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| <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> */<a name="line.19"></a> |
| <span class="sourceLineNo">020</span>package org.apache.mina.util;<a name="line.20"></a> |
| <span class="sourceLineNo">021</span><a name="line.21"></a> |
| <span class="sourceLineNo">022</span>import java.util.Collection;<a name="line.22"></a> |
| <span class="sourceLineNo">023</span>import java.util.Map;<a name="line.23"></a> |
| <span class="sourceLineNo">024</span>import java.util.Set;<a name="line.24"></a> |
| <span class="sourceLineNo">025</span>import java.util.concurrent.ConcurrentHashMap;<a name="line.25"></a> |
| <span class="sourceLineNo">026</span>import java.util.concurrent.ConcurrentMap;<a name="line.26"></a> |
| <span class="sourceLineNo">027</span><a name="line.27"></a> |
| <span class="sourceLineNo">028</span>import org.apache.mina.core.buffer.IoBuffer;<a name="line.28"></a> |
| <span class="sourceLineNo">029</span><a name="line.29"></a> |
| <span class="sourceLineNo">030</span>/**<a name="line.30"></a> |
| <span class="sourceLineNo">031</span> * This map is specially useful when reads are much more frequent than writes and <a name="line.31"></a> |
| <span class="sourceLineNo">032</span> * if the cost of instantiating the values is high like allocating an <a name="line.32"></a> |
| <span class="sourceLineNo">033</span> * {@link IoBuffer} for example.<a name="line.33"></a> |
| <span class="sourceLineNo">034</span> * <a name="line.34"></a> |
| <span class="sourceLineNo">035</span> * Based on the final implementation of Memoizer written by Brian Goetz and Tim<a name="line.35"></a> |
| <span class="sourceLineNo">036</span> * Peierls. This implementation will return an<a name="line.36"></a> |
| <span class="sourceLineNo">037</span> * {@link UnsupportedOperationException} on each method that is not intended to<a name="line.37"></a> |
| <span class="sourceLineNo">038</span> * be called by user code for performance reasons.<a name="line.38"></a> |
| <span class="sourceLineNo">039</span> * <a name="line.39"></a> |
| <span class="sourceLineNo">040</span> * @author <a href="http://mina.apache.org">Apache MINA Project</a><a name="line.40"></a> |
| <span class="sourceLineNo">041</span> * @since MINA 2.0.0-M2<a name="line.41"></a> |
| <span class="sourceLineNo">042</span> */<a name="line.42"></a> |
| <span class="sourceLineNo">043</span>public class LazyInitializedCacheMap<K, V> implements Map<K, V> {<a name="line.43"></a> |
| <span class="sourceLineNo">044</span> private ConcurrentMap<K, LazyInitializer<V>> cache;<a name="line.44"></a> |
| <span class="sourceLineNo">045</span><a name="line.45"></a> |
| <span class="sourceLineNo">046</span> /**<a name="line.46"></a> |
| <span class="sourceLineNo">047</span> * This class provides a noop {@link LazyInitializer} meaning it <a name="line.47"></a> |
| <span class="sourceLineNo">048</span> * will return the same object it received when instantiated.<a name="line.48"></a> |
| <span class="sourceLineNo">049</span> */<a name="line.49"></a> |
| <span class="sourceLineNo">050</span> public class NoopInitializer extends LazyInitializer<V> {<a name="line.50"></a> |
| <span class="sourceLineNo">051</span> private V value;<a name="line.51"></a> |
| <span class="sourceLineNo">052</span><a name="line.52"></a> |
| <span class="sourceLineNo">053</span> public NoopInitializer(V value) {<a name="line.53"></a> |
| <span class="sourceLineNo">054</span> this.value = value;<a name="line.54"></a> |
| <span class="sourceLineNo">055</span> }<a name="line.55"></a> |
| <span class="sourceLineNo">056</span><a name="line.56"></a> |
| <span class="sourceLineNo">057</span> public V init() {<a name="line.57"></a> |
| <span class="sourceLineNo">058</span> return value;<a name="line.58"></a> |
| <span class="sourceLineNo">059</span> }<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> }<a name="line.60"></a> |
| <span class="sourceLineNo">061</span><a name="line.61"></a> |
| <span class="sourceLineNo">062</span> /**<a name="line.62"></a> |
