b/services/core/java/com/android/server/cpu/CpuMonitorService.java
@@ -41,6 +41,7 @@ import android.util.SparseArrayMap;
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.DumpUtils;
+import com.android.internal.util.Preconditions;
 import com.android.server.ServiceThread;
 import com.android.server.SystemService;
 import com.android.server.Watchdog;
@@ -52,17 +53,18 @@ import java.io.PrintWriter;
 import java.util.Objects;
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
-import java.util.function.BiConsumer;
 
 /** Service to monitor CPU availability and usage. */
 public final class CpuMonitorService extends SystemService {
     static final String TAG = CpuMonitorService.class.getSimpleName();
-    static final boolean DEBUG =  Log.isLoggable(TAG, Log.DEBUG);
+    static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
     // TODO(b/267500110): Make these constants resource overlay properties.
     /** Default monitoring interval when no monitoring is in progress. */
     static final long DEFAULT_MONITORING_INTERVAL_MILLISECONDS = -1;
-    // TODO(b/242722241): Add a constant for normal monitoring interval when callbacks are
-    //  registered.
+    /** Monitoring interval when callbacks are registered and the CPU load is normal. */
+    private static final long NORMAL_MONITORING_INTERVAL_MILLISECONDS =
+            TimeUnit.SECONDS.toMillis(5);
+
     /**
      * Monitoring interval when no registered callbacks and the build is either user-debug or eng.
      */
@@ -85,6 +87,7 @@ public final class CpuMonitorService extends SystemService {
     private final HandlerThread mHandlerThread;
     private final CpuInfoReader mCpuInfoReader;
     private final boolean mShouldDebugMonitor;
+    private final long mNormalMonitoringIntervalMillis;
     private final long mDebugMonitoringIntervalMillis;
     private final long mLatestAvailabilityDurationMillis;
     private final Object mLock = new Object();
@@ -94,8 +97,6 @@ public final class CpuMonitorService extends SystemService {
     @GuardedBy("mLock")
     private final SparseArray<CpusetInfo> mCpusetInfosByCpuset;
     private final Runnable mMonitorCpuStats = this::monitorCpuStats;
-    private final NotifyCpuAvailabilityFunctor mNotifyCpuAvailabilityFunctor =
-            new NotifyCpuAvailabilityFunctor();
 
     @GuardedBy("mLock")
     private long mCurrentMonitoringIntervalMillis = DEFAULT_MONITORING_INTERVAL_MILLISECONDS;
@@ -107,29 +108,24 @@ public final class CpuMonitorService extends SystemService {
                 CpuAvailabilityMonitoringConfig config, CpuAvailabilityCallback callback) {
             Objects.requireNonNull(callback, "Callback must be non-null");
             Objects.requireNonNull(config, "Config must be non-null");
+            CpuAvailabilityCallbackInfo callbackInfo;
             synchronized (mLock) {
                 // Verify all CPUSET entries before adding the callback because this will help
                 // delete any previously added callback for a different CPUSET.
                 for (int i = 0; i < mAvailabilityCallbackInfosByCallbacksByCpuset.numMaps(); i++) {
                     int cpuset = mAvailabilityCallbackInfosByCallbacksByCpuset.keyAt(i);
-                    CpuAvailabilityCallbackInfo callbackInfo =
-                            mAvailabilityCallbackInfosByCallbacksByCpuset.delete(cpuset, callback);
+                    callbackInfo = mAvailabilityCallbackInfosByCallbacksByCpuset.delete(cpuset,
+                            callback);
                     if (callbackInfo != null) {
                         Slogf.i(TAG, "Overwriting the existing %s", callbackInfo);
                     }
                 }
-                CpuAvailabilityCallbackInfo callbackInfo = new CpuAvailabilityCallbackInfo(config,
-                        callback, executor);
-                mAvailabilityCallbackInfosByCallbacksByCpuset.add(config.cpuset, callback,
-                        callbackInfo);
-                if (DEBUG) {
-                    Slogf.d(TAG, "Added a CPU availability callback: %s", callbackInfo);
-                }
+                callbackInfo = newCallbackInfoLocked(config, callback, executor);
+            }
+            asyncNotifyMonitoringIntervalChangeToClient(callbackInfo);
+            if (DEBUG) {
+                Slogf.d(TAG, "Successfully added %s", callbackInfo);
             }
-            // TODO(b/242722241):
-            //  * On the executor or on the handler thread, call the callback with the latest CPU
-            //    availability info and monitoring interval.
-            //  * Monitor the CPU stats more frequently when the first callback is added.
         }
 
         @Override
@@ -143,6 +139,7 @@ public final class CpuMonitorService extends SystemService {
                         if (DEBUG) {
                             Slogf.d(TAG, "Successfully removed %s", callbackInfo);
                         }
+                        checkAndStopMonitoringLocked();
                         return;
                     }
                 }
@@ -154,19 +151,20 @@ public final class CpuMonitorService extends SystemService {
 
     public CpuMonitorService(Context context) {
         this(context, new CpuInfoReader(), new ServiceThread(TAG,
-                Process.THREAD_PRIORITY_BACKGROUND, /* allowIo= */ true),
-                Build.IS_USERDEBUG || Build.IS_ENG, DEBUG_MONITORING_INTERVAL_MILLISECONDS,
-                LATEST_AVAILABILITY_DURATION_MILLISECONDS);
+                        Process.THREAD_PRIORITY_BACKGROUND, /* allowIo= */ true),
+                Build.IS_USERDEBUG || Build.IS_ENG, NORMAL_MONITORING_INTERVAL_MILLISECONDS,
+                DEBUG_MONITORING_INTERVAL_MILLISECONDS, LATEST_AVAILABILITY_DURATION_MILLISECONDS);
     }
 
