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| <pre><span class="source-line-no">001</span><span id="line-1">/*</span> |
| <span class="source-line-no">002</span><span id="line-2"> * Licensed to the Apache Software Foundation (ASF) under one</span> |
| <span class="source-line-no">003</span><span id="line-3"> * or more contributor license agreements. See the NOTICE file</span> |
| <span class="source-line-no">004</span><span id="line-4"> * distributed with this work for additional information</span> |
| <span class="source-line-no">005</span><span id="line-5"> * regarding copyright ownership. The ASF licenses this file</span> |
| <span class="source-line-no">006</span><span id="line-6"> * to you under the Apache License, Version 2.0 (the</span> |
| <span class="source-line-no">007</span><span id="line-7"> * "License"); you may not use this file except in compliance</span> |
| <span class="source-line-no">008</span><span id="line-8"> * with the License. You may obtain a copy of the License at</span> |
| <span class="source-line-no">009</span><span id="line-9"> *</span> |
| <span class="source-line-no">010</span><span id="line-10"> * http://www.apache.org/licenses/LICENSE-2.0</span> |
| <span class="source-line-no">011</span><span id="line-11"> *</span> |
| <span class="source-line-no">012</span><span id="line-12"> * Unless required by applicable law or agreed to in writing, software</span> |
| <span class="source-line-no">013</span><span id="line-13"> * distributed under the License is distributed on an "AS IS" BASIS,</span> |
| <span class="source-line-no">014</span><span id="line-14"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span> |
| <span class="source-line-no">015</span><span id="line-15"> * See the License for the specific language governing permissions and</span> |
| <span class="source-line-no">016</span><span id="line-16"> * limitations under the License.</span> |
| <span class="source-line-no">017</span><span id="line-17"> */</span> |
| <span class="source-line-no">018</span><span id="line-18">package org.apache.hadoop.hbase.util;</span> |
| <span class="source-line-no">019</span><span id="line-19"></span> |
| <span class="source-line-no">020</span><span id="line-20">import java.io.IOException;</span> |
| <span class="source-line-no">021</span><span id="line-21">import java.io.InterruptedIOException;</span> |
| <span class="source-line-no">022</span><span id="line-22">import java.util.concurrent.ConcurrentHashMap;</span> |
| <span class="source-line-no">023</span><span id="line-23">import java.util.concurrent.ConcurrentMap;</span> |
| <span class="source-line-no">024</span><span id="line-24">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">025</span><span id="line-25">import org.slf4j.Logger;</span> |
| <span class="source-line-no">026</span><span id="line-26">import org.slf4j.LoggerFactory;</span> |
| <span class="source-line-no">027</span><span id="line-27"></span> |
| <span class="source-line-no">028</span><span id="line-28">import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;</span> |
| <span class="source-line-no">029</span><span id="line-29"></span> |
| <span class="source-line-no">030</span><span id="line-30">/**</span> |
| <span class="source-line-no">031</span><span id="line-31"> * Allows multiple concurrent clients to lock on a numeric id with a minimal memory overhead. The</span> |
| <span class="source-line-no">032</span><span id="line-32"> * intended usage is as follows:</span> |
| <span class="source-line-no">033</span><span id="line-33"> *</span> |
| <span class="source-line-no">034</span><span id="line-34"> * <pre></span> |
| <span class="source-line-no">035</span><span id="line-35"> * IdLock.Entry lockEntry = idLock.getLockEntry(id);</span> |
| <span class="source-line-no">036</span><span id="line-36"> * try {</span> |
| <span class="source-line-no">037</span><span id="line-37"> * // User code.</span> |
| <span class="source-line-no">038</span><span id="line-38"> * } finally {</span> |
| <span class="source-line-no">039</span><span id="line-39"> * idLock.releaseLockEntry(lockEntry);</span> |
| <span class="source-line-no">040</span><span id="line-40"> * }</span> |
| <span class="source-line-no">041</span><span id="line-41"> * </pre></span> |
| <span class="source-line-no">042</span><span id="line-42"> */</span> |
| <span class="source-line-no">043</span><span id="line-43">@InterfaceAudience.Private</span> |
| <span class="source-line-no">044</span><span id="line-44">public class IdLock {</span> |
