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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.regionserver;</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.util.LinkedList;</span> |
| <span class="source-line-no">021</span><span id="line-21">import java.util.Optional;</span> |
| <span class="source-line-no">022</span><span id="line-22">import java.util.concurrent.atomic.AtomicLong;</span> |
| <span class="source-line-no">023</span><span id="line-23">import org.apache.hadoop.hbase.util.Bytes;</span> |
| <span class="source-line-no">024</span><span id="line-24">import org.apache.hadoop.hbase.util.ClassSize;</span> |
| <span class="source-line-no">025</span><span id="line-25">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">026</span><span id="line-26">import org.slf4j.Logger;</span> |
| <span class="source-line-no">027</span><span id="line-27">import org.slf4j.LoggerFactory;</span> |
| <span class="source-line-no">028</span><span id="line-28"></span> |
| <span class="source-line-no">029</span><span id="line-29">import org.apache.hbase.thirdparty.com.google.common.base.MoreObjects;</span> |
| <span class="source-line-no">030</span><span id="line-30">import org.apache.hbase.thirdparty.com.google.common.base.MoreObjects.ToStringHelper;</span> |
| <span class="source-line-no">031</span><span id="line-31"></span> |
| <span class="source-line-no">032</span><span id="line-32">/**</span> |
| <span class="source-line-no">033</span><span id="line-33"> * Manages the read/write consistency. This provides an interface for readers to determine what</span> |
| <span class="source-line-no">034</span><span id="line-34"> * entries to ignore, and a mechanism for writers to obtain new write numbers, then "commit" the new</span> |
| <span class="source-line-no">035</span><span id="line-35"> * writes for readers to read (thus forming atomic transactions).</span> |
| <span class="source-line-no">036</span><span id="line-36"> */</span> |
| <span class="source-line-no">037</span><span id="line-37">@InterfaceAudience.Private</span> |
| <span class="source-line-no">038</span><span id="line-38">public class MultiVersionConcurrencyControl {</span> |
| <span class="source-line-no">039</span><span id="line-39"> private static final Logger LOG = LoggerFactory.getLogger(MultiVersionConcurrencyControl.class);</span> |
| <span class="source-line-no">040</span><span id="line-40"> private static final long READPOINT_ADVANCE_WAIT_TIME = 10L;</span> |
| <span class="source-line-no">041</span><span id="line-41"></span> |
| <span class="source-line-no">042</span><span id="line-42"> final String regionName;</span> |
| <span class="source-line-no">043</span><span id="line-43"> final AtomicLong readPoint = new AtomicLong(0);</span> |
| <span class="source-line-no">044</span><span id="line-44"> final AtomicLong writePoint = new AtomicLong(0);</span> |
| <span class="source-line-no">045</span><span id="line-45"> private final Object readWaiters = new Object();</span> |
| <span class="source-line-no">046</span><span id="line-46"> /**</span> |
| <span class="source-line-no">047</span><span id="line-47"> * Represents no value, or not set.</span> |
| <span class="source-line-no">048</span><span id="line-48"> */</span> |
| <span class="source-line-no">049</span><span id="line-49"> public static final long NONE = -1;</span> |
| <span class="source-line-no">050</span><span id="line-50"></span> |
| <span class="source-line-no">051</span><span id="line-51"> // This is the pending queue of writes.</span> |
| <span class="source-line-no">052</span><span id="line-52"> //</span> |
| <span class="source-line-no">053</span><span id="line-53"> // TODO(eclark): Should this be an array of fixed size to</span> |
| <span class="source-line-no">054</span><span id="line-54"> // reduce the number of allocations on the write path?</span> |
| <span class="source-line-no">055</span><span id="line-55"> // This could be equal to the number of handlers + a small number.</span> |
