| <!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.master, class: CachedClusterId"> |
| <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.master;</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.util.concurrent.atomic.AtomicBoolean;</span> |
| <span class="source-line-no">022</span><span id="line-22">import java.util.concurrent.atomic.AtomicInteger;</span> |
| <span class="source-line-no">023</span><span id="line-23">import org.apache.hadoop.conf.Configuration;</span> |
| <span class="source-line-no">024</span><span id="line-24">import org.apache.hadoop.fs.FileSystem;</span> |
| <span class="source-line-no">025</span><span id="line-25">import org.apache.hadoop.fs.Path;</span> |
| <span class="source-line-no">026</span><span id="line-26">import org.apache.hadoop.hbase.ClusterId;</span> |
| <span class="source-line-no">027</span><span id="line-27">import org.apache.hadoop.hbase.Server;</span> |
| <span class="source-line-no">028</span><span id="line-28">import org.apache.hadoop.hbase.util.CommonFSUtils;</span> |
| <span class="source-line-no">029</span><span id="line-29">import org.apache.hadoop.hbase.util.FSUtils;</span> |
| <span class="source-line-no">030</span><span id="line-30">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">031</span><span id="line-31">import org.slf4j.Logger;</span> |
| <span class="source-line-no">032</span><span id="line-32">import org.slf4j.LoggerFactory;</span> |
| <span class="source-line-no">033</span><span id="line-33"></span> |
| <span class="source-line-no">034</span><span id="line-34">import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;</span> |
| <span class="source-line-no">035</span><span id="line-35"></span> |
| <span class="source-line-no">036</span><span id="line-36">/**</span> |
| <span class="source-line-no">037</span><span id="line-37"> * Caches the cluster ID of the cluster. For standby masters, this is used to serve the client RPCs</span> |
| <span class="source-line-no">038</span><span id="line-38"> * that fetch the cluster ID. ClusterID is only created by an active master if one does not already</span> |
| <span class="source-line-no">039</span><span id="line-39"> * exist. Standby masters just read the information from the file system. This class is thread-safe.</span> |
| <span class="source-line-no">040</span><span id="line-40"> * TODO: Make it a singleton without affecting concurrent junit tests.</span> |
| <span class="source-line-no">041</span><span id="line-41"> */</span> |
| <span class="source-line-no">042</span><span id="line-42">@InterfaceAudience.Private</span> |
| <span class="source-line-no">043</span><span id="line-43">public class CachedClusterId {</span> |
| <span class="source-line-no">044</span><span id="line-44"></span> |
| <span class="source-line-no">045</span><span id="line-45"> public static final Logger LOG = LoggerFactory.getLogger(CachedClusterId.class);</span> |
| <span class="source-line-no">046</span><span id="line-46"> private static final int MAX_FETCH_TIMEOUT_MS = 10000;</span> |
| <span class="source-line-no">047</span><span id="line-47"></span> |
| <span class="source-line-no">048</span><span id="line-48"> private final Path rootDir;</span> |
| <span class="source-line-no">049</span><span id="line-49"> private final FileSystem fs;</span> |
| <span class="source-line-no">050</span><span id="line-50"></span> |
| <span class="source-line-no">051</span><span id="line-51"> // When true, indicates that a FileSystem fetch of ClusterID is in progress. This is used to</span> |
| <span class="source-line-no">052</span><span id="line-52"> // avoid multiple fetches from FS and let only one thread fetch the information.</span> |
| <span class="source-line-no">053</span><span id="line-53"> AtomicBoolean fetchInProgress = new AtomicBoolean(false);</span> |
| <span class="source-line-no">054</span><span id="line-54"></span> |
| <span class="source-line-no">055</span><span id="line-55"> // When true, it means that the cluster ID has been fetched successfully from fs.</span> |
| <span class="source-line-no">056</span><span id="line-56"> private AtomicBoolean isClusterIdSet = new AtomicBoolean(false);</span> |
| <span class="source-line-no">057</span><span id="line-57"> // Immutable once set and read multiple times.</span> |
| <span class="source-line-no">058</span><span id="line-58"> private ClusterId clusterId;</span> |
| <span class="source-line-no">059</span><span id="line-59"></span> |
| <span class="source-line-no">060</span><span id="line-60"> private final Server server;</span> |
| <span class="source-line-no">061</span><span id="line-61"></span> |
| <span class="source-line-no">062</span><span id="line-62"> // cache stats for testing.</span> |
