Check CPU time_in_state from one place

Move the check whether CPU eBPF tracking is supported to one place to
avoid repeating it in every reader.

Bug: 179485697
Test: existing tests pass
Change-Id: Id6d23614c3d1dde86b66de14bc09f5976f183625

core/java/com/android/internal/os/KernelCpuBpfTracking.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.internal.os;
+
+/** CPU tracking using eBPF. */
+public final class KernelCpuBpfTracking {
+    private KernelCpuBpfTracking() {
+    }
+
+    /** Returns whether CPU tracking using eBPF is supported. */
+    public static native boolean isSupported();
+}

core/java/com/android/internal/os/KernelCpuTotalBpfMapReader.java

@@ -23,9 +23,6 @@ public final class KernelCpuTotalBpfMapReader {
     private KernelCpuTotalBpfMapReader() {
     }
 
-    /** Returns whether total CPU time is measured. */
-    public static native boolean isSupported();
-
     /** Reads total CPU time from bpf map. */
     public static native boolean read(Callback callback);
 

core/jni/Android.bp

@@ -184,6 +184,7 @@ cc_library_shared {
                 "com_android_internal_net_NetworkUtilsInternal.cpp",
                 "com_android_internal_os_ClassLoaderFactory.cpp",
                 "com_android_internal_os_FuseAppLoop.cpp",
+                "com_android_internal_os_KernelCpuBpfTracking.cpp",
                 "com_android_internal_os_KernelCpuTotalBpfMapReader.cpp",
                 "com_android_internal_os_KernelCpuUidBpfMapReader.cpp",
                 "com_android_internal_os_KernelSingleProcessCpuThreadReader.cpp",

core/jni/AndroidRuntime.cpp

@@ -190,6 +190,7 @@ extern int register_com_android_internal_content_om_OverlayConfig(JNIEnv *env);
 extern int register_com_android_internal_net_NetworkUtilsInternal(JNIEnv* env);
 extern int register_com_android_internal_os_ClassLoaderFactory(JNIEnv* env);
 extern int register_com_android_internal_os_FuseAppLoop(JNIEnv* env);
+extern int register_com_android_internal_os_KernelCpuBpfTracking(JNIEnv* env);
 extern int register_com_android_internal_os_KernelCpuTotalBpfMapReader(JNIEnv* env);
 extern int register_com_android_internal_os_KernelCpuUidBpfMapReader(JNIEnv *env);
 extern int register_com_android_internal_os_KernelSingleProcessCpuThreadReader(JNIEnv* env);
@@ -1586,6 +1587,7 @@ static const RegJNIRec gRegJNI[] = {
         REG_JNI(register_android_security_Scrypt),
         REG_JNI(register_com_android_internal_content_NativeLibraryHelper),
         REG_JNI(register_com_android_internal_os_FuseAppLoop),
+        REG_JNI(register_com_android_internal_os_KernelCpuBpfTracking),
         REG_JNI(register_com_android_internal_os_KernelCpuTotalBpfMapReader),
         REG_JNI(register_com_android_internal_os_KernelCpuUidBpfMapReader),
         REG_JNI(register_com_android_internal_os_KernelSingleProcessCpuThreadReader),

core/jni/com_android_internal_os_KernelCpuBpfTracking.cpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "core_jni_helpers.h"
+
+#include <cputimeinstate.h>
+
+namespace android {
+
+static jboolean KernelCpuBpfTracking_isSupported(JNIEnv *, jobject) {
+    return android::bpf::isTrackingUidTimesSupported() ? JNI_TRUE : JNI_FALSE;
+}
+
+static const JNINativeMethod methods[] = {
+        {"isSupported", "()Z", (void *)KernelCpuBpfTracking_isSupported},
+};
+
+int register_com_android_internal_os_KernelCpuBpfTracking(JNIEnv *env) {
+    return RegisterMethodsOrDie(env, "com/android/internal/os/KernelCpuBpfTracking", methods,
+                                NELEM(methods));
+}
+
+} // namespace android

core/jni/com_android_internal_os_KernelCpuTotalBpfMapReader.cpp

@@ -20,10 +20,6 @@
 
 namespace android {
 
-static jboolean KernelCpuTotalBpfMapReader_isSupported(JNIEnv *, jobject) {
-    return android::bpf::isTrackingUidTimesSupported() ? JNI_TRUE : JNI_FALSE;
-}
-
 static jboolean KernelCpuTotalBpfMapReader_read(JNIEnv *env, jobject, jobject callback) {
     jclass callbackClass = env->GetObjectClass(callback);
     jmethodID callbackMethod = env->GetMethodID(callbackClass, "accept", "(IIJ)V");
@@ -51,7 +47,6 @@ static jboolean KernelCpuTotalBpfMapReader_read(JNIEnv *env, jobject, jobject ca
 static const JNINativeMethod methods[] = {
         {"read", "(Lcom/android/internal/os/KernelCpuTotalBpfMapReader$Callback;)Z",
          (void *)KernelCpuTotalBpfMapReader_read},
-        {"isSupported", "()Z", (void *)KernelCpuTotalBpfMapReader_isSupported},
 };
 
 int register_com_android_internal_os_KernelCpuTotalBpfMapReader(JNIEnv *env) {

services/core/java/com/android/server/stats/pull/StatsPullAtomService.java

@@ -139,6 +139,7 @@ import com.android.internal.os.BackgroundThread;
 import com.android.internal.os.BatterySipper;
 import com.android.internal.os.BatteryStatsHelper;
 import com.android.internal.os.BinderCallsStats.ExportedCallStat;
+import com.android.internal.os.KernelCpuBpfTracking;
 import com.android.internal.os.KernelCpuThreadReader;
 import com.android.internal.os.KernelCpuThreadReaderDiff;
 import com.android.internal.os.KernelCpuThreadReaderSettingsObserver;
@@ -1455,7 +1456,7 @@ public class StatsPullAtomService extends SystemService {
     }
 
     private void registerCpuTimePerClusterFreq() {
-        if (KernelCpuTotalBpfMapReader.isSupported()) {
+        if (KernelCpuBpfTracking.isSupported()) {
             int tagId = FrameworkStatsLog.CPU_TIME_PER_CLUSTER_FREQ;
             PullAtomMetadata metadata = new PullAtomMetadata.Builder()
                     .setAdditiveFields(new int[] {3})
@@ -1660,17 +1661,18 @@ public class StatsPullAtomService extends SystemService {
     }
 
     private void registerCpuCyclesPerThreadGroupCluster() {
-        // TODO(b/173227907): Register only when supported.
-        int tagId = FrameworkStatsLog.CPU_CYCLES_PER_THREAD_GROUP_CLUSTER;
-        PullAtomMetadata metadata = new PullAtomMetadata.Builder()
-                .setAdditiveFields(new int[] {3, 4})
-                .build();
-        mStatsManager.setPullAtomCallback(
-                tagId,
-                metadata,
-                DIRECT_EXECUTOR,
-                mStatsCallbackImpl
-        );
+        if (KernelCpuBpfTracking.isSupported()) {
+            int tagId = FrameworkStatsLog.CPU_CYCLES_PER_THREAD_GROUP_CLUSTER;
+            PullAtomMetadata metadata = new PullAtomMetadata.Builder()
+                    .setAdditiveFields(new int[] {3, 4})
+                    .build();
+            mStatsManager.setPullAtomCallback(
+                    tagId,
+                    metadata,
+                    DIRECT_EXECUTOR,
+                    mStatsCallbackImpl
+            );
+        }
     }
 
     int pullCpuCyclesPerThreadGroupCluster(int atomTag, List<StatsEvent> pulledData) {