| <span class="source-line-no">056</span><span id="line-56"> // TODO: St.Ack 20150903 Sounds good to me.</span> |
| <span class="source-line-no">057</span><span id="line-57"> private final LinkedList<WriteEntry> writeQueue = new LinkedList<>();</span> |
| <span class="source-line-no">058</span><span id="line-58"></span> |
| <span class="source-line-no">059</span><span id="line-59"> public MultiVersionConcurrencyControl() {</span> |
| <span class="source-line-no">060</span><span id="line-60"> this(null);</span> |
| <span class="source-line-no">061</span><span id="line-61"> }</span> |
| <span class="source-line-no">062</span><span id="line-62"></span> |
| <span class="source-line-no">063</span><span id="line-63"> public MultiVersionConcurrencyControl(String regionName) {</span> |
| <span class="source-line-no">064</span><span id="line-64"> this.regionName = regionName;</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"> /**</span> |
| <span class="source-line-no">068</span><span id="line-68"> * Construct and set read point. Write point is uninitialized.</span> |
| <span class="source-line-no">069</span><span id="line-69"> */</span> |
| <span class="source-line-no">070</span><span id="line-70"> public MultiVersionConcurrencyControl(long startPoint) {</span> |
| <span class="source-line-no">071</span><span id="line-71"> this(null);</span> |
| <span class="source-line-no">072</span><span id="line-72"> tryAdvanceTo(startPoint, NONE);</span> |
| <span class="source-line-no">073</span><span id="line-73"> }</span> |
| <span class="source-line-no">074</span><span id="line-74"></span> |
| <span class="source-line-no">075</span><span id="line-75"> /**</span> |
| <span class="source-line-no">076</span><span id="line-76"> * Step the MVCC forward on to a new read/write basis.</span> |
| <span class="source-line-no">077</span><span id="line-77"> */</span> |
| <span class="source-line-no">078</span><span id="line-78"> public void advanceTo(long newStartPoint) {</span> |
| <span class="source-line-no">079</span><span id="line-79"> while (true) {</span> |
| <span class="source-line-no">080</span><span id="line-80"> long seqId = this.getWritePoint();</span> |
| <span class="source-line-no">081</span><span id="line-81"> if (seqId >= newStartPoint) {</span> |
| <span class="source-line-no">082</span><span id="line-82"> break;</span> |
| <span class="source-line-no">083</span><span id="line-83"> }</span> |
| <span class="source-line-no">084</span><span id="line-84"> if (this.tryAdvanceTo(newStartPoint, seqId)) {</span> |
| <span class="source-line-no">085</span><span id="line-85"> break;</span> |
| <span class="source-line-no">086</span><span id="line-86"> }</span> |
| <span class="source-line-no">087</span><span id="line-87"> }</span> |
| <span class="source-line-no">088</span><span id="line-88"> }</span> |
| <span class="source-line-no">089</span><span id="line-89"></span> |
| <span class="source-line-no">090</span><span id="line-90"> /**</span> |
| <span class="source-line-no">091</span><span id="line-91"> * Step the MVCC forward on to a new read/write basis.</span> |
| <span class="source-line-no">092</span><span id="line-92"> * @param newStartPoint Point to move read and write points to.</span> |
| <span class="source-line-no">093</span><span id="line-93"> * @param expected If not -1 (#NONE)</span> |
| <span class="source-line-no">094</span><span id="line-94"> * @return Returns false if <code>expected</code> is not equal to the current</span> |
| <span class="source-line-no">095</span><span id="line-95"> * <code>readPoint</code> or if <code>startPoint</code> is less than current</span> |
| <span class="source-line-no">096</span><span id="line-96"> * <code>readPoint</code></span> |
| <span class="source-line-no">097</span><span id="line-97"> */</span> |
| <span class="source-line-no">098</span><span id="line-98"> boolean tryAdvanceTo(long newStartPoint, long expected) {</span> |
| <span class="source-line-no">099</span><span id="line-99"> synchronized (writeQueue) {</span> |
