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| <FONT color="green">001</FONT> /*<a name="line.1"></a> |
| <FONT color="green">002</FONT> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a> |
| <FONT color="green">003</FONT> * or more contributor license agreements. See the NOTICE file<a name="line.3"></a> |
| <FONT color="green">004</FONT> * distributed with this work for additional information<a name="line.4"></a> |
| <FONT color="green">005</FONT> * regarding copyright ownership. The ASF licenses this file<a name="line.5"></a> |
| <FONT color="green">006</FONT> * to you under the Apache License, Version 2.0 (the<a name="line.6"></a> |
| <FONT color="green">007</FONT> * "License"); you may not use this file except in compliance<a name="line.7"></a> |
| <FONT color="green">008</FONT> * with the License. You may obtain a copy of the License at<a name="line.8"></a> |
| <FONT color="green">009</FONT> *<a name="line.9"></a> |
| <FONT color="green">010</FONT> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a> |
| <FONT color="green">011</FONT> *<a name="line.11"></a> |
| <FONT color="green">012</FONT> * Unless required by applicable law or agreed to in writing,<a name="line.12"></a> |
| <FONT color="green">013</FONT> * software distributed under the License is distributed on an<a name="line.13"></a> |
| <FONT color="green">014</FONT> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY<a name="line.14"></a> |
| <FONT color="green">015</FONT> * KIND, either express or implied. See the License for the<a name="line.15"></a> |
| <FONT color="green">016</FONT> * specific language governing permissions and limitations<a name="line.16"></a> |
| <FONT color="green">017</FONT> * under the License.<a name="line.17"></a> |
| <FONT color="green">018</FONT> */<a name="line.18"></a> |
| <FONT color="green">019</FONT> package org.apache.shiro.util;<a name="line.19"></a> |
| <FONT color="green">020</FONT> <a name="line.20"></a> |
| <FONT color="green">021</FONT> import java.lang.ref.ReferenceQueue;<a name="line.21"></a> |
| <FONT color="green">022</FONT> import java.lang.ref.SoftReference;<a name="line.22"></a> |
| <FONT color="green">023</FONT> import java.util.*;<a name="line.23"></a> |
| <FONT color="green">024</FONT> import java.util.concurrent.ConcurrentHashMap;<a name="line.24"></a> |
| <FONT color="green">025</FONT> import java.util.concurrent.ConcurrentLinkedQueue;<a name="line.25"></a> |
| <FONT color="green">026</FONT> import java.util.concurrent.locks.ReentrantLock;<a name="line.26"></a> |
| <FONT color="green">027</FONT> <a name="line.27"></a> |
| <FONT color="green">028</FONT> <a name="line.28"></a> |
| <FONT color="green">029</FONT> /**<a name="line.29"></a> |
| <FONT color="green">030</FONT> * A <code><em>Soft</em>HashMap</code> is a memory-constrained map that stores its <em>values</em> in<a name="line.30"></a> |
| <FONT color="green">031</FONT> * {@link SoftReference SoftReference}s. (Contrast this with the JDK's<a name="line.31"></a> |
| <FONT color="green">032</FONT> * {@link WeakHashMap WeakHashMap}, which uses weak references for its <em>keys</em>, which is of little value if you<a name="line.32"></a> |
| <FONT color="green">033</FONT> * want the cache to auto-resize itself based on memory constraints).<a name="line.33"></a> |
| <FONT color="green">034</FONT> * <p/><a name="line.34"></a> |
| <FONT color="green">035</FONT> * Having the values wrapped by soft references allows the cache to automatically reduce its size based on memory<a name="line.35"></a> |
