Google GitGoogle Git
Sign in
apache/hbase-site/fcb4b8235c10aedafc78eb4abc86ba5a987ef94e/./devapidocs/src-html/org/apache/hadoop/hbase/executor/EventHandler.html
blob: 2c5d7c33739095e56785c723b8d1d3ace357c6b1 [file]
<!DOCTYPE HTML>
<html lang="en">
<head>
<!-- Generated by javadoc (17) -->
<title>Source code</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="source: package: org.apache.hadoop.hbase.executor, class: EventHandler">
<meta name="generator" content="javadoc/SourceToHTMLConverter">
<link rel="stylesheet" type="text/css" href="../../../../../../stylesheet.css" title="Style">
</head>
<body class="source-page">
<main role="main">
<div class="source-container">
<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.executor;</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 io.opentelemetry.api.trace.Span;</span>
<span class="source-line-no">021</span><span id="line-21">import io.opentelemetry.context.Context;</span>
<span class="source-line-no">022</span><span id="line-22">import io.opentelemetry.context.Scope;</span>
<span class="source-line-no">023</span><span id="line-23">import java.io.IOException;</span>
<span class="source-line-no">024</span><span id="line-24">import java.util.concurrent.atomic.AtomicLong;</span>
<span class="source-line-no">025</span><span id="line-25">import org.apache.hadoop.hbase.Server;</span>
<span class="source-line-no">026</span><span id="line-26">import org.apache.hadoop.hbase.trace.TraceUtil;</span>
<span class="source-line-no">027</span><span id="line-27">import org.apache.yetus.audience.InterfaceAudience;</span>
<span class="source-line-no">028</span><span id="line-28">import org.slf4j.Logger;</span>
<span class="source-line-no">029</span><span id="line-29">import org.slf4j.LoggerFactory;</span>
<span class="source-line-no">030</span><span id="line-30">import org.slf4j.MDC;</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"> * Abstract base class for all HBase event handlers. Subclasses should implement the</span>
<span class="source-line-no">034</span><span id="line-34"> * {@link #process()} and {@link #prepare()} methods. Subclasses should also do all necessary checks</span>
<span class="source-line-no">035</span><span id="line-35"> * up in their prepare() if possible -- check table exists, is disabled, etc. -- so they fail fast</span>
<span class="source-line-no">036</span><span id="line-36"> * rather than later when process is running. Do it this way because process be invoked directly but</span>
<span class="source-line-no">037</span><span id="line-37"> * event handlers are also run in an executor context -- i.e. asynchronously -- and in this case,</span>
<span class="source-line-no">038</span><span id="line-38"> * exceptions thrown at process time will not be seen by the invoker, not till we implement a</span>
<span class="source-line-no">039</span><span id="line-39"> * call-back mechanism so the client can pick them up later.</span>
<span class="source-line-no">040</span><span id="line-40"> * &lt;p&gt;</span>
<span class="source-line-no">041</span><span id="line-41"> * Event handlers have an {@link EventType}. {@link EventType} is a list of ALL handler event types.</span>
<span class="source-line-no">042</span><span id="line-42"> * We need to keep a full list in one place -- and as enums is a good shorthand for an</span>
<span class="source-line-no">043</span><span id="line-43"> * implemenations -- because event handlers can be passed to executors when they are to be run</span>
<span class="source-line-no">044</span><span id="line-44"> * asynchronously. The hbase executor, see ExecutorService, has a switch for passing event type to</span>
<span class="source-line-no">045</span><span id="line-45"> * executor.</span>
<span class="source-line-no">046</span><span id="line-46"> * &lt;p&gt;</span>
<span class="source-line-no">047</span><span id="line-47"> * @see ExecutorService</span>
<span class="source-line-no">048</span><span id="line-48"> */</span>
<span class="source-line-no">049</span><span id="line-49">@InterfaceAudience.Private</span>
<span class="source-line-no">050</span><span id="line-50">public abstract class EventHandler implements Runnable, Comparable&lt;EventHandler&gt; {</span>