| <span class="source-line-no">100</span><span id="line-100"> long currentRead = this.readPoint.get();</span> |
| <span class="source-line-no">101</span><span id="line-101"> long currentWrite = this.writePoint.get();</span> |
| <span class="source-line-no">102</span><span id="line-102"> if (currentRead != currentWrite) {</span> |
| <span class="source-line-no">103</span><span id="line-103"> throw new RuntimeException("Already used this mvcc; currentRead=" + currentRead</span> |
| <span class="source-line-no">104</span><span id="line-104"> + ", currentWrite=" + currentWrite + "; too late to tryAdvanceTo");</span> |
| <span class="source-line-no">105</span><span id="line-105"> }</span> |
| <span class="source-line-no">106</span><span id="line-106"> if (expected != NONE && expected != currentRead) {</span> |
| <span class="source-line-no">107</span><span id="line-107"> return false;</span> |
| <span class="source-line-no">108</span><span id="line-108"> }</span> |
| <span class="source-line-no">109</span><span id="line-109"></span> |
| <span class="source-line-no">110</span><span id="line-110"> if (newStartPoint < currentRead) {</span> |
| <span class="source-line-no">111</span><span id="line-111"> return false;</span> |
| <span class="source-line-no">112</span><span id="line-112"> }</span> |
| <span class="source-line-no">113</span><span id="line-113"></span> |
| <span class="source-line-no">114</span><span id="line-114"> readPoint.set(newStartPoint);</span> |
| <span class="source-line-no">115</span><span id="line-115"> writePoint.set(newStartPoint);</span> |
| <span class="source-line-no">116</span><span id="line-116"> }</span> |
| <span class="source-line-no">117</span><span id="line-117"> return true;</span> |
| <span class="source-line-no">118</span><span id="line-118"> }</span> |
| <span class="source-line-no">119</span><span id="line-119"></span> |
| <span class="source-line-no">120</span><span id="line-120"> /**</span> |
| <span class="source-line-no">121</span><span id="line-121"> * Call {@link #begin(Runnable)} with an empty {@link Runnable}.</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 WriteEntry begin() {</span> |
| <span class="source-line-no">124</span><span id="line-124"> return begin(() -> {</span> |
| <span class="source-line-no">125</span><span id="line-125"> });</span> |
| <span class="source-line-no">126</span><span id="line-126"> }</span> |
| <span class="source-line-no">127</span><span id="line-127"></span> |
| <span class="source-line-no">128</span><span id="line-128"> /**</span> |
| <span class="source-line-no">129</span><span id="line-129"> * Start a write transaction. Create a new {@link WriteEntry} with a new write number and add it</span> |
| <span class="source-line-no">130</span><span id="line-130"> * to our queue of ongoing writes. Return this WriteEntry instance. To complete the write</span> |
| <span class="source-line-no">131</span><span id="line-131"> * transaction and wait for it to be visible, call {@link #completeAndWait(WriteEntry)}. If the</span> |
| <span class="source-line-no">132</span><span id="line-132"> * write failed, call {@link #complete(WriteEntry)} so we can clean up AFTER removing ALL trace of</span> |
| <span class="source-line-no">133</span><span id="line-133"> * the failed write transaction.</span> |
| <span class="source-line-no">134</span><span id="line-134"> * <p></span> |
| <span class="source-line-no">135</span><span id="line-135"> * The {@code action} will be executed under the lock which means it can keep the same order with</span> |
| <span class="source-line-no">136</span><span id="line-136"> * mvcc.</span> |
| <span class="source-line-no">137</span><span id="line-137"> * @see #complete(WriteEntry)</span> |
| <span class="source-line-no">138</span><span id="line-138"> * @see #completeAndWait(WriteEntry)</span> |
| <span class="source-line-no">139</span><span id="line-139"> */</span> |
| <span class="source-line-no">140</span><span id="line-140"> public WriteEntry begin(Runnable action) {</span> |
