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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 or more<a name="line.2"></a> |
| <span class="sourceLineNo">003</span> * contributor license agreements. See the NOTICE file distributed with<a name="line.3"></a> |
| <span class="sourceLineNo">004</span> * this work for additional information regarding copyright ownership.<a name="line.4"></a> |
| <span class="sourceLineNo">005</span> * The ASF licenses this file to You under the Apache license, Version 2.0<a name="line.5"></a> |
| <span class="sourceLineNo">006</span> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a> |
| <span class="sourceLineNo">007</span> * the License. You may obtain a copy of the License at<a name="line.7"></a> |
| <span class="sourceLineNo">008</span> *<a name="line.8"></a> |
| <span class="sourceLineNo">009</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a> |
| <span class="sourceLineNo">010</span> *<a name="line.10"></a> |
| <span class="sourceLineNo">011</span> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a> |
| <span class="sourceLineNo">012</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a> |
| <span class="sourceLineNo">013</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a> |
| <span class="sourceLineNo">014</span> * See the license for the specific language governing permissions and<a name="line.14"></a> |
| <span class="sourceLineNo">015</span> * limitations under the license.<a name="line.15"></a> |
| <span class="sourceLineNo">016</span> */<a name="line.16"></a> |
| <span class="sourceLineNo">017</span>package org.apache.log4j;<a name="line.17"></a> |
| <span class="sourceLineNo">018</span><a name="line.18"></a> |
| <span class="sourceLineNo">019</span>import java.util.Stack;<a name="line.19"></a> |
| <span class="sourceLineNo">020</span><a name="line.20"></a> |
| <span class="sourceLineNo">021</span>/**<a name="line.21"></a> |
| <span class="sourceLineNo">022</span> *<a name="line.22"></a> |
| <span class="sourceLineNo">023</span> */<a name="line.23"></a> |
| <span class="sourceLineNo">024</span>public final class NDC {<a name="line.24"></a> |
| <span class="sourceLineNo">025</span><a name="line.25"></a> |
| <span class="sourceLineNo">026</span> private NDC() {<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> * Clear any nested diagnostic information if any. This method is<a name="line.30"></a> |
| <span class="sourceLineNo">031</span> * useful in cases where the same thread can be potentially used<a name="line.31"></a> |
| <span class="sourceLineNo">032</span> * over and over in different unrelated contexts.<a name="line.32"></a> |
| <span class="sourceLineNo">033</span> * <p><a name="line.33"></a> |
| <span class="sourceLineNo">034</span> * This method is equivalent to calling the {@link #setMaxDepth}<a name="line.34"></a> |
| <span class="sourceLineNo">035</span> * method with a zero <code>maxDepth</code> argument.<a name="line.35"></a> |
| <span class="sourceLineNo">036</span> * </p><a name="line.36"></a> |
| <span class="sourceLineNo">037</span> */<a name="line.37"></a> |
| <span class="sourceLineNo">038</span> public static void clear() {<a name="line.38"></a> |
| <span class="sourceLineNo">039</span> org.apache.logging.log4j.ThreadContext.clearStack();<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><a name="line.42"></a> |
| <span class="sourceLineNo">043</span> /**<a name="line.43"></a> |
| <span class="sourceLineNo">044</span> * Clone the diagnostic context for the current thread.<a name="line.44"></a> |
| <span class="sourceLineNo">045</span> * <p><a name="line.45"></a> |
| <span class="sourceLineNo">046</span> * Internally a diagnostic context is represented as a stack. A<a name="line.46"></a> |
| <span class="sourceLineNo">047</span> * given thread can supply the stack (i.e. diagnostic context) to a<a name="line.47"></a> |
| <span class="sourceLineNo">048</span> * child thread so that the child can inherit the parent thread's<a name="line.48"></a> |
| <span class="sourceLineNo">049</span> * diagnostic context.<a name="line.49"></a> |
| <span class="sourceLineNo">050</span> * </p><a name="line.50"></a> |
| <span class="sourceLineNo">051</span> * <p><a name="line.51"></a> |
| <span class="sourceLineNo">052</span> * The child thread uses the {@link #inherit inherit} method to<a name="line.52"></a> |
| <span class="sourceLineNo">053</span> * inherit the parent's diagnostic context.<a name="line.53"></a> |
