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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, software<a name="line.12"></a>
<FONT color="green">013</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<FONT color="green">014</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<FONT color="green">015</FONT>     * See the License for the specific language governing permissions and<a name="line.15"></a>
<FONT color="green">016</FONT>     * limitations under the License.<a name="line.16"></a>
<FONT color="green">017</FONT>     */<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    package org.apache.hadoop.metrics.spi;<a name="line.19"></a>
<FONT color="green">020</FONT>    <a name="line.20"></a>
<FONT color="green">021</FONT>    import org.apache.hadoop.classification.InterfaceAudience;<a name="line.21"></a>
<FONT color="green">022</FONT>    import org.apache.hadoop.classification.InterfaceStability;<a name="line.22"></a>
<FONT color="green">023</FONT>    import org.apache.hadoop.metrics.ContextFactory;<a name="line.23"></a>
<FONT color="green">024</FONT>    import org.apache.hadoop.metrics.MetricsException;<a name="line.24"></a>
<FONT color="green">025</FONT>    <a name="line.25"></a>
<FONT color="green">026</FONT>    /**<a name="line.26"></a>
<FONT color="green">027</FONT>     * A null context which has a thread calling <a name="line.27"></a>
<FONT color="green">028</FONT>     * periodically when monitoring is started. This keeps the data sampled <a name="line.28"></a>
<FONT color="green">029</FONT>     * correctly.<a name="line.29"></a>
<FONT color="green">030</FONT>     * In all other respects, this is like the NULL context: No data is emitted.<a name="line.30"></a>
<FONT color="green">031</FONT>     * This is suitable for Monitoring systems like JMX which reads the metrics<a name="line.31"></a>
<FONT color="green">032</FONT>     *  when someone reads the data from JMX.<a name="line.32"></a>
<FONT color="green">033</FONT>     * <a name="line.33"></a>
<FONT color="green">034</FONT>     * The default impl of start and stop monitoring:<a name="line.34"></a>
<FONT color="green">035</FONT>     *  is the AbstractMetricsContext is good enough.<a name="line.35"></a>
<FONT color="green">036</FONT>     * <a name="line.36"></a>
<FONT color="green">037</FONT>     */<a name="line.37"></a>
<FONT color="green">038</FONT>    @InterfaceAudience.Public<a name="line.38"></a>
<FONT color="green">039</FONT>    @InterfaceStability.Evolving<a name="line.39"></a>
<FONT color="green">040</FONT>    public class NullContextWithUpdateThread extends AbstractMetricsContext {<a name="line.40"></a>
<FONT color="green">041</FONT>      <a name="line.41"></a>
<FONT color="green">042</FONT>      private static final String PERIOD_PROPERTY = "period";<a name="line.42"></a>
<FONT color="green">043</FONT>        <a name="line.43"></a>
<FONT color="green">044</FONT>      /** Creates a new instance of NullContextWithUpdateThread */<a name="line.44"></a>
<FONT color="green">045</FONT>      @InterfaceAudience.Private<a name="line.45"></a>
<FONT color="green">046</FONT>      public NullContextWithUpdateThread() {<a name="line.46"></a>
<FONT color="green">047</FONT>      }<a name="line.47"></a>
<FONT color="green">048</FONT>      <a name="line.48"></a>
<FONT color="green">049</FONT>      @InterfaceAudience.Private<a name="line.49"></a>
<FONT color="green">050</FONT>      public void init(String contextName, ContextFactory factory) {<a name="line.50"></a>
<FONT color="green">051</FONT>        super.init(contextName, factory);<a name="line.51"></a>
<FONT color="green">052</FONT>        parseAndSetPeriod(PERIOD_PROPERTY);<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>        <a name="line.55"></a>
<FONT color="green">056</FONT>      /**<a name="line.56"></a>
<FONT color="green">057</FONT>       * Do-nothing version of emitRecord<a name="line.57"></a>
<FONT color="green">058</FONT>       */<a name="line.58"></a>
<FONT color="green">059</FONT>      @InterfaceAudience.Private<a name="line.59"></a>
<FONT color="green">060</FONT>      protected void emitRecord(String contextName, String recordName,<a name="line.60"></a>
<FONT color="green">061</FONT>                                OutputRecord outRec) <a name="line.61"></a>
<FONT color="green">062</FONT>      {}<a name="line.62"></a>
<FONT color="green">063</FONT>        <a name="line.63"></a>
<FONT color="green">064</FONT>      /**<a name="line.64"></a>
<FONT color="green">065</FONT>       * Do-nothing version of update<a name="line.65"></a>
<FONT color="green">066</FONT>       */<a name="line.66"></a>
<FONT color="green">067</FONT>      @InterfaceAudience.Private<a name="line.67"></a>
<FONT color="green">068</FONT>      protected void update(MetricsRecordImpl record) {<a name="line.68"></a>
<FONT color="green">069</FONT>      }<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>       * Do-nothing version of remove<a name="line.72"></a>
<FONT color="green">073</FONT>       */<a name="line.73"></a>
<FONT color="green">074</FONT>      @InterfaceAudience.Private<a name="line.74"></a>
<FONT color="green">075</FONT>      protected void remove(MetricsRecordImpl record) {<a name="line.75"></a>
<FONT color="green">076</FONT>      }<a name="line.76"></a>
<FONT color="green">077</FONT>    }<a name="line.77"></a>




























































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