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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, 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.zookeeper;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import org.apache.hadoop.hbase.Abortable;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import org.apache.zookeeper.KeeperException;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.slf4j.Logger;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import org.slf4j.LoggerFactory;<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> * Tracks the availability and value of a single ZooKeeper node.<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> * Utilizes the {@link ZKListener} interface to get the necessary ZooKeeper events related to the<a name="line.30"></a>
<span class="sourceLineNo">031</span> * node.<a name="line.31"></a>
<span class="sourceLineNo">032</span> * &lt;p&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> * This is the base class used by trackers in both the Master and RegionServers.<a name="line.33"></a>
<span class="sourceLineNo">034</span> */<a name="line.34"></a>
<span class="sourceLineNo">035</span>@InterfaceAudience.Private<a name="line.35"></a>
<span class="sourceLineNo">036</span>public abstract class ZKNodeTracker extends ZKListener {<a name="line.36"></a>
<span class="sourceLineNo">037</span> // LOG is being used in subclasses, hence keeping it protected<a name="line.37"></a>
<span class="sourceLineNo">038</span> protected static final Logger LOG = LoggerFactory.getLogger(ZKNodeTracker.class);<a name="line.38"></a>
<span class="sourceLineNo">039</span> /** Path of node being tracked */<a name="line.39"></a>
<span class="sourceLineNo">040</span> protected final String node;<a name="line.40"></a>
<span class="sourceLineNo">041</span><a name="line.41"></a>
<span class="sourceLineNo">042</span> /** Data of the node being tracked */<a name="line.42"></a>
<span class="sourceLineNo">043</span> private byte[] data;<a name="line.43"></a>
<span class="sourceLineNo">044</span><a name="line.44"></a>
<span class="sourceLineNo">045</span> /** Used to abort if a fatal error occurs */<a name="line.45"></a>
<span class="sourceLineNo">046</span> protected final Abortable abortable;<a name="line.46"></a>
<span class="sourceLineNo">047</span><a name="line.47"></a>
<span class="sourceLineNo">048</span> private boolean stopped = false;<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>
<span class="sourceLineNo">050</span> /**<a name="line.50"></a>
<span class="sourceLineNo">051</span> * Constructs a new ZK node tracker.<a name="line.51"></a>
<span class="sourceLineNo">052</span> * &lt;p/&gt;<a name="line.52"></a>
<span class="sourceLineNo">053</span> * After construction, use {@link #start} to kick off tracking.<a name="line.53"></a>
<span class="sourceLineNo">054</span> * @param watcher reference to the {@link ZKWatcher} which also contains configuration and<a name="line.54"></a>
<span class="sourceLineNo">055</span> * constants<a name="line.55"></a>
<span class="sourceLineNo">056</span> * @param node path of the node being tracked<a name="line.56"></a>
<span class="sourceLineNo">057</span> * @param abortable used to abort if a fatal error occurs<a name="line.57"></a>
<span class="sourceLineNo">058</span> */<a name="line.58"></a>
<span class="sourceLineNo">059</span> public ZKNodeTracker(ZKWatcher watcher, String node, Abortable abortable) {<a name="line.59"></a>
<span class="sourceLineNo">060</span> super(watcher);<a name="line.60"></a>
<span class="sourceLineNo">061</span> this.node = node;<a name="line.61"></a>
<span class="sourceLineNo">062</span> this.abortable = abortable;<a name="line.62"></a>
<span class="sourceLineNo">063</span> this.data = null;<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> * Starts the tracking of the node in ZooKeeper.<a name="line.67"></a>
<span class="sourceLineNo">068</span> * &lt;p/&gt;<a name="line.68"></a>
<span class="sourceLineNo">069</span> * Use {@link #blockUntilAvailable()} to block until the node is available or<a name="line.69"></a>
<span class="sourceLineNo">070</span> * {@link #getData(boolean)} to get the data of the node if it is available.<a name="line.70"></a>
<span class="sourceLineNo">071</span> */<a name="line.71"></a>
<span class="sourceLineNo">072</span> public synchronized void start() {<a name="line.72"></a>
<span class="sourceLineNo">073</span> this.watcher.registerListener(this);<a name="line.73"></a>
<span class="sourceLineNo">074</span> try {<a name="line.74"></a>
<span class="sourceLineNo">075</span> if (ZKUtil.watchAndCheckExists(watcher, node)) {<a name="line.75"></a>
