Google Git
Sign in
apache / hbase-site / 13af3b7ae16429fe8dc3116a7ec6863d5e579657 / . / devapidocs / src-html / org / apache / hadoop / hbase / ZNodeClearer.html
blob: 473b26ea55ff451a91039daaf696d43ea656ee37 [file] [log] [blame]
<!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, software<a name="line.12"></a>
<span class="sourceLineNo">013</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<span class="sourceLineNo">014</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<span class="sourceLineNo">015</span> * See the License for the specific language governing permissions and<a name="line.15"></a>
<span class="sourceLineNo">016</span> * limitations under the License.<a name="line.16"></a>
<span class="sourceLineNo">017</span> */<a name="line.17"></a>
<span class="sourceLineNo">018</span>package org.apache.hadoop.hbase;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.io.BufferedReader;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.io.BufferedWriter;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.io.File;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.io.FileNotFoundException;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.io.FileReader;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import java.io.FileWriter;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import java.io.IOException;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import org.apache.hadoop.conf.Configuration;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import org.apache.hadoop.hbase.zookeeper.ZKWatcher;<a name="line.29"></a>
<span class="sourceLineNo">030</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.30"></a>
<span class="sourceLineNo">031</span>import org.slf4j.Logger;<a name="line.31"></a>
<span class="sourceLineNo">032</span>import org.slf4j.LoggerFactory;<a name="line.32"></a>
<span class="sourceLineNo">033</span><a name="line.33"></a>
<span class="sourceLineNo">034</span>/**<a name="line.34"></a>
<span class="sourceLineNo">035</span> * &lt;p&gt;<a name="line.35"></a>
<span class="sourceLineNo">036</span> * Contains a set of methods for the collaboration between the start/stop scripts and the servers.<a name="line.36"></a>
<span class="sourceLineNo">037</span> * It allows to delete immediately the znode when the master or the regions server crashes. The<a name="line.37"></a>
<span class="sourceLineNo">038</span> * region server / master writes a specific file when it starts / becomes main master. When they end<a name="line.38"></a>
<span class="sourceLineNo">039</span> * properly, they delete the file.<a name="line.39"></a>
<span class="sourceLineNo">040</span> * &lt;/p&gt;<a name="line.40"></a>
<span class="sourceLineNo">041</span> * &lt;p&gt;<a name="line.41"></a>
<span class="sourceLineNo">042</span> * In the script, we check for the existence of these files when the program ends. If they still<a name="line.42"></a>
<span class="sourceLineNo">043</span> * exist we conclude that the server crashed, likely without deleting their znode. To have a faster<a name="line.43"></a>
<span class="sourceLineNo">044</span> * recovery we delete immediately the znode.<a name="line.44"></a>
<span class="sourceLineNo">045</span> * &lt;/p&gt;<a name="line.45"></a>
<span class="sourceLineNo">046</span> * &lt;p&gt;<a name="line.46"></a>
<span class="sourceLineNo">047</span> * The strategy depends on the server type. For a region server we store the znode path in the file,<a name="line.47"></a>
<span class="sourceLineNo">048</span> * and use it to delete it. for a master, as the znode path constant whatever the server, we check<a name="line.48"></a>
<span class="sourceLineNo">049</span> * its content to make sure that the backup server is not now in charge.<a name="line.49"></a>
<span class="sourceLineNo">050</span> * &lt;/p&gt;<a name="line.50"></a>
<span class="sourceLineNo">051</span> */<a name="line.51"></a>
<span class="sourceLineNo">052</span>@InterfaceAudience.Private<a name="line.52"></a>
<span class="sourceLineNo">053</span>public final class ZNodeClearer {<a name="line.53"></a>
<span class="sourceLineNo">054</span> private static final Logger LOG = LoggerFactory.getLogger(ZNodeClearer.class);<a name="line.54"></a>
<span class="sourceLineNo">055</span><a name="line.55"></a>
<span class="sourceLineNo">056</span> private ZNodeClearer() {<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> * Logs the errors without failing on exception.<a name="line.60"></a>
<span class="sourceLineNo">061</span> */<a name="line.61"></a>
<span class="sourceLineNo">062</span> public static void writeMyEphemeralNodeOnDisk(String fileContent) {<a name="line.62"></a>
<span class="sourceLineNo">063</span> String fileName = ZNodeClearer.getMyEphemeralNodeFileName();<a name="line.63"></a>
<span class="sourceLineNo">064</span> if (fileName == null) {<a name="line.64"></a>