<span class="source-line-no">051</span><span id="line-51"> private static final Logger LOG = LoggerFactory.getLogger(EventHandler.class);</span>
<span class="source-line-no">052</span><span id="line-52"></span>
<span class="source-line-no">053</span><span id="line-53"> // type of event this object represents</span>
<span class="source-line-no">054</span><span id="line-54"> protected EventType eventType;</span>
<span class="source-line-no">055</span><span id="line-55"></span>
<span class="source-line-no">056</span><span id="line-56"> protected Server server;</span>
<span class="source-line-no">057</span><span id="line-57"></span>
<span class="source-line-no">058</span><span id="line-58"> // sequence id generator for default FIFO ordering of events</span>
<span class="source-line-no">059</span><span id="line-59"> protected static final AtomicLong seqids = new AtomicLong(0);</span>
<span class="source-line-no">060</span><span id="line-60"></span>
<span class="source-line-no">061</span><span id="line-61"> // sequence id for this event</span>
<span class="source-line-no">062</span><span id="line-62"> private final long seqid;</span>
<span class="source-line-no">063</span><span id="line-63"></span>
<span class="source-line-no">064</span><span id="line-64"> // Time to wait for events to happen, should be kept short</span>
<span class="source-line-no">065</span><span id="line-65"> protected int waitingTimeForEvents;</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 final Span parent;</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"> * Default base class constructor.</span>
<span class="source-line-no">071</span><span id="line-71"> */</span>
<span class="source-line-no">072</span><span id="line-72"> public EventHandler(Server server, EventType eventType) {</span>
<span class="source-line-no">073</span><span id="line-73"> this.parent = Span.current();</span>
<span class="source-line-no">074</span><span id="line-74"> this.server = server;</span>
<span class="source-line-no">075</span><span id="line-75"> this.eventType = eventType;</span>
<span class="source-line-no">076</span><span id="line-76"> seqid = seqids.incrementAndGet();</span>
<span class="source-line-no">077</span><span id="line-77"> if (server != null) {</span>
<span class="source-line-no">078</span><span id="line-78"> this.waitingTimeForEvents =</span>
<span class="source-line-no">079</span><span id="line-79"> server.getConfiguration().getInt("hbase.master.event.waiting.time", 1000);</span>
<span class="source-line-no">080</span><span id="line-80"> }</span>
<span class="source-line-no">081</span><span id="line-81"> }</span>
<span class="source-line-no">082</span><span id="line-82"></span>
<span class="source-line-no">083</span><span id="line-83"> /**</span>
<span class="source-line-no">084</span><span id="line-84"> * Event handlers should do all the necessary checks in this method (rather than in the</span>
<span class="source-line-no">085</span><span id="line-85"> * constructor, or in process()) so that the caller, which is mostly executed in the ipc context</span>
<span class="source-line-no">086</span><span id="line-86"> * can fail fast. Process is executed async from the client ipc, so this method gives a quick</span>
<span class="source-line-no">087</span><span id="line-87"> * chance to do some basic checks. Should be called after constructing the EventHandler, and</span>
<span class="source-line-no">088</span><span id="line-88"> * before process().</span>
<span class="source-line-no">089</span><span id="line-89"> * @return the instance of this class</span>
<span class="source-line-no">090</span><span id="line-90"> * @throws Exception when something goes wrong</span>
<span class="source-line-no">091</span><span id="line-91"> */</span>
<span class="source-line-no">092</span><span id="line-92"> public EventHandler prepare() throws Exception {</span>
<span class="source-line-no">093</span><span id="line-93"> return this;</span>
<span class="source-line-no">094</span><span id="line-94"> }</span>
<span class="source-line-no">095</span><span id="line-95"></span>
<span class="source-line-no">096</span><span id="line-96"> @Override</span>