| <FONT color="green">036</FONT> * limitations and garbage collection. This ensures that the cache will not cause memory leaks by holding strong<a name="line.36"></a> |
| <FONT color="green">037</FONT> * references to all of its values.<a name="line.37"></a> |
| <FONT color="green">038</FONT> * <p/><a name="line.38"></a> |
| <FONT color="green">039</FONT> * This class is a generics-enabled Map based on initial ideas from Heinz Kabutz's and Sydney Redelinghuys's<a name="line.39"></a> |
| <FONT color="green">040</FONT> * <a href="http://www.javaspecialists.eu/archive/Issue015.html">publicly posted version (with their approval)</a>, with<a name="line.40"></a> |
| <FONT color="green">041</FONT> * continued modifications.<a name="line.41"></a> |
| <FONT color="green">042</FONT> * <p/><a name="line.42"></a> |
| <FONT color="green">043</FONT> * This implementation is thread-safe and usable in concurrent environments.<a name="line.43"></a> |
| <FONT color="green">044</FONT> *<a name="line.44"></a> |
| <FONT color="green">045</FONT> * @since 1.0<a name="line.45"></a> |
| <FONT color="green">046</FONT> */<a name="line.46"></a> |
| <FONT color="green">047</FONT> public class SoftHashMap<K, V> implements Map<K, V> {<a name="line.47"></a> |
| <FONT color="green">048</FONT> <a name="line.48"></a> |
| <FONT color="green">049</FONT> /**<a name="line.49"></a> |
| <FONT color="green">050</FONT> * The default value of the RETENTION_SIZE attribute, equal to 100.<a name="line.50"></a> |
| <FONT color="green">051</FONT> */<a name="line.51"></a> |
| <FONT color="green">052</FONT> private static final int DEFAULT_RETENTION_SIZE = 100;<a name="line.52"></a> |
| <FONT color="green">053</FONT> <a name="line.53"></a> |
| <FONT color="green">054</FONT> /**<a name="line.54"></a> |
| <FONT color="green">055</FONT> * The internal HashMap that will hold the SoftReference.<a name="line.55"></a> |
| <FONT color="green">056</FONT> */<a name="line.56"></a> |
| <FONT color="green">057</FONT> private final Map<K, SoftValue<V, K>> map;<a name="line.57"></a> |
| <FONT color="green">058</FONT> <a name="line.58"></a> |
| <FONT color="green">059</FONT> /**<a name="line.59"></a> |
| <FONT color="green">060</FONT> * The number of strong references to hold internally, that is, the number of instances to prevent<a name="line.60"></a> |
| <FONT color="green">061</FONT> * from being garbage collected automatically (unlike other soft references).<a name="line.61"></a> |
| <FONT color="green">062</FONT> */<a name="line.62"></a> |
| <FONT color="green">063</FONT> private final int RETENTION_SIZE;<a name="line.63"></a> |
| <FONT color="green">064</FONT> <a name="line.64"></a> |
| <FONT color="green">065</FONT> /**<a name="line.65"></a> |
| <FONT color="green">066</FONT> * The FIFO list of strong references (not to be garbage collected), order of last access.<a name="line.66"></a> |
| <FONT color="green">067</FONT> */<a name="line.67"></a> |
| <FONT color="green">068</FONT> private final Queue<V> strongReferences; //guarded by 'strongReferencesLock'<a name="line.68"></a> |
| <FONT color="green">069</FONT> private final ReentrantLock strongReferencesLock;<a name="line.69"></a> |
| <FONT color="green">070</FONT> <a name="line.70"></a> |
| <FONT color="green">071</FONT> /**<a name="line.71"></a> |
| <FONT color="green">072</FONT> * Reference queue for cleared SoftReference objects.<a name="line.72"></a> |
| <FONT color="green">073</FONT> */<a name="line.73"></a> |
| <FONT color="green">074</FONT> private final ReferenceQueue<? super V> queue;<a name="line.74"></a> |
