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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.HashMap;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.util.Map;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import java.util.Set;<a name="line.25"></a>
<span class="sourceLineNo">026</span><a name="line.26"></a>
<span class="sourceLineNo">027</span>/**<a name="line.27"></a>
<span class="sourceLineNo">028</span> * A thread-safe version of {@link Map} in which all operations that change the<a name="line.28"></a>
<span class="sourceLineNo">029</span> * Map are implemented by making a new copy of the underlying Map.<a name="line.29"></a>
<span class="sourceLineNo">030</span> *<a name="line.30"></a>
<span class="sourceLineNo">031</span> * While the creation of a new Map can be expensive, this class is designed for<a name="line.31"></a>
<span class="sourceLineNo">032</span> * cases in which the primary function is to read data from the Map, not to<a name="line.32"></a>
<span class="sourceLineNo">033</span> * modify the Map. Therefore the operations that do not cause a change to this<a name="line.33"></a>
<span class="sourceLineNo">034</span> * class happen quickly and concurrently.<a name="line.34"></a>
<span class="sourceLineNo">035</span> *<a name="line.35"></a>
<span class="sourceLineNo">036</span> * @author &lt;a href="http://mina.apache.org"&gt;Apache MINA Project&lt;/a&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> */<a name="line.37"></a>
<span class="sourceLineNo">038</span>public class CopyOnWriteMap&lt;K, V&gt; implements Map&lt;K, V&gt;, Cloneable {<a name="line.38"></a>
<span class="sourceLineNo">039</span> private volatile Map&lt;K, V&gt; internalMap;<a name="line.39"></a>
<span class="sourceLineNo">040</span><a name="line.40"></a>
<span class="sourceLineNo">041</span> /**<a name="line.41"></a>
<span class="sourceLineNo">042</span> * Creates a new instance of CopyOnWriteMap.<a name="line.42"></a>
<span class="sourceLineNo">043</span> *<a name="line.43"></a>
<span class="sourceLineNo">044</span> */<a name="line.44"></a>
<span class="sourceLineNo">045</span> public CopyOnWriteMap() {<a name="line.45"></a>
<span class="sourceLineNo">046</span> internalMap = new HashMap&lt;K, V&gt;();<a name="line.46"></a>
<span class="sourceLineNo">047</span> }<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> * Creates a new instance of CopyOnWriteMap with the specified initial size<a name="line.50"></a>
<span class="sourceLineNo">051</span> *<a name="line.51"></a>
<span class="sourceLineNo">052</span> * @param initialCapacity<a name="line.52"></a>
<span class="sourceLineNo">053</span> * The initial size of the Map.<a name="line.53"></a>
<span class="sourceLineNo">054</span> */<a name="line.54"></a>
<span class="sourceLineNo">055</span> public CopyOnWriteMap(int initialCapacity) {<a name="line.55"></a>
<span class="sourceLineNo">056</span> internalMap = new HashMap&lt;K, V&gt;(initialCapacity);<a name="line.56"></a>
<span class="sourceLineNo">057</span> }<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> * Creates a new instance of CopyOnWriteMap in which the<a name="line.60"></a>
<span class="sourceLineNo">061</span> * initial data being held by this map is contained in<a name="line.61"></a>
<span class="sourceLineNo">062</span> * the supplied map.<a name="line.62"></a>
<span class="sourceLineNo">063</span> *<a name="line.63"></a>
<span class="sourceLineNo">064</span> * @param data<a name="line.64"></a>
<span class="sourceLineNo">065</span> * A Map containing the initial contents to be placed into<a name="line.65"></a>
<span class="sourceLineNo">066</span> * this class.<a name="line.66"></a>
<span class="sourceLineNo">067</span> */<a name="line.67"></a>
<span class="sourceLineNo">068</span> public CopyOnWriteMap(Map&lt;K, V&gt; data) {<a name="line.68"></a>
<span class="sourceLineNo">069</span> internalMap = new HashMap&lt;K, V&gt;(data);<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> /**<a name="line.72"></a>
<span class="sourceLineNo">073</span> * Adds the provided key and value to this map.<a name="line.73"></a>
<span class="sourceLineNo">074</span> *<a name="line.74"></a>
<span class="sourceLineNo">075</span> * @see java.util.Map#put(java.lang.Object, java.lang.Object)<a name="line.75"></a>
<span class="sourceLineNo">076</span> */<a name="line.76"></a>
<span class="sourceLineNo">077</span> public V put(K key, V value) {<a name="line.77"></a>
<span class="sourceLineNo">078</span> synchronized (this) {<a name="line.78"></a>