| <span class="sourceLineNo">054</span> * </p><a name="line.54"></a> |
| <span class="sourceLineNo">055</span> * @return Stack A clone of the current thread's diagnostic context.<a name="line.55"></a> |
| <span class="sourceLineNo">056</span> */<a name="line.56"></a> |
| <span class="sourceLineNo">057</span> @SuppressWarnings("rawtypes")<a name="line.57"></a> |
| <span class="sourceLineNo">058</span> public static Stack cloneStack() {<a name="line.58"></a> |
| <span class="sourceLineNo">059</span> final Stack<String> stack = new Stack<>();<a name="line.59"></a> |
| <span class="sourceLineNo">060</span> for (final String element : org.apache.logging.log4j.ThreadContext.cloneStack().asList()) {<a name="line.60"></a> |
| <span class="sourceLineNo">061</span> stack.push(element);<a name="line.61"></a> |
| <span class="sourceLineNo">062</span> }<a name="line.62"></a> |
| <span class="sourceLineNo">063</span> return stack;<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><a name="line.66"></a> |
| <span class="sourceLineNo">067</span> /**<a name="line.67"></a> |
| <span class="sourceLineNo">068</span> * Inherit the diagnostic context of another thread.<a name="line.68"></a> |
| <span class="sourceLineNo">069</span> * <p><a name="line.69"></a> |
| <span class="sourceLineNo">070</span> * The parent thread can obtain a reference to its diagnostic<a name="line.70"></a> |
| <span class="sourceLineNo">071</span> * context using the {@link #cloneStack} method. It should<a name="line.71"></a> |
| <span class="sourceLineNo">072</span> * communicate this information to its child so that it may inherit<a name="line.72"></a> |
| <span class="sourceLineNo">073</span> * the parent's diagnostic context.<a name="line.73"></a> |
| <span class="sourceLineNo">074</span> * </p><a name="line.74"></a> |
| <span class="sourceLineNo">075</span> * <p><a name="line.75"></a> |
| <span class="sourceLineNo">076</span> * The parent's diagnostic context is cloned before being<a name="line.76"></a> |
| <span class="sourceLineNo">077</span> * inherited. In other words, once inherited, the two diagnostic<a name="line.77"></a> |
| <span class="sourceLineNo">078</span> * contexts can be managed independently.<a name="line.78"></a> |
| <span class="sourceLineNo">079</span> * </p><a name="line.79"></a> |
| <span class="sourceLineNo">080</span> * <p><a name="line.80"></a> |
| <span class="sourceLineNo">081</span> * In java, a child thread cannot obtain a reference to its<a name="line.81"></a> |
| <span class="sourceLineNo">082</span> * parent, unless it is directly handed the reference. Consequently,<a name="line.82"></a> |
| <span class="sourceLineNo">083</span> * there is no client-transparent way of inheriting diagnostic<a name="line.83"></a> |
| <span class="sourceLineNo">084</span> * contexts. Do you know any solution to this problem?<a name="line.84"></a> |
| <span class="sourceLineNo">085</span> * </p><a name="line.85"></a> |
| <span class="sourceLineNo">086</span> * @param stack The diagnostic context of the parent thread.<a name="line.86"></a> |
| <span class="sourceLineNo">087</span> */<a name="line.87"></a> |
| <span class="sourceLineNo">088</span> public static void inherit(final Stack<String> stack) {<a name="line.88"></a> |
| <span class="sourceLineNo">089</span> org.apache.logging.log4j.ThreadContext.setStack(stack);<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> /**<a name="line.93"></a> |
| <span class="sourceLineNo">094</span> * <strong style="color:#FF4040">Never use this method directly.</strong><a name="line.94"></a> |
| <span class="sourceLineNo">095</span> *<a name="line.95"></a> |
| <span class="sourceLineNo">096</span> * @return The string value of the specified key.<a name="line.96"></a> |
| <span class="sourceLineNo">097</span> */<a name="line.97"></a> |
| <span class="sourceLineNo">098</span> public static String get() {<a name="line.98"></a> |
| <span class="sourceLineNo">099</span> return org.apache.logging.log4j.ThreadContext.peek();<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> /**<a name="line.102"></a> |
| <span class="sourceLineNo">103</span> * Get the current nesting depth of this diagnostic context.<a name="line.103"></a> |
| <span class="sourceLineNo">104</span> * @return int The number of elements in the call stack.<a name="line.104"></a> |
| <span class="sourceLineNo">105</span> * @see #setMaxDepth<a name="line.105"></a> |