| <span class="source-line-no">045</span><span id="line-45"></span> |
| <span class="source-line-no">046</span><span id="line-46"> private static final Logger LOG = LoggerFactory.getLogger(IdLock.class);</span> |
| <span class="source-line-no">047</span><span id="line-47"></span> |
| <span class="source-line-no">048</span><span id="line-48"> /** An entry returned to the client as a lock object */</span> |
| <span class="source-line-no">049</span><span id="line-49"> public static final class Entry {</span> |
| <span class="source-line-no">050</span><span id="line-50"> private final long id;</span> |
| <span class="source-line-no">051</span><span id="line-51"> private int numWaiters;</span> |
| <span class="source-line-no">052</span><span id="line-52"> private boolean locked = true;</span> |
| <span class="source-line-no">053</span><span id="line-53"> private Thread holder;</span> |
| <span class="source-line-no">054</span><span id="line-54"></span> |
| <span class="source-line-no">055</span><span id="line-55"> private Entry(long id, Thread holder) {</span> |
| <span class="source-line-no">056</span><span id="line-56"> this.id = id;</span> |
| <span class="source-line-no">057</span><span id="line-57"> this.holder = holder;</span> |
| <span class="source-line-no">058</span><span id="line-58"> }</span> |
| <span class="source-line-no">059</span><span id="line-59"></span> |
| <span class="source-line-no">060</span><span id="line-60"> @Override</span> |
| <span class="source-line-no">061</span><span id="line-61"> public String toString() {</span> |
| <span class="source-line-no">062</span><span id="line-62"> return "id=" + id + ", numWaiter=" + numWaiters + ", isLocked=" + locked + ", holder="</span> |
| <span class="source-line-no">063</span><span id="line-63"> + holder;</span> |
| <span class="source-line-no">064</span><span id="line-64"> }</span> |
| <span class="source-line-no">065</span><span id="line-65"> }</span> |
| <span class="source-line-no">066</span><span id="line-66"></span> |
| <span class="source-line-no">067</span><span id="line-67"> private ConcurrentMap<Long, Entry> map = new ConcurrentHashMap<>();</span> |
| <span class="source-line-no">068</span><span id="line-68"></span> |
| <span class="source-line-no">069</span><span id="line-69"> /**</span> |
| <span class="source-line-no">070</span><span id="line-70"> * Blocks until the lock corresponding to the given id is acquired.</span> |
| <span class="source-line-no">071</span><span id="line-71"> * @param id an arbitrary number to lock on</span> |
| <span class="source-line-no">072</span><span id="line-72"> * @return an "entry" to pass to {@link #releaseLockEntry(Entry)} to release the lock</span> |
| <span class="source-line-no">073</span><span id="line-73"> * @throws IOException if interrupted</span> |
| <span class="source-line-no">074</span><span id="line-74"> */</span> |
| <span class="source-line-no">075</span><span id="line-75"> public Entry getLockEntry(long id) throws IOException {</span> |
| <span class="source-line-no">076</span><span id="line-76"> Thread currentThread = Thread.currentThread();</span> |
| <span class="source-line-no">077</span><span id="line-77"> Entry entry = new Entry(id, currentThread);</span> |
| <span class="source-line-no">078</span><span id="line-78"> Entry existing;</span> |
| <span class="source-line-no">079</span><span id="line-79"> while ((existing = map.putIfAbsent(entry.id, entry)) != null) {</span> |
| <span class="source-line-no">080</span><span id="line-80"> synchronized (existing) {</span> |
| <span class="source-line-no">081</span><span id="line-81"> if (existing.locked) {</span> |
| <span class="source-line-no">082</span><span id="line-82"> ++existing.numWaiters; // Add ourselves to waiters.</span> |
| <span class="source-line-no">083</span><span id="line-83"> while (existing.locked) {</span> |
| <span class="source-line-no">084</span><span id="line-84"> try {</span> |
| <span class="source-line-no">085</span><span id="line-85"> existing.wait();</span> |
| <span class="source-line-no">086</span><span id="line-86"> } catch (InterruptedException e) {</span> |
| <span class="source-line-no">087</span><span id="line-87"> --existing.numWaiters; // Remove ourselves from waiters.</span> |
| <span class="source-line-no">088</span><span id="line-88"> // HBASE-21292</span> |
| <span class="source-line-no">089</span><span id="line-89"> // There is a rare case that interrupting and the lock owner thread call</span> |
| <span class="source-line-no">090</span><span id="line-90"> // releaseLockEntry at the same time. Since the owner thread found there</span> |