     @VisibleForTesting
     CpuMonitorService(Context context, CpuInfoReader cpuInfoReader, HandlerThread handlerThread,
-            boolean shouldDebugMonitor, long debugMonitoringIntervalMillis,
-            long latestAvailabilityDurationMillis) {
+            boolean shouldDebugMonitor, long normalMonitoringIntervalMillis,
+            long debugMonitoringIntervalMillis, long latestAvailabilityDurationMillis) {
         super(context);
         mContext = context;
         mHandlerThread = handlerThread;
         mShouldDebugMonitor = shouldDebugMonitor;
+        mNormalMonitoringIntervalMillis = normalMonitoringIntervalMillis;
         mDebugMonitoringIntervalMillis = debugMonitoringIntervalMillis;
         mLatestAvailabilityDurationMillis = latestAvailabilityDurationMillis;
         mCpuInfoReader = cpuInfoReader;
@@ -202,12 +200,24 @@ public final class CpuMonitorService extends SystemService {
         }
     }
 
+    @VisibleForTesting
+    long getCurrentMonitoringIntervalMillis() {
+        synchronized (mLock) {
+            return mCurrentMonitoringIntervalMillis;
+        }
+    }
+
     private void doDump(IndentingPrintWriter writer) {
         writer.printf("*%s*\n", getClass().getSimpleName());
         writer.increaseIndent();
         mCpuInfoReader.dump(writer);
+        writer.printf("mShouldDebugMonitor = %s\n", mShouldDebugMonitor ? "Yes" : "No");
+        writer.printf("mNormalMonitoringIntervalMillis = %d\n", mNormalMonitoringIntervalMillis);
+        writer.printf("mDebugMonitoringIntervalMillis = %d\n", mDebugMonitoringIntervalMillis);
+        writer.printf("mLatestAvailabilityDurationMillis = %d\n",
+                mLatestAvailabilityDurationMillis);
         synchronized (mLock) {
-            writer.printf("Current CPU monitoring interval: %d ms\n",
+            writer.printf("mCurrentMonitoringIntervalMillis = %d\n",
                     mCurrentMonitoringIntervalMillis);
             if (hasClientCallbacksLocked()) {
                 writer.println("CPU availability change callbacks:");
@@ -230,6 +240,11 @@ public final class CpuMonitorService extends SystemService {
 
     private void monitorCpuStats() {
         long uptimeMillis = SystemClock.uptimeMillis();
+        // Remove duplicate callbacks caused by switching form debug to normal monitoring.
+        // The removal of the duplicate callback done in the {@link newCallbackInfoLocked} method
+        // may result in a no-op when a duplicate execution of this callback has already started
+        // on the handler thread.
+        mHandler.removeCallbacks(mMonitorCpuStats);
         SparseArray<CpuInfoReader.CpuInfo> cpuInfosByCoreId = mCpuInfoReader.readCpuInfos();
         if (cpuInfosByCoreId == null) {
             // This shouldn't happen because the CPU infos are read & verified during
@@ -262,7 +277,7 @@ public final class CpuMonitorService extends SystemService {
             }
 
             // TODO(b/267500110): Detect heavy CPU load. On detecting heavy CPU load, increase
-            //  the monitoring interval and notify the clients.
+            // the monitoring interval and notify the clients.
 
             // 3. Continue monitoring only when either there is at least one registered client
             // callback or debug monitoring is enabled.
@@ -280,34 +295,94 @@ public final class CpuMonitorService extends SystemService {
     private void checkClientThresholdsAndNotifyLocked(CpusetInfo cpusetInfo) {
         int prevAvailabilityPercent = cpusetInfo.getPrevCpuAvailabilityPercent();
         CpuAvailabilityInfo latestAvailabilityInfo = cpusetInfo.getLatestCpuAvailabilityInfo();
-        ArrayMap<CpuMonitorInternal.CpuAvailabilityCallback,
-                CpuAvailabilityCallbackInfo> callbackMap =
-                mAvailabilityCallbackInfosByCallbacksByCpuset.get(cpusetInfo.cpuset);
         if (latestAvailabilityInfo == null || prevAvailabilityPercent < 0
-                || callbackMap.isEmpty()) {
+                || mAvailabilityCallbackInfosByCallbacksByCpuset.numElementsForKey(
+                cpusetInfo.cpuset) == 0) {
             // When either the current or the previous CPU availability percents are
             // missing, skip the current cpuset as there is not enough data to verify
             // whether the CPU availability has crossed any monitoring threshold.
             return;
         }
-        for (int i = 0; i < callbackMap.size(); i++) {
-            CpuAvailabilityCallbackInfo callbackInfo = callbackMap.valueAt(i);
-            if (didCrossAnyThreshold(prevAvailabilityPercent,
-                    latestAvailabilityInfo.latestAvgAvailabilityPercent,
-                    callbackInfo.config.getThresholds())) {
-                asyncNotifyCpuAvailabilityToClient(latestAvailabilityInfo, callbackInfo);
+        for (int i = 0; i < mAvailabilityCallbackInfosByCallbacksByCpuset.numMaps(); i++) {
+            for (int j = 0; j < mAvailabilityCallbackInfosByCallbacksByCpuset.numElementsForKeyAt(
+                    i); j++) {
+                CpuAvailabilityCallbackInfo callbackInfo =
+                        mAvailabilityCallbackInfosByCallbacksByCpuset.valueAt(i, j);
+                if (callbackInfo.config.cpuset != cpusetInfo.cpuset) {
+                    continue;
+                }
+                if (didCrossAnyThreshold(prevAvailabilityPercent,
+                        latestAvailabilityInfo.latestAvgAvailabilityPercent,
+                        callbackInfo.config.getThresholds())) {
+                    asyncNotifyCpuAvailabilityToClient(latestAvailabilityInfo, callbackInfo);
+                }
             }
         }
     }
 