| <span class="sourceLineNo">106</span> */<a name="line.106"></a> |
| <span class="sourceLineNo">107</span> public static int getDepth() {<a name="line.107"></a> |
| <span class="sourceLineNo">108</span> return org.apache.logging.log4j.ThreadContext.getDepth();<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> * Clients should call this method before leaving a diagnostic<a name="line.112"></a> |
| <span class="sourceLineNo">113</span> * context.<a name="line.113"></a> |
| <span class="sourceLineNo">114</span> * <p><a name="line.114"></a> |
| <span class="sourceLineNo">115</span> * The returned value is the value that was pushed last. If no<a name="line.115"></a> |
| <span class="sourceLineNo">116</span> * context is available, then the empty string "" is returned.<a name="line.116"></a> |
| <span class="sourceLineNo">117</span> * </p><a name="line.117"></a> |
| <span class="sourceLineNo">118</span> * @return String The innermost diagnostic context.<a name="line.118"></a> |
| <span class="sourceLineNo">119</span> */<a name="line.119"></a> |
| <span class="sourceLineNo">120</span> public static String pop() {<a name="line.120"></a> |
| <span class="sourceLineNo">121</span> return org.apache.logging.log4j.ThreadContext.pop();<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> /**<a name="line.124"></a> |
| <span class="sourceLineNo">125</span> * Looks at the last diagnostic context at the top of this NDC<a name="line.125"></a> |
| <span class="sourceLineNo">126</span> * without removing it.<a name="line.126"></a> |
| <span class="sourceLineNo">127</span> * <p><a name="line.127"></a> |
| <span class="sourceLineNo">128</span> * The returned value is the value that was pushed last. If no<a name="line.128"></a> |
| <span class="sourceLineNo">129</span> * context is available, then the empty string "" is returned.<a name="line.129"></a> |
| <span class="sourceLineNo">130</span> * </p><a name="line.130"></a> |
| <span class="sourceLineNo">131</span> * @return String The innermost diagnostic context.<a name="line.131"></a> |
| <span class="sourceLineNo">132</span> */<a name="line.132"></a> |
| <span class="sourceLineNo">133</span> public static String peek() {<a name="line.133"></a> |
| <span class="sourceLineNo">134</span> return org.apache.logging.log4j.ThreadContext.peek();<a name="line.134"></a> |
| <span class="sourceLineNo">135</span> }<a name="line.135"></a> |
| <span class="sourceLineNo">136</span><a name="line.136"></a> |
| <span class="sourceLineNo">137</span> /**<a name="line.137"></a> |
| <span class="sourceLineNo">138</span> * Push new diagnostic context information for the current thread.<a name="line.138"></a> |
| <span class="sourceLineNo">139</span> * <p><a name="line.139"></a> |
| <span class="sourceLineNo">140</span> * The contents of the <code>message</code> parameter is<a name="line.140"></a> |
| <span class="sourceLineNo">141</span> * determined solely by the client.<a name="line.141"></a> |
| <span class="sourceLineNo">142</span> * </p><a name="line.142"></a> |
| <span class="sourceLineNo">143</span> * @param message The new diagnostic context information.<a name="line.143"></a> |
| <span class="sourceLineNo">144</span> */<a name="line.144"></a> |
| <span class="sourceLineNo">145</span> public static void push(final String message) {<a name="line.145"></a> |
| <span class="sourceLineNo">146</span> org.apache.logging.log4j.ThreadContext.push(message);<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> /**<a name="line.149"></a> |
| <span class="sourceLineNo">150</span> * Remove the diagnostic context for this thread.<a name="line.150"></a> |
| <span class="sourceLineNo">151</span> * <p><a name="line.151"></a> |
| <span class="sourceLineNo">152</span> * Each thread that created a diagnostic context by calling<a name="line.152"></a> |
| <span class="sourceLineNo">153</span> * {@link #push} should call this method before exiting. Otherwise,<a name="line.153"></a> |
| <span class="sourceLineNo">154</span> * the memory used by the <b>thread</b> cannot be reclaimed by the<a name="line.154"></a> |
| <span class="sourceLineNo">155</span> * VM.<a name="line.155"></a> |
| <span class="sourceLineNo">156</span> * </p><a name="line.156"></a> |
| <span class="sourceLineNo">157</span> * <p><a name="line.157"></a> |
| <span class="sourceLineNo">158</span> * As this is such an important problem in heavy duty systems and<a name="line.158"></a> |