<span class="sourceLineNo">065</span> LOG.warn("Environment variable HBASE_ZNODE_FILE not set; znodes will not be cleared "<a name="line.65"></a>
<span class="sourceLineNo">066</span> + "on crash by start scripts (Longer MTTR!)");<a name="line.66"></a>
<span class="sourceLineNo">067</span> return;<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> FileWriter fstream;<a name="line.70"></a>
<span class="sourceLineNo">071</span> try {<a name="line.71"></a>
<span class="sourceLineNo">072</span> fstream = new FileWriter(fileName);<a name="line.72"></a>
<span class="sourceLineNo">073</span> } catch (IOException e) {<a name="line.73"></a>
<span class="sourceLineNo">074</span> LOG.warn("Can't write znode file " + fileName, e);<a name="line.74"></a>
<span class="sourceLineNo">075</span> return;<a name="line.75"></a>
<span class="sourceLineNo">076</span> }<a name="line.76"></a>
<span class="sourceLineNo">077</span><a name="line.77"></a>
<span class="sourceLineNo">078</span> BufferedWriter out = new BufferedWriter(fstream);<a name="line.78"></a>
<span class="sourceLineNo">079</span><a name="line.79"></a>
<span class="sourceLineNo">080</span> try {<a name="line.80"></a>
<span class="sourceLineNo">081</span> try {<a name="line.81"></a>
<span class="sourceLineNo">082</span> out.write(fileContent + "\n");<a name="line.82"></a>
<span class="sourceLineNo">083</span> } finally {<a name="line.83"></a>
<span class="sourceLineNo">084</span> try {<a name="line.84"></a>
<span class="sourceLineNo">085</span> out.close();<a name="line.85"></a>
<span class="sourceLineNo">086</span> } finally {<a name="line.86"></a>
<span class="sourceLineNo">087</span> fstream.close();<a name="line.87"></a>
<span class="sourceLineNo">088</span> }<a name="line.88"></a>
<span class="sourceLineNo">089</span> }<a name="line.89"></a>
<span class="sourceLineNo">090</span> } catch (IOException e) {<a name="line.90"></a>
<span class="sourceLineNo">091</span> LOG.warn("Can't write znode file " + fileName, e);<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><a name="line.94"></a>
<span class="sourceLineNo">095</span> /**<a name="line.95"></a>
<span class="sourceLineNo">096</span> * read the content of znode file, expects a single line.<a name="line.96"></a>
<span class="sourceLineNo">097</span> */<a name="line.97"></a>
<span class="sourceLineNo">098</span> public static String readMyEphemeralNodeOnDisk() throws IOException {<a name="line.98"></a>
<span class="sourceLineNo">099</span> String fileName = getMyEphemeralNodeFileName();<a name="line.99"></a>
<span class="sourceLineNo">100</span> if (fileName == null) {<a name="line.100"></a>
<span class="sourceLineNo">101</span> throw new FileNotFoundException("No filename; set environment variable HBASE_ZNODE_FILE");<a name="line.101"></a>
<span class="sourceLineNo">102</span> }<a name="line.102"></a>
<span class="sourceLineNo">103</span> FileReader znodeFile = new FileReader(fileName);<a name="line.103"></a>
<span class="sourceLineNo">104</span> BufferedReader br = null;<a name="line.104"></a>
<span class="sourceLineNo">105</span> try {<a name="line.105"></a>
<span class="sourceLineNo">106</span> br = new BufferedReader(znodeFile);<a name="line.106"></a>
<span class="sourceLineNo">107</span> String file_content = br.readLine();<a name="line.107"></a>
<span class="sourceLineNo">108</span> return file_content;<a name="line.108"></a>
<span class="sourceLineNo">109</span> } finally {<a name="line.109"></a>
<span class="sourceLineNo">110</span> if (br != null) br.close();<a name="line.110"></a>
<span class="sourceLineNo">111</span> }<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> * Get the name of the file used to store the znode contents<a name="line.115"></a>
<span class="sourceLineNo">116</span> */<a name="line.116"></a>
<span class="sourceLineNo">117</span> public static String getMyEphemeralNodeFileName() {<a name="line.117"></a>
<span class="sourceLineNo">118</span> return System.getenv().get("HBASE_ZNODE_FILE");<a name="line.118"></a>
<span class="sourceLineNo">119</span> }<a name="line.119"></a>
<span class="sourceLineNo">120</span><a name="line.120"></a>
<span class="sourceLineNo">121</span> /**<a name="line.121"></a>
<span class="sourceLineNo">122</span> * delete the znode file<a name="line.122"></a>
<span class="sourceLineNo">123</span> */<a name="line.123"></a>
<span class="sourceLineNo">124</span> public static void deleteMyEphemeralNodeOnDisk() {<a name="line.124"></a>
<span class="sourceLineNo">125</span> String fileName = getMyEphemeralNodeFileName();<a name="line.125"></a>
<span class="sourceLineNo">126</span><a name="line.126"></a>
<span class="sourceLineNo">127</span> if (fileName != null) {<a name="line.127"></a>
<span class="sourceLineNo">128</span> new File(fileName).delete();<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><a name="line.131"></a>
<span class="sourceLineNo">132</span> /**<a name="line.132"></a>