+    private void asyncNotifyMonitoringIntervalChangeToClient(
+            CpuAvailabilityCallbackInfo callbackInfo) {
+        if (callbackInfo.executor == null) {
+            mHandler.post(callbackInfo.notifyMonitoringIntervalChangeRunnable);
+        } else {
+            callbackInfo.executor.execute(callbackInfo.notifyMonitoringIntervalChangeRunnable);
+        }
+    }
+
     private void asyncNotifyCpuAvailabilityToClient(CpuAvailabilityInfo availabilityInfo,
             CpuAvailabilityCallbackInfo callbackInfo) {
+        callbackInfo.notifyCpuAvailabilityChangeRunnable.prepare(availabilityInfo);
         if (callbackInfo.executor == null) {
-            mHandler.post(() -> mNotifyCpuAvailabilityFunctor.accept(callbackInfo.callback,
-                    availabilityInfo));
+            mHandler.post(callbackInfo.notifyCpuAvailabilityChangeRunnable);
         } else {
-            callbackInfo.executor.execute(() -> mNotifyCpuAvailabilityFunctor.accept(
-                    callbackInfo.callback, availabilityInfo));
+            callbackInfo.executor.execute(callbackInfo.notifyCpuAvailabilityChangeRunnable);
+        }
+    }
+
+    @GuardedBy("mLock")
+    private CpuAvailabilityCallbackInfo newCallbackInfoLocked(
+            CpuAvailabilityMonitoringConfig config,
+            CpuMonitorInternal.CpuAvailabilityCallback callback, Executor executor) {
+        CpuAvailabilityCallbackInfo callbackInfo = new CpuAvailabilityCallbackInfo(this, config,
+                callback, executor);
+        String cpusetStr = CpuAvailabilityMonitoringConfig.toCpusetString(
+                callbackInfo.config.cpuset);
+        CpusetInfo cpusetInfo = mCpusetInfosByCpuset.get(callbackInfo.config.cpuset);
+        Preconditions.checkState(cpusetInfo != null, "Missing cpuset info for cpuset %s",
+                cpusetStr);
+        boolean hasExistingClientCallbacks = hasClientCallbacksLocked();
+        mAvailabilityCallbackInfosByCallbacksByCpuset.add(callbackInfo.config.cpuset,
+                callbackInfo.callback, callbackInfo);
+        if (DEBUG) {
+            Slogf.d(TAG, "Added a CPU availability callback: %s", callbackInfo);
+        }
+        CpuAvailabilityInfo latestInfo = cpusetInfo.getLatestCpuAvailabilityInfo();
+        if (latestInfo != null) {
+            asyncNotifyCpuAvailabilityToClient(latestInfo, callbackInfo);
+        }
+        if (hasExistingClientCallbacks && mHandler.hasCallbacks(mMonitorCpuStats)) {
+            return callbackInfo;
+        }
+        // Remove existing callbacks to ensure any debug monitoring (if started) is stopped before
+        // starting normal monitoring.
+        mHandler.removeCallbacks(mMonitorCpuStats);
+        mCurrentMonitoringIntervalMillis = mNormalMonitoringIntervalMillis;
+        mHandler.post(mMonitorCpuStats);
+        return callbackInfo;
+    }
+
+    @GuardedBy("mLock")
+    private void checkAndStopMonitoringLocked() {
+        if (hasClientCallbacksLocked()) {
+            return;
+        }
+        if (mShouldDebugMonitor) {
+            if (DEBUG) {
+                Slogf.e(TAG, "Switching to debug monitoring");
+            }
+            mCurrentMonitoringIntervalMillis = mDebugMonitoringIntervalMillis;
+        } else {
+            stopMonitoringCpuStatsLocked();
         }
     }
 
@@ -370,13 +445,24 @@ public final class CpuMonitorService extends SystemService {
     }
 
     private static final class CpuAvailabilityCallbackInfo {
+        public final CpuMonitorService service;
         public final CpuAvailabilityMonitoringConfig config;
         public final CpuMonitorInternal.CpuAvailabilityCallback callback;
         @Nullable
         public final Executor executor;
+        public final Runnable notifyMonitoringIntervalChangeRunnable = new Runnable() {
+            @Override
+            public void run() {
+                callback.onMonitoringIntervalChanged(service.getCurrentMonitoringIntervalMillis());
+            }
+        };
+        public final NotifyCpuAvailabilityChangeRunnable notifyCpuAvailabilityChangeRunnable =
+                new NotifyCpuAvailabilityChangeRunnable();
 
-        CpuAvailabilityCallbackInfo(CpuAvailabilityMonitoringConfig config,
+        CpuAvailabilityCallbackInfo(CpuMonitorService service,
+                CpuAvailabilityMonitoringConfig config,
                 CpuMonitorInternal.CpuAvailabilityCallback callback, @Nullable Executor executor) {
+            this.service = service;
             this.config = config;
             this.callback = callback;
             this.executor = executor;
@@ -387,6 +473,25 @@ public final class CpuMonitorService extends SystemService {
             return "CpuAvailabilityCallbackInfo{config = " + config + ", callback = " + callback
                     + ", mExecutor = " + executor + '}';
         }
+
+        private final class NotifyCpuAvailabilityChangeRunnable implements Runnable {
+            private final Object mLock = new Object();
+            @GuardedBy("mLock")
+            private CpuAvailabilityInfo mCpuAvailabilityInfo;
+
+            public void prepare(CpuAvailabilityInfo cpuAvailabilityInfo) {
+                synchronized (mLock) {
+                    mCpuAvailabilityInfo = cpuAvailabilityInfo;
+                }
+            }
+
+            @Override
+            public void run() {
+                synchronized (mLock) {
+                    callback.onAvailabilityChanged(mCpuAvailabilityInfo);
+                }
+            }
+        }
     }
 