| <span class="sourceLineNo">159</span> * because it is difficult to always guarantee that the remove<a name="line.159"></a> |
| <span class="sourceLineNo">160</span> * method is called before exiting a thread, this method has been<a name="line.160"></a> |
| <span class="sourceLineNo">161</span> * augmented to lazily remove references to dead threads. In<a name="line.161"></a> |
| <span class="sourceLineNo">162</span> * practice, this means that you can be a little sloppy and<a name="line.162"></a> |
| <span class="sourceLineNo">163</span> * occasionally forget to call {@code remove} before exiting a<a name="line.163"></a> |
| <span class="sourceLineNo">164</span> * thread. However, you must call <code>remove</code> sometime. If<a name="line.164"></a> |
| <span class="sourceLineNo">165</span> * you never call it, then your application is sure to run out of<a name="line.165"></a> |
| <span class="sourceLineNo">166</span> * memory.<a name="line.166"></a> |
| <span class="sourceLineNo">167</span> * </p><a name="line.167"></a> |
| <span class="sourceLineNo">168</span> */<a name="line.168"></a> |
| <span class="sourceLineNo">169</span> public static void remove() {<a name="line.169"></a> |
| <span class="sourceLineNo">170</span> org.apache.logging.log4j.ThreadContext.removeStack();<a name="line.170"></a> |
| <span class="sourceLineNo">171</span> }<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> * Set maximum depth of this diagnostic context. If the current<a name="line.174"></a> |
| <span class="sourceLineNo">175</span> * depth is smaller or equal to <code>maxDepth</code>, then no<a name="line.175"></a> |
| <span class="sourceLineNo">176</span> * action is taken.<a name="line.176"></a> |
| <span class="sourceLineNo">177</span> * <p><a name="line.177"></a> |
| <span class="sourceLineNo">178</span> * This method is a convenient alternative to multiple {@link<a name="line.178"></a> |
| <span class="sourceLineNo">179</span> * #pop} calls. Moreover, it is often the case that at the end of<a name="line.179"></a> |
| <span class="sourceLineNo">180</span> * complex call sequences, the depth of the NDC is<a name="line.180"></a> |
| <span class="sourceLineNo">181</span> * unpredictable. The <code>setMaxDepth</code> method circumvents<a name="line.181"></a> |
| <span class="sourceLineNo">182</span> * this problem.<a name="line.182"></a> |
| <span class="sourceLineNo">183</span> * </p><a name="line.183"></a> |
| <span class="sourceLineNo">184</span> * <p><a name="line.184"></a> |
| <span class="sourceLineNo">185</span> * For example, the combination<a name="line.185"></a> |
| <span class="sourceLineNo">186</span> * </p><a name="line.186"></a> |
| <span class="sourceLineNo">187</span> * <pre><a name="line.187"></a> |
| <span class="sourceLineNo">188</span> * void foo() {<a name="line.188"></a> |
| <span class="sourceLineNo">189</span> * &nbsp; int depth = NDC.getDepth();<a name="line.189"></a> |
| <span class="sourceLineNo">190</span> *<a name="line.190"></a> |
| <span class="sourceLineNo">191</span> * &nbsp; ... complex sequence of calls<a name="line.191"></a> |
| <span class="sourceLineNo">192</span> *<a name="line.192"></a> |
| <span class="sourceLineNo">193</span> * &nbsp; NDC.setMaxDepth(depth);<a name="line.193"></a> |
| <span class="sourceLineNo">194</span> * }<a name="line.194"></a> |
| <span class="sourceLineNo">195</span> * </pre><a name="line.195"></a> |
| <span class="sourceLineNo">196</span> * <p><a name="line.196"></a> |
| <span class="sourceLineNo">197</span> * ensures that between the entry and exit of foo the depth of the<a name="line.197"></a> |
| <span class="sourceLineNo">198</span> * diagnostic stack is conserved.<a name="line.198"></a> |
| <span class="sourceLineNo">199</span> * </p><a name="line.199"></a> |
| <span class="sourceLineNo">200</span> *<a name="line.200"></a> |
| <span class="sourceLineNo">201</span> * @see #getDepth<a name="line.201"></a> |
| <span class="sourceLineNo">202</span> * @param maxDepth The maximum depth of the stack.<a name="line.202"></a> |
| <span class="sourceLineNo">203</span> */<a name="line.203"></a> |
| <span class="sourceLineNo">204</span> public static void setMaxDepth(final int maxDepth) {<a name="line.204"></a> |
| <span class="sourceLineNo">205</span> org.apache.logging.log4j.ThreadContext.trim(maxDepth);<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> |
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