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      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 java.lang.ref.Reference;
     20 import java.lang.ref.ReferenceQueue;
     21 import java.lang.ref.WeakReference;
     22 import java.util.Collection;
     23 import java.util.HashMap;
     24 import java.util.Map;
     25 import java.util.Set;
     26 
     27 /**
     28  * Like WeakHashMap, but uses identity instead of equality when comparing keys.
     29  */
     30 public class WeakIdentityHashMap<K,V> {
     31 
     32     private final HashMap<WeakReference<K>,V> mMap = new HashMap<>();
     33     private final ReferenceQueue<Object> mRefQueue = new ReferenceQueue<>();
     34 
     35     private void cleanUp() {
     36         Reference<?> ref;
     37         while ((ref = mRefQueue.poll()) != null) {
     38             mMap.remove(ref);
     39         }
     40     }
     41 
     42     public void put(K key, V value) {
     43         cleanUp();
     44         mMap.put(new CmpWeakReference<>(key, mRefQueue), value);
     45     }
     46 
     47     public V get(K key) {
     48         cleanUp();
     49         return mMap.get(new CmpWeakReference<>(key));
     50     }
     51 
     52     public Collection<V> values() {
     53         cleanUp();
     54         return mMap.values();
     55     }
     56 
     57     public Set<Map.Entry<WeakReference<K>, V>> entrySet() {
     58         return mMap.entrySet();
     59     }
     60 
     61     public int size() {
     62         cleanUp();
     63         return mMap.size();
     64     }
     65 
     66     public boolean isEmpty() {
     67         cleanUp();
     68         return mMap.isEmpty();
     69     }
     70 
     71     private static class CmpWeakReference<K> extends WeakReference<K> {
     72         private final int mHashCode;
     73 
     74         public CmpWeakReference(K key) {
     75             super(key);
     76             mHashCode = System.identityHashCode(key);
     77         }
     78 
     79         public CmpWeakReference(K key, ReferenceQueue<Object> refQueue) {
     80             super(key, refQueue);
     81             mHashCode = System.identityHashCode(key);
     82         }
     83 
     84         @Override
     85         public boolean equals(Object o) {
     86             if (o == this) {
     87                 return true;
     88             }
     89             K k = get();
     90             if (k != null && o instanceof CmpWeakReference) {
     91                 return ((CmpWeakReference) o).get() == k;
     92             }
     93             return false;
     94         }
     95 
     96         @Override
     97         public int hashCode() {
     98             return mHashCode;
     99         }
    100     }
    101 }
    102