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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.master.assignment;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.util.ArrayDeque;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.util.Queue;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.concurrent.locks.Condition;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.util.concurrent.locks.Lock;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.util.concurrent.locks.ReentrantLock;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import org.apache.hadoop.hbase.client.RegionInfo;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import org.apache.hadoop.hbase.procedure2.Procedure;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import org.apache.hadoop.hbase.procedure2.ProcedureFutureUtil;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import org.apache.hadoop.hbase.procedure2.ProcedureSuspendedException;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.29"></a>
<span class="sourceLineNo">030</span><a name="line.30"></a>
<span class="sourceLineNo">031</span>/**<a name="line.31"></a>
<span class="sourceLineNo">032</span> * A lock implementation which supports unlock by another thread.<a name="line.32"></a>
<span class="sourceLineNo">033</span> * &lt;p&gt;<a name="line.33"></a>
<span class="sourceLineNo">034</span> * This is because we need to hold region state node lock while updating region state to meta(for<a name="line.34"></a>
<span class="sourceLineNo">035</span> * keeping consistency), so it is better to yield the procedure to release the procedure worker. But<a name="line.35"></a>
<span class="sourceLineNo">036</span> * after waking up the procedure, we may use another procedure worker to execute the procedure,<a name="line.36"></a>
<span class="sourceLineNo">037</span> * which means we need to unlock by another thread.<a name="line.37"></a>
<span class="sourceLineNo">038</span> * &lt;p&gt;<a name="line.38"></a>
<span class="sourceLineNo">039</span> * For locking by procedure, we will also suspend the procedure if the lock is not ready, and<a name="line.39"></a>
<span class="sourceLineNo">040</span> * schedule it again when lock is ready. This is very important to not block the PEWorker as we may<a name="line.40"></a>
<span class="sourceLineNo">041</span> * hold the lock when updating meta, which could take a lot of time.<a name="line.41"></a>
<span class="sourceLineNo">042</span> * &lt;p&gt;<a name="line.42"></a>
<span class="sourceLineNo">043</span> * Please see HBASE-28196 for more details.<a name="line.43"></a>
<span class="sourceLineNo">044</span> */<a name="line.44"></a>
<span class="sourceLineNo">045</span>@InterfaceAudience.Private<a name="line.45"></a>
<span class="sourceLineNo">046</span>class RegionStateNodeLock {<a name="line.46"></a>
<span class="sourceLineNo">047</span><a name="line.47"></a>
<span class="sourceLineNo">048</span> // for better logging message<a name="line.48"></a>
<span class="sourceLineNo">049</span> private final RegionInfo regionInfo;<a name="line.49"></a>
<span class="sourceLineNo">050</span><a name="line.50"></a>
<span class="sourceLineNo">051</span> private final Lock lock = new ReentrantLock();<a name="line.51"></a>
<span class="sourceLineNo">052</span><a name="line.52"></a>
<span class="sourceLineNo">053</span> private final Queue&lt;QueueEntry&gt; waitingQueue = new ArrayDeque&lt;&gt;();<a name="line.53"></a>
<span class="sourceLineNo">054</span><a name="line.54"></a>
<span class="sourceLineNo">055</span> private Object owner;<a name="line.55"></a>
<span class="sourceLineNo">056</span><a name="line.56"></a>
<span class="sourceLineNo">057</span> private int count;<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> * This is for abstraction the common lock/unlock logic for both Thread and Procedure.<a name="line.60"></a>
<span class="sourceLineNo">061</span> */<a name="line.61"></a>
<span class="sourceLineNo">062</span> private interface QueueEntry {<a name="line.62"></a>
<span class="sourceLineNo">063</span><a name="line.63"></a>
<span class="sourceLineNo">064</span> /**<a name="line.64"></a>