| <span class="source-line-no">091</span><span id="line-91"> // still one waiting, it won't remove the entry from the map. If the interrupted</span> |
| <span class="source-line-no">092</span><span id="line-92"> // thread is the last one waiting on the lock, and since an exception is thrown,</span> |
| <span class="source-line-no">093</span><span id="line-93"> // the 'existing' entry will stay in the map forever. Later threads which try to</span> |
| <span class="source-line-no">094</span><span id="line-94"> // get this lock will stuck in a infinite loop because</span> |
| <span class="source-line-no">095</span><span id="line-95"> // existing = map.putIfAbsent(entry.id, entry)) != null and existing.locked=false.</span> |
| <span class="source-line-no">096</span><span id="line-96"> if (!existing.locked && existing.numWaiters == 0) {</span> |
| <span class="source-line-no">097</span><span id="line-97"> map.remove(existing.id);</span> |
| <span class="source-line-no">098</span><span id="line-98"> }</span> |
| <span class="source-line-no">099</span><span id="line-99"> throw new InterruptedIOException("Interrupted waiting to acquire sparse lock");</span> |
| <span class="source-line-no">100</span><span id="line-100"> }</span> |
| <span class="source-line-no">101</span><span id="line-101"> }</span> |
| <span class="source-line-no">102</span><span id="line-102"></span> |
| <span class="source-line-no">103</span><span id="line-103"> --existing.numWaiters; // Remove ourselves from waiters.</span> |
| <span class="source-line-no">104</span><span id="line-104"> existing.locked = true;</span> |
| <span class="source-line-no">105</span><span id="line-105"> existing.holder = currentThread;</span> |
| <span class="source-line-no">106</span><span id="line-106"> return existing;</span> |
| <span class="source-line-no">107</span><span id="line-107"> }</span> |
| <span class="source-line-no">108</span><span id="line-108"> // If the entry is not locked, it might already be deleted from the</span> |
| <span class="source-line-no">109</span><span id="line-109"> // map, so we cannot return it. We need to get our entry into the map</span> |
| <span class="source-line-no">110</span><span id="line-110"> // or get someone else's locked entry.</span> |
| <span class="source-line-no">111</span><span id="line-111"> }</span> |
| <span class="source-line-no">112</span><span id="line-112"> }</span> |
| <span class="source-line-no">113</span><span id="line-113"> return entry;</span> |
| <span class="source-line-no">114</span><span id="line-114"> }</span> |
| <span class="source-line-no">115</span><span id="line-115"></span> |
| <span class="source-line-no">116</span><span id="line-116"> /**</span> |
| <span class="source-line-no">117</span><span id="line-117"> * Blocks until the lock corresponding to the given id is acquired.</span> |
| <span class="source-line-no">118</span><span id="line-118"> * @param id an arbitrary number to lock on</span> |
| <span class="source-line-no">119</span><span id="line-119"> * @param time time to wait in ms</span> |
| <span class="source-line-no">120</span><span id="line-120"> * @return an "entry" to pass to {@link #releaseLockEntry(Entry)} to release the lock</span> |
| <span class="source-line-no">121</span><span id="line-121"> * @throws IOException if interrupted</span> |
| <span class="source-line-no">122</span><span id="line-122"> */</span> |
| <span class="source-line-no">123</span><span id="line-123"> public Entry tryLockEntry(long id, long time) throws IOException {</span> |
| <span class="source-line-no">124</span><span id="line-124"> Preconditions.checkArgument(time >= 0);</span> |
| <span class="source-line-no">125</span><span id="line-125"> Thread currentThread = Thread.currentThread();</span> |
| <span class="source-line-no">126</span><span id="line-126"> Entry entry = new Entry(id, currentThread);</span> |
| <span class="source-line-no">127</span><span id="line-127"> Entry existing;</span> |
| <span class="source-line-no">128</span><span id="line-128"> long waitUtilTS = EnvironmentEdgeManager.currentTime() + time;</span> |
| <span class="source-line-no">129</span><span id="line-129"> long remaining = time;</span> |
| <span class="source-line-no">130</span><span id="line-130"> while ((existing = map.putIfAbsent(entry.id, entry)) != null) {</span> |
| <span class="source-line-no">131</span><span id="line-131"> synchronized (existing) {</span> |
| <span class="source-line-no">132</span><span id="line-132"> if (existing.locked) {</span> |