| <span class="sourceLineNo">063</span> * Default constructor. Uses the default parameters to initialize its internal<a name="line.63"></a> |
| <span class="sourceLineNo">064</span> * {@link ConcurrentHashMap}.<a name="line.64"></a> |
| <span class="sourceLineNo">065</span> */<a name="line.65"></a> |
| <span class="sourceLineNo">066</span> public LazyInitializedCacheMap() {<a name="line.66"></a> |
| <span class="sourceLineNo">067</span> this.cache = new ConcurrentHashMap<K, LazyInitializer<V>>();<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> }<a name="line.68"></a> |
| <span class="sourceLineNo">069</span><a name="line.69"></a> |
| <span class="sourceLineNo">070</span> /**<a name="line.70"></a> |
| <span class="sourceLineNo">071</span> * This constructor allows to provide a fine tuned {@link ConcurrentHashMap}<a name="line.71"></a> |
| <span class="sourceLineNo">072</span> * to stick with each special case the user needs.<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> * <a name="line.73"></a> |
| <span class="sourceLineNo">074</span> * @param map The map to use as a cache<a name="line.74"></a> |
| <span class="sourceLineNo">075</span> */<a name="line.75"></a> |
| <span class="sourceLineNo">076</span> public LazyInitializedCacheMap(final ConcurrentHashMap<K, LazyInitializer<V>> map) {<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> this.cache = map;<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> }<a name="line.78"></a> |
| <span class="sourceLineNo">079</span><a name="line.79"></a> |
| <span class="sourceLineNo">080</span> /**<a name="line.80"></a> |
| <span class="sourceLineNo">081</span> * {@inheritDoc}<a name="line.81"></a> |
| <span class="sourceLineNo">082</span> */<a name="line.82"></a> |
| <span class="sourceLineNo">083</span> public V get(Object key) {<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> LazyInitializer<V> c = cache.get(key);<a name="line.84"></a> |
| <span class="sourceLineNo">085</span> if (c != null) {<a name="line.85"></a> |
| <span class="sourceLineNo">086</span> return c.get();<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> }<a name="line.87"></a> |
| <span class="sourceLineNo">088</span><a name="line.88"></a> |
| <span class="sourceLineNo">089</span> return null;<a name="line.89"></a> |
| <span class="sourceLineNo">090</span> }<a name="line.90"></a> |
| <span class="sourceLineNo">091</span><a name="line.91"></a> |
| <span class="sourceLineNo">092</span> /**<a name="line.92"></a> |
| <span class="sourceLineNo">093</span> * {@inheritDoc}<a name="line.93"></a> |
| <span class="sourceLineNo">094</span> */<a name="line.94"></a> |
| <span class="sourceLineNo">095</span> public V remove(Object key) {<a name="line.95"></a> |
| <span class="sourceLineNo">096</span> LazyInitializer<V> c = cache.remove(key);<a name="line.96"></a> |
| <span class="sourceLineNo">097</span> if (c != null) {<a name="line.97"></a> |
| <span class="sourceLineNo">098</span> return c.get();<a name="line.98"></a> |
| <span class="sourceLineNo">099</span> }<a name="line.99"></a> |
| <span class="sourceLineNo">100</span><a name="line.100"></a> |
| <span class="sourceLineNo">101</span> return null;<a name="line.101"></a> |
| <span class="sourceLineNo">102</span> }<a name="line.102"></a> |
| <span class="sourceLineNo">103</span><a name="line.103"></a> |
| <span class="sourceLineNo">104</span> /**<a name="line.104"></a> |
| <span class="sourceLineNo">105</span> * If the specified key is not already associated<a name="line.105"></a> |
| <span class="sourceLineNo">106</span> * with a value, associate it with the given value.<a name="line.106"></a> |
| <span class="sourceLineNo">107</span> * This is equivalent to<a name="line.107"></a> |
| <span class="sourceLineNo">108</span> * <pre><a name="line.108"></a> |
| <span class="sourceLineNo">109</span> * if (!map.containsKey(key))<a name="line.109"></a> |
| <span class="sourceLineNo">110</span> * return map.put(key, value);<a name="line.110"></a> |
| <span class="sourceLineNo">111</span> * else<a name="line.111"></a> |
| <span class="sourceLineNo">112</span> * return map.get(key);</pre><a name="line.112"></a> |
