1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.systemui.util.leak; 18 19 import android.os.SystemClock; 20 import android.util.ArrayMap; 21 22 import java.io.PrintWriter; 23 import java.lang.ref.Reference; 24 import java.lang.ref.ReferenceQueue; 25 import java.lang.ref.WeakReference; 26 import java.util.HashSet; 27 import java.util.Map; 28 29 /** 30 * Tracks objects that have been marked as garbage. 31 */ 32 public class TrackedGarbage { 33 34 /** Duration after which we consider garbage to be old. */ 35 private static final long GARBAGE_COLLECTION_DEADLINE_MILLIS = 60000; // 1min 36 37 private final HashSet<LeakReference> mGarbage = new HashSet<>(); 38 private final ReferenceQueue<Object> mRefQueue = new ReferenceQueue<>(); 39 private final TrackedCollections mTrackedCollections; 40 TrackedGarbage(TrackedCollections trackedCollections)41 public TrackedGarbage(TrackedCollections trackedCollections) { 42 mTrackedCollections = trackedCollections; 43 } 44 45 /** 46 * @see LeakDetector#trackGarbage(Object) 47 */ track(Object o)48 public synchronized void track(Object o) { 49 cleanUp(); 50 mGarbage.add(new LeakReference(o, mRefQueue)); 51 mTrackedCollections.track(mGarbage, "Garbage"); 52 } 53 cleanUp()54 private void cleanUp() { 55 Reference<?> ref; 56 while ((ref = mRefQueue.poll()) != null) { 57 mGarbage.remove(ref); 58 } 59 } 60 61 /** 62 * A reference to something we consider leaked if it still has strong references. 63 * 64 * Helpful for finding potential leaks in a heapdump: Simply find an instance of 65 * LeakReference, find the object it refers to, then find a strong path to a GC root. 66 */ 67 private static class LeakReference extends WeakReference<Object> { 68 private final Class<?> clazz; 69 private final long createdUptimeMillis; 70 LeakReference(Object t, ReferenceQueue<Object> queue)71 LeakReference(Object t, ReferenceQueue<Object> queue) { 72 super(t, queue); 73 clazz = t.getClass(); 74 createdUptimeMillis = SystemClock.uptimeMillis(); 75 } 76 } 77 78 /** 79 * Dump statistics about the garbage. 80 * 81 * For each class, dumps the number of "garbage objects" that have not been collected yet. 82 * A large number of old instances indicates a probable leak. 83 */ dump(PrintWriter pw)84 public synchronized void dump(PrintWriter pw) { 85 cleanUp(); 86 87 long now = SystemClock.uptimeMillis(); 88 89 ArrayMap<Class<?>, Integer> acc = new ArrayMap<>(); 90 ArrayMap<Class<?>, Integer> accOld = new ArrayMap<>(); 91 for (LeakReference ref : mGarbage) { 92 acc.put(ref.clazz, acc.getOrDefault(ref.clazz, 0) + 1); 93 if (isOld(ref.createdUptimeMillis, now)) { 94 accOld.put(ref.clazz, accOld.getOrDefault(ref.clazz, 0) + 1); 95 } 96 } 97 98 for (Map.Entry<Class<?>, Integer> entry : acc.entrySet()) { 99 pw.print(entry.getKey().getName()); 100 pw.print(": "); 101 pw.print(entry.getValue()); 102 pw.print(" total, "); 103 pw.print(accOld.getOrDefault(entry.getKey(), 0)); 104 pw.print(" old"); 105 pw.println(); 106 } 107 } 108 countOldGarbage()109 public synchronized int countOldGarbage() { 110 cleanUp(); 111 112 long now = SystemClock.uptimeMillis(); 113 114 int result = 0; 115 for (LeakReference ref : mGarbage) { 116 if (isOld(ref.createdUptimeMillis, now)) { 117 result++; 118 } 119 } 120 return result; 121 } 122 isOld(long createdUptimeMillis, long now)123 private boolean isOld(long createdUptimeMillis, long now) { 124 return createdUptimeMillis + GARBAGE_COLLECTION_DEADLINE_MILLIS < now; 125 } 126 } 127