     private final class CpuMonitorBinder extends Binder {
@@ -563,13 +668,4 @@ public final class CpuMonitorService extends SystemService {
             }
         }
     }
-
-    private static final class NotifyCpuAvailabilityFunctor implements
-            BiConsumer<CpuMonitorInternal.CpuAvailabilityCallback, CpuAvailabilityInfo> {
-        @Override
-        public void accept(CpuMonitorInternal.CpuAvailabilityCallback callback,
-                CpuAvailabilityInfo availabilityInfo) {
-            callback.onAvailabilityChanged(availabilityInfo);
-        }
-    }
 }
diff --git a/services/tests/mockingservicestests/src/com/android/server/cpu/CpuMonitorServiceTest.java b/services/tests/mockingservicestests/src/com/android/server/cpu/CpuMonitorServiceTest.java
index 49a2cc6967442..5a5f5256e37db 100644
--- a/services/tests/mockingservicestests/src/com/android/server/cpu/CpuMonitorServiceTest.java
+++ b/services/tests/mockingservicestests/src/com/android/server/cpu/CpuMonitorServiceTest.java
@@ -17,105 +17,659 @@
 package com.android.server.cpu;
 
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.doNothing;
+import static com.android.dx.mockito.inline.extended.ExtendedMockito.doReturn;
+import static com.android.dx.mockito.inline.extended.ExtendedMockito.verify;
+import static com.android.server.cpu.CpuAvailabilityInfo.MISSING_CPU_AVAILABILITY_PERCENT;
 import static com.android.server.cpu.CpuAvailabilityMonitoringConfig.CPUSET_ALL;
+import static com.android.server.cpu.CpuAvailabilityMonitoringConfig.CPUSET_BACKGROUND;
+import static com.android.server.cpu.CpuInfoReader.CpuInfo.MISSING_FREQUENCY;
+import static com.android.server.cpu.CpuInfoReader.FLAG_CPUSET_CATEGORY_BACKGROUND;
+import static com.android.server.cpu.CpuInfoReader.FLAG_CPUSET_CATEGORY_TOP_APP;
+import static com.android.server.cpu.CpuMonitorService.DEFAULT_MONITORING_INTERVAL_MILLISECONDS;
+
+import static com.google.common.truth.Truth.assertWithMessage;
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.timeout;
+import static org.mockito.Mockito.when;
 
 import android.content.Context;
 import android.os.Binder;
 import android.os.Handler;
 import android.os.HandlerExecutor;
+import android.os.HandlerThread;
 import android.os.Looper;
 import android.os.ServiceManager;
+import android.util.ArraySet;
+import android.util.SparseArray;
 
 import com.android.server.ExtendedMockitoRule;
 import com.android.server.LocalServices;
+import com.android.server.Watchdog;
 
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
 import org.mockito.Mock;
+import org.mockito.stubbing.OngoingStubbing;
+
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 public final class CpuMonitorServiceTest {
-    private static final CpuAvailabilityMonitoringConfig TEST_CPU_AVAILABILITY_MONITORING_CONFIG =
+    private static final String TAG = CpuMonitorServiceTest.class.getSimpleName();
+    private static final String USER_BUILD_TAG = TAG + "UserBuild";
+    private static final long ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS =
+            TimeUnit.SECONDS.toMillis(1);
+    private static final long HANDLER_THREAD_SYNC_TIMEOUT_MILLISECONDS =
+            TimeUnit.SECONDS.toMillis(5);
+    private static final long TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS = 100;
+    private static final long TEST_DEBUG_MONITORING_INTERVAL_MILLISECONDS = 150;
+    private static final long TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS = 300;
+    private static final CpuAvailabilityMonitoringConfig TEST_MONITORING_CONFIG_ALL_CPUSET =
             new CpuAvailabilityMonitoringConfig.Builder(CPUSET_ALL)
                     .addThreshold(30).addThreshold(70).build();
-
-    private static final CpuAvailabilityMonitoringConfig TEST_CPU_AVAILABILITY_MONITORING_CONFIG_2 =
-            new CpuAvailabilityMonitoringConfig.Builder(CPUSET_ALL)
-                    .addThreshold(10).addThreshold(90).build();
+    private static final CpuAvailabilityMonitoringConfig TEST_MONITORING_CONFIG_BG_CPUSET =
+            new CpuAvailabilityMonitoringConfig.Builder(CPUSET_BACKGROUND)
+                    .addThreshold(50).addThreshold(90).build();
+    private static final List<StaticCpuInfo> STATIC_CPU_INFOS = List.of(
+            new StaticCpuInfo(/* cpuCore= */ 0,
+                    /* cpusetCategories= */ FLAG_CPUSET_CATEGORY_TOP_APP,
+                    /* maxCpuFreqKHz= */ 4000),
+            new StaticCpuInfo(/* cpuCore= */ 1,
+                    /* cpusetCategories= */ FLAG_CPUSET_CATEGORY_TOP_APP,
+                    /* maxCpuFreqKHz= */ 3000),
+            new StaticCpuInfo(/* cpuCore= */ 2, /* cpusetCategories= */ FLAG_CPUSET_CATEGORY_TOP_APP
+                    | FLAG_CPUSET_CATEGORY_BACKGROUND, /* maxCpuFreqKHz= */ 3000),
+            new StaticCpuInfo(/* cpuCore= */ 3, /* cpusetCategories= */ FLAG_CPUSET_CATEGORY_TOP_APP
+                    | FLAG_CPUSET_CATEGORY_BACKGROUND, /* maxCpuFreqKHz= */ 3000),
+            new StaticCpuInfo(/* cpuCore= */ 4, /* cpusetCategories= */ FLAG_CPUSET_CATEGORY_TOP_APP
+                    | FLAG_CPUSET_CATEGORY_BACKGROUND, /* maxCpuFreqKHz= */ 2000));
+    private static final ArraySet<Integer> NO_OFFLINE_CORES = new ArraySet<>();
 
