| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html lang="en"> |
| <head> |
| <title>Source code</title> |
| <link rel="stylesheet" type="text/css" href="../../../../../stylesheet.css" title="Style"> |
| </head> |
| <body> |
| <div class="sourceContainer"> |
| <pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a> |
| <span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a> |
| <span class="sourceLineNo">003</span> * or more contributor license agreements. See the NOTICE file<a name="line.3"></a> |
| <span class="sourceLineNo">004</span> * distributed with this work for additional information<a name="line.4"></a> |
| <span class="sourceLineNo">005</span> * regarding copyright ownership. The ASF licenses this file<a name="line.5"></a> |
| <span class="sourceLineNo">006</span> * to you under the Apache License, Version 2.0 (the<a name="line.6"></a> |
| <span class="sourceLineNo">007</span> * "License"); you may not use this file except in compliance<a name="line.7"></a> |
| <span class="sourceLineNo">008</span> * with the License. You may obtain a copy of the License at<a name="line.8"></a> |
| <span class="sourceLineNo">009</span> *<a name="line.9"></a> |
| <span class="sourceLineNo">010</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a> |
| <span class="sourceLineNo">011</span> *<a name="line.11"></a> |
| <span class="sourceLineNo">012</span> * Unless required by applicable law or agreed to in writing,<a name="line.12"></a> |
| <span class="sourceLineNo">013</span> * software distributed under the License is distributed on an<a name="line.13"></a> |
| <span class="sourceLineNo">014</span> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY<a name="line.14"></a> |
| <span class="sourceLineNo">015</span> * KIND, either express or implied. See the License for the<a name="line.15"></a> |
| <span class="sourceLineNo">016</span> * specific language governing permissions and limitations<a name="line.16"></a> |
| <span class="sourceLineNo">017</span> * under the License.<a name="line.17"></a> |
| <span class="sourceLineNo">018</span> */<a name="line.18"></a> |
| <span class="sourceLineNo">019</span>package org.apache.shiro.util;<a name="line.19"></a> |
| <span class="sourceLineNo">020</span><a name="line.20"></a> |
| <span class="sourceLineNo">021</span>import java.lang.ref.ReferenceQueue;<a name="line.21"></a> |
| <span class="sourceLineNo">022</span>import java.lang.ref.SoftReference;<a name="line.22"></a> |
| <span class="sourceLineNo">023</span>import java.util.*;<a name="line.23"></a> |
| <span class="sourceLineNo">024</span>import java.util.concurrent.ConcurrentHashMap;<a name="line.24"></a> |
| <span class="sourceLineNo">025</span>import java.util.concurrent.ConcurrentLinkedQueue;<a name="line.25"></a> |
| <span class="sourceLineNo">026</span>import java.util.concurrent.locks.ReentrantLock;<a name="line.26"></a> |
| <span class="sourceLineNo">027</span><a name="line.27"></a> |
| <span class="sourceLineNo">028</span><a name="line.28"></a> |
| <span class="sourceLineNo">029</span>/**<a name="line.29"></a> |
| <span class="sourceLineNo">030</span> * A <code><em>Soft</em>HashMap</code> is a memory-constrained map that stores its <em>values</em> in<a name="line.30"></a> |
| <span class="sourceLineNo">031</span> * {@link SoftReference SoftReference}s. (Contrast this with the JDK's<a name="line.31"></a> |
| <span class="sourceLineNo">032</span> * {@link WeakHashMap WeakHashMap}, which uses weak references for its <em>keys</em>, which is of little value if you<a name="line.32"></a> |
| <span class="sourceLineNo">033</span> * want the cache to auto-resize itself based on memory constraints).<a name="line.33"></a> |
| <span class="sourceLineNo">034</span> * <p/><a name="line.34"></a> |