<span class="sourceLineNo">076</span> byte[] data = ZKUtil.getDataAndWatch(watcher, node);<a name="line.76"></a>
<span class="sourceLineNo">077</span> if (data != null) {<a name="line.77"></a>
<span class="sourceLineNo">078</span> this.data = data;<a name="line.78"></a>
<span class="sourceLineNo">079</span> } else {<a name="line.79"></a>
<span class="sourceLineNo">080</span> // It existed but now does not, try again to ensure a watch is set<a name="line.80"></a>
<span class="sourceLineNo">081</span> LOG.debug("Try starting again because there is no data from {}", node);<a name="line.81"></a>
<span class="sourceLineNo">082</span> start();<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> } catch (KeeperException e) {<a name="line.85"></a>
<span class="sourceLineNo">086</span> abortable.abort("Unexpected exception during initialization, aborting", e);<a name="line.86"></a>
<span class="sourceLineNo">087</span> }<a name="line.87"></a>
<span class="sourceLineNo">088</span> postStart();<a name="line.88"></a>
<span class="sourceLineNo">089</span> }<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> * Called after start is called. Sub classes could implement this method to load more data on zk.<a name="line.92"></a>
<span class="sourceLineNo">093</span> */<a name="line.93"></a>
<span class="sourceLineNo">094</span> protected void postStart() {<a name="line.94"></a>
<span class="sourceLineNo">095</span> }<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span> public synchronized void stop() {<a name="line.97"></a>
<span class="sourceLineNo">098</span> this.stopped = true;<a name="line.98"></a>
<span class="sourceLineNo">099</span> notifyAll();<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> * Gets the data of the node, blocking until the node is available.<a name="line.103"></a>
<span class="sourceLineNo">104</span> * @return data of the node<a name="line.104"></a>
<span class="sourceLineNo">105</span> * @throws InterruptedException if the waiting thread is interrupted<a name="line.105"></a>
<span class="sourceLineNo">106</span> */<a name="line.106"></a>
<span class="sourceLineNo">107</span> public synchronized byte[] blockUntilAvailable() throws InterruptedException {<a name="line.107"></a>
<span class="sourceLineNo">108</span> return blockUntilAvailable(0, false);<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> * Gets the data of the node, blocking until the node is available or the specified timeout has<a name="line.112"></a>
<span class="sourceLineNo">113</span> * elapsed.<a name="line.113"></a>
<span class="sourceLineNo">114</span> * @param timeout maximum time to wait for the node data to be available, n milliseconds. Pass 0<a name="line.114"></a>
<span class="sourceLineNo">115</span> * for no timeout.<a name="line.115"></a>
<span class="sourceLineNo">116</span> * @return data of the node<a name="line.116"></a>
<span class="sourceLineNo">117</span> * @throws InterruptedException if the waiting thread is interrupted<a name="line.117"></a>
<span class="sourceLineNo">118</span> */<a name="line.118"></a>
<span class="sourceLineNo">119</span> public synchronized byte[] blockUntilAvailable(long timeout, boolean refresh)<a name="line.119"></a>
<span class="sourceLineNo">120</span> throws InterruptedException {<a name="line.120"></a>
<span class="sourceLineNo">121</span> if (timeout &lt; 0) {<a name="line.121"></a>
<span class="sourceLineNo">122</span> throw new IllegalArgumentException();<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> boolean notimeout = timeout == 0;<a name="line.125"></a>
<span class="sourceLineNo">126</span> long startTime = EnvironmentEdgeManager.currentTime();<a name="line.126"></a>
<span class="sourceLineNo">127</span> long remaining = timeout;<a name="line.127"></a>
<span class="sourceLineNo">128</span> if (refresh) {<a name="line.128"></a>
<span class="sourceLineNo">129</span> try {<a name="line.129"></a>
<span class="sourceLineNo">130</span> // This does not create a watch if the node does not exists<a name="line.130"></a>
<span class="sourceLineNo">131</span> this.data = ZKUtil.getDataAndWatch(watcher, node);<a name="line.131"></a>
<span class="sourceLineNo">132</span> } catch (KeeperException e) {<a name="line.132"></a>
<span class="sourceLineNo">133</span> // We use to abort here, but in some cases the abort is ignored (<a name="line.133"></a>
<span class="sourceLineNo">134</span> // (empty Abortable), so it's better to log...<a name="line.134"></a>
<span class="sourceLineNo">135</span> LOG.warn("Unexpected exception handling blockUntilAvailable", e);<a name="line.135"></a>