| <span class="source-line-no">133</span><span id="line-133"> ++existing.numWaiters; // Add ourselves to waiters.</span> |
| <span class="source-line-no">134</span><span id="line-134"> try {</span> |
| <span class="source-line-no">135</span><span id="line-135"> while (existing.locked) {</span> |
| <span class="source-line-no">136</span><span id="line-136"> existing.wait(remaining);</span> |
| <span class="source-line-no">137</span><span id="line-137"> if (existing.locked) {</span> |
| <span class="source-line-no">138</span><span id="line-138"> long currentTS = EnvironmentEdgeManager.currentTime();</span> |
| <span class="source-line-no">139</span><span id="line-139"> if (currentTS >= waitUtilTS) {</span> |
| <span class="source-line-no">140</span><span id="line-140"> // time is up</span> |
| <span class="source-line-no">141</span><span id="line-141"> return null;</span> |
| <span class="source-line-no">142</span><span id="line-142"> } else {</span> |
| <span class="source-line-no">143</span><span id="line-143"> // our wait is waken, but the lock is still taken, this can happen</span> |
| <span class="source-line-no">144</span><span id="line-144"> // due to JDK Object's wait/notify mechanism.</span> |
| <span class="source-line-no">145</span><span id="line-145"> // Calculate the new remaining time to wait</span> |
| <span class="source-line-no">146</span><span id="line-146"> remaining = waitUtilTS - currentTS;</span> |
| <span class="source-line-no">147</span><span id="line-147"> }</span> |
| <span class="source-line-no">148</span><span id="line-148"> }</span> |
| <span class="source-line-no">149</span><span id="line-149"></span> |
| <span class="source-line-no">150</span><span id="line-150"> }</span> |
| <span class="source-line-no">151</span><span id="line-151"> } catch (InterruptedException e) {</span> |
| <span class="source-line-no">152</span><span id="line-152"> // HBASE-21292</span> |
| <span class="source-line-no">153</span><span id="line-153"> // Please refer to the comments in getLockEntry()</span> |
| <span class="source-line-no">154</span><span id="line-154"> // the difference here is that we decrease numWaiters in finally block</span> |
| <span class="source-line-no">155</span><span id="line-155"> if (!existing.locked && existing.numWaiters == 1) {</span> |
| <span class="source-line-no">156</span><span id="line-156"> map.remove(existing.id);</span> |
| <span class="source-line-no">157</span><span id="line-157"> }</span> |
| <span class="source-line-no">158</span><span id="line-158"> throw new InterruptedIOException("Interrupted waiting to acquire sparse lock");</span> |
| <span class="source-line-no">159</span><span id="line-159"> } finally {</span> |
| <span class="source-line-no">160</span><span id="line-160"> --existing.numWaiters; // Remove ourselves from waiters.</span> |
| <span class="source-line-no">161</span><span id="line-161"> }</span> |
| <span class="source-line-no">162</span><span id="line-162"> existing.locked = true;</span> |
| <span class="source-line-no">163</span><span id="line-163"> existing.holder = currentThread;</span> |
| <span class="source-line-no">164</span><span id="line-164"> return existing;</span> |
| <span class="source-line-no">165</span><span id="line-165"> }</span> |
| <span class="source-line-no">166</span><span id="line-166"> // If the entry is not locked, it might already be deleted from the</span> |
| <span class="source-line-no">167</span><span id="line-167"> // map, so we cannot return it. We need to get our entry into the map</span> |
| <span class="source-line-no">168</span><span id="line-168"> // or get someone else's locked entry.</span> |
| <span class="source-line-no">169</span><span id="line-169"> }</span> |
| <span class="source-line-no">170</span><span id="line-170"> }</span> |
| <span class="source-line-no">171</span><span id="line-171"> return entry;</span> |
| <span class="source-line-no">172</span><span id="line-172"> }</span> |
| <span class="source-line-no">173</span><span id="line-173"></span> |
| <span class="source-line-no">174</span><span id="line-174"> /**</span> |
| <span class="source-line-no">175</span><span id="line-175"> * Must be called in a finally block to decrease the internal counter and remove the monitor</span> |
| <span class="source-line-no">176</span><span id="line-176"> * object for the given id if the caller is the last client.</span> |
| <span class="source-line-no">177</span><span id="line-177"> * @param entry the return value of {@link #getLockEntry(long)}</span> |