| <span class="sourceLineNo">113</span> * except that the action is performed atomically.<a name="line.113"></a> |
| <span class="sourceLineNo">114</span> *<a name="line.114"></a> |
| <span class="sourceLineNo">115</span> * @param key key with which the specified value is to be associated<a name="line.115"></a> |
| <span class="sourceLineNo">116</span> * @param value a lazy initialized value object.<a name="line.116"></a> |
| <span class="sourceLineNo">117</span> * <a name="line.117"></a> |
| <span class="sourceLineNo">118</span> * @return the previous value associated with the specified key,<a name="line.118"></a> |
| <span class="sourceLineNo">119</span> * or <tt>null</tt> if there was no mapping for the key<a name="line.119"></a> |
| <span class="sourceLineNo">120</span> */<a name="line.120"></a> |
| <span class="sourceLineNo">121</span> public V putIfAbsent(K key, LazyInitializer<V> value) {<a name="line.121"></a> |
| <span class="sourceLineNo">122</span> LazyInitializer<V> v = cache.get(key);<a name="line.122"></a> |
| <span class="sourceLineNo">123</span> if (v == null) {<a name="line.123"></a> |
| <span class="sourceLineNo">124</span> v = cache.putIfAbsent(key, value);<a name="line.124"></a> |
| <span class="sourceLineNo">125</span> if (v == null) {<a name="line.125"></a> |
| <span class="sourceLineNo">126</span> return value.get();<a name="line.126"></a> |
| <span class="sourceLineNo">127</span> }<a name="line.127"></a> |
| <span class="sourceLineNo">128</span> }<a name="line.128"></a> |
| <span class="sourceLineNo">129</span><a name="line.129"></a> |
| <span class="sourceLineNo">130</span> return v.get();<a name="line.130"></a> |
| <span class="sourceLineNo">131</span> }<a name="line.131"></a> |
| <span class="sourceLineNo">132</span><a name="line.132"></a> |
| <span class="sourceLineNo">133</span> /**<a name="line.133"></a> |
| <span class="sourceLineNo">134</span> * {@inheritDoc}<a name="line.134"></a> |
| <span class="sourceLineNo">135</span> */<a name="line.135"></a> |
| <span class="sourceLineNo">136</span> public V put(K key, V value) {<a name="line.136"></a> |
| <span class="sourceLineNo">137</span> LazyInitializer<V> c = cache.put(key, new NoopInitializer(value));<a name="line.137"></a> |
| <span class="sourceLineNo">138</span> if (c != null) {<a name="line.138"></a> |
| <span class="sourceLineNo">139</span> return c.get();<a name="line.139"></a> |
| <span class="sourceLineNo">140</span> }<a name="line.140"></a> |
| <span class="sourceLineNo">141</span><a name="line.141"></a> |
| <span class="sourceLineNo">142</span> return null;<a name="line.142"></a> |
| <span class="sourceLineNo">143</span> }<a name="line.143"></a> |
| <span class="sourceLineNo">144</span><a name="line.144"></a> |
| <span class="sourceLineNo">145</span> /**<a name="line.145"></a> |
| <span class="sourceLineNo">146</span> * Throws {@link UnsupportedOperationException} as this method would imply<a name="line.146"></a> |
| <span class="sourceLineNo">147</span> * performance drops.<a name="line.147"></a> |
| <span class="sourceLineNo">148</span> */<a name="line.148"></a> |
| <span class="sourceLineNo">149</span> public boolean containsValue(Object value) {<a name="line.149"></a> |
| <span class="sourceLineNo">150</span> throw new UnsupportedOperationException();<a name="line.150"></a> |
| <span class="sourceLineNo">151</span> }<a name="line.151"></a> |
| <span class="sourceLineNo">152</span><a name="line.152"></a> |
| <span class="sourceLineNo">153</span> /**<a name="line.153"></a> |
| <span class="sourceLineNo">154</span> * Throws {@link UnsupportedOperationException} as this method would imply<a name="line.154"></a> |
| <span class="sourceLineNo">155</span> * performance drops.<a name="line.155"></a> |
| <span class="sourceLineNo">156</span> */<a name="line.156"></a> |
| <span class="sourceLineNo">157</span> public Collection<V> values() {<a name="line.157"></a> |
| <span class="sourceLineNo">158</span> throw new UnsupportedOperationException();<a name="line.158"></a> |
| <span class="sourceLineNo">159</span> }<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> * Throws {@link UnsupportedOperationException} as this method would imply<a name="line.162"></a> |