     @Mock
-    private Context mContext;
+    private Context mMockContext;
+    @Mock
+    private CpuInfoReader mMockCpuInfoReader;
+    @Captor
+    private ArgumentCaptor<CpuAvailabilityInfo> mCpuAvailabilityInfoCaptor;
+    private HandlerThread mServiceHandlerThread;
+    private Handler mServiceHandler;
     private CpuMonitorService mService;
-    private HandlerExecutor mHandlerExecutor;
     private CpuMonitorInternal mLocalService;
 
     @Rule
     public final ExtendedMockitoRule mExtendedMockitoRule = new ExtendedMockitoRule.Builder(this)
             .mockStatic(ServiceManager.class)
+            .mockStatic(Watchdog.class)
             .build();
 
     @Before
-    public void setUp() {
-        mService = new CpuMonitorService(mContext);
-        mHandlerExecutor = new HandlerExecutor(new Handler(Looper.getMainLooper()));
+    public void setUp() throws Exception {
+        mServiceHandlerThread = new HandlerThread(TAG);
+        mService = new CpuMonitorService(mMockContext, mMockCpuInfoReader, mServiceHandlerThread,
+                /* shouldDebugMonitor= */ true, TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS,
+                TEST_DEBUG_MONITORING_INTERVAL_MILLISECONDS,
+                TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS);
+
         doNothing().when(() -> ServiceManager.addService(eq("cpu_monitor"), any(Binder.class),
                 anyBoolean(), anyInt()));
-        mService.onStart();
-        mLocalService = LocalServices.getService(CpuMonitorInternal.class);
+        doReturn(mock(Watchdog.class)).when(Watchdog::getInstance);
+        when(mMockCpuInfoReader.init()).thenReturn(true);
+        when(mMockCpuInfoReader.readCpuInfos()).thenReturn(new SparseArray<>());
+
+        startService();
     }
 
