WeakIdentityHashMap [1010613]

// by Apache; modified
sclass WeakIdentityHashMap<K, V> implements Map<K, V> {
  private final ReferenceQueue<K> queue = new ReferenceQueue<K>();
  private Map<IdentityWeakReference, V> backingStore
    = new HashMap<IdentityWeakReference, V>();
    
  *() {
    _registerWeakMap(this);
  }

  public synchronized void clear() {
    backingStore.clear();
    reap();
  }

  public synchronized boolean containsKey(Object key) {
    reap();
    return backingStore.containsKey(new IdentityWeakReference(key));
  }

  public synchronized boolean containsValue(Object value)  {
    reap();
    return backingStore.containsValue(value);
  }

  public synchronized Set<Map.Entry<K, V>> entrySet() {
    reap();
    Set<Map.Entry<K, V>> ret = new HashSet<Map.Entry<K, V>>();
    for (Map.Entry<IdentityWeakReference, V> ref : backingStore.entrySet()) {
      final K key = ref.getKey().get();
      final V value = ref.getValue();
      Map.Entry<K, V> entry = new Map.Entry<K, V>() {
        public synchronized K getKey() {
          return key;
        }
        public synchronized V getValue() {
          return value;
        }
        public synchronized V setValue(V value) {
          throw new UnsupportedOperationException();
        }
      };
      ret.add(entry);
    }
    return Collections.unmodifiableSet(ret);
  }

  public synchronized Set<K> keySet() {
    reap();
    new IdentityHashMap<K, Bool> map;
    for (IdentityWeakReference ref : backingStore.keySet()) {
      K k = ref.get();
      if (k != null) map.put(k, Bool.TRUE);
    }
    return map.keySet();
  }

  public synchronized boolean equals(Object o) {
    if (!(o instanceof WeakIdentityHashMap)) {
      return false;
    }
    return backingStore.equals(((WeakIdentityHashMap)o).backingStore);
  }

  public synchronized V get(Object key) {
    reap();
    return backingStore.get(new IdentityWeakReference(key));
  }
  
  // return value seems unreliable (see ButtonImageLoader)
  public synchronized V put(K key, V value) {
    reap();
    return backingStore.put(new IdentityWeakReference(key), value);
  }

  public synchronized int hashCode() {
    reap();
    return backingStore.hashCode();
  }
  public synchronized boolean isEmpty() {
    reap();
    return backingStore.isEmpty();
  }
  public synchronized void putAll(Map t) {
    throw new UnsupportedOperationException();
  }
  
  // TODO: the IdentityWeakReference made is later enqueued,
  // even though it's not added to the map. Is that a problem?
  public synchronized V remove(Object key) {
    reap();
    return backingStore.remove(new IdentityWeakReference(key));
  }
  public synchronized int size() {
    reap();
    return backingStore.size();
  }
  public synchronized Collection<V> values() {
    reap();
    return backingStore.values();
  }

  private synchronized void reap() {
    O zombie = queue.poll();

    while (zombie != null) {
      IdentityWeakReference victim = (IdentityWeakReference) zombie;
      ifdef WeakIdentityHashMap_debug
        print("WeakIdentityHashMap removing: " + victim.get());
      endifdef
      backingStore.remove(victim);
      zombie = queue.poll();
    }
  }

  class IdentityWeakReference extends WeakReference<K> {
    int hash;

    @SuppressWarnings("unchecked")
      IdentityWeakReference(Object obj) {
      super((K)obj, queue);
      hash = System.identityHashCode(obj);
    }

    public synchronized int hashCode() {
      return hash;
    }

    public synchronized boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (!(o instanceof WeakIdentityHashMap.IdentityWeakReference)) {
        return false;
      }
      IdentityWeakReference ref = (IdentityWeakReference)o;
      if (this.get() == ref.get()) {
        return true;
      }
      return false;
    }
  }
}