| <FONT color="green">075</FONT> <a name="line.75"></a> |
| <FONT color="green">076</FONT> /**<a name="line.76"></a> |
| <FONT color="green">077</FONT> * Creates a new SoftHashMap with a default retention size size of<a name="line.77"></a> |
| <FONT color="green">078</FONT> * {@link #DEFAULT_RETENTION_SIZE DEFAULT_RETENTION_SIZE} (100 entries).<a name="line.78"></a> |
| <FONT color="green">079</FONT> *<a name="line.79"></a> |
| <FONT color="green">080</FONT> * @see #SoftHashMap(int)<a name="line.80"></a> |
| <FONT color="green">081</FONT> */<a name="line.81"></a> |
| <FONT color="green">082</FONT> public SoftHashMap() {<a name="line.82"></a> |
| <FONT color="green">083</FONT> this(DEFAULT_RETENTION_SIZE);<a name="line.83"></a> |
| <FONT color="green">084</FONT> }<a name="line.84"></a> |
| <FONT color="green">085</FONT> <a name="line.85"></a> |
| <FONT color="green">086</FONT> /**<a name="line.86"></a> |
| <FONT color="green">087</FONT> * Creates a new SoftHashMap with the specified retention size.<a name="line.87"></a> |
| <FONT color="green">088</FONT> * <p/><a name="line.88"></a> |
| <FONT color="green">089</FONT> * The retention size (n) is the total number of most recent entries in the map that will be strongly referenced<a name="line.89"></a> |
| <FONT color="green">090</FONT> * (ie 'retained') to prevent them from being eagerly garbage collected. That is, the point of a SoftHashMap is to<a name="line.90"></a> |
| <FONT color="green">091</FONT> * allow the garbage collector to remove as many entries from this map as it desires, but there will always be (n)<a name="line.91"></a> |
| <FONT color="green">092</FONT> * elements retained after a GC due to the strong references.<a name="line.92"></a> |
| <FONT color="green">093</FONT> * <p/><a name="line.93"></a> |
| <FONT color="green">094</FONT> * Note that in a highly concurrent environments the exact total number of strong references may differ slightly<a name="line.94"></a> |
| <FONT color="green">095</FONT> * than the actual <code>retentionSize</code> value. This number is intended to be a best-effort retention low<a name="line.95"></a> |
| <FONT color="green">096</FONT> * water mark.<a name="line.96"></a> |
| <FONT color="green">097</FONT> *<a name="line.97"></a> |
| <FONT color="green">098</FONT> * @param retentionSize the total number of most recent entries in the map that will be strongly referenced<a name="line.98"></a> |
| <FONT color="green">099</FONT> * (retained), preventing them from being eagerly garbage collected by the JVM.<a name="line.99"></a> |
| <FONT color="green">100</FONT> */<a name="line.100"></a> |
| <FONT color="green">101</FONT> @SuppressWarnings({"unchecked"})<a name="line.101"></a> |
| <FONT color="green">102</FONT> public SoftHashMap(int retentionSize) {<a name="line.102"></a> |
| <FONT color="green">103</FONT> super();<a name="line.103"></a> |
| <FONT color="green">104</FONT> RETENTION_SIZE = Math.max(0, retentionSize);<a name="line.104"></a> |
| <FONT color="green">105</FONT> queue = new ReferenceQueue<V>();<a name="line.105"></a> |
| <FONT color="green">106</FONT> strongReferencesLock = new ReentrantLock();<a name="line.106"></a> |
| <FONT color="green">107</FONT> map = new ConcurrentHashMap<K, SoftValue<V, K>>();<a name="line.107"></a> |
| <FONT color="green">108</FONT> strongReferences = new ConcurrentLinkedQueue<V>();<a name="line.108"></a> |
| <FONT color="green">109</FONT> }<a name="line.109"></a> |
| <FONT color="green">110</FONT> <a name="line.110"></a> |