| <span class="source-line-no">141</span><span id="line-141"> synchronized (writeQueue) {</span> |
| <span class="source-line-no">142</span><span id="line-142"> long nextWriteNumber = writePoint.incrementAndGet();</span> |
| <span class="source-line-no">143</span><span id="line-143"> WriteEntry e = new WriteEntry(nextWriteNumber);</span> |
| <span class="source-line-no">144</span><span id="line-144"> writeQueue.add(e);</span> |
| <span class="source-line-no">145</span><span id="line-145"> action.run();</span> |
| <span class="source-line-no">146</span><span id="line-146"> return e;</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"> * Wait until the read point catches up to the write point; i.e. wait on all outstanding mvccs to</span> |
| <span class="source-line-no">152</span><span id="line-152"> * complete.</span> |
| <span class="source-line-no">153</span><span id="line-153"> */</span> |
| <span class="source-line-no">154</span><span id="line-154"> public void await() {</span> |
| <span class="source-line-no">155</span><span id="line-155"> // Add a write and then wait on reads to catch up to it.</span> |
| <span class="source-line-no">156</span><span id="line-156"> completeAndWait(begin());</span> |
| <span class="source-line-no">157</span><span id="line-157"> }</span> |
| <span class="source-line-no">158</span><span id="line-158"></span> |
| <span class="source-line-no">159</span><span id="line-159"> /**</span> |
| <span class="source-line-no">160</span><span id="line-160"> * Complete a {@link WriteEntry} that was created by {@link #begin()} then wait until the read</span> |
| <span class="source-line-no">161</span><span id="line-161"> * point catches up to our write. At the end of this call, the global read point is at least as</span> |
| <span class="source-line-no">162</span><span id="line-162"> * large as the write point of the passed in WriteEntry. Thus, the write is visible to MVCC</span> |
| <span class="source-line-no">163</span><span id="line-163"> * readers.</span> |
| <span class="source-line-no">164</span><span id="line-164"> */</span> |
| <span class="source-line-no">165</span><span id="line-165"> public void completeAndWait(WriteEntry e) {</span> |
| <span class="source-line-no">166</span><span id="line-166"> if (!complete(e)) {</span> |
| <span class="source-line-no">167</span><span id="line-167"> waitForRead(e);</span> |
| <span class="source-line-no">168</span><span id="line-168"> }</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"> /**</span> |
| <span class="source-line-no">172</span><span id="line-172"> * Mark the {@link WriteEntry} as complete and advance the read point as much as possible. Call</span> |
| <span class="source-line-no">173</span><span id="line-173"> * this even if the write has FAILED (AFTER backing out the write transaction changes completely)</span> |
| <span class="source-line-no">174</span><span id="line-174"> * so we can clean up the outstanding transaction. How much is the read point advanced? Let S be</span> |
| <span class="source-line-no">175</span><span id="line-175"> * the set of all write numbers that are completed. Set the read point to the highest numbered</span> |
| <span class="source-line-no">176</span><span id="line-176"> * write of S.</span> |
| <span class="source-line-no">177</span><span id="line-177"> * @return true if e is visible to MVCC readers (that is, readpoint >= e.writeNumber)</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 boolean complete(WriteEntry writeEntry) {</span> |
| <span class="source-line-no">180</span><span id="line-180"> synchronized (writeQueue) {</span> |
| <span class="source-line-no">181</span><span id="line-181"> writeEntry.markCompleted();</span> |
| <span class="source-line-no">182</span><span id="line-182"> long nextReadValue = NONE;</span> |
| <span class="source-line-no">183</span><span id="line-183"> boolean ranOnce = false;</span> |