<span class="sourceLineNo">136</span> abortable.abort("Unexpected exception handling blockUntilAvailable", e);<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> boolean nodeExistsChecked = (!refresh || data != null);<a name="line.139"></a>
<span class="sourceLineNo">140</span> while (!this.stopped &amp;&amp; (notimeout || remaining &gt; 0) &amp;&amp; this.data == null) {<a name="line.140"></a>
<span class="sourceLineNo">141</span> if (!nodeExistsChecked) {<a name="line.141"></a>
<span class="sourceLineNo">142</span> try {<a name="line.142"></a>
<span class="sourceLineNo">143</span> nodeExistsChecked = (ZKUtil.checkExists(watcher, node) != -1);<a name="line.143"></a>
<span class="sourceLineNo">144</span> } catch (KeeperException e) {<a name="line.144"></a>
<span class="sourceLineNo">145</span> LOG.warn("Got exception while trying to check existence in ZooKeeper" + " of the node: "<a name="line.145"></a>
<span class="sourceLineNo">146</span> + node + ", retrying if timeout not reached", e);<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> // It did not exists, and now it does.<a name="line.149"></a>
<span class="sourceLineNo">150</span> if (nodeExistsChecked) {<a name="line.150"></a>
<span class="sourceLineNo">151</span> LOG.debug("Node {} now exists, resetting a watcher", node);<a name="line.151"></a>
<span class="sourceLineNo">152</span> try {<a name="line.152"></a>
<span class="sourceLineNo">153</span> // This does not create a watch if the node does not exists<a name="line.153"></a>
<span class="sourceLineNo">154</span> this.data = ZKUtil.getDataAndWatch(watcher, node);<a name="line.154"></a>
<span class="sourceLineNo">155</span> } catch (KeeperException e) {<a name="line.155"></a>
<span class="sourceLineNo">156</span> LOG.warn("Unexpected exception handling blockUntilAvailable", e);<a name="line.156"></a>
<span class="sourceLineNo">157</span> abortable.abort("Unexpected exception handling blockUntilAvailable", e);<a name="line.157"></a>
<span class="sourceLineNo">158</span> }<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> // We expect a notification; but we wait with a<a name="line.161"></a>
<span class="sourceLineNo">162</span> // a timeout to lower the impact of a race condition if any<a name="line.162"></a>
<span class="sourceLineNo">163</span> wait(100);<a name="line.163"></a>
<span class="sourceLineNo">164</span> remaining = timeout - (EnvironmentEdgeManager.currentTime() - startTime);<a name="line.164"></a>
<span class="sourceLineNo">165</span> }<a name="line.165"></a>
<span class="sourceLineNo">166</span> return this.data;<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> * Gets the data of the node.<a name="line.170"></a>
<span class="sourceLineNo">171</span> * &lt;p&gt;<a name="line.171"></a>
<span class="sourceLineNo">172</span> * If the node is currently available, the most up-to-date known version of the data is returned.<a name="line.172"></a>
<span class="sourceLineNo">173</span> * If the node is not currently available, null is returned.<a name="line.173"></a>
<span class="sourceLineNo">174</span> * @param refresh whether to refresh the data by calling ZK directly.<a name="line.174"></a>
<span class="sourceLineNo">175</span> * @return data of the node, null if unavailable<a name="line.175"></a>
<span class="sourceLineNo">176</span> */<a name="line.176"></a>
<span class="sourceLineNo">177</span> public synchronized byte[] getData(boolean refresh) {<a name="line.177"></a>
<span class="sourceLineNo">178</span> if (refresh) {<a name="line.178"></a>
<span class="sourceLineNo">179</span> try {<a name="line.179"></a>
<span class="sourceLineNo">180</span> this.data = ZKUtil.getDataAndWatch(watcher, node);<a name="line.180"></a>
<span class="sourceLineNo">181</span> } catch (KeeperException e) {<a name="line.181"></a>
<span class="sourceLineNo">182</span> abortable.abort("Unexpected exception handling getData", e);<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> return this.data;<a name="line.185"></a>
<span class="sourceLineNo">186</span> }<a name="line.186"></a>
<span class="sourceLineNo">187</span><a name="line.187"></a>
<span class="sourceLineNo">188</span> public String getNode() {<a name="line.188"></a>
<span class="sourceLineNo">189</span> return this.node;<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> @Override<a name="line.192"></a>
<span class="sourceLineNo">193</span> public synchronized void nodeCreated(String path) {<a name="line.193"></a>
<span class="sourceLineNo">194</span> if (!path.equals(node)) {<a name="line.194"></a>
<span class="sourceLineNo">195</span> return;<a name="line.195"></a>
<span class="sourceLineNo">196</span> }<a name="line.196"></a>
<span class="sourceLineNo">197</span><a name="line.197"></a>