| <span class="source-line-no">063</span><span id="line-63"> private AtomicInteger cacheMisses = new AtomicInteger(0);</span> |
| <span class="source-line-no">064</span><span id="line-64"></span> |
| <span class="source-line-no">065</span><span id="line-65"> public CachedClusterId(Server server, Configuration conf) throws IOException {</span> |
| <span class="source-line-no">066</span><span id="line-66"> this.rootDir = CommonFSUtils.getRootDir(conf);</span> |
| <span class="source-line-no">067</span><span id="line-67"> this.fs = rootDir.getFileSystem(conf);</span> |
| <span class="source-line-no">068</span><span id="line-68"> this.server = server;</span> |
| <span class="source-line-no">069</span><span id="line-69"> }</span> |
| <span class="source-line-no">070</span><span id="line-70"></span> |
| <span class="source-line-no">071</span><span id="line-71"> /**</span> |
| <span class="source-line-no">072</span><span id="line-72"> * Succeeds only once, when setting to a non-null value. Overwrites are not allowed.</span> |
| <span class="source-line-no">073</span><span id="line-73"> */</span> |
| <span class="source-line-no">074</span><span id="line-74"> private void setClusterId(ClusterId id) {</span> |
| <span class="source-line-no">075</span><span id="line-75"> if (id == null || isClusterIdSet.get()) {</span> |
| <span class="source-line-no">076</span><span id="line-76"> return;</span> |
| <span class="source-line-no">077</span><span id="line-77"> }</span> |
| <span class="source-line-no">078</span><span id="line-78"> clusterId = id;</span> |
| <span class="source-line-no">079</span><span id="line-79"> isClusterIdSet.set(true);</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"> * Returns a cached copy of the cluster ID. null if the cache is not populated.</span> |
| <span class="source-line-no">084</span><span id="line-84"> */</span> |
| <span class="source-line-no">085</span><span id="line-85"> private String getClusterId() {</span> |
| <span class="source-line-no">086</span><span id="line-86"> if (!isClusterIdSet.get()) {</span> |
| <span class="source-line-no">087</span><span id="line-87"> return null;</span> |
| <span class="source-line-no">088</span><span id="line-88"> }</span> |
| <span class="source-line-no">089</span><span id="line-89"> // It is ok to read without a lock since clusterId is immutable once set.</span> |
| <span class="source-line-no">090</span><span id="line-90"> return clusterId.toString();</span> |
| <span class="source-line-no">091</span><span id="line-91"> }</span> |
| <span class="source-line-no">092</span><span id="line-92"></span> |
| <span class="source-line-no">093</span><span id="line-93"> /**</span> |
| <span class="source-line-no">094</span><span id="line-94"> * Attempts to fetch the cluster ID from the file system. If no attempt is already in progress,</span> |
| <span class="source-line-no">095</span><span id="line-95"> * synchronously fetches the cluster ID and sets it. If an attempt is already in progress, returns</span> |
| <span class="source-line-no">096</span><span id="line-96"> * right away and the caller is expected to wait for the fetch to finish.</span> |
| <span class="source-line-no">097</span><span id="line-97"> * @return true if the attempt is done, false if another thread is already fetching it.</span> |
| <span class="source-line-no">098</span><span id="line-98"> */</span> |
| <span class="source-line-no">099</span><span id="line-99"> private boolean attemptFetch() {</span> |
| <span class="source-line-no">100</span><span id="line-100"> if (fetchInProgress.compareAndSet(false, true)) {</span> |
| <span class="source-line-no">101</span><span id="line-101"> // A fetch is not in progress, so try fetching the cluster ID synchronously and then notify</span> |
| <span class="source-line-no">102</span><span id="line-102"> // the waiting threads.</span> |
| <span class="source-line-no">103</span><span id="line-103"> try {</span> |
| <span class="source-line-no">104</span><span id="line-104"> cacheMisses.incrementAndGet();</span> |
| <span class="source-line-no">105</span><span id="line-105"> setClusterId(FSUtils.getClusterId(fs, rootDir));</span> |
| <span class="source-line-no">106</span><span id="line-106"> } catch (IOException e) {</span> |
| <span class="source-line-no">107</span><span id="line-107"> LOG.warn("Error fetching cluster ID", e);</span> |
| <span class="source-line-no">108</span><span id="line-108"> } finally {</span> |
| <span class="source-line-no">109</span><span id="line-109"> Preconditions.checkState(fetchInProgress.compareAndSet(true, false));</span> |
| <span class="source-line-no">110</span><span id="line-110"> synchronized (fetchInProgress) {</span> |
| <span class="source-line-no">111</span><span id="line-111"> fetchInProgress.notifyAll();</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"