| <FONT color="green">111</FONT> /**<a name="line.111"></a> |
| <FONT color="green">112</FONT> * Creates a {@code SoftHashMap} backed by the specified {@code source}, with a default retention<a name="line.112"></a> |
| <FONT color="green">113</FONT> * size of {@link #DEFAULT_RETENTION_SIZE DEFAULT_RETENTION_SIZE} (100 entries).<a name="line.113"></a> |
| <FONT color="green">114</FONT> *<a name="line.114"></a> |
| <FONT color="green">115</FONT> * @param source the backing map to populate this {@code SoftHashMap}<a name="line.115"></a> |
| <FONT color="green">116</FONT> * @see #SoftHashMap(Map,int)<a name="line.116"></a> |
| <FONT color="green">117</FONT> */<a name="line.117"></a> |
| <FONT color="green">118</FONT> public SoftHashMap(Map<K, V> source) {<a name="line.118"></a> |
| <FONT color="green">119</FONT> this(DEFAULT_RETENTION_SIZE);<a name="line.119"></a> |
| <FONT color="green">120</FONT> putAll(source);<a name="line.120"></a> |
| <FONT color="green">121</FONT> }<a name="line.121"></a> |
| <FONT color="green">122</FONT> <a name="line.122"></a> |
| <FONT color="green">123</FONT> /**<a name="line.123"></a> |
| <FONT color="green">124</FONT> * Creates a {@code SoftHashMap} backed by the specified {@code source}, with the specified retention size.<a name="line.124"></a> |
| <FONT color="green">125</FONT> * <p/><a name="line.125"></a> |
| <FONT color="green">126</FONT> * The retention size (n) is the total number of most recent entries in the map that will be strongly referenced<a name="line.126"></a> |
| <FONT color="green">127</FONT> * (ie 'retained') to prevent them from being eagerly garbage collected. That is, the point of a SoftHashMap is to<a name="line.127"></a> |
| <FONT color="green">128</FONT> * allow the garbage collector to remove as many entries from this map as it desires, but there will always be (n)<a name="line.128"></a> |
| <FONT color="green">129</FONT> * elements retained after a GC due to the strong references.<a name="line.129"></a> |
| <FONT color="green">130</FONT> * <p/><a name="line.130"></a> |
| <FONT color="green">131</FONT> * Note that in a highly concurrent environments the exact total number of strong references may differ slightly<a name="line.131"></a> |
| <FONT color="green">132</FONT> * than the actual <code>retentionSize</code> value. This number is intended to be a best-effort retention low<a name="line.132"></a> |
| <FONT color="green">133</FONT> * water mark.<a name="line.133"></a> |
| <FONT color="green">134</FONT> *<a name="line.134"></a> |
| <FONT color="green">135</FONT> * @param source the backing map to populate this {@code SoftHashMap}<a name="line.135"></a> |
| <FONT color="green">136</FONT> * @param retentionSize the total number of most recent entries in the map that will be strongly referenced<a name="line.136"></a> |
| <FONT color="green">137</FONT> * (retained), preventing them from being eagerly garbage collected by the JVM.<a name="line.137"></a> |
| <FONT color="green">138</FONT> */<a name="line.138"></a> |
| <FONT color="green">139</FONT> public SoftHashMap(Map<K, V> source, int retentionSize) {<a name="line.139"></a> |
| <FONT color="green">140</FONT> this(retentionSize);<a name="line.140"></a> |
| <FONT color="green">141</FONT> putAll(source);<a name="line.141"></a> |
| <FONT color="green">142</FONT> }<a name="line.142"></a> |
| <FONT color="green">143</FONT> <a name="line.143"></a> |
| <FONT color="green">144</FONT> public V get(Object key) {<a name="line.144"></a> |
| <FONT color="green">145</FONT> processQueue();<a name="line.145"></a> |