| <span class="sourceLineNo">035</span> * Having the values wrapped by soft references allows the cache to automatically reduce its size based on memory<a name="line.35"></a> |
| <span class="sourceLineNo">036</span> * limitations and garbage collection. This ensures that the cache will not cause memory leaks by holding strong<a name="line.36"></a> |
| <span class="sourceLineNo">037</span> * references to all of its values.<a name="line.37"></a> |
| <span class="sourceLineNo">038</span> * <p/><a name="line.38"></a> |
| <span class="sourceLineNo">039</span> * This class is a generics-enabled Map based on initial ideas from Heinz Kabutz's and Sydney Redelinghuys's<a name="line.39"></a> |
| <span class="sourceLineNo">040</span> * <a href="http://www.javaspecialists.eu/archive/Issue015.html">publicly posted version (with their approval)</a>, with<a name="line.40"></a> |
| <span class="sourceLineNo">041</span> * continued modifications.<a name="line.41"></a> |
| <span class="sourceLineNo">042</span> * <p/><a name="line.42"></a> |
| <span class="sourceLineNo">043</span> * This implementation is thread-safe and usable in concurrent environments.<a name="line.43"></a> |
| <span class="sourceLineNo">044</span> *<a name="line.44"></a> |
| <span class="sourceLineNo">045</span> * @since 1.0<a name="line.45"></a> |
| <span class="sourceLineNo">046</span> */<a name="line.46"></a> |
| <span class="sourceLineNo">047</span>public class SoftHashMap<K, V> implements Map<K, V> {<a name="line.47"></a> |
| <span class="sourceLineNo">048</span><a name="line.48"></a> |
| <span class="sourceLineNo">049</span> /**<a name="line.49"></a> |
| <span class="sourceLineNo">050</span> * The default value of the RETENTION_SIZE attribute, equal to 100.<a name="line.50"></a> |
| <span class="sourceLineNo">051</span> */<a name="line.51"></a> |
| <span class="sourceLineNo">052</span> private static final int DEFAULT_RETENTION_SIZE = 100;<a name="line.52"></a> |
| <span class="sourceLineNo">053</span><a name="line.53"></a> |
| <span class="sourceLineNo">054</span> /**<a name="line.54"></a> |
| <span class="sourceLineNo">055</span> * The internal HashMap that will hold the SoftReference.<a name="line.55"></a> |
| <span class="sourceLineNo">056</span> */<a name="line.56"></a> |
| <span class="sourceLineNo">057</span> private final Map<K, SoftValue<V, K>> map;<a name="line.57"></a> |
| <span class="sourceLineNo">058</span><a name="line.58"></a> |
| <span class="sourceLineNo">059</span> /**<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> * The number of strong references to hold internally, that is, the number of instances to prevent<a name="line.60"></a> |
| <span class="sourceLineNo">061</span> * from being garbage collected automatically (unlike other soft references).<a name="line.61"></a> |
| <span class="sourceLineNo">062</span> */<a name="line.62"></a> |
| <span class="sourceLineNo">063</span> private final int RETENTION_SIZE;<a name="line.63"></a> |
| <span class="sourceLineNo">064</span><a name="line.64"></a> |
| <span class="sourceLineNo">065</span> /**<a name="line.65"></a> |
| <span class="sourceLineNo">066</span> * The FIFO list of strong references (not to be garbage collected), order of last access.<a name="line.66"></a> |
| <span class="sourceLineNo">067</span> */<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> private final Queue<V> strongReferences; //guarded by 'strongReferencesLock'<a name="line.68"></a> |
| <span class="sourceLineNo">069</span> private final ReentrantLock strongReferencesLock;<a name="line.69"></a> |
| <span class="sourceLineNo">070</span><a name="line.70"></a> |
| <span class="sourceLineNo">071</span> /**<a name="line.71"></a> |
| <span class="sourceLineNo">072</span> * Reference queue for cleared SoftReference objects.<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> */<a name="line.73"></a> |