<span class="sourceLineNo">079</span> Map&lt;K, V&gt; newMap = new HashMap&lt;K, V&gt;(internalMap);<a name="line.79"></a>
<span class="sourceLineNo">080</span> V val = newMap.put(key, value);<a name="line.80"></a>
<span class="sourceLineNo">081</span> internalMap = newMap;<a name="line.81"></a>
<span class="sourceLineNo">082</span> return val;<a name="line.82"></a>
<span class="sourceLineNo">083</span> }<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> * Removed the value and key from this map based on the<a name="line.87"></a>
<span class="sourceLineNo">088</span> * provided key.<a name="line.88"></a>
<span class="sourceLineNo">089</span> *<a name="line.89"></a>
<span class="sourceLineNo">090</span> * @see java.util.Map#remove(java.lang.Object)<a name="line.90"></a>
<span class="sourceLineNo">091</span> */<a name="line.91"></a>
<span class="sourceLineNo">092</span> public V remove(Object key) {<a name="line.92"></a>
<span class="sourceLineNo">093</span> synchronized (this) {<a name="line.93"></a>
<span class="sourceLineNo">094</span> Map&lt;K, V&gt; newMap = new HashMap&lt;K, V&gt;(internalMap);<a name="line.94"></a>
<span class="sourceLineNo">095</span> V val = newMap.remove(key);<a name="line.95"></a>
<span class="sourceLineNo">096</span> internalMap = newMap;<a name="line.96"></a>
<span class="sourceLineNo">097</span> return val;<a name="line.97"></a>
<span class="sourceLineNo">098</span> }<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> /**<a name="line.101"></a>
<span class="sourceLineNo">102</span> * Inserts all the keys and values contained in the<a name="line.102"></a>
<span class="sourceLineNo">103</span> * provided map to this map.<a name="line.103"></a>
<span class="sourceLineNo">104</span> *<a name="line.104"></a>
<span class="sourceLineNo">105</span> * @see java.util.Map#putAll(java.util.Map)<a name="line.105"></a>
<span class="sourceLineNo">106</span> */<a name="line.106"></a>
<span class="sourceLineNo">107</span> public void putAll(Map&lt;? extends K, ? extends V&gt; newData) {<a name="line.107"></a>
<span class="sourceLineNo">108</span> synchronized (this) {<a name="line.108"></a>
<span class="sourceLineNo">109</span> Map&lt;K, V&gt; newMap = new HashMap&lt;K, V&gt;(internalMap);<a name="line.109"></a>
<span class="sourceLineNo">110</span> newMap.putAll(newData);<a name="line.110"></a>
<span class="sourceLineNo">111</span> internalMap = newMap;<a name="line.111"></a>
<span class="sourceLineNo">112</span> }<a name="line.112"></a>
<span class="sourceLineNo">113</span> }<a name="line.113"></a>
<span class="sourceLineNo">114</span><a name="line.114"></a>
<span class="sourceLineNo">115</span> /**<a name="line.115"></a>
<span class="sourceLineNo">116</span> * Removes all entries in this map.<a name="line.116"></a>
<span class="sourceLineNo">117</span> *<a name="line.117"></a>
<span class="sourceLineNo">118</span> * @see java.util.Map#clear()<a name="line.118"></a>
<span class="sourceLineNo">119</span> */<a name="line.119"></a>
<span class="sourceLineNo">120</span> public void clear() {<a name="line.120"></a>
<span class="sourceLineNo">121</span> synchronized (this) {<a name="line.121"></a>
<span class="sourceLineNo">122</span> internalMap = new HashMap&lt;K, V&gt;();<a name="line.122"></a>
<span class="sourceLineNo">123</span> }<a name="line.123"></a>
<span class="sourceLineNo">124</span> }<a name="line.124"></a>
<span class="sourceLineNo">125</span><a name="line.125"></a>
<span class="sourceLineNo">126</span> // ==============================================<a name="line.126"></a>
<span class="sourceLineNo">127</span> // ==== Below are methods that do not modify ====<a name="line.127"></a>
<span class="sourceLineNo">128</span> // ==== the internal Maps ====<a name="line.128"></a>
<span class="sourceLineNo">129</span> // ==============================================<a name="line.129"></a>
<span class="sourceLineNo">130</span> /**<a name="line.130"></a>
<span class="sourceLineNo">131</span> * @return the number of key/value pairs in this map.<a name="line.131"></a>
<span class="sourceLineNo">132</span> *<a name="line.132"></a>
<span class="sourceLineNo">133</span> * @see java.util.Map#size()<a name="line.133"></a>
<span class="sourceLineNo">134</span> */<a name="line.134"></a>
<span class="sourceLineNo">135</span> public int size() {<a name="line.135"></a>
<span class="sourceLineNo">136</span> return internalMap.size();<a name="line.136"></a>
<span class="sourceLineNo">137</span> }<a name="line.137"></a>
<span class="sourceLineNo">138</span><a name="line.138"></a>
<span class="sourceLineNo">139</span> /**<a name="line.139"></a>