| <FONT color="green">146</FONT> <a name="line.146"></a> |
| <FONT color="green">147</FONT> V result = null;<a name="line.147"></a> |
| <FONT color="green">148</FONT> SoftValue<V, K> value = map.get(key);<a name="line.148"></a> |
| <FONT color="green">149</FONT> <a name="line.149"></a> |
| <FONT color="green">150</FONT> if (value != null) {<a name="line.150"></a> |
| <FONT color="green">151</FONT> //unwrap the 'real' value from the SoftReference<a name="line.151"></a> |
| <FONT color="green">152</FONT> result = value.get();<a name="line.152"></a> |
| <FONT color="green">153</FONT> if (result == null) {<a name="line.153"></a> |
| <FONT color="green">154</FONT> //The wrapped value was garbage collected, so remove this entry from the backing map:<a name="line.154"></a> |
| <FONT color="green">155</FONT> //noinspection SuspiciousMethodCalls<a name="line.155"></a> |
| <FONT color="green">156</FONT> map.remove(key);<a name="line.156"></a> |
| <FONT color="green">157</FONT> } else {<a name="line.157"></a> |
| <FONT color="green">158</FONT> //Add this value to the beginning of the strong reference queue (FIFO).<a name="line.158"></a> |
| <FONT color="green">159</FONT> addToStrongReferences(result);<a name="line.159"></a> |
| <FONT color="green">160</FONT> }<a name="line.160"></a> |
| <FONT color="green">161</FONT> }<a name="line.161"></a> |
| <FONT color="green">162</FONT> return result;<a name="line.162"></a> |
| <FONT color="green">163</FONT> }<a name="line.163"></a> |
| <FONT color="green">164</FONT> <a name="line.164"></a> |
| <FONT color="green">165</FONT> private void addToStrongReferences(V result) {<a name="line.165"></a> |
| <FONT color="green">166</FONT> strongReferencesLock.lock();<a name="line.166"></a> |
| <FONT color="green">167</FONT> try {<a name="line.167"></a> |
| <FONT color="green">168</FONT> strongReferences.add(result);<a name="line.168"></a> |
| <FONT color="green">169</FONT> trimStrongReferencesIfNecessary();<a name="line.169"></a> |
| <FONT color="green">170</FONT> } finally {<a name="line.170"></a> |
| <FONT color="green">171</FONT> strongReferencesLock.unlock();<a name="line.171"></a> |
| <FONT color="green">172</FONT> }<a name="line.172"></a> |
| <FONT color="green">173</FONT> <a name="line.173"></a> |
| <FONT color="green">174</FONT> }<a name="line.174"></a> |
| <FONT color="green">175</FONT> <a name="line.175"></a> |
| <FONT color="green">176</FONT> //Guarded by the strongReferencesLock in the addToStrongReferences method<a name="line.176"></a> |
| <FONT color="green">177</FONT> <a name="line.177"></a> |
| <FONT color="green">178</FONT> private void trimStrongReferencesIfNecessary() {<a name="line.178"></a> |
| <FONT color="green">179</FONT> //trim the strong ref queue if necessary:<a name="line.179"></a> |
| <FONT color="green">180</FONT> while (strongReferences.size() > RETENTION_SIZE) {<a name="line.180"></a> |
| <FONT color="green">181</FONT> strongReferences.poll();<a name="line.181"></a> |
| <FONT color="green">182</FONT> }<a name="line.182"></a> |
| <FONT color="green">183</FONT> }<a name="line.183"></a> |
| <FONT color="green">184</FONT> <a name="line.184"></a> |
| <FONT color="green">185</FONT> /**<a name="line.185"></a> |
| <FONT color="green">186</FONT> * Traverses the ReferenceQueue and removes garbage-collected SoftValue objects from the backing map<a name="line.186"></a> |
| <FONT color="green">187</FONT> * by looking them up using the SoftValue.key data member.<a name="line.187"></a> |
| <FONT color="green">188</FONT> */<a name="line.188"></a> |