| <span class="sourceLineNo">074</span> private final ReferenceQueue<? super V> queue;<a name="line.74"></a> |
| <span class="sourceLineNo">075</span><a name="line.75"></a> |
| <span class="sourceLineNo">076</span> /**<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> * Creates a new SoftHashMap with a default retention size size of<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> * {@link #DEFAULT_RETENTION_SIZE DEFAULT_RETENTION_SIZE} (100 entries).<a name="line.78"></a> |
| <span class="sourceLineNo">079</span> *<a name="line.79"></a> |
| <span class="sourceLineNo">080</span> * @see #SoftHashMap(int)<a name="line.80"></a> |
| <span class="sourceLineNo">081</span> */<a name="line.81"></a> |
| <span class="sourceLineNo">082</span> public SoftHashMap() {<a name="line.82"></a> |
| <span class="sourceLineNo">083</span> this(DEFAULT_RETENTION_SIZE);<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> }<a name="line.84"></a> |
| <span class="sourceLineNo">085</span><a name="line.85"></a> |
| <span class="sourceLineNo">086</span> /**<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> * Creates a new SoftHashMap with the specified retention size.<a name="line.87"></a> |
| <span class="sourceLineNo">088</span> * <p/><a name="line.88"></a> |
| <span class="sourceLineNo">089</span> * 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> |
| <span class="sourceLineNo">090</span> * (ie 'retained') to prevent them from being eagerly garbage collected. That is, the point of a SoftHashMap is to<a name="line.90"></a> |
| <span class="sourceLineNo">091</span> * 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> |
| <span class="sourceLineNo">092</span> * elements retained after a GC due to the strong references.<a name="line.92"></a> |
| <span class="sourceLineNo">093</span> * <p/><a name="line.93"></a> |
| <span class="sourceLineNo">094</span> * Note that in a highly concurrent environments the exact total number of strong references may differ slightly<a name="line.94"></a> |
| <span class="sourceLineNo">095</span> * than the actual <code>retentionSize</code> value. This number is intended to be a best-effort retention low<a name="line.95"></a> |
| <span class="sourceLineNo">096</span> * water mark.<a name="line.96"></a> |
| <span class="sourceLineNo">097</span> *<a name="line.97"></a> |
| <span class="sourceLineNo">098</span> * @param retentionSize the total number of most recent entries in the map that will be strongly referenced<a name="line.98"></a> |
| <span class="sourceLineNo">099</span> * (retained), preventing them from being eagerly garbage collected by the JVM.<a name="line.99"></a> |
| <span class="sourceLineNo">100</span> */<a name="line.100"></a> |
| <span class="sourceLineNo">101</span> @SuppressWarnings({"unchecked"})<a name="line.101"></a> |
| <span class="sourceLineNo">102</span> public SoftHashMap(int retentionSize) {<a name="line.102"></a> |
| <span class="sourceLineNo">103</span> super();<a name="line.103"></a> |
| <span class="sourceLineNo">104</span> RETENTION_SIZE = Math.max(0, retentionSize);<a name="line.104"></a> |
| <span class="sourceLineNo">105</span> queue = new ReferenceQueue<V>();<a name="line.105"></a> |
| <span class="sourceLineNo">106</span> strongReferencesLock = new ReentrantLock();<a name="line.106"></a> |
| <span class="sourceLineNo">107</span> map = new ConcurrentHashMap<K, SoftValue<V, K>>();<a name="line.107"></a> |
| <span class="sourceLineNo">108</span> strongReferences = new ConcurrentLinkedQueue<V>();<a name="line.108"></a> |
| <span class="sourceLineNo">109</span> }<a name="line.109"></a> |
| <span class="sourceLineNo">110</span><a name="line.110"></a> |
| <span class="sourceLineNo">111</span> /**<a name="line.111"></a> |