<span class="sourceLineNo">133</span> * See HBASE-14861. We are extracting master ServerName from rsZnodePath example:<a name="line.133"></a>
<span class="sourceLineNo">134</span> * "/hbase/rs/server.example.com,16020,1448266496481"<a name="line.134"></a>
<span class="sourceLineNo">135</span> * @param rsZnodePath from HBASE_ZNODE_FILE<a name="line.135"></a>
<span class="sourceLineNo">136</span> * @return String representation of ServerName or null if fails<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> public static String parseMasterServerName(String rsZnodePath) {<a name="line.139"></a>
<span class="sourceLineNo">140</span> String masterServerName = null;<a name="line.140"></a>
<span class="sourceLineNo">141</span> try {<a name="line.141"></a>
<span class="sourceLineNo">142</span> String[] rsZnodeParts = rsZnodePath.split("/");<a name="line.142"></a>
<span class="sourceLineNo">143</span> masterServerName = rsZnodeParts[rsZnodeParts.length - 1];<a name="line.143"></a>
<span class="sourceLineNo">144</span> } catch (IndexOutOfBoundsException e) {<a name="line.144"></a>
<span class="sourceLineNo">145</span> LOG.warn("String " + rsZnodePath + " has wrong format", e);<a name="line.145"></a>
<span class="sourceLineNo">146</span> }<a name="line.146"></a>
<span class="sourceLineNo">147</span> return masterServerName;<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> /**<a name="line.150"></a>
<span class="sourceLineNo">151</span> * Delete the master znode if its content (ServerName string) is the same as the one in the znode<a name="line.151"></a>
<span class="sourceLineNo">152</span> * file. (env: HBASE_ZNODE_FILE). I case of master-rs colloaction we extract ServerName string<a name="line.152"></a>
<span class="sourceLineNo">153</span> * from rsZnode path.(HBASE-14861)<a name="line.153"></a>
<span class="sourceLineNo">154</span> * @return true on successful deletion, false otherwise.<a name="line.154"></a>
<span class="sourceLineNo">155</span> */<a name="line.155"></a>
<span class="sourceLineNo">156</span> public static boolean clear(Configuration conf) {<a name="line.156"></a>
<span class="sourceLineNo">157</span> Configuration tempConf = new Configuration(conf);<a name="line.157"></a>
<span class="sourceLineNo">158</span> tempConf.setInt("zookeeper.recovery.retry", 0);<a name="line.158"></a>
<span class="sourceLineNo">159</span><a name="line.159"></a>
<span class="sourceLineNo">160</span> ZKWatcher zkw;<a name="line.160"></a>
<span class="sourceLineNo">161</span> try {<a name="line.161"></a>
<span class="sourceLineNo">162</span> zkw = new ZKWatcher(tempConf, "clean znode for master", new Abortable() {<a name="line.162"></a>
<span class="sourceLineNo">163</span> @Override<a name="line.163"></a>
<span class="sourceLineNo">164</span> public void abort(String why, Throwable e) {<a name="line.164"></a>
<span class="sourceLineNo">165</span> }<a name="line.165"></a>
<span class="sourceLineNo">166</span><a name="line.166"></a>
<span class="sourceLineNo">167</span> @Override<a name="line.167"></a>
<span class="sourceLineNo">168</span> public boolean isAborted() {<a name="line.168"></a>
<span class="sourceLineNo">169</span> return false;<a name="line.169"></a>
<span class="sourceLineNo">170</span> }<a name="line.170"></a>
<span class="sourceLineNo">171</span> });<a name="line.171"></a>
<span class="sourceLineNo">172</span> } catch (IOException e) {<a name="line.172"></a>
<span class="sourceLineNo">173</span> LOG.warn("Can't connect to zookeeper to read the master znode", e);<a name="line.173"></a>
<span class="sourceLineNo">174</span> return false;<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> String znodeFileContent;<a name="line.177"></a>
<span class="sourceLineNo">178</span> try {<a name="line.178"></a>
<span class="sourceLineNo">179</span> znodeFileContent = ZNodeClearer.readMyEphemeralNodeOnDisk();<a name="line.179"></a>
<span class="sourceLineNo">180</span> return MasterAddressTracker.deleteIfEquals(zkw, znodeFileContent);<a name="line.180"></a>
<span class="sourceLineNo">181</span> } catch (FileNotFoundException fnfe) {<a name="line.181"></a>
<span class="sourceLineNo">182</span> // If no file, just keep going -- return success.<a name="line.182"></a>
<span class="sourceLineNo">183</span> LOG.warn("Can't find the znode file; presume non-fatal", fnfe);<a name="line.183"></a>
<span class="sourceLineNo">184</span> return true;<a name="line.184"></a>
<span class="sourceLineNo">185</span> } catch (IOException e) {<a name="line.185"></a>
<span class="sourceLineNo">186</span> LOG.warn("Can't read the content of the znode file", e);<a name="line.186"></a>
<span class="sourceLineNo">187</span> return false;<a name="line.187"></a>
<span class="sourceLineNo">188</span> } finally {<a name="line.188"></a>
<span class="sourceLineNo">189</span> zkw.close();<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>
</pre>
</div>
</body>
</html>