| <span class="source-line-no">178</span><span id="line-178"> */</span> |
| <span class="source-line-no">179</span><span id="line-179"> public void releaseLockEntry(Entry entry) {</span> |
| <span class="source-line-no">180</span><span id="line-180"> Thread currentThread = Thread.currentThread();</span> |
| <span class="source-line-no">181</span><span id="line-181"> synchronized (entry) {</span> |
| <span class="source-line-no">182</span><span id="line-182"> if (entry.holder != currentThread) {</span> |
| <span class="source-line-no">183</span><span id="line-183"> LOG.warn("{} is trying to release lock entry {}, but it is not the holder.", currentThread,</span> |
| <span class="source-line-no">184</span><span id="line-184"> entry);</span> |
| <span class="source-line-no">185</span><span id="line-185"> }</span> |
| <span class="source-line-no">186</span><span id="line-186"> entry.locked = false;</span> |
| <span class="source-line-no">187</span><span id="line-187"> if (entry.numWaiters > 0) {</span> |
| <span class="source-line-no">188</span><span id="line-188"> entry.notify();</span> |
| <span class="source-line-no">189</span><span id="line-189"> } else {</span> |
| <span class="source-line-no">190</span><span id="line-190"> map.remove(entry.id);</span> |
| <span class="source-line-no">191</span><span id="line-191"> }</span> |
| <span class="source-line-no">192</span><span id="line-192"> }</span> |
| <span class="source-line-no">193</span><span id="line-193"> }</span> |
| <span class="source-line-no">194</span><span id="line-194"></span> |
| <span class="source-line-no">195</span><span id="line-195"> /**</span> |
| <span class="source-line-no">196</span><span id="line-196"> * Test whether the given id is already locked by the current thread.</span> |
| <span class="source-line-no">197</span><span id="line-197"> */</span> |
| <span class="source-line-no">198</span><span id="line-198"> public boolean isHeldByCurrentThread(long id) {</span> |
| <span class="source-line-no">199</span><span id="line-199"> Thread currentThread = Thread.currentThread();</span> |
| <span class="source-line-no">200</span><span id="line-200"> Entry entry = map.get(id);</span> |
| <span class="source-line-no">201</span><span id="line-201"> if (entry == null) {</span> |
| <span class="source-line-no">202</span><span id="line-202"> return false;</span> |
| <span class="source-line-no">203</span><span id="line-203"> }</span> |
| <span class="source-line-no">204</span><span id="line-204"> synchronized (entry) {</span> |
| <span class="source-line-no">205</span><span id="line-205"> return currentThread.equals(entry.holder);</span> |
| <span class="source-line-no">206</span><span id="line-206"> }</span> |
| <span class="source-line-no">207</span><span id="line-207"> }</span> |
| <span class="source-line-no">208</span><span id="line-208"></span> |
| <span class="source-line-no">209</span><span id="line-209"> void assertMapEmpty() {</span> |
| <span class="source-line-no">210</span><span id="line-210"> assert map.isEmpty();</span> |
| <span class="source-line-no">211</span><span id="line-211"> }</span> |
| <span class="source-line-no">212</span><span id="line-212"></span> |
| <span class="source-line-no">213</span><span id="line-213"> public void waitForWaiters(long id, int numWaiters) throws InterruptedException {</span> |
| <span class="source-line-no">214</span><span id="line-214"> for (Entry entry;;) {</span> |
| <span class="source-line-no">215</span><span id="line-215"> entry = map.get(id);</span> |
| <span class="source-line-no">216</span><span id="line-216"> if (entry != null) {</span> |
| <span class="source-line-no">217</span><span id="line-217"> synchronized (entry) {</span> |
| <span class="source-line-no">218</span><span id="line-218"> if (entry.numWaiters >= numWaiters) {</span> |
| <span class="source-line-no">219</span><span id="line-219"> return;</span> |
| <span class="source-line-no">220</span><span id="line-220"> }</span> |
| <span class="source-line-no">221</span><span id="line-221"> }</span> |
| <span class="source-line-no">222</span><span id="line-222"> }</span> |
| <span class="source-line-no">223</span><span id="line-223"> Thread.sleep(100);</span> |
| <span class="source-line-no">224</span><span id="line-224"> }</span> |
| <span class="source-line-no">225</span><span id="line-225"> }</span> |
| <span class="source-line-no">226</span><span id="line-226">}</span> |
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| </pre> |
| </div> |
| </main> |
| </body> |
| </html> |