| <span class="source-line-no">184</span><span id="line-184"> while (!writeQueue.isEmpty()) {</span> |
| <span class="source-line-no">185</span><span id="line-185"> ranOnce = true;</span> |
| <span class="source-line-no">186</span><span id="line-186"> WriteEntry queueFirst = writeQueue.getFirst();</span> |
| <span class="source-line-no">187</span><span id="line-187"></span> |
| <span class="source-line-no">188</span><span id="line-188"> if (nextReadValue > 0) {</span> |
| <span class="source-line-no">189</span><span id="line-189"> if (nextReadValue + 1 != queueFirst.getWriteNumber()) {</span> |
| <span class="source-line-no">190</span><span id="line-190"> throw new RuntimeException("Invariant in complete violated, nextReadValue="</span> |
| <span class="source-line-no">191</span><span id="line-191"> + nextReadValue + ", writeNumber=" + queueFirst.getWriteNumber());</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"> if (queueFirst.isCompleted()) {</span> |
| <span class="source-line-no">196</span><span id="line-196"> nextReadValue = queueFirst.getWriteNumber();</span> |
| <span class="source-line-no">197</span><span id="line-197"> writeQueue.removeFirst();</span> |
| <span class="source-line-no">198</span><span id="line-198"> queueFirst.runCompletionAction();</span> |
| <span class="source-line-no">199</span><span id="line-199"> } else {</span> |
| <span class="source-line-no">200</span><span id="line-200"> break;</span> |
| <span class="source-line-no">201</span><span id="line-201"> }</span> |
| <span class="source-line-no">202</span><span id="line-202"> }</span> |
| <span class="source-line-no">203</span><span id="line-203"></span> |
| <span class="source-line-no">204</span><span id="line-204"> if (!ranOnce) {</span> |
| <span class="source-line-no">205</span><span id="line-205"> throw new RuntimeException("There is no first!");</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"> if (nextReadValue > 0) {</span> |
| <span class="source-line-no">209</span><span id="line-209"> synchronized (readWaiters) {</span> |
| <span class="source-line-no">210</span><span id="line-210"> readPoint.set(nextReadValue);</span> |
| <span class="source-line-no">211</span><span id="line-211"> readWaiters.notifyAll();</span> |
| <span class="source-line-no">212</span><span id="line-212"> }</span> |
| <span class="source-line-no">213</span><span id="line-213"> }</span> |
| <span class="source-line-no">214</span><span id="line-214"> return readPoint.get() >= writeEntry.getWriteNumber();</span> |
| <span class="source-line-no">215</span><span id="line-215"> }</span> |
| <span class="source-line-no">216</span><span id="line-216"> }</span> |
| <span class="source-line-no">217</span><span id="line-217"></span> |
| <span class="source-line-no">218</span><span id="line-218"> /**</span> |
| <span class="source-line-no">219</span><span id="line-219"> * Wait for the global readPoint to advance up to the passed in write entry number.</span> |
| <span class="source-line-no">220</span><span id="line-220"> */</span> |
| <span class="source-line-no">221</span><span id="line-221"> void waitForRead(WriteEntry e) {</span> |
| <span class="source-line-no">222</span><span id="line-222"> boolean interrupted = false;</span> |
| <span class="source-line-no">223</span><span id="line-223"> int count = 0;</span> |
| <span class="source-line-no">224</span><span id="line-224"> synchronized (readWaiters) {</span> |
| <span class="source-line-no">225</span><span id="line-225"> while (readPoint.get() < e.getWriteNumber()) {</span> |
| <span class="source-line-no">226</span><span id="line-226"> if (count % 100 == 0 && count > 0) {</span> |
| <span class="source-line-no">227</span><span id="line-227"> long totalWaitTillNow = READPOINT_ADVANCE_WAIT_TIME * count;</span> |
| <span class="source-line-no">228</span><span id="line-228"> LOG.warn("STUCK for : " + totalWaitTillNow + " millis. " + this);</span> |
| <span class="source-line-no">229</span><span id="line-229"> }</span> |
| <span class="source-line-no">230</span><span id="line-230"> count++;</span> |