<span class="source-line-no">097</span><span id="line-97"> public void run() {</span>
<span class="source-line-no">098</span><span id="line-98"> Span span = TraceUtil.getGlobalTracer().spanBuilder(getClass().getSimpleName())</span>
<span class="source-line-no">099</span><span id="line-99"> .setParent(Context.current().with(parent)).startSpan();</span>
<span class="source-line-no">100</span><span id="line-100"> // assume that this is the top of an execution on a new or reused thread, that we're safe to</span>
<span class="source-line-no">101</span><span id="line-101"> // blast any existing MDC state.</span>
<span class="source-line-no">102</span><span id="line-102"> try (Scope scope = span.makeCurrent()) {</span>
<span class="source-line-no">103</span><span id="line-103"> MDC.put("event_type", eventType.toString());</span>
<span class="source-line-no">104</span><span id="line-104"> process();</span>
<span class="source-line-no">105</span><span id="line-105"> } catch (Throwable t) {</span>
<span class="source-line-no">106</span><span id="line-106"> handleException(t);</span>
<span class="source-line-no">107</span><span id="line-107"> } finally {</span>
<span class="source-line-no">108</span><span id="line-108"> span.end();</span>
<span class="source-line-no">109</span><span id="line-109"> MDC.clear();</span>
<span class="source-line-no">110</span><span id="line-110"> }</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"> /**</span>
<span class="source-line-no">114</span><span id="line-114"> * This method is the main processing loop to be implemented by the various subclasses.</span>
<span class="source-line-no">115</span><span id="line-115"> */</span>
<span class="source-line-no">116</span><span id="line-116"> public abstract void process() throws IOException;</span>
<span class="source-line-no">117</span><span id="line-117"></span>
<span class="source-line-no">118</span><span id="line-118"> /**</span>
<span class="source-line-no">119</span><span id="line-119"> * Return the event type</span>
<span class="source-line-no">120</span><span id="line-120"> * @return The event type.</span>
<span class="source-line-no">121</span><span id="line-121"> */</span>
<span class="source-line-no">122</span><span id="line-122"> public EventType getEventType() {</span>
<span class="source-line-no">123</span><span id="line-123"> return this.eventType;</span>
<span class="source-line-no">124</span><span id="line-124"> }</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"> * Get the priority level for this handler instance. This uses natural ordering so lower numbers</span>
<span class="source-line-no">128</span><span id="line-128"> * are higher priority.</span>
<span class="source-line-no">129</span><span id="line-129"> * &lt;p&gt;</span>
<span class="source-line-no">130</span><span id="line-130"> * Lowest priority is Integer.MAX_VALUE. Highest priority is 0.</span>
<span class="source-line-no">131</span><span id="line-131"> * &lt;p&gt;</span>
<span class="source-line-no">132</span><span id="line-132"> * Subclasses should override this method to allow prioritizing handlers.</span>
<span class="source-line-no">133</span><span id="line-133"> * &lt;p&gt;</span>
<span class="source-line-no">134</span><span id="line-134"> * Handlers with the same priority are handled in FIFO order.</span>
<span class="source-line-no">135</span><span id="line-135"> * &lt;p&gt;</span>
<span class="source-line-no">136</span><span id="line-136"> * @return Integer.MAX_VALUE by default, override to set higher priorities</span>
<span class="source-line-no">137</span><span id="line-137"> */</span>
<span class="source-line-no">138</span><span id="line-138"> public int getPriority() {</span>
<span class="source-line-no">139</span><span id="line-139"> return Integer.MAX_VALUE;</span>
<span class="source-line-no">140</span><span id="line-140"> }</span>
<span class="source-line-no">141</span><span id="line-141"></span>
<span class="source-line-no">142</span><span id="line-142"> /** Returns This events' sequence id. */</span>
<span class="source-line-no">143</span><span id="line-143"> public long getSeqid() {</span>