<span class="sourceLineNo">065</span> * A thread, or a procedure.<a name="line.65"></a>
<span class="sourceLineNo">066</span> */<a name="line.66"></a>
<span class="sourceLineNo">067</span> Object getOwner();<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> * Called when we can not hold the lock and should wait. For thread, you should wait on a<a name="line.70"></a>
<span class="sourceLineNo">071</span> * condition, and for procedure, a ProcedureSuspendedException should be thrown.<a name="line.71"></a>
<span class="sourceLineNo">072</span> */<a name="line.72"></a>
<span class="sourceLineNo">073</span> void await() throws ProcedureSuspendedException;<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span> /**<a name="line.75"></a>
<span class="sourceLineNo">076</span> * Called when it is your turn to get the lock. For thread, just delegate the call to<a name="line.76"></a>
<span class="sourceLineNo">077</span> * condition's signal method, and for procedure, you should call the {@code wakeUp} action, to<a name="line.77"></a>
<span class="sourceLineNo">078</span> * add the procedure back to procedure scheduler.<a name="line.78"></a>
<span class="sourceLineNo">079</span> */<a name="line.79"></a>
<span class="sourceLineNo">080</span> void signal();<a name="line.80"></a>
<span class="sourceLineNo">081</span> }<a name="line.81"></a>
<span class="sourceLineNo">082</span><a name="line.82"></a>
<span class="sourceLineNo">083</span> RegionStateNodeLock(RegionInfo regionInfo) {<a name="line.83"></a>
<span class="sourceLineNo">084</span> this.regionInfo = regionInfo;<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> private void lock0(QueueEntry entry) throws ProcedureSuspendedException {<a name="line.87"></a>
<span class="sourceLineNo">088</span> lock.lock();<a name="line.88"></a>
<span class="sourceLineNo">089</span> try {<a name="line.89"></a>
<span class="sourceLineNo">090</span> for (;;) {<a name="line.90"></a>
<span class="sourceLineNo">091</span> if (owner == null) {<a name="line.91"></a>
<span class="sourceLineNo">092</span> owner = entry.getOwner();<a name="line.92"></a>
<span class="sourceLineNo">093</span> count = 1;<a name="line.93"></a>
<span class="sourceLineNo">094</span> return;<a name="line.94"></a>
<span class="sourceLineNo">095</span> }<a name="line.95"></a>
<span class="sourceLineNo">096</span> if (owner == entry.getOwner()) {<a name="line.96"></a>
<span class="sourceLineNo">097</span> count++;<a name="line.97"></a>
<span class="sourceLineNo">098</span> return;<a name="line.98"></a>
<span class="sourceLineNo">099</span> }<a name="line.99"></a>
<span class="sourceLineNo">100</span> waitingQueue.add(entry);<a name="line.100"></a>
<span class="sourceLineNo">101</span> entry.await();<a name="line.101"></a>
<span class="sourceLineNo">102</span> }<a name="line.102"></a>
<span class="sourceLineNo">103</span> } finally {<a name="line.103"></a>
<span class="sourceLineNo">104</span> lock.unlock();<a name="line.104"></a>
<span class="sourceLineNo">105</span> }<a name="line.105"></a>
<span class="sourceLineNo">106</span> }<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span> private boolean tryLock0(Object lockBy) {<a name="line.108"></a>
<span class="sourceLineNo">109</span> if (!lock.tryLock()) {<a name="line.109"></a>
<span class="sourceLineNo">110</span> return false;<a name="line.110"></a>
<span class="sourceLineNo">111</span> }<a name="line.111"></a>
<span class="sourceLineNo">112</span> try {<a name="line.112"></a>
<span class="sourceLineNo">113</span> if (owner == null) {<a name="line.113"></a>
<span class="sourceLineNo">114</span> owner = lockBy;<a name="line.114"></a>
<span class="sourceLineNo">115</span> count = 1;<a name="line.115"></a>
<span class="sourceLineNo">116</span> return true;<a name="line.116"></a>
<span class="sourceLineNo">117</span> }<a name="line.117"></a>
<span class="sourceLineNo">118</span> if (owner == lockBy) {<a name="line.118"></a>
<span class="sourceLineNo">119</span> count++;<a name="line.119"></a>
<span class="sourceLineNo">120</span> return true;<a name="line.120"></a>