<span class="sourceLineNo">140</span> * @return true if this map is empty, otherwise false.<a name="line.140"></a>
<span class="sourceLineNo">141</span> *<a name="line.141"></a>
<span class="sourceLineNo">142</span> * @see java.util.Map#isEmpty()<a name="line.142"></a>
<span class="sourceLineNo">143</span> */<a name="line.143"></a>
<span class="sourceLineNo">144</span> public boolean isEmpty() {<a name="line.144"></a>
<span class="sourceLineNo">145</span> return internalMap.isEmpty();<a name="line.145"></a>
<span class="sourceLineNo">146</span> }<a name="line.146"></a>
<span class="sourceLineNo">147</span><a name="line.147"></a>
<span class="sourceLineNo">148</span> /**<a name="line.148"></a>
<span class="sourceLineNo">149</span> * @return true if this map contains the provided key, otherwise<a name="line.149"></a>
<span class="sourceLineNo">150</span> * this method return false.<a name="line.150"></a>
<span class="sourceLineNo">151</span> *<a name="line.151"></a>
<span class="sourceLineNo">152</span> * @see java.util.Map#containsKey(java.lang.Object)<a name="line.152"></a>
<span class="sourceLineNo">153</span> */<a name="line.153"></a>
<span class="sourceLineNo">154</span> public boolean containsKey(Object key) {<a name="line.154"></a>
<span class="sourceLineNo">155</span> return internalMap.containsKey(key);<a name="line.155"></a>
<span class="sourceLineNo">156</span> }<a name="line.156"></a>
<span class="sourceLineNo">157</span><a name="line.157"></a>
<span class="sourceLineNo">158</span> /**<a name="line.158"></a>
<span class="sourceLineNo">159</span> * @return true if this map contains the provided value, otherwise<a name="line.159"></a>
<span class="sourceLineNo">160</span> * this method returns false.<a name="line.160"></a>
<span class="sourceLineNo">161</span> *<a name="line.161"></a>
<span class="sourceLineNo">162</span> * @see java.util.Map#containsValue(java.lang.Object)<a name="line.162"></a>
<span class="sourceLineNo">163</span> */<a name="line.163"></a>
<span class="sourceLineNo">164</span> public boolean containsValue(Object value) {<a name="line.164"></a>
<span class="sourceLineNo">165</span> return internalMap.containsValue(value);<a name="line.165"></a>
<span class="sourceLineNo">166</span> }<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> * @return the value associated with the provided key from this<a name="line.169"></a>
<span class="sourceLineNo">170</span> * map.<a name="line.170"></a>
<span class="sourceLineNo">171</span> *<a name="line.171"></a>
<span class="sourceLineNo">172</span> * @see java.util.Map#get(java.lang.Object)<a name="line.172"></a>
<span class="sourceLineNo">173</span> */<a name="line.173"></a>
<span class="sourceLineNo">174</span> public V get(Object key) {<a name="line.174"></a>
<span class="sourceLineNo">175</span> return internalMap.get(key);<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> * This method will return a read-only {@link Set}.<a name="line.179"></a>
<span class="sourceLineNo">180</span> */<a name="line.180"></a>
<span class="sourceLineNo">181</span> public Set&lt;K&gt; keySet() {<a name="line.181"></a>
<span class="sourceLineNo">182</span> return internalMap.keySet();<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> * This method will return a read-only {@link Collection}.<a name="line.186"></a>
<span class="sourceLineNo">187</span> */<a name="line.187"></a>
<span class="sourceLineNo">188</span> public Collection&lt;V&gt; values() {<a name="line.188"></a>
<span class="sourceLineNo">189</span> return internalMap.values();<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> * This method will return a read-only {@link Set}.<a name="line.193"></a>
<span class="sourceLineNo">194</span> */<a name="line.194"></a>
<span class="sourceLineNo">195</span> public Set&lt;Entry&lt;K, V&gt;&gt; entrySet() {<a name="line.195"></a>
<span class="sourceLineNo">196</span> return internalMap.entrySet();<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> @Override<a name="line.199"></a>
<span class="sourceLineNo">200</span> public Object clone() {<a name="line.200"></a>
<span class="sourceLineNo">201</span> try {<a name="line.201"></a>
<span class="sourceLineNo">202</span> return super.clone();<a name="line.202"></a>
<span class="sourceLineNo">203</span> } catch (CloneNotSupportedException e) {<a name="line.203"></a>
<span class="sourceLineNo">204</span> throw new InternalError();<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>}<a name="line.207"></a>
</pre>
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