<span class="source-line-no">144</span><span id="line-144"> return this.seqid;</span>
<span class="source-line-no">145</span><span id="line-145"> }</span>
<span class="source-line-no">146</span><span id="line-146"></span>
<span class="source-line-no">147</span><span id="line-147"> /**</span>
<span class="source-line-no">148</span><span id="line-148"> * Default prioritized runnable comparator which implements a FIFO ordering.</span>
<span class="source-line-no">149</span><span id="line-149"> * &lt;p&gt;</span>
<span class="source-line-no">150</span><span id="line-150"> * Subclasses should not override this. Instead, if they want to implement priority beyond FIFO,</span>
<span class="source-line-no">151</span><span id="line-151"> * they should override {@link #getPriority()}.</span>
<span class="source-line-no">152</span><span id="line-152"> */</span>
<span class="source-line-no">153</span><span id="line-153"> @Override</span>
<span class="source-line-no">154</span><span id="line-154"> public int compareTo(EventHandler o) {</span>
<span class="source-line-no">155</span><span id="line-155"> if (o == null) {</span>
<span class="source-line-no">156</span><span id="line-156"> return 1;</span>
<span class="source-line-no">157</span><span id="line-157"> }</span>
<span class="source-line-no">158</span><span id="line-158"> if (getPriority() != o.getPriority()) {</span>
<span class="source-line-no">159</span><span id="line-159"> return (getPriority() &lt; o.getPriority()) ? -1 : 1;</span>
<span class="source-line-no">160</span><span id="line-160"> }</span>
<span class="source-line-no">161</span><span id="line-161"> return (this.seqid &lt; o.seqid) ? -1 : 1;</span>
<span class="source-line-no">162</span><span id="line-162"> }</span>
<span class="source-line-no">163</span><span id="line-163"></span>
<span class="source-line-no">164</span><span id="line-164"> @Override</span>
<span class="source-line-no">165</span><span id="line-165"> public String toString() {</span>
<span class="source-line-no">166</span><span id="line-166"> return "Event #" + getSeqid() + " of type " + eventType + " (" + getInformativeName() + ")";</span>
<span class="source-line-no">167</span><span id="line-167"> }</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"> * Event implementations should override thie class to provide an informative name about what</span>
<span class="source-line-no">171</span><span id="line-171"> * event they are handling. For example, event-specific information such as which region or server</span>
<span class="source-line-no">172</span><span id="line-172"> * is being processed should be included if possible.</span>
<span class="source-line-no">173</span><span id="line-173"> */</span>
<span class="source-line-no">174</span><span id="line-174"> public String getInformativeName() {</span>
<span class="source-line-no">175</span><span id="line-175"> return this.getClass().toString();</span>
<span class="source-line-no">176</span><span id="line-176"> }</span>
<span class="source-line-no">177</span><span id="line-177"></span>
<span class="source-line-no">178</span><span id="line-178"> /**</span>
<span class="source-line-no">179</span><span id="line-179"> * Event exception handler, may be overridden</span>
<span class="source-line-no">180</span><span id="line-180"> * @param t Throwable object</span>
<span class="source-line-no">181</span><span id="line-181"> */</span>
<span class="source-line-no">182</span><span id="line-182"> protected void handleException(Throwable t) {</span>
<span class="source-line-no">183</span><span id="line-183"> String msg = "Caught throwable while processing event " + eventType;</span>
<span class="source-line-no">184</span><span id="line-184"> LOG.error(msg, t);</span>
<span class="source-line-no">185</span><span id="line-185"> if (server != null &amp;&amp; (t instanceof Error || t instanceof RuntimeException)) {</span>
<span class="source-line-no">186</span><span id="line-186"> server.abort(msg, t);</span>
<span class="source-line-no">187</span><span id="line-187"> }</span>
<span class="source-line-no">188</span><span id="line-188"> }</span>
<span class="source-line-no">189</span><span id="line-189">}</span>
</pre>
</div>
</main>
</body>
</html>