<span class="sourceLineNo">121</span> }<a name="line.121"></a>
<span class="sourceLineNo">122</span> return false;<a name="line.122"></a>
<span class="sourceLineNo">123</span> } finally {<a name="line.123"></a>
<span class="sourceLineNo">124</span> lock.unlock();<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><a name="line.127"></a>
<span class="sourceLineNo">128</span> private void unlock0(Object unlockBy) {<a name="line.128"></a>
<span class="sourceLineNo">129</span> lock.lock();<a name="line.129"></a>
<span class="sourceLineNo">130</span> try {<a name="line.130"></a>
<span class="sourceLineNo">131</span> if (owner == null) {<a name="line.131"></a>
<span class="sourceLineNo">132</span> throw new IllegalMonitorStateException("RegionStateNode " + regionInfo + " is not locked");<a name="line.132"></a>
<span class="sourceLineNo">133</span> }<a name="line.133"></a>
<span class="sourceLineNo">134</span> if (owner != unlockBy) {<a name="line.134"></a>
<span class="sourceLineNo">135</span> throw new IllegalMonitorStateException("RegionStateNode " + regionInfo + " is locked by "<a name="line.135"></a>
<span class="sourceLineNo">136</span> + owner + ", can not be unlocked by " + unlockBy);<a name="line.136"></a>
<span class="sourceLineNo">137</span> }<a name="line.137"></a>
<span class="sourceLineNo">138</span> count--;<a name="line.138"></a>
<span class="sourceLineNo">139</span> if (count == 0) {<a name="line.139"></a>
<span class="sourceLineNo">140</span> owner = null;<a name="line.140"></a>
<span class="sourceLineNo">141</span> QueueEntry entry = waitingQueue.poll();<a name="line.141"></a>
<span class="sourceLineNo">142</span> if (entry != null) {<a name="line.142"></a>
<span class="sourceLineNo">143</span> entry.signal();<a name="line.143"></a>
<span class="sourceLineNo">144</span> }<a name="line.144"></a>
<span class="sourceLineNo">145</span> }<a name="line.145"></a>
<span class="sourceLineNo">146</span> } finally {<a name="line.146"></a>
<span class="sourceLineNo">147</span> lock.unlock();<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> /**<a name="line.151"></a>
<span class="sourceLineNo">152</span> * Normal lock, will set the current thread as owner. Typically you should use try...finally to<a name="line.152"></a>
<span class="sourceLineNo">153</span> * call unlock in the finally block.<a name="line.153"></a>
<span class="sourceLineNo">154</span> */<a name="line.154"></a>
<span class="sourceLineNo">155</span> void lock() {<a name="line.155"></a>
<span class="sourceLineNo">156</span> Thread currentThread = Thread.currentThread();<a name="line.156"></a>
<span class="sourceLineNo">157</span> try {<a name="line.157"></a>
<span class="sourceLineNo">158</span> lock0(new QueueEntry() {<a name="line.158"></a>
<span class="sourceLineNo">159</span><a name="line.159"></a>
<span class="sourceLineNo">160</span> private Condition cond;<a name="line.160"></a>
<span class="sourceLineNo">161</span><a name="line.161"></a>
<span class="sourceLineNo">162</span> @Override<a name="line.162"></a>
<span class="sourceLineNo">163</span> public void signal() {<a name="line.163"></a>
<span class="sourceLineNo">164</span> cond.signal();<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 Object getOwner() {<a name="line.168"></a>
<span class="sourceLineNo">169</span> return currentThread;<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> @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "WA_AWAIT_NOT_IN_LOOP",<a name="line.172"></a>
<span class="sourceLineNo">173</span> justification = "Loop is in the caller method")<a name="line.173"></a>
<span class="sourceLineNo">174</span> @Override<a name="line.174"></a>
<span class="sourceLineNo">175</span> public void await() {<a name="line.175"></a>
<span class="sourceLineNo">176</span> if (cond == null) {<a name="line.176"></a>
<span class="sourceLineNo">177</span> cond = lock.newCondition();<a name="line.177"></a>
<span class="sourceLineNo">178</span> }<a name="line.178"></a>
<span class="sourceLineNo">179</span> cond.awaitUninterruptibly();<a name="line.179"></a>
<span class="sourceLineNo">180</span> }<a name="line.180"></a>