| <span class="source-line-no">231</span><span id="line-231"> try {</span> |
| <span class="source-line-no">232</span><span id="line-232"> readWaiters.wait(READPOINT_ADVANCE_WAIT_TIME);</span> |
| <span class="source-line-no">233</span><span id="line-233"> } catch (InterruptedException ie) {</span> |
| <span class="source-line-no">234</span><span id="line-234"> // We were interrupted... finish the loop -- i.e. cleanup --and then</span> |
| <span class="source-line-no">235</span><span id="line-235"> // on our way out, reset the interrupt flag.</span> |
| <span class="source-line-no">236</span><span id="line-236"> interrupted = true;</span> |
| <span class="source-line-no">237</span><span id="line-237"> }</span> |
| <span class="source-line-no">238</span><span id="line-238"> }</span> |
| <span class="source-line-no">239</span><span id="line-239"> }</span> |
| <span class="source-line-no">240</span><span id="line-240"> if (interrupted) {</span> |
| <span class="source-line-no">241</span><span id="line-241"> Thread.currentThread().interrupt();</span> |
| <span class="source-line-no">242</span><span id="line-242"> }</span> |
| <span class="source-line-no">243</span><span id="line-243"> }</span> |
| <span class="source-line-no">244</span><span id="line-244"></span> |
| <span class="source-line-no">245</span><span id="line-245"> @Override</span> |
| <span class="source-line-no">246</span><span id="line-246"> public String toString() {</span> |
| <span class="source-line-no">247</span><span id="line-247"> ToStringHelper helper =</span> |
| <span class="source-line-no">248</span><span id="line-248"> MoreObjects.toStringHelper(this).add("readPoint", readPoint).add("writePoint", writePoint);</span> |
| <span class="source-line-no">249</span><span id="line-249"> if (this.regionName != null) {</span> |
| <span class="source-line-no">250</span><span id="line-250"> helper.add("regionName", this.regionName);</span> |
| <span class="source-line-no">251</span><span id="line-251"> }</span> |
| <span class="source-line-no">252</span><span id="line-252"> return helper.toString();</span> |
| <span class="source-line-no">253</span><span id="line-253"> }</span> |
| <span class="source-line-no">254</span><span id="line-254"></span> |
| <span class="source-line-no">255</span><span id="line-255"> public long getReadPoint() {</span> |
| <span class="source-line-no">256</span><span id="line-256"> return readPoint.get();</span> |
| <span class="source-line-no">257</span><span id="line-257"> }</span> |
| <span class="source-line-no">258</span><span id="line-258"></span> |
| <span class="source-line-no">259</span><span id="line-259"> public long getWritePoint() {</span> |
| <span class="source-line-no">260</span><span id="line-260"> return writePoint.get();</span> |
| <span class="source-line-no">261</span><span id="line-261"> }</span> |
| <span class="source-line-no">262</span><span id="line-262"></span> |
| <span class="source-line-no">263</span><span id="line-263"> /**</span> |
| <span class="source-line-no">264</span><span id="line-264"> * Write number and whether write has completed given out at start of a write transaction. Every</span> |
| <span class="source-line-no">265</span><span id="line-265"> * created WriteEntry must be completed by calling mvcc#complete or #completeAndWait.</span> |
| <span class="source-line-no">266</span><span id="line-266"> */</span> |
| <span class="source-line-no">267</span><span id="line-267"> @InterfaceAudience.Private</span> |
| <span class="source-line-no">268</span><span id="line-268"> public static final class WriteEntry {</span> |
| <span class="source-line-no">269</span><span id="line-269"> private final long writeNumber;</span> |
| <span class="source-line-no">270</span><span id="line-270"> private boolean completed = false;</span> |
| <span class="source-line-no">271</span><span id="line-271"> /**</span> |
| <span class="source-line-no">272</span><span id="line-272"> * Will be called after completion, i.e, when being removed from the</span> |