| <FONT color="green">189</FONT> private void processQueue() {<a name="line.189"></a> |
| <FONT color="green">190</FONT> SoftValue sv;<a name="line.190"></a> |
| <FONT color="green">191</FONT> while ((sv = (SoftValue) queue.poll()) != null) {<a name="line.191"></a> |
| <FONT color="green">192</FONT> //noinspection SuspiciousMethodCalls<a name="line.192"></a> |
| <FONT color="green">193</FONT> map.remove(sv.key); // we can access private data!<a name="line.193"></a> |
| <FONT color="green">194</FONT> }<a name="line.194"></a> |
| <FONT color="green">195</FONT> }<a name="line.195"></a> |
| <FONT color="green">196</FONT> <a name="line.196"></a> |
| <FONT color="green">197</FONT> public boolean isEmpty() {<a name="line.197"></a> |
| <FONT color="green">198</FONT> processQueue();<a name="line.198"></a> |
| <FONT color="green">199</FONT> return map.isEmpty();<a name="line.199"></a> |
| <FONT color="green">200</FONT> }<a name="line.200"></a> |
| <FONT color="green">201</FONT> <a name="line.201"></a> |
| <FONT color="green">202</FONT> public boolean containsKey(Object key) {<a name="line.202"></a> |
| <FONT color="green">203</FONT> processQueue();<a name="line.203"></a> |
| <FONT color="green">204</FONT> return map.containsKey(key);<a name="line.204"></a> |
| <FONT color="green">205</FONT> }<a name="line.205"></a> |
| <FONT color="green">206</FONT> <a name="line.206"></a> |
| <FONT color="green">207</FONT> public boolean containsValue(Object value) {<a name="line.207"></a> |
| <FONT color="green">208</FONT> processQueue();<a name="line.208"></a> |
| <FONT color="green">209</FONT> Collection values = values();<a name="line.209"></a> |
| <FONT color="green">210</FONT> return values != null && values.contains(value);<a name="line.210"></a> |
| <FONT color="green">211</FONT> }<a name="line.211"></a> |
| <FONT color="green">212</FONT> <a name="line.212"></a> |
| <FONT color="green">213</FONT> public void putAll(Map<? extends K, ? extends V> m) {<a name="line.213"></a> |
| <FONT color="green">214</FONT> if (m == null || m.isEmpty()) {<a name="line.214"></a> |
| <FONT color="green">215</FONT> processQueue();<a name="line.215"></a> |
| <FONT color="green">216</FONT> return;<a name="line.216"></a> |
| <FONT color="green">217</FONT> }<a name="line.217"></a> |
| <FONT color="green">218</FONT> for (Map.Entry<? extends K, ? extends V> entry : m.entrySet()) {<a name="line.218"></a> |
| <FONT color="green">219</FONT> put(entry.getKey(), entry.getValue());<a name="line.219"></a> |
| <FONT color="green">220</FONT> }<a name="line.220"></a> |
| <FONT color="green">221</FONT> }<a name="line.221"></a> |
| <FONT color="green">222</FONT> <a name="line.222"></a> |
| <FONT color="green">223</FONT> public Set<K> keySet() {<a name="line.223"></a> |
| <FONT color="green">224</FONT> processQueue();<a name="line.224"></a> |
| <FONT color="green">225</FONT> return map.keySet();<a name="line.225"></a> |
| <FONT color="green">226</FONT> }<a name="line.226"></a> |
| <FONT color="green">227</FONT> <a name="line.227"></a> |
| <FONT color="green">228</FONT> public Collection<V> values() {<a name="line.228"></a> |
| <FONT color="green">229</FONT> processQueue();<a name="line.229"></a> |
| <FONT color="green">230</FONT> Collection<K> keys = map.keySet();<a name="line.230"></a> |
| <FONT color="green">231</FONT> if (keys.isEmpty()) {<a name="line.231"></a> |
| <FONT color="green">232</FONT> //noinspection unchecked<a name="line.232"></a> |
| <FONT color="green">233</FONT> return Collections.EMPTY_SET;<a name="line.233"></a> |