| <span class="sourceLineNo">112</span> * Creates a {@code SoftHashMap} backed by the specified {@code source}, with a default retention<a name="line.112"></a> |
| <span class="sourceLineNo">113</span> * size of {@link #DEFAULT_RETENTION_SIZE DEFAULT_RETENTION_SIZE} (100 entries).<a name="line.113"></a> |
| <span class="sourceLineNo">114</span> *<a name="line.114"></a> |
| <span class="sourceLineNo">115</span> * @param source the backing map to populate this {@code SoftHashMap}<a name="line.115"></a> |
| <span class="sourceLineNo">116</span> * @see #SoftHashMap(Map,int)<a name="line.116"></a> |
| <span class="sourceLineNo">117</span> */<a name="line.117"></a> |
| <span class="sourceLineNo">118</span> public SoftHashMap(Map<K, V> source) {<a name="line.118"></a> |
| <span class="sourceLineNo">119</span> this(DEFAULT_RETENTION_SIZE);<a name="line.119"></a> |
| <span class="sourceLineNo">120</span> putAll(source);<a name="line.120"></a> |
| <span class="sourceLineNo">121</span> }<a name="line.121"></a> |
| <span class="sourceLineNo">122</span><a name="line.122"></a> |
| <span class="sourceLineNo">123</span> /**<a name="line.123"></a> |
| <span class="sourceLineNo">124</span> * Creates a {@code SoftHashMap} backed by the specified {@code source}, with the specified retention size.<a name="line.124"></a> |
| <span class="sourceLineNo">125</span> * <p/><a name="line.125"></a> |
| <span class="sourceLineNo">126</span> * 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> |
| <span class="sourceLineNo">127</span> * (ie 'retained') to prevent them from being eagerly garbage collected. That is, the point of a SoftHashMap is to<a name="line.127"></a> |
| <span class="sourceLineNo">128</span> * 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> |
| <span class="sourceLineNo">129</span> * elements retained after a GC due to the strong references.<a name="line.129"></a> |
| <span class="sourceLineNo">130</span> * <p/><a name="line.130"></a> |
| <span class="sourceLineNo">131</span> * Note that in a highly concurrent environments the exact total number of strong references may differ slightly<a name="line.131"></a> |
| <span class="sourceLineNo">132</span> * than the actual <code>retentionSize</code> value. This number is intended to be a best-effort retention low<a name="line.132"></a> |
| <span class="sourceLineNo">133</span> * water mark.<a name="line.133"></a> |
| <span class="sourceLineNo">134</span> *<a name="line.134"></a> |
| <span class="sourceLineNo">135</span> * @param source the backing map to populate this {@code SoftHashMap}<a name="line.135"></a> |
| <span class="sourceLineNo">136</span> * @param retentionSize the total number of most recent entries in the map that will be strongly referenced<a name="line.136"></a> |
| <span class="sourceLineNo">137</span> * (retained), preventing them from being eagerly garbage collected by the JVM.<a name="line.137"></a> |
| <span class="sourceLineNo">138</span> */<a name="line.138"></a> |
| <span class="sourceLineNo">139</span> public SoftHashMap(Map<K, V> source, int retentionSize) {<a name="line.139"></a> |
| <span class="sourceLineNo">140</span> this(retentionSize);<a name="line.140"></a> |
| <span class="sourceLineNo">141</span> putAll(source);<a name="line.141"></a> |
| <span class="sourceLineNo">142</span> }<a name="line.142"></a> |
| <span class="sourceLineNo">143</span><a name="line.143"></a> |
| <span class="sourceLineNo">144</span> public V get(Object key) {<a name="line.144"></a> |
| <span class="sourceLineNo">145</span> processQueue();<a name="line.145"></a> |
| <span class="sourceLineNo">146</span><a name="line.146"></a> |
| <span class="sourceLineNo">147</span> V result = null;<a name="line.147"></a> |
| <span class="sourceLineNo">148</span> SoftValue<V, K> value = map.get(key);<a name="line.148"></a> |