     @After
-    public void tearDown() {
-        // The CpuMonitorInternal.class service is added by the mService.onStart call.
-        // Remove the service to ensure the setUp procedure can add this service again.
+    public void tearDown() throws Exception {
+        terminateService();
+    }
+
+    @Test
+    public void testAddRemoveCpuAvailabilityCallbackOnDebugBuild() throws Exception {
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback = mock(
+                CpuMonitorInternal.CpuAvailabilityCallback.class);
+
+        mLocalService.addCpuAvailabilityCallback(/* executor= */ null,
+                TEST_MONITORING_CONFIG_ALL_CPUSET, mockCallback);
+
+        assertWithMessage("Monitoring interval after adding a client callback")
+                .that(mService.getCurrentMonitoringIntervalMillis())
+                .isEqualTo(TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS);
+
+        // Monitoring interval changed notification is sent asynchronously from the handler thread.
+        // So, sync with this thread before verifying the client call.
+        syncWithHandler(mServiceHandler, /* delayMillis= */ 0);
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS))
+                .onMonitoringIntervalChanged(TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS);
+
+        verify(mockCallback, never()).onAvailabilityChanged(any());
+
+        mLocalService.removeCpuAvailabilityCallback(mockCallback);
+
+        assertWithMessage("Monitoring interval after removing all client callbacks")
+                .that(mService.getCurrentMonitoringIntervalMillis())
+                .isEqualTo(TEST_DEBUG_MONITORING_INTERVAL_MILLISECONDS);
+    }
+
+    @Test
+    public void testAddRemoveCpuAvailabilityCallbackOnUserBuild() throws Exception {
+        // The default service instantiated during test setUp has the debug monitoring enabled.
+        // But on a user build, debug monitoring is disabled. So, replace the default service with
+        // an equivalent user build service.
+        replaceServiceWithUserBuildService();
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback = mock(
+                CpuMonitorInternal.CpuAvailabilityCallback.class);
+
+        mLocalService.addCpuAvailabilityCallback(/* executor= */ null,
+                TEST_MONITORING_CONFIG_ALL_CPUSET, mockCallback);
+
+        assertWithMessage("Monitoring interval after adding a client callback")
+                .that(mService.getCurrentMonitoringIntervalMillis())
+                .isEqualTo(TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS);
+
+        // Monitoring interval changed notification is sent asynchronously from the handler thread.
+        // So, sync with this thread before verifying the client call.
+        syncWithHandler(mServiceHandler, /* delayMillis= */ 0);
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS))
+                .onMonitoringIntervalChanged(TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS);
+
+        verify(mockCallback, never()).onAvailabilityChanged(any());
+
+        mLocalService.removeCpuAvailabilityCallback(mockCallback);
+
+        assertWithMessage("Monitoring interval after removing all client callbacks")
+                .that(mService.getCurrentMonitoringIntervalMillis())
+                .isEqualTo(DEFAULT_MONITORING_INTERVAL_MILLISECONDS);
+    }
+
+    @Test
+    public void testRemoveInvalidCpuAvailabilityCallback() throws Exception {
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback = mock(
+                CpuMonitorInternal.CpuAvailabilityCallback.class);
+
+        mLocalService.removeCpuAvailabilityCallback(mockCallback);
+    }
+
+    @Test
+    public void testReceiveCpuAvailabilityCallbackOnAddingFirstCallback() throws Exception {
+        // Debug monitoring is in progress but the default {@link CpuInfoReader.CpuInfo} returned by
+        // the {@link CpuInfoReader.readCpuInfos} is empty, so the client won't be notified when
+        // adding a callback. Inject {@link CpuInfoReader.CpuInfo}, so the client callback is
+        // notified on adding a callback.
+        injectCpuInfosAndWait(List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 10.0f,
+                        NO_OFFLINE_CORES)));
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 10, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos").that(actual).isEqualTo(expected);
+    }
+
+    @Test
+    public void testReceiveCpuAvailabilityCallbackOnAddingMultipleCallbacks() throws Exception {
+        addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_BG_CPUSET);
+
+        injectCpuInfosAndWait(List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 10.0f,
+                        NO_OFFLINE_CORES)));
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 10, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos").that(actual).isEqualTo(expected);
+    }
+
+    @Test
+    public void testCrossCpuAvailabilityThresholdsWithSingleCallback() throws Exception {
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        injectCpuInfosAndWait(List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 10.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 90.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 15.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 30.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 60.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 82.0f,
+                        NO_OFFLINE_CORES)));
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(4))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 90, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 15, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(2).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 30,
+                        /* pastNMillisAvgAvailabilityPercent= */ 45,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(3).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 82,
+                        /* pastNMillisAvgAvailabilityPercent= */ 57,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos").that(actual).isEqualTo(expected);
+    }
+
+    @Test
+    public void testCrossCpuAvailabilityThresholdsWithMultipleCallbacks() throws Exception {
+        CpuMonitorInternal.CpuAvailabilityCallback mockAllCpusetCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockBgCpusetCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_BG_CPUSET);
+
+        injectCpuInfosAndWait(List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 5.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 20.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 30.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 60.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 75.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 90.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 15.0f,
+                        NO_OFFLINE_CORES)));
+
+        verify(mockAllCpusetCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(3))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 30, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 75,
+                        /* pastNMillisAvgAvailabilityPercent= */ 55,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(2).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 15,
+                        /* pastNMillisAvgAvailabilityPercent= */ 60,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos for CPUSET_ALL callback").that(actual)
+                .isEqualTo(expected);
+
+        ArgumentCaptor<CpuAvailabilityInfo> bgCpusetAvailabilityInfoCaptor =
+                ArgumentCaptor.forClass(CpuAvailabilityInfo.class);
+
+        verify(mockBgCpusetCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(3))
+                .onAvailabilityChanged(bgCpusetAvailabilityInfoCaptor.capture());
+
+        actual = bgCpusetAvailabilityInfoCaptor.getAllValues();
+        expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 60,
+                        /* pastNMillisAvgAvailabilityPercent= */ 36,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 90,
+                        /* pastNMillisAvgAvailabilityPercent= */ 75,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(2).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 15,
+                        /* pastNMillisAvgAvailabilityPercent= */ 60,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos for CPUSET_BACKGROUND callback").that(actual)
+                .isEqualTo(expected);
+    }
+
+    @Test
+    public void testCrossCpuAvailabilityThresholdsWithOfflineCores() throws Exception {
+        CpuMonitorInternal.CpuAvailabilityCallback mockAllCpusetCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockBgCpusetCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_BG_CPUSET);
+
+        // Disable one top-app and one all cpuset core.
+        ArraySet<Integer> offlineCoresA = new ArraySet<>();
+        offlineCoresA.add(1);
+        offlineCoresA.add(3);
+
+        // Disable two all cpuset cores.
+        ArraySet<Integer> offlineCoresB = new ArraySet<>();
+        offlineCoresB.add(2);
+        offlineCoresB.add(4);
+
+        injectCpuInfosAndWait(List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 5.0f, offlineCoresA),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 20.0f, offlineCoresB),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 30.0f, offlineCoresA),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 60.0f, offlineCoresB),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 75.0f, offlineCoresA),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 90.0f, offlineCoresB),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 15.0f,
+                        offlineCoresA)));
+
+        verify(mockAllCpusetCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(3))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 30, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 75,
+                        /* pastNMillisAvgAvailabilityPercent= */ 55,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(2).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 15,
+                        /* pastNMillisAvgAvailabilityPercent= */ 61,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos for CPUSET_ALL callback").that(actual)
+                .isEqualTo(expected);
+
+        ArgumentCaptor<CpuAvailabilityInfo> bgCpusetAvailabilityInfoCaptor =
+                ArgumentCaptor.forClass(CpuAvailabilityInfo.class);
+
+        verify(mockBgCpusetCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(3))
+                .onAvailabilityChanged(bgCpusetAvailabilityInfoCaptor.capture());
+
+        actual = bgCpusetAvailabilityInfoCaptor.getAllValues();
+        expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 60,
+                        /* pastNMillisAvgAvailabilityPercent= */ 35,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 90,
+                        /* pastNMillisAvgAvailabilityPercent= */ 75,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(2).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 15,
+                        /* pastNMillisAvgAvailabilityPercent= */ 55,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos for CPUSET_BACKGROUND callback").that(actual)
+                .isEqualTo(expected);
+    }
+
+    @Test
+    public void testReceiveCpuAvailabilityCallbacksOnExecutorThread() throws Exception {
+        Handler testHandler = new Handler(Looper.getMainLooper());
+
+        assertWithMessage("Test main handler").that(testHandler).isNotNull();
+
+        HandlerExecutor testExecutor = new HandlerExecutor(testHandler);
+
+        assertWithMessage("Test main executor").that(testExecutor).isNotNull();
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback =
+                addCpuAvailabilityCallback(testHandler, testExecutor,
+                        TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        // CPU monitoring is started on the service handler thread. Sync with this thread before
+        // proceeding. Otherwise, debug monitoring may consume the injected CPU infos and cause
+        // the test to be flaky. Because the {@link addCpuAvailabilityCallback} syncs only with
+        // the passed handler, the test must explicitly sync with the service handler.
+        syncWithHandler(mServiceHandler, /* delayMillis= */ 0);
+
+        injectCpuInfosAndWait(testHandler, List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 10.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 90.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 15.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 30.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 60.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 82.0f,
+                        NO_OFFLINE_CORES)));
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(4))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 90, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 15, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(2).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 30,
+                        /* pastNMillisAvgAvailabilityPercent= */ 45,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_ALL, actual.get(3).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 82,
+                        /* pastNMillisAvgAvailabilityPercent= */ 57,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos").that(actual).isEqualTo(expected);
+    }
+
+    @Test
+    public void testDuplicateAddCpuAvailabilityCallback() throws Exception {
+        addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_ALL_CPUSET);
+
+        CpuMonitorInternal.CpuAvailabilityCallback mockCallback =
+                addCpuAvailabilityCallback(TEST_MONITORING_CONFIG_BG_CPUSET);
+
+        injectCpuInfosAndWait(List.of(
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 10.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 40.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 60.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 80.0f,
+                        NO_OFFLINE_CORES),
+                generateCpuInfosForAvailability(/* cpuAvailabilityPercent= */ 95.0f,
+                        NO_OFFLINE_CORES)));
+
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS).times(2))
+                .onAvailabilityChanged(mCpuAvailabilityInfoCaptor.capture());
+
+        List<CpuAvailabilityInfo> actual = mCpuAvailabilityInfoCaptor.getAllValues();
+
+        // Verify that the callback is called for the last added monitoring config.
+        List<CpuAvailabilityInfo> expected = List.of(
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(0).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 60, MISSING_CPU_AVAILABILITY_PERCENT,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS),
+                new CpuAvailabilityInfo(CPUSET_BACKGROUND, actual.get(1).dataTimestampUptimeMillis,
+                        /* latestAvgAvailabilityPercent= */ 95,
+                        /* pastNMillisAvgAvailabilityPercent= */ 78,
+                        TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS));
+
+        assertWithMessage("CPU availability infos").that(actual).isEqualTo(expected);
+    }
+
+    @Test
+    public void testHeavyCpuLoadMonitoring() throws Exception {
+        // TODO(b/267500110): Once heavy CPU load detection logic is added, add unittest.
+    }
+
+    private void startService() {
+        mService.onStart();
+        mServiceHandler = mServiceHandlerThread.getThreadHandler();
+
+        assertWithMessage("Service thread handler").that(mServiceHandler).isNotNull();
+
+        mLocalService = LocalServices.getService(CpuMonitorInternal.class);
+
+        assertWithMessage("CpuMonitorInternal local service").that(mLocalService).isNotNull();
+    }
+
+    private void terminateService() {
+        // The CpuMonitorInternal.class service is added by the {@link CpuMonitorService#onStart}
+        // call. Remove the service to ensure this service can be added again during
+        // the {@link CpuMonitorService#onStart} call.
         LocalServices.removeServiceForTest(CpuMonitorInternal.class);
+        if (mServiceHandlerThread != null && mServiceHandlerThread.isAlive()) {
+            mServiceHandlerThread.quitSafely();
+        }
     }
 