| <FONT color="green">234</FONT> }<a name="line.234"></a> |
| <FONT color="green">235</FONT> Collection<V> values = new ArrayList<V>(keys.size());<a name="line.235"></a> |
| <FONT color="green">236</FONT> for (K key : keys) {<a name="line.236"></a> |
| <FONT color="green">237</FONT> V v = get(key);<a name="line.237"></a> |
| <FONT color="green">238</FONT> if (v != null) {<a name="line.238"></a> |
| <FONT color="green">239</FONT> values.add(v);<a name="line.239"></a> |
| <FONT color="green">240</FONT> }<a name="line.240"></a> |
| <FONT color="green">241</FONT> }<a name="line.241"></a> |
| <FONT color="green">242</FONT> return values;<a name="line.242"></a> |
| <FONT color="green">243</FONT> }<a name="line.243"></a> |
| <FONT color="green">244</FONT> <a name="line.244"></a> |
| <FONT color="green">245</FONT> /**<a name="line.245"></a> |
| <FONT color="green">246</FONT> * Creates a new entry, but wraps the value in a SoftValue instance to enable auto garbage collection.<a name="line.246"></a> |
| <FONT color="green">247</FONT> */<a name="line.247"></a> |
| <FONT color="green">248</FONT> public V put(K key, V value) {<a name="line.248"></a> |
| <FONT color="green">249</FONT> processQueue(); // throw out garbage collected values first<a name="line.249"></a> |
| <FONT color="green">250</FONT> SoftValue<V, K> sv = new SoftValue<V, K>(value, key, queue);<a name="line.250"></a> |
| <FONT color="green">251</FONT> SoftValue<V, K> previous = map.put(key, sv);<a name="line.251"></a> |
| <FONT color="green">252</FONT> addToStrongReferences(value);<a name="line.252"></a> |
| <FONT color="green">253</FONT> return previous != null ? previous.get() : null;<a name="line.253"></a> |
| <FONT color="green">254</FONT> }<a name="line.254"></a> |
| <FONT color="green">255</FONT> <a name="line.255"></a> |
| <FONT color="green">256</FONT> public V remove(Object key) {<a name="line.256"></a> |
| <FONT color="green">257</FONT> processQueue(); // throw out garbage collected values first<a name="line.257"></a> |
| <FONT color="green">258</FONT> SoftValue<V, K> raw = map.remove(key);<a name="line.258"></a> |
| <FONT color="green">259</FONT> return raw != null ? raw.get() : null;<a name="line.259"></a> |
| <FONT color="green">260</FONT> }<a name="line.260"></a> |
| <FONT color="green">261</FONT> <a name="line.261"></a> |
| <FONT color="green">262</FONT> public void clear() {<a name="line.262"></a> |
| <FONT color="green">263</FONT> strongReferencesLock.lock();<a name="line.263"></a> |
| <FONT color="green">264</FONT> try {<a name="line.264"></a> |
| <FONT color="green">265</FONT> strongReferences.clear();<a name="line.265"></a> |
| <FONT color="green">266</FONT> } finally {<a name="line.266"></a> |
| <FONT color="green">267</FONT> strongReferencesLock.unlock();<a name="line.267"></a> |
| <FONT color="green">268</FONT> }<a name="line.268"></a> |
| <FONT color="green">269</FONT> processQueue(); // throw out garbage collected values<a name="line.269"></a> |
| <FONT color="green">270</FONT> map.clear();<a name="line.270"></a> |
| <FONT color="green">271</FONT> }<a name="line.271"></a> |
| <FONT color="green">272</FONT> <a name="line.272"></a> |
| <FONT color="green">273</FONT> public int size() {<a name="line.273"></a> |
| <FONT color="green">274</FONT> processQueue(); // throw out garbage collected values first<a name="line.274"></a> |
| <FONT color="green">275</FONT> return map.size();<a name="line.275"></a> |
| <FONT color="green">276</FONT> }<a name="line.276"></a> |
| <FONT color="green">277</FONT> <a name="line.277"></a> |