<span class="sourceLineNo">198</span> try {<a name="line.198"></a>
<span class="sourceLineNo">199</span> byte[] data = ZKUtil.getDataAndWatch(watcher, node);<a name="line.199"></a>
<span class="sourceLineNo">200</span> if (data != null) {<a name="line.200"></a>
<span class="sourceLineNo">201</span> this.data = data;<a name="line.201"></a>
<span class="sourceLineNo">202</span> notifyAll();<a name="line.202"></a>
<span class="sourceLineNo">203</span> } else {<a name="line.203"></a>
<span class="sourceLineNo">204</span> nodeDeleted(path);<a name="line.204"></a>
<span class="sourceLineNo">205</span> }<a name="line.205"></a>
<span class="sourceLineNo">206</span> } catch (KeeperException e) {<a name="line.206"></a>
<span class="sourceLineNo">207</span> abortable.abort("Unexpected exception handling nodeCreated event", e);<a name="line.207"></a>
<span class="sourceLineNo">208</span> }<a name="line.208"></a>
<span class="sourceLineNo">209</span> }<a name="line.209"></a>
<span class="sourceLineNo">210</span><a name="line.210"></a>
<span class="sourceLineNo">211</span> @Override<a name="line.211"></a>
<span class="sourceLineNo">212</span> public synchronized void nodeDeleted(String path) {<a name="line.212"></a>
<span class="sourceLineNo">213</span> if (path.equals(node)) {<a name="line.213"></a>
<span class="sourceLineNo">214</span> try {<a name="line.214"></a>
<span class="sourceLineNo">215</span> if (ZKUtil.watchAndCheckExists(watcher, node)) {<a name="line.215"></a>
<span class="sourceLineNo">216</span> nodeCreated(path);<a name="line.216"></a>
<span class="sourceLineNo">217</span> } else {<a name="line.217"></a>
<span class="sourceLineNo">218</span> this.data = null;<a name="line.218"></a>
<span class="sourceLineNo">219</span> }<a name="line.219"></a>
<span class="sourceLineNo">220</span> } catch (KeeperException e) {<a name="line.220"></a>
<span class="sourceLineNo">221</span> abortable.abort("Unexpected exception handling nodeDeleted event", e);<a name="line.221"></a>
<span class="sourceLineNo">222</span> }<a name="line.222"></a>
<span class="sourceLineNo">223</span> }<a name="line.223"></a>
<span class="sourceLineNo">224</span> }<a name="line.224"></a>
<span class="sourceLineNo">225</span><a name="line.225"></a>
<span class="sourceLineNo">226</span> @Override<a name="line.226"></a>
<span class="sourceLineNo">227</span> public synchronized void nodeDataChanged(String path) {<a name="line.227"></a>
<span class="sourceLineNo">228</span> if (path.equals(node)) {<a name="line.228"></a>
<span class="sourceLineNo">229</span> nodeCreated(path);<a name="line.229"></a>
<span class="sourceLineNo">230</span> }<a name="line.230"></a>
<span class="sourceLineNo">231</span> }<a name="line.231"></a>
<span class="sourceLineNo">232</span><a name="line.232"></a>
<span class="sourceLineNo">233</span> /**<a name="line.233"></a>
<span class="sourceLineNo">234</span> * Checks if the baseznode set as per the property 'zookeeper.znode.parent' exists.<a name="line.234"></a>
<span class="sourceLineNo">235</span> * @return true if baseznode exists. false if doesnot exists.<a name="line.235"></a>
<span class="sourceLineNo">236</span> */<a name="line.236"></a>
<span class="sourceLineNo">237</span> public boolean checkIfBaseNodeAvailable() {<a name="line.237"></a>
<span class="sourceLineNo">238</span> try {<a name="line.238"></a>
<span class="sourceLineNo">239</span> if (ZKUtil.checkExists(watcher, watcher.getZNodePaths().baseZNode) == -1) {<a name="line.239"></a>
<span class="sourceLineNo">240</span> return false;<a name="line.240"></a>
<span class="sourceLineNo">241</span> }<a name="line.241"></a>
<span class="sourceLineNo">242</span> } catch (KeeperException e) {<a name="line.242"></a>
<span class="sourceLineNo">243</span> abortable.abort("Exception while checking if basenode (" + watcher.getZNodePaths().baseZNode<a name="line.243"></a>
<span class="sourceLineNo">244</span> + ") exists in ZooKeeper.", e);<a name="line.244"></a>
<span class="sourceLineNo">245</span> }<a name="line.245"></a>
<span class="sourceLineNo">246</span> return true;<a name="line.246"></a>
<span class="sourceLineNo">247</span> }<a name="line.247"></a>
<span class="sourceLineNo">248</span><a name="line.248"></a>
<span class="sourceLineNo">249</span> @Override<a name="line.249"></a>
<span class="sourceLineNo">250</span> public String toString() {<a name="line.250"></a>
<span class="sourceLineNo">251</span> return "ZKNodeTracker{" + "node='" + node + ", stopped=" + stopped + '}';<a name="line.251"></a>
<span class="sourceLineNo">252</span> }<a name="line.252"></a>
<span class="sourceLineNo">253</span>}<a name="line.253"></a>
</pre>
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