Merge "Extend LocalLog to enable UTC timestamps"

core/java/android/util/LocalLog.java

@@ -17,9 +17,11 @@
 package android.util;
 
 import android.annotation.UnsupportedAppUsage;
+import android.os.SystemClock;
 
 import java.io.FileDescriptor;
 import java.io.PrintWriter;
+import java.time.Instant;
 import java.time.LocalDateTime;
 import java.util.ArrayDeque;
 import java.util.Deque;
@@ -33,10 +35,22 @@ public final class LocalLog {
     private final Deque<String> mLog;
     private final int mMaxLines;
 
+    /**
+     * {@code true} to use log timestamps expressed in local date/time, {@code false} to use log
+     * timestamped expressed with the elapsed realtime clock and UTC system clock. {@code false} is
+     * useful when logging behavior that modifies device time zone or system clock.
+     */
+    private final boolean mUseLocalTimestamps;
+
     @UnsupportedAppUsage
     public LocalLog(int maxLines) {
+        this(maxLines, true /* useLocalTimestamps */);
+    }
+
+    public LocalLog(int maxLines, boolean useLocalTimestamps) {
         mMaxLines = Math.max(0, maxLines);
         mLog = new ArrayDeque<>(mMaxLines);
+        mUseLocalTimestamps = useLocalTimestamps;
     }
 
     @UnsupportedAppUsage
@@ -44,7 +58,14 @@ public final class LocalLog {
         if (mMaxLines <= 0) {
             return;
         }
-        append(String.format("%s - %s", LocalDateTime.now(), msg));
+        final String logLine;
+        if (mUseLocalTimestamps) {
+            logLine = String.format("%s - %s", LocalDateTime.now(), msg);
+        } else {
+            logLine = String.format(
+                    "%s / %s - %s", SystemClock.elapsedRealtime(), Instant.now(), msg);
+        }
+        append(logLine);
     }
 
     private synchronized void append(String logLine) {

core/tests/coretests/src/android/util/LocalLogTest.java

@@ -29,14 +29,24 @@ import java.util.List;
 @LargeTest
 public class LocalLogTest extends TestCase {
 
-    public void testA() {
+    public void testA_localTimestamps() {
+        boolean localTimestamps = true;
+        doTestA(localTimestamps);
+    }
+
+    public void testA_nonLocalTimestamps() {
+        boolean localTimestamps = false;
+        doTestA(localTimestamps);
+    }
+
+    private void doTestA(boolean localTimestamps) {
         String[] lines = {
-            "foo",
-            "bar",
-            "baz"
+                "foo",
+                "bar",
+                "baz"
         };
         String[] want = lines;
-        testcase(new LocalLog(10), lines, want);
+        testcase(new LocalLog(10, localTimestamps), lines, want);
     }
 
     public void testB() {

services/core/java/com/android/server/timedetector/SimpleTimeDetectorStrategy.java

@@ -66,7 +66,8 @@ public final class SimpleTimeDetectorStrategy implements TimeDetectorStrategy {
     private static final long SYSTEM_CLOCK_PARANOIA_THRESHOLD_MILLIS = 2 * 1000;
 
     // A log for changes made to the system clock and why.
-    @NonNull private final LocalLog mTimeChangesLog = new LocalLog(30);
+    @NonNull
+    private final LocalLog mTimeChangesLog = new LocalLog(30, false /* useLocalTimestamps */);
 
     // @NonNull after initialize()
     private Callback mCallback;

services/core/java/com/android/server/timezonedetector/TimeZoneDetectorStrategy.java

@@ -172,7 +172,7 @@ public class TimeZoneDetectorStrategy {
      * (for use during debugging).
      */
     @NonNull
-    private final LocalLog mTimeZoneChangesLog = new LocalLog(30);
+    private final LocalLog mTimeZoneChangesLog = new LocalLog(30, false /* useLocalTimestamps */);
 
     /**
      * A mapping from phoneId to a linked list of phone time zone suggestions (the head being the