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/*
* Copyright (C) 2017 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.systemui.util.leak;
import android.os.SystemClock;
import android.util.ArrayMap;
import java.io.PrintWriter;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.HashSet;
import java.util.Map;
/**
* Tracks objects that have been marked as garbage.
*/
public class TrackedGarbage {
/** Duration after which we consider garbage to be old. */
private static final long GARBAGE_COLLECTION_DEADLINE_MILLIS = 60000; // 1min
private final HashSet<LeakReference> mGarbage = new HashSet<>();
private final ReferenceQueue<Object> mRefQueue = new ReferenceQueue<>();
private final TrackedCollections mTrackedCollections;
public TrackedGarbage(TrackedCollections trackedCollections) {
mTrackedCollections = trackedCollections;
}
/**
* @see LeakDetector#trackGarbage(Object)
*/
public synchronized void track(Object o) {
cleanUp();
mGarbage.add(new LeakReference(o, mRefQueue));
mTrackedCollections.track(mGarbage, "Garbage");
}
private void cleanUp() {
Reference<?> ref;
while ((ref = mRefQueue.poll()) != null) {
mGarbage.remove(ref);
}
}
/**
* A reference to something we consider leaked if it still has strong references.
*
* Helpful for finding potential leaks in a heapdump: Simply find an instance of
* LeakReference, find the object it refers to, then find a strong path to a GC root.
*/
private static class LeakReference extends WeakReference<Object> {
private final Class<?> clazz;
private final long createdUptimeMillis;
LeakReference(Object t, ReferenceQueue<Object> queue) {
super(t, queue);
clazz = t.getClass();
createdUptimeMillis = SystemClock.uptimeMillis();
}
}
/**
* Dump statistics about the garbage.
*
* For each class, dumps the number of "garbage objects" that have not been collected yet.
* A large number of old instances indicates a probable leak.
*/
public synchronized void dump(PrintWriter pw) {
cleanUp();
long now = SystemClock.uptimeMillis();
ArrayMap<Class<?>, Integer> acc = new ArrayMap<>();
ArrayMap<Class<?>, Integer> accOld = new ArrayMap<>();
for (LeakReference ref : mGarbage) {
acc.put(ref.clazz, acc.getOrDefault(ref.clazz, 0) + 1);
if (isOld(ref.createdUptimeMillis, now)) {
accOld.put(ref.clazz, accOld.getOrDefault(ref.clazz, 0) + 1);
}
}
for (Map.Entry<Class<?>, Integer> entry : acc.entrySet()) {
pw.print(entry.getKey().getName());
pw.print(": ");
pw.print(entry.getValue());
pw.print(" total, ");
pw.print(accOld.getOrDefault(entry.getKey(), 0));
pw.print(" old");
pw.println();
}
}
public synchronized int countOldGarbage() {
cleanUp();
long now = SystemClock.uptimeMillis();
int result = 0;
for (LeakReference ref : mGarbage) {
if (isOld(ref.createdUptimeMillis, now)) {
result++;
}
}
return result;
}
private boolean isOld(long createdUptimeMillis, long now) {
return createdUptimeMillis + GARBAGE_COLLECTION_DEADLINE_MILLIS < now;
}
}
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