| <span class="sourceLineNo">149</span><a name="line.149"></a> |
| <span class="sourceLineNo">150</span> if (value != null) {<a name="line.150"></a> |
| <span class="sourceLineNo">151</span> //unwrap the 'real' value from the SoftReference<a name="line.151"></a> |
| <span class="sourceLineNo">152</span> result = value.get();<a name="line.152"></a> |
| <span class="sourceLineNo">153</span> if (result == null) {<a name="line.153"></a> |
| <span class="sourceLineNo">154</span> //The wrapped value was garbage collected, so remove this entry from the backing map:<a name="line.154"></a> |
| <span class="sourceLineNo">155</span> //noinspection SuspiciousMethodCalls<a name="line.155"></a> |
| <span class="sourceLineNo">156</span> map.remove(key);<a name="line.156"></a> |
| <span class="sourceLineNo">157</span> } else {<a name="line.157"></a> |
| <span class="sourceLineNo">158</span> //Add this value to the beginning of the strong reference queue (FIFO).<a name="line.158"></a> |
| <span class="sourceLineNo">159</span> addToStrongReferences(result);<a name="line.159"></a> |
| <span class="sourceLineNo">160</span> }<a name="line.160"></a> |
| <span class="sourceLineNo">161</span> }<a name="line.161"></a> |
| <span class="sourceLineNo">162</span> return result;<a name="line.162"></a> |
| <span class="sourceLineNo">163</span> }<a name="line.163"></a> |
| <span class="sourceLineNo">164</span><a name="line.164"></a> |
| <span class="sourceLineNo">165</span> private void addToStrongReferences(V result) {<a name="line.165"></a> |
| <span class="sourceLineNo">166</span> strongReferencesLock.lock();<a name="line.166"></a> |
| <span class="sourceLineNo">167</span> try {<a name="line.167"></a> |
| <span class="sourceLineNo">168</span> strongReferences.add(result);<a name="line.168"></a> |
| <span class="sourceLineNo">169</span> trimStrongReferencesIfNecessary();<a name="line.169"></a> |
| <span class="sourceLineNo">170</span> } finally {<a name="line.170"></a> |
| <span class="sourceLineNo">171</span> strongReferencesLock.unlock();<a name="line.171"></a> |
| <span class="sourceLineNo">172</span> }<a name="line.172"></a> |
| <span class="sourceLineNo">173</span><a name="line.173"></a> |
| <span class="sourceLineNo">174</span> }<a name="line.174"></a> |
| <span class="sourceLineNo">175</span><a name="line.175"></a> |
| <span class="sourceLineNo">176</span> //Guarded by the strongReferencesLock in the addToStrongReferences method<a name="line.176"></a> |
| <span class="sourceLineNo">177</span><a name="line.177"></a> |
| <span class="sourceLineNo">178</span> private void trimStrongReferencesIfNecessary() {<a name="line.178"></a> |
| <span class="sourceLineNo">179</span> //trim the strong ref queue if necessary:<a name="line.179"></a> |
| <span class="sourceLineNo">180</span> while (strongReferences.size() > RETENTION_SIZE) {<a name="line.180"></a> |
| <span class="sourceLineNo">181</span> strongReferences.poll();<a name="line.181"></a> |
| <span class="sourceLineNo">182</span> }<a name="line.182"></a> |
| <span class="sourceLineNo">183</span> }<a name="line.183"></a> |
| <span class="sourceLineNo">184</span><a name="line.184"></a> |
| <span class="sourceLineNo">185</span> /**<a name="line.185"></a> |
| <span class="sourceLineNo">186</span> * Traverses the ReferenceQueue and removes garbage-collected SoftValue objects from the backing map<a name="line.186"></a> |
| <span class="sourceLineNo">187</span> * by looking them up using the SoftValue.key data member.<a name="line.187"></a> |
| <span class="sourceLineNo">188</span> */<a name="line.188"></a> |
| <span class="sourceLineNo">189</span> private void processQueue() {<a name="line.189"></a> |
| <span class="sourceLineNo">190</span> SoftValue sv;<a name="line.190"></a> |