-    @Test
-    public void testAddRemoveCpuAvailabilityCallback() {
+    private void replaceServiceWithUserBuildService() {
+        terminateService();
+        mServiceHandlerThread = new HandlerThread(USER_BUILD_TAG);
+        mService = new CpuMonitorService(mMockContext, mMockCpuInfoReader,
+                mServiceHandlerThread, /* shouldDebugMonitor= */ false,
+                TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS,
+                TEST_DEBUG_MONITORING_INTERVAL_MILLISECONDS,
+                TEST_LATEST_AVAILABILITY_DURATION_MILLISECONDS);
+
+        startService();
+    }
+
+    private CpuMonitorInternal.CpuAvailabilityCallback addCpuAvailabilityCallback(
+            CpuAvailabilityMonitoringConfig config) throws Exception {
+        return addCpuAvailabilityCallback(mServiceHandler, /* executor= */ null, config);
+    }
+
+    private CpuMonitorInternal.CpuAvailabilityCallback addCpuAvailabilityCallback(Handler handler,
+            HandlerExecutor executor, CpuAvailabilityMonitoringConfig config) throws Exception {
         CpuMonitorInternal.CpuAvailabilityCallback mockCallback = mock(
                 CpuMonitorInternal.CpuAvailabilityCallback.class);
 
-        mLocalService.addCpuAvailabilityCallback(mHandlerExecutor,
-                TEST_CPU_AVAILABILITY_MONITORING_CONFIG, mockCallback);
+        mLocalService.addCpuAvailabilityCallback(executor, config, mockCallback);
 
-        // TODO(b/242722241): Verify that {@link mockCallback.onAvailabilityChanged} and
-        //  {@link mockCallback.onMonitoringIntervalChanged} are called when the callback is added.
+        // Monitoring interval changed notification is sent asynchronously from the given handler.
+        // So, sync with this thread before verifying the client call.
+        syncWithHandler(handler, /* delayMillis= */ 0);
 
-        mLocalService.removeCpuAvailabilityCallback(mockCallback);
+        verify(mockCallback, timeout(ASYNC_CALLBACK_WAIT_TIMEOUT_MILLISECONDS))
+                .onMonitoringIntervalChanged(TEST_NORMAL_MONITORING_INTERVAL_MILLISECONDS);
+
+        return mockCallback;
     }
 