| <FONT color="green">278</FONT> public Set<Map.Entry<K, V>> entrySet() {<a name="line.278"></a> |
| <FONT color="green">279</FONT> processQueue(); // throw out garbage collected values first<a name="line.279"></a> |
| <FONT color="green">280</FONT> Collection<K> keys = map.keySet();<a name="line.280"></a> |
| <FONT color="green">281</FONT> if (keys.isEmpty()) {<a name="line.281"></a> |
| <FONT color="green">282</FONT> //noinspection unchecked<a name="line.282"></a> |
| <FONT color="green">283</FONT> return Collections.EMPTY_SET;<a name="line.283"></a> |
| <FONT color="green">284</FONT> }<a name="line.284"></a> |
| <FONT color="green">285</FONT> <a name="line.285"></a> |
| <FONT color="green">286</FONT> Map<K, V> kvPairs = new HashMap<K, V>(keys.size());<a name="line.286"></a> |
| <FONT color="green">287</FONT> for (K key : keys) {<a name="line.287"></a> |
| <FONT color="green">288</FONT> V v = get(key);<a name="line.288"></a> |
| <FONT color="green">289</FONT> if (v != null) {<a name="line.289"></a> |
| <FONT color="green">290</FONT> kvPairs.put(key, v);<a name="line.290"></a> |
| <FONT color="green">291</FONT> }<a name="line.291"></a> |
| <FONT color="green">292</FONT> }<a name="line.292"></a> |
| <FONT color="green">293</FONT> return kvPairs.entrySet();<a name="line.293"></a> |
| <FONT color="green">294</FONT> }<a name="line.294"></a> |
| <FONT color="green">295</FONT> <a name="line.295"></a> |
| <FONT color="green">296</FONT> /**<a name="line.296"></a> |
| <FONT color="green">297</FONT> * We define our own subclass of SoftReference which contains<a name="line.297"></a> |
| <FONT color="green">298</FONT> * not only the value but also the key to make it easier to find<a name="line.298"></a> |
| <FONT color="green">299</FONT> * the entry in the HashMap after it's been garbage collected.<a name="line.299"></a> |
| <FONT color="green">300</FONT> */<a name="line.300"></a> |
| <FONT color="green">301</FONT> private static class SoftValue<V, K> extends SoftReference<V> {<a name="line.301"></a> |
| <FONT color="green">302</FONT> <a name="line.302"></a> |
| <FONT color="green">303</FONT> private final K key;<a name="line.303"></a> |
| <FONT color="green">304</FONT> <a name="line.304"></a> |
| <FONT color="green">305</FONT> /**<a name="line.305"></a> |
| <FONT color="green">306</FONT> * Constructs a new instance, wrapping the value, key, and queue, as<a name="line.306"></a> |
| <FONT color="green">307</FONT> * required by the superclass.<a name="line.307"></a> |
| <FONT color="green">308</FONT> *<a name="line.308"></a> |
| <FONT color="green">309</FONT> * @param value the map value<a name="line.309"></a> |
| <FONT color="green">310</FONT> * @param key the map key<a name="line.310"></a> |
| <FONT color="green">311</FONT> * @param queue the soft reference queue to poll to determine if the entry had been reaped by the GC.<a name="line.311"></a> |
| <FONT color="green">312</FONT> */<a name="line.312"></a> |
| <FONT color="green">313</FONT> private SoftValue(V value, K key, ReferenceQueue<? super V> queue) {<a name="line.313"></a> |
| <FONT color="green">314</FONT> super(value, queue);<a name="line.314"></a> |
| <FONT color="green">315</FONT> this.key = key;<a name="line.315"></a> |
| <FONT color="green">316</FONT> }<a name="line.316"></a> |
| <FONT color="green">317</FONT> <a name="line.317"></a> |
| <FONT color="green">318</FONT> }<a name="line.318"></a> |
| <FONT color="green">319</FONT> }<a name="line.319"></a> |
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