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Commit e036a133 authored by Dmitri Plotnikov's avatar Dmitri Plotnikov
Browse files

Reduce array locking in LongArrayMultiStateCounter 

Do this by checking if the data is all-zeros and returning
false in that case, without locking the java long array in JNI

Bug: 395954049
Test: atest PowerStatsTests; atest PowerStatsTests:BatteryUsageStatsProviderPerfTest#getBatteryUsageStats_accumulated
Flag: EXEMPT bugfix

Change-Id: I81639d9d571afcbb61ea047d8b2ab5e1b2bcf6f0
parent 241cfec9

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

+6 −3
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


package com.android.internal.os;



import android.annotation.CheckResult;

import android.annotation.Nullable;

import android.os.Parcel;

import android.os.Parcelable;
@@ -196,7 +197,8 @@ public final class LongArrayMultiStateCounter implements Parcelable { 
    /**

     * Populates the array with the accumulated counts for the specified state.

     */

    public void getCounts(long[] counts, int state) {

    @CheckResult

    public boolean getCounts(long[] counts, int state) {

        if (state < 0 || state >= mStateCount) {

            throw new IllegalArgumentException(

                    "State: " + state + ", outside the range: [0-" + mStateCount + "]");
@@ -205,7 +207,7 @@ public final class LongArrayMultiStateCounter implements Parcelable { 
            throw new IllegalArgumentException(

                    "Invalid array length: " + counts.length + ", expected: " + mLength);

        }

        native_getCounts(mNativeObject, counts, state);

        return native_getCounts(mNativeObject, counts, state);

    }



    @Override
@@ -282,7 +284,8 @@ public final class LongArrayMultiStateCounter implements Parcelable { 


    @FastNative

    @RavenwoodRedirect

    private static native void native_getCounts(long nativeObject, long[] counts, int state);

    @CheckResult

    private static native boolean native_getCounts(long nativeObject, long[] counts, int state);



    @FastNative

    @RavenwoodRedirect

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

+16 −4
Original line number Diff line number Diff line
@@ -168,8 +168,20 @@ class LongArrayMultiStateCounter_ravenwood { 
            }

        }



        public void getValues(long[] values, int state) {

            System.arraycopy(mStates[state].mCounter, 0, values, 0, mArrayLength);

        public boolean getValues(long[] values, int state) {

            long[] counts = mStates[state].mCounter;

            boolean allZeros = true;

            for (int i = 0; i < counts.length; i++) {

                if (counts[i] != 0) {

                    allZeros = false;

                    break;

                }

            }

            if (allZeros) {

                return false;

            }

            System.arraycopy(counts, 0, values, 0, mArrayLength);

            return true;

        }



        public void reset() {
@@ -316,8 +328,8 @@ class LongArrayMultiStateCounter_ravenwood { 
        getInstance(instanceId).addCounts(counts);

    }



    public static void native_getCounts(long instanceId, long[] counts, int state) {

        getInstance(instanceId).getValues(counts, state);

    public static boolean native_getCounts(long instanceId, long[] counts, int state) {

        return getInstance(instanceId).getValues(counts, state);

    }



    public static void native_reset(long instanceId) {

core/jni/com_android_internal_os_LongArrayMultiStateCounter.cpp

+17 −8
Original line number Diff line number Diff line
@@ -116,17 +116,26 @@ static void native_reset(jlong nativePtr) { 
    counter->reset();

}



static void native_getCounts(JNIEnv *env, jclass, jlong nativePtr, jlongArray values, jint state) {

static bool native_getCounts(JNIEnv *env, jclass, jlong nativePtr, jlongArray values, jint state) {

    auto *counter = reinterpret_cast<LongArrayMultiStateCounter *>(nativePtr);

    ScopedLongArrayRW scopedArray(env, values);

    auto *data = counter->getCount(state).data();

    auto size = env->GetArrayLength(values);

    auto *outData = scopedArray.get();

    if (data == nullptr) {

        memset(outData, 0, size * sizeof(uint64_t));

    } else {

        memcpy(outData, data, size * sizeof(uint64_t));

        return false;

    }

    auto size = env->GetArrayLength(values);

    bool allZeros = true;

    for (int i = 0; i < size; i++) {

        if (data[i]) {

            allZeros = false;

            break;

        }

    }

    if (allZeros) {

        return false;

    }

    ScopedLongArrayRW scopedArray(env, values);

    memcpy(scopedArray.get(), data, size * sizeof(uint64_t));

    return true;

}



static jobject native_toString(JNIEnv *env, jclass, jlong nativePtr) {
@@ -255,7 +264,7 @@ static const JNINativeMethod g_LongArrayMultiStateCounter_methods[] = { 
        // @CriticalNative

        {"native_reset", "(J)V", (void *)native_reset},

        // @FastNative

        {"native_getCounts", "(J[JI)V", (void *)native_getCounts},

        {"native_getCounts", "(J[JI)Z", (void *)native_getCounts},

        // @FastNative

        {"native_toString", "(J)Ljava/lang/String;", (void *)native_toString},

        // @FastNative

core/tests/coretests/src/com/android/internal/os/KernelSingleUidTimeReaderTest.java

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ import static org.junit.Assert.assertEquals; 
import static org.junit.Assert.assertFalse;

import static org.junit.Assert.assertTrue;



import android.annotation.SuppressLint;

import android.platform.test.annotations.IgnoreUnderRavenwood;

import android.platform.test.ravenwood.RavenwoodRule;

import android.util.SparseArray;
@@ -287,6 +288,7 @@ public class KernelSingleUidTimeReaderTest { 
                0, lastUidCpuTimes.size());

    }



    @SuppressLint("CheckResult")

    @Test

    public void testAddDeltaFromBpf() {

        LongArrayMultiStateCounter counter = new LongArrayMultiStateCounter(2, 5);

core/tests/coretests/src/com/android/internal/os/LongArrayMultiStateCounterTest.java

+2 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ import static com.google.common.truth.Truth.assertThat; 


import static org.junit.Assert.assertThrows;



import android.annotation.SuppressLint;

import android.os.BadParcelableException;

import android.os.Parcel;

import android.platform.test.ravenwood.RavenwoodRule;
@@ -176,6 +177,7 @@ public class LongArrayMultiStateCounterTest { 
        assertCounts(newCounter, 0, new long[]{116, 232, 364, 528});

    }



    @SuppressLint("CheckResult")

    private void assertCounts(LongArrayMultiStateCounter counter, int state, long[] expected) {

        long[] counts = new long[expected.length];

        counter.getCounts(counts, state);