| <span class="source-line-no">273</span><span id="line-273"> * {@link MultiVersionConcurrencyControl#writeQueue}.</span> |
| <span class="source-line-no">274</span><span id="line-274"> */</span> |
| <span class="source-line-no">275</span><span id="line-275"> private Optional<Runnable> completionAction = Optional.empty();</span> |
| <span class="source-line-no">276</span><span id="line-276"></span> |
| <span class="source-line-no">277</span><span id="line-277"> private WriteEntry(long writeNumber) {</span> |
| <span class="source-line-no">278</span><span id="line-278"> this.writeNumber = writeNumber;</span> |
| <span class="source-line-no">279</span><span id="line-279"> }</span> |
| <span class="source-line-no">280</span><span id="line-280"></span> |
| <span class="source-line-no">281</span><span id="line-281"> private void markCompleted() {</span> |
| <span class="source-line-no">282</span><span id="line-282"> this.completed = true;</span> |
| <span class="source-line-no">283</span><span id="line-283"> }</span> |
| <span class="source-line-no">284</span><span id="line-284"></span> |
| <span class="source-line-no">285</span><span id="line-285"> private boolean isCompleted() {</span> |
| <span class="source-line-no">286</span><span id="line-286"> return this.completed;</span> |
| <span class="source-line-no">287</span><span id="line-287"> }</span> |
| <span class="source-line-no">288</span><span id="line-288"></span> |
| <span class="source-line-no">289</span><span id="line-289"> public void attachCompletionAction(Runnable action) {</span> |
| <span class="source-line-no">290</span><span id="line-290"> assert !completionAction.isPresent();</span> |
| <span class="source-line-no">291</span><span id="line-291"> completionAction = Optional.of(action);</span> |
| <span class="source-line-no">292</span><span id="line-292"> }</span> |
| <span class="source-line-no">293</span><span id="line-293"></span> |
| <span class="source-line-no">294</span><span id="line-294"> private void runCompletionAction() {</span> |
| <span class="source-line-no">295</span><span id="line-295"> completionAction.ifPresent(Runnable::run);</span> |
| <span class="source-line-no">296</span><span id="line-296"> }</span> |
| <span class="source-line-no">297</span><span id="line-297"></span> |
| <span class="source-line-no">298</span><span id="line-298"> public Optional<Runnable> getCompletionAction() {</span> |
| <span class="source-line-no">299</span><span id="line-299"> return completionAction;</span> |
| <span class="source-line-no">300</span><span id="line-300"> }</span> |
| <span class="source-line-no">301</span><span id="line-301"></span> |
| <span class="source-line-no">302</span><span id="line-302"> public long getWriteNumber() {</span> |
| <span class="source-line-no">303</span><span id="line-303"> return this.writeNumber;</span> |
| <span class="source-line-no">304</span><span id="line-304"> }</span> |
| <span class="source-line-no">305</span><span id="line-305"></span> |
| <span class="source-line-no">306</span><span id="line-306"> @Override</span> |
| <span class="source-line-no">307</span><span id="line-307"> public String toString() {</span> |
| <span class="source-line-no">308</span><span id="line-308"> return this.writeNumber + ", " + this.completed;</span> |
| <span class="source-line-no">309</span><span id="line-309"> }</span> |
| <span class="source-line-no">310</span><span id="line-310"> }</span> |
| <span class="source-line-no">311</span><span id="line-311"></span> |
| <span class="source-line-no">312</span><span id="line-312"> public static final long FIXED_SIZE =</span> |
| <span class="source-line-no">313</span><span id="line-313"> ClassSize.align(ClassSize.OBJECT + 2 * Bytes.SIZEOF_LONG + 2 * ClassSize.REFERENCE);</span> |
| <span class="source-line-no">314</span><span id="line-314">}</span> |
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| </pre> |
| </div> |
| </main> |
| </body> |
| </html> |