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1	// by Apache; modified
2	sclass WeakIdentityHashMap<K, V> implements Map<K, V> {
3	private final ReferenceQueue<K> queue = new ReferenceQueue<K>();
4	private Map<IdentityWeakReference, V> backingStore
5	= new HashMap<IdentityWeakReference, V>();
6
7	*() {
8	_registerWeakMap(this);
9	}
10
11	public synchronized void clear() {
12	backingStore.clear();
13	reap();
14	}
15
16	public synchronized boolean containsKey(Object key) {
17	reap();
18	return backingStore.containsKey(new IdentityWeakReference(key));
19	}
20
21	public synchronized boolean containsValue(Object value) {
22	reap();
23	return backingStore.containsValue(value);
24	}
25
26	public synchronized Set<Map.Entry<K, V>> entrySet() {
27	reap();
28	Set<Map.Entry<K, V>> ret = new HashSet<Map.Entry<K, V>>();
29	for (Map.Entry<IdentityWeakReference, V> ref : backingStore.entrySet()) {
30	final K key = ref.getKey().get();
31	final V value = ref.getValue();
32	Map.Entry<K, V> entry = new Map.Entry<K, V>() {
33	public synchronized K getKey() {
34	return key;
35	}
36	public synchronized V getValue() {
37	return value;
38	}
39	public synchronized V setValue(V value) {
40	throw new UnsupportedOperationException();
41	}
42	};
43	ret.add(entry);
44	}
45	return Collections.unmodifiableSet(ret);
46	}
47
48	public synchronized Set<K> keySet() {
49	reap();
50	new IdentityHashMap<K, Bool> map;
51	for (IdentityWeakReference ref : backingStore.keySet()) {
52	K k = ref.get();
53	if (k != null) map.put(k, Bool.TRUE);
54	}
55	return map.keySet();
56	}
57
58	public synchronized boolean equals(Object o) {
59	if (!(o instanceof WeakIdentityHashMap)) {
60	return false;
61	}
62	return backingStore.equals(((WeakIdentityHashMap)o).backingStore);
63	}
64
65	public synchronized V get(Object key) {
66	reap();
67	return backingStore.get(new IdentityWeakReference(key));
68	}
69
70	// return value seems unreliable (see ButtonImageLoader)
71	public synchronized V put(K key, V value) {
72	reap();
73	return backingStore.put(new IdentityWeakReference(key), value);
74	}
75
76	public synchronized int hashCode() {
77	reap();
78	return backingStore.hashCode();
79	}
80	public synchronized boolean isEmpty() {
81	reap();
82	return backingStore.isEmpty();
83	}
84	public synchronized void putAll(Map t) {
85	throw new UnsupportedOperationException();
86	}
87
88	// TODO: the IdentityWeakReference made is later enqueued,
89	// even though it's not added to the map. Is that a problem?
90	public synchronized V remove(Object key) {
91	reap();
92	return backingStore.remove(new IdentityWeakReference(key));
93	}
94	public synchronized int size() {
95	reap();
96	return backingStore.size();
97	}
98	public synchronized Collection<V> values() {
99	reap();
100	return backingStore.values();
101	}
102
103	private synchronized void reap() {
104	O zombie = queue.poll();
105
106	while (zombie != null) {
107	IdentityWeakReference victim = (IdentityWeakReference) zombie;
108	ifdef WeakIdentityHashMap_debug
109	print("WeakIdentityHashMap removing: " + victim.get());
110	endifdef
111	backingStore.remove(victim);
112	zombie = queue.poll();
113	}
114	}
115
116	class IdentityWeakReference extends WeakReference<K> {
117	int hash;
118
119	@SuppressWarnings("unchecked")
120	IdentityWeakReference(Object obj) {
121	super((K)obj, queue);
122	hash = System.identityHashCode(obj);
123	}
124
125	public synchronized int hashCode() {
126	return hash;
127	}
128
129	public synchronized boolean equals(Object o) {
130	if (this == o) {
131	return true;
132	}
133	if (!(o instanceof WeakIdentityHashMap.IdentityWeakReference)) {
134	return false;
135	}
136	IdentityWeakReference ref = (IdentityWeakReference)o;
137	if (this.get() == ref.get()) {
138	return true;
139	}
140	return false;
141	}
142	}
143	}

Snippet ID:	#1010613
Snippet name:	WeakIdentityHashMap
Eternal ID of this version:	#1010613/10
Text MD5:	14f1e5c9bc0f22afaded52438ab1040f
Author:	stefan
Category:	javax
Type:	JavaX fragment (include)
Public (visible to everyone):	Yes
Archived (hidden from active list):	No
Created/modified:	2018-06-06 12:25:09
Source code size:	3959 bytes / 143 lines
Pitched / IR pitched:	No / No
Views / Downloads:	454 / 1592
Version history:	9 change(s)
Referenced in:	[show references]

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