<span class="sourceLineNo">181</span> });<a name="line.181"></a>
<span class="sourceLineNo">182</span> } catch (ProcedureSuspendedException e) {<a name="line.182"></a>
<span class="sourceLineNo">183</span> // should not happen<a name="line.183"></a>
<span class="sourceLineNo">184</span> throw new AssertionError(e);<a name="line.184"></a>
<span class="sourceLineNo">185</span> }<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> /**<a name="line.188"></a>
<span class="sourceLineNo">189</span> * Normal tryLock, will set the current thread as owner. Typically you should use try...finally to<a name="line.189"></a>
<span class="sourceLineNo">190</span> * call unlock in the finally block.<a name="line.190"></a>
<span class="sourceLineNo">191</span> */<a name="line.191"></a>
<span class="sourceLineNo">192</span> boolean tryLock() {<a name="line.192"></a>
<span class="sourceLineNo">193</span> return tryLock0(Thread.currentThread());<a name="line.193"></a>
<span class="sourceLineNo">194</span> }<a name="line.194"></a>
<span class="sourceLineNo">195</span><a name="line.195"></a>
<span class="sourceLineNo">196</span> /**<a name="line.196"></a>
<span class="sourceLineNo">197</span> * Normal unLock, will use the current thread as owner. Typically you should use try...finally to<a name="line.197"></a>
<span class="sourceLineNo">198</span> * call unlock in the finally block.<a name="line.198"></a>
<span class="sourceLineNo">199</span> */<a name="line.199"></a>
<span class="sourceLineNo">200</span> void unlock() {<a name="line.200"></a>
<span class="sourceLineNo">201</span> unlock0(Thread.currentThread());<a name="line.201"></a>
<span class="sourceLineNo">202</span> }<a name="line.202"></a>
<span class="sourceLineNo">203</span><a name="line.203"></a>
<span class="sourceLineNo">204</span> /**<a name="line.204"></a>
<span class="sourceLineNo">205</span> * Lock by a procedure. You can release the lock in another thread.<a name="line.205"></a>
<span class="sourceLineNo">206</span> * &lt;p&gt;<a name="line.206"></a>
<span class="sourceLineNo">207</span> * When the procedure can not get the lock immediately, a ProcedureSuspendedException will be<a name="line.207"></a>
<span class="sourceLineNo">208</span> * thrown to suspend the procedure. And when we want to wake up a procedure, we will call the<a name="line.208"></a>
<span class="sourceLineNo">209</span> * {@code wakeUp} action. Usually in the {@code wakeUp} action you should add the procedure back<a name="line.209"></a>
<span class="sourceLineNo">210</span> * to procedure scheduler.<a name="line.210"></a>
<span class="sourceLineNo">211</span> */<a name="line.211"></a>
<span class="sourceLineNo">212</span> void lock(Procedure&lt;?&gt; proc, Runnable wakeUp) throws ProcedureSuspendedException {<a name="line.212"></a>
<span class="sourceLineNo">213</span> lock0(new QueueEntry() {<a name="line.213"></a>
<span class="sourceLineNo">214</span><a name="line.214"></a>
<span class="sourceLineNo">215</span> @Override<a name="line.215"></a>
<span class="sourceLineNo">216</span> public Object getOwner() {<a name="line.216"></a>
<span class="sourceLineNo">217</span> return proc;<a name="line.217"></a>
<span class="sourceLineNo">218</span> }<a name="line.218"></a>
<span class="sourceLineNo">219</span><a name="line.219"></a>
<span class="sourceLineNo">220</span> @Override<a name="line.220"></a>
<span class="sourceLineNo">221</span> public void await() throws ProcedureSuspendedException {<a name="line.221"></a>
<span class="sourceLineNo">222</span> ProcedureFutureUtil.suspend(proc);<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> @Override<a name="line.225"></a>
<span class="sourceLineNo">226</span> public void signal() {<a name="line.226"></a>
<span class="sourceLineNo">227</span> // Here we need to set the owner to the procedure directly.<a name="line.227"></a>
<span class="sourceLineNo">228</span> // For thread, we just block inside the lock0 method, so after signal we will continue and<a name="line.228"></a>
<span class="sourceLineNo">229</span> // get the lock<a name="line.229"></a>
<span class="sourceLineNo">230</span> // For procedure, the waking up here is actually a reschedule of the procedure to<a name="line.230"></a>