| <span class="sourceLineNo">191</span> while ((sv = (SoftValue) queue.poll()) != null) {<a name="line.191"></a> |
| <span class="sourceLineNo">192</span> //noinspection SuspiciousMethodCalls<a name="line.192"></a> |
| <span class="sourceLineNo">193</span> map.remove(sv.key); // we can access private data!<a name="line.193"></a> |
| <span class="sourceLineNo">194</span> }<a name="line.194"></a> |
| <span class="sourceLineNo">195</span> }<a name="line.195"></a> |
| <span class="sourceLineNo">196</span><a name="line.196"></a> |
| <span class="sourceLineNo">197</span> public boolean isEmpty() {<a name="line.197"></a> |
| <span class="sourceLineNo">198</span> processQueue();<a name="line.198"></a> |
| <span class="sourceLineNo">199</span> return map.isEmpty();<a name="line.199"></a> |
| <span class="sourceLineNo">200</span> }<a name="line.200"></a> |
| <span class="sourceLineNo">201</span><a name="line.201"></a> |
| <span class="sourceLineNo">202</span> public boolean containsKey(Object key) {<a name="line.202"></a> |
| <span class="sourceLineNo">203</span> processQueue();<a name="line.203"></a> |
| <span class="sourceLineNo">204</span> return map.containsKey(key);<a name="line.204"></a> |
| <span class="sourceLineNo">205</span> }<a name="line.205"></a> |
| <span class="sourceLineNo">206</span><a name="line.206"></a> |
| <span class="sourceLineNo">207</span> public boolean containsValue(Object value) {<a name="line.207"></a> |
| <span class="sourceLineNo">208</span> processQueue();<a name="line.208"></a> |
| <span class="sourceLineNo">209</span> Collection values = values();<a name="line.209"></a> |
| <span class="sourceLineNo">210</span> return values != null && values.contains(value);<a name="line.210"></a> |
| <span class="sourceLineNo">211</span> }<a name="line.211"></a> |
| <span class="sourceLineNo">212</span><a name="line.212"></a> |
| <span class="sourceLineNo">213</span> public void putAll(Map<? extends K, ? extends V> m) {<a name="line.213"></a> |
| <span class="sourceLineNo">214</span> if (m == null || m.isEmpty()) {<a name="line.214"></a> |
| <span class="sourceLineNo">215</span> processQueue();<a name="line.215"></a> |
| <span class="sourceLineNo">216</span> return;<a name="line.216"></a> |
| <span class="sourceLineNo">217</span> }<a name="line.217"></a> |
| <span class="sourceLineNo">218</span> for (Map.Entry<? extends K, ? extends V> entry : m.entrySet()) {<a name="line.218"></a> |
| <span class="sourceLineNo">219</span> put(entry.getKey(), entry.getValue());<a name="line.219"></a> |
| <span class="sourceLineNo">220</span> }<a name="line.220"></a> |
| <span class="sourceLineNo">221</span> }<a name="line.221"></a> |
| <span class="sourceLineNo">222</span><a name="line.222"></a> |
| <span class="sourceLineNo">223</span> public Set<K> keySet() {<a name="line.223"></a> |
| <span class="sourceLineNo">224</span> processQueue();<a name="line.224"></a> |
| <span class="sourceLineNo">225</span> return map.keySet();<a name="line.225"></a> |
| <span class="sourceLineNo">226</span> }<a name="line.226"></a> |
| <span class="sourceLineNo">227</span><a name="line.227"></a> |
| <span class="sourceLineNo">228</span> public Collection<V> values() {<a name="line.228"></a> |
| <span class="sourceLineNo">229</span> processQueue();<a name="line.229"></a> |
| <span class="sourceLineNo">230</span> Collection<K> keys = map.keySet();<a name="line.230"></a> |
| <span class="sourceLineNo">231</span> if (keys.isEmpty()) {<a name="line.231"></a> |
| <span class="sourceLineNo">232</span> //noinspection unchecked<a name="line.232"></a> |
| <span class="sourceLineNo">233</span> return Collections.EMPTY_SET;<a name="line.233"></a> |
| <span class="sourceLineNo">234</span> }<a name="line.234"></a> |
| <span class="sourceLineNo">235</span> Collection<V> values = new ArrayList<V>(keys.size());<a name="line.235"></a> |
| <span class="sourceLineNo">236</span> for (K key : keys) {<a name="line.236"></a> |
| <span class="sourceLineNo">237</span> V v = get(key);<a name="line.237"></a> |
| <span class="sourceLineNo">238</span> if (v != null) {<a name="line.238"></a> |
| <span class="sourceLineNo">239</span> values.add(v);<a name="line.239"></a> |
| <span class="sourceLineNo">240</span> }<a name="line.240"></a> |
| <span class="sourceLineNo">241</span> }<a name="line.241"></a> |
| <span class="sourceLineNo">242</span> return values;<a name="line.242"></a> |
| <span class="sourceLineNo">243</span> }<a name="line.243"></a> |
| <span class="sourceLineNo">244</span><a name="line.244"></a> |
| <span class="sourceLineNo">245</span> /**<a name="line.245"></a> |
| <span class="sourceLineNo">246</span> * Creates a new entry, but wraps the value in a SoftValue instance to enable auto garbage collection.<a name="line.246"></a> |
| <span class="sourceLineNo">247</span> */<a name="line.247"></a> |
| <span class="sourceLineNo">248</span> public V put(K key, V value) {<a name="line.248"></a> |
| <span class="sourceLineNo">249</span> processQueue(); // throw out garbage collected values first<a name="line.249"></a> |
| <span class="sourceLineNo">250</span> SoftValue<V, K> sv = new SoftValue<V, K>(value, key, queue);<a name="line.250"></a> |
| <span class="sourceLineNo">251</span> SoftValue<V, K> previous = map.put(key, sv);<a name="line.251"></a> |
| <span class="sourceLineNo">252</span> addToStrongReferences(value);<a name="line.252"></a> |
| <span class="sourceLineNo">253</span> return previous != null ? previous.get() : null;<a name="line.253"></a> |
| <span class="sourceLineNo">254</span> }<a name="line.254"></a> |
| <span class="sourceLineNo">255</span><a name="line.255"></a> |
| <span class="sourceLineNo">256</span> public V remove(Object key) {<a name="line.256"></a> |
| <span class="sourceLineNo">257</span> processQueue(); // throw out garbage collected values first<a name="line.257"></a> |
| <span class="sourceLineNo">258</span> SoftValue<V, K> raw = map.remove(key);<a name="line.258"></a> |
| <span class="sourceLineNo">259</span> return raw != null ? raw.get() : null;<a name="line.259"></a> |
| <span class="sourceLineNo">260</span> }<a name="line.260"></a> |
| <span class="sourceLineNo">261</span><a name="line.261"></a> |
| <span class="sourceLineNo">262</span> public void clear() {<a name="line.262"></a> |
| <span class="sourceLineNo">263</span> strongReferencesLock.lock();<a name="line.263"></a> |
| <span class="sourceLineNo">264</span> try {<a name="line.264"></a> |
| <span class="sourceLineNo">265</span> strongReferences.clear();<a name="line.265"></a> |
| <span class="sourceLineNo">266</span> } finally {<a name="line.266"></a> |
| <span class="sourceLineNo">267</span> strongReferencesLock.unlock();<a name="line.267"></a> |
| <span class="sourceLineNo">268</span> }<a name="line.268"></a> |
| <span class="sourceLineNo">269</span> processQueue(); // throw out garbage collected values<a name="line.269"></a> |
| <span class="sourceLineNo">270</span> map.clear();<a name="line.270"></a> |
| <span class="sourceLineNo">271</span> }<a name="line.271"></a> |
| <span class="sourceLineNo">272</span><a name="line.272"></a> |
| <span class="sourceLineNo">273</span> public int size() {<a name="line.273"></a> |
| <span class="sourceLineNo">274</span> processQueue(); // throw out garbage collected values first<a name="line.274"></a> |
| <span class="sourceLineNo">275</span> return map.size();<a name="line.275"></a> |
| <span class="sourceLineNo">276</span> }<a name="line.276"></a> |
| <span class="sourceLineNo">277</span><a name="line.277"></a> |
| <span class="sourceLineNo">278</span> public Set<Map.Entry<K, V>> entrySet() {<a name="line.278"></a> |