| <span class="sourceLineNo">163</span> * performance drops.<a name="line.163"></a> |
| <span class="sourceLineNo">164</span> */<a name="line.164"></a> |
| <span class="sourceLineNo">165</span> public Set<java.util.Map.Entry<K, V>> entrySet() {<a name="line.165"></a> |
| <span class="sourceLineNo">166</span> throw new UnsupportedOperationException();<a name="line.166"></a> |
| <span class="sourceLineNo">167</span> }<a name="line.167"></a> |
| <span class="sourceLineNo">168</span><a name="line.168"></a> |
| <span class="sourceLineNo">169</span> /**<a name="line.169"></a> |
| <span class="sourceLineNo">170</span> * {@inheritDoc}<a name="line.170"></a> |
| <span class="sourceLineNo">171</span> */<a name="line.171"></a> |
| <span class="sourceLineNo">172</span> public void putAll(Map<? extends K, ? extends V> m) {<a name="line.172"></a> |
| <span class="sourceLineNo">173</span> for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {<a name="line.173"></a> |
| <span class="sourceLineNo">174</span> cache.put(e.getKey(), new NoopInitializer(e.getValue()));<a name="line.174"></a> |
| <span class="sourceLineNo">175</span> }<a name="line.175"></a> |
| <span class="sourceLineNo">176</span> }<a name="line.176"></a> |
| <span class="sourceLineNo">177</span><a name="line.177"></a> |
| <span class="sourceLineNo">178</span> /**<a name="line.178"></a> |
| <span class="sourceLineNo">179</span> * @return return the values from the cache<a name="line.179"></a> |
| <span class="sourceLineNo">180</span> */<a name="line.180"></a> |
| <span class="sourceLineNo">181</span> public Collection<LazyInitializer<V>> getValues() {<a name="line.181"></a> |
| <span class="sourceLineNo">182</span> return cache.values();<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> * {@inheritDoc}<a name="line.186"></a> |
| <span class="sourceLineNo">187</span> */<a name="line.187"></a> |
| <span class="sourceLineNo">188</span> public void clear() {<a name="line.188"></a> |
| <span class="sourceLineNo">189</span> cache.clear();<a name="line.189"></a> |
| <span class="sourceLineNo">190</span> }<a name="line.190"></a> |
| <span class="sourceLineNo">191</span><a name="line.191"></a> |
| <span class="sourceLineNo">192</span> /**<a name="line.192"></a> |
| <span class="sourceLineNo">193</span> * {@inheritDoc}<a name="line.193"></a> |
| <span class="sourceLineNo">194</span> */<a name="line.194"></a> |
| <span class="sourceLineNo">195</span> public boolean containsKey(Object key) {<a name="line.195"></a> |
| <span class="sourceLineNo">196</span> return cache.containsKey(key);<a name="line.196"></a> |
| <span class="sourceLineNo">197</span> }<a name="line.197"></a> |
| <span class="sourceLineNo">198</span><a name="line.198"></a> |
| <span class="sourceLineNo">199</span> /**<a name="line.199"></a> |
| <span class="sourceLineNo">200</span> * {@inheritDoc}<a name="line.200"></a> |
| <span class="sourceLineNo">201</span> */<a name="line.201"></a> |
| <span class="sourceLineNo">202</span> public boolean isEmpty() {<a name="line.202"></a> |
| <span class="sourceLineNo">203</span> return cache.isEmpty();<a name="line.203"></a> |
| <span class="sourceLineNo">204</span> }<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> * {@inheritDoc}<a name="line.207"></a> |
| <span class="sourceLineNo">208</span> */<a name="line.208"></a> |
| <span class="sourceLineNo">209</span> public Set<K> keySet() {<a name="line.209"></a> |
| <span class="sourceLineNo">210</span> return cache.keySet();<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> /**<a name="line.213"></a> |
| <span class="sourceLineNo">214</span> * {@inheritDoc}<a name="line.214"></a> |
| <span class="sourceLineNo">215</span> */<a name="line.215"></a> |
| <span class="sourceLineNo">216</span> public int size() {<a name="line.216"></a> |
| <span class="sourceLineNo">217</span> return cache.size();<a name="line.217"></a> |
| <span class="sourceLineNo">218</span> }<a name="line.218"></a> |
| <span class="sourceLineNo">219</span>}<a name="line.219"></a> |
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