<span class="sourceLineNo">231</span> // ProcedureExecutor, so here we need to set the owner first, and it is the procedure's duty<a name="line.231"></a>
<span class="sourceLineNo">232</span> // to make sure that it has already hold the lock so do not need to call lock again, usually<a name="line.232"></a>
<span class="sourceLineNo">233</span> // this should be done by calling isLockedBy method below<a name="line.233"></a>
<span class="sourceLineNo">234</span> assert owner == null;<a name="line.234"></a>
<span class="sourceLineNo">235</span> assert count == 0;<a name="line.235"></a>
<span class="sourceLineNo">236</span> owner = proc;<a name="line.236"></a>
<span class="sourceLineNo">237</span> count = 1;<a name="line.237"></a>
<span class="sourceLineNo">238</span> wakeUp.run();<a name="line.238"></a>
<span class="sourceLineNo">239</span> }<a name="line.239"></a>
<span class="sourceLineNo">240</span> });<a name="line.240"></a>
<span class="sourceLineNo">241</span> }<a name="line.241"></a>
<span class="sourceLineNo">242</span><a name="line.242"></a>
<span class="sourceLineNo">243</span> /**<a name="line.243"></a>
<span class="sourceLineNo">244</span> * TryLock by a procedure. You can release the lock in another thread.<a name="line.244"></a>
<span class="sourceLineNo">245</span> */<a name="line.245"></a>
<span class="sourceLineNo">246</span> boolean tryLock(Procedure&lt;?&gt; proc) {<a name="line.246"></a>
<span class="sourceLineNo">247</span> return tryLock0(proc);<a name="line.247"></a>
<span class="sourceLineNo">248</span> }<a name="line.248"></a>
<span class="sourceLineNo">249</span><a name="line.249"></a>
<span class="sourceLineNo">250</span> /**<a name="line.250"></a>
<span class="sourceLineNo">251</span> * Unlock by a procedure. You do not need to call this method in the same thread with lock.<a name="line.251"></a>
<span class="sourceLineNo">252</span> */<a name="line.252"></a>
<span class="sourceLineNo">253</span> void unlock(Procedure&lt;?&gt; proc) {<a name="line.253"></a>
<span class="sourceLineNo">254</span> unlock0(proc);<a name="line.254"></a>
<span class="sourceLineNo">255</span> }<a name="line.255"></a>
<span class="sourceLineNo">256</span><a name="line.256"></a>
<span class="sourceLineNo">257</span> /**<a name="line.257"></a>
<span class="sourceLineNo">258</span> * Check whether the lock is locked by someone.<a name="line.258"></a>
<span class="sourceLineNo">259</span> */<a name="line.259"></a>
<span class="sourceLineNo">260</span> boolean isLocked() {<a name="line.260"></a>
<span class="sourceLineNo">261</span> lock.lock();<a name="line.261"></a>
<span class="sourceLineNo">262</span> try {<a name="line.262"></a>
<span class="sourceLineNo">263</span> return owner != null;<a name="line.263"></a>
<span class="sourceLineNo">264</span> } finally {<a name="line.264"></a>
<span class="sourceLineNo">265</span> lock.unlock();<a name="line.265"></a>
<span class="sourceLineNo">266</span> }<a name="line.266"></a>
<span class="sourceLineNo">267</span> }<a name="line.267"></a>
<span class="sourceLineNo">268</span><a name="line.268"></a>
<span class="sourceLineNo">269</span> /**<a name="line.269"></a>
<span class="sourceLineNo">270</span> * Check whether the lock is locked by the given {@code lockBy}.<a name="line.270"></a>
<span class="sourceLineNo">271</span> */<a name="line.271"></a>
<span class="sourceLineNo">272</span> boolean isLockedBy(Object lockBy) {<a name="line.272"></a>
<span class="sourceLineNo">273</span> lock.lock();<a name="line.273"></a>
<span class="sourceLineNo">274</span> try {<a name="line.274"></a>
<span class="sourceLineNo">275</span> return owner == lockBy;<a name="line.275"></a>
<span class="sourceLineNo">276</span> } finally {<a name="line.276"></a>
<span class="sourceLineNo">277</span> lock.unlock();<a name="line.277"></a>
<span class="sourceLineNo">278</span> }<a name="line.278"></a>
<span class="sourceLineNo">279</span> }<a name="line.279"></a>
<span class="sourceLineNo">280</span>}<a name="line.280"></a>
</pre>
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