| <span class="sourceLineNo">279</span> processQueue(); // throw out garbage collected values first<a name="line.279"></a> |
| <span class="sourceLineNo">280</span> Collection<K> keys = map.keySet();<a name="line.280"></a> |
| <span class="sourceLineNo">281</span> if (keys.isEmpty()) {<a name="line.281"></a> |
| <span class="sourceLineNo">282</span> //noinspection unchecked<a name="line.282"></a> |
| <span class="sourceLineNo">283</span> return Collections.EMPTY_SET;<a name="line.283"></a> |
| <span class="sourceLineNo">284</span> }<a name="line.284"></a> |
| <span class="sourceLineNo">285</span><a name="line.285"></a> |
| <span class="sourceLineNo">286</span> Map<K, V> kvPairs = new HashMap<K, V>(keys.size());<a name="line.286"></a> |
| <span class="sourceLineNo">287</span> for (K key : keys) {<a name="line.287"></a> |
| <span class="sourceLineNo">288</span> V v = get(key);<a name="line.288"></a> |
| <span class="sourceLineNo">289</span> if (v != null) {<a name="line.289"></a> |
| <span class="sourceLineNo">290</span> kvPairs.put(key, v);<a name="line.290"></a> |
| <span class="sourceLineNo">291</span> }<a name="line.291"></a> |
| <span class="sourceLineNo">292</span> }<a name="line.292"></a> |
| <span class="sourceLineNo">293</span> return kvPairs.entrySet();<a name="line.293"></a> |
| <span class="sourceLineNo">294</span> }<a name="line.294"></a> |
| <span class="sourceLineNo">295</span><a name="line.295"></a> |
| <span class="sourceLineNo">296</span> /**<a name="line.296"></a> |
| <span class="sourceLineNo">297</span> * We define our own subclass of SoftReference which contains<a name="line.297"></a> |
| <span class="sourceLineNo">298</span> * not only the value but also the key to make it easier to find<a name="line.298"></a> |
| <span class="sourceLineNo">299</span> * the entry in the HashMap after it's been garbage collected.<a name="line.299"></a> |
| <span class="sourceLineNo">300</span> */<a name="line.300"></a> |
| <span class="sourceLineNo">301</span> private static class SoftValue<V, K> extends SoftReference<V> {<a name="line.301"></a> |
| <span class="sourceLineNo">302</span><a name="line.302"></a> |
| <span class="sourceLineNo">303</span> private final K key;<a name="line.303"></a> |
| <span class="sourceLineNo">304</span><a name="line.304"></a> |
| <span class="sourceLineNo">305</span> /**<a name="line.305"></a> |
| <span class="sourceLineNo">306</span> * Constructs a new instance, wrapping the value, key, and queue, as<a name="line.306"></a> |
| <span class="sourceLineNo">307</span> * required by the superclass.<a name="line.307"></a> |
| <span class="sourceLineNo">308</span> *<a name="line.308"></a> |
| <span class="sourceLineNo">309</span> * @param value the map value<a name="line.309"></a> |
| <span class="sourceLineNo">310</span> * @param key the map key<a name="line.310"></a> |
| <span class="sourceLineNo">311</span> * @param queue the soft reference queue to poll to determine if the entry had been reaped by the GC.<a name="line.311"></a> |
| <span class="sourceLineNo">312</span> */<a name="line.312"></a> |
| <span class="sourceLineNo">313</span> private SoftValue(V value, K key, ReferenceQueue<? super V> queue) {<a name="line.313"></a> |
| <span class="sourceLineNo">314</span> super(value, queue);<a name="line.314"></a> |
| <span class="sourceLineNo">315</span> this.key = key;<a name="line.315"></a> |
| <span class="sourceLineNo">316</span> }<a name="line.316"></a> |
| <span class="sourceLineNo">317</span><a name="line.317"></a> |
| <span class="sourceLineNo">318</span> }<a name="line.318"></a> |
| <span class="sourceLineNo">319</span>}<a name="line.319"></a> |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| </pre> |
| </div> |
| </body> |
| </html> |