-
-    @Test
-    public void testDuplicateAddCpuAvailabilityCallback() {
-        CpuMonitorInternal.CpuAvailabilityCallback mockCallback = mock(
-                CpuMonitorInternal.CpuAvailabilityCallback.class);
-
-        mLocalService.addCpuAvailabilityCallback(mHandlerExecutor,
-                TEST_CPU_AVAILABILITY_MONITORING_CONFIG, mockCallback);
-
-        mLocalService.addCpuAvailabilityCallback(mHandlerExecutor,
-                TEST_CPU_AVAILABILITY_MONITORING_CONFIG_2, mockCallback);
-
-        // TODO(b/242722241): Verify that {@link mockCallback} is called only when CPU availability
-        //  thresholds cross the bounds specified in the
-        //  {@link TEST_CPU_AVAILABILITY_MONITORING_CONFIG_2} config.
-
-        mLocalService.removeCpuAvailabilityCallback(mockCallback);
+    private void injectCpuInfosAndWait(List<SparseArray<CpuInfoReader.CpuInfo>> cpuInfos)
+            throws Exception {
+        injectCpuInfosAndWait(mServiceHandler, cpuInfos);
     }
 
-    @Test
-    public void testRemoveInvalidCpuAvailabilityCallback() {
-        CpuMonitorInternal.CpuAvailabilityCallback mockCallback = mock(
-                CpuMonitorInternal.CpuAvailabilityCallback.class);
+    private void injectCpuInfosAndWait(Handler handler,
+            List<SparseArray<CpuInfoReader.CpuInfo>> cpuInfos) throws Exception {
+        assertWithMessage("CPU info configs").that(cpuInfos).isNotEmpty();
 
-        mLocalService.removeCpuAvailabilityCallback(mockCallback);
+        OngoingStubbing<SparseArray<CpuInfoReader.CpuInfo>> ongoingStubbing =
+                when(mMockCpuInfoReader.readCpuInfos());
+        for (SparseArray<CpuInfoReader.CpuInfo> cpuInfo : cpuInfos) {
+            ongoingStubbing = ongoingStubbing.thenReturn(cpuInfo);
+        }
+
+        // CPU infos are read asynchronously on a separate handler thread. So, wait based on
+        // the current monitoring interval and the number of CPU infos were injected.
+        syncWithHandler(handler,
+                /* delayMillis= */ mService.getCurrentMonitoringIntervalMillis() * cpuInfos.size());
+    }
+
+    private void syncWithHandler(Handler handler, long delayMillis) throws Exception {
+        AtomicBoolean didRun = new AtomicBoolean(false);
+        handler.postDelayed(() -> {
+            synchronized (didRun) {
+                didRun.set(true);
+                didRun.notifyAll();
+            }
+        }, delayMillis);
+        synchronized (didRun) {
+            while (!didRun.get()) {
+                didRun.wait(HANDLER_THREAD_SYNC_TIMEOUT_MILLISECONDS);
+            }
+        }
+    }
+
+    private static SparseArray<CpuInfoReader.CpuInfo> generateCpuInfosForAvailability(
+            double cpuAvailabilityPercent, ArraySet<Integer> offlineCores) {
+        SparseArray<CpuInfoReader.CpuInfo> cpuInfos = new SparseArray<>(STATIC_CPU_INFOS.size());
+        for (StaticCpuInfo staticCpuInfo : STATIC_CPU_INFOS) {
+            boolean isOnline = !offlineCores.contains(staticCpuInfo.cpuCore);
+            cpuInfos.append(staticCpuInfo.cpuCore, constructCpuInfo(staticCpuInfo.cpuCore,
+                    staticCpuInfo.cpusetCategories, isOnline, staticCpuInfo.maxCpuFreqKHz,
+                    cpuAvailabilityPercent));
+        }
+        return cpuInfos;
+    }
+
+    private static CpuInfoReader.CpuInfo constructCpuInfo(int cpuCore,
+            @CpuInfoReader.CpusetCategory int cpusetCategories, boolean isOnline,
+            long maxCpuFreqKHz, double cpuAvailabilityPercent) {
+        long availCpuFreqKHz = (long) (maxCpuFreqKHz * (cpuAvailabilityPercent / 100.0));
+        long curCpuFreqKHz = maxCpuFreqKHz - availCpuFreqKHz;
+        return new CpuInfoReader.CpuInfo(cpuCore, cpusetCategories, isOnline,
+                isOnline ? curCpuFreqKHz : MISSING_FREQUENCY, maxCpuFreqKHz,
+                /* avgTimeInStateCpuFreqKHz= */ MISSING_FREQUENCY,
+                isOnline ? availCpuFreqKHz : MISSING_FREQUENCY,
+                /* latestCpuUsageStats= */ null);
+    }
+
+    private static final class StaticCpuInfo {
+        public final int cpuCore;
+        public final int cpusetCategories;
+        public final int maxCpuFreqKHz;
+
+        StaticCpuInfo(int cpuCore, @CpuInfoReader.CpusetCategory int cpusetCategories,
+                int maxCpuFreqKHz) {
+            this.cpuCore = cpuCore;
+            this.cpusetCategories = cpusetCategories;
+            this.maxCpuFreqKHz = maxCpuFreqKHz;
+        }
+
+        @Override
+        public String toString() {
+            return "StaticCpuInfo{cpuCore=" + cpuCore + ", cpusetCategories=" + cpusetCategories
+                    + ", maxCpuFreqKHz=" + maxCpuFreqKHz + '}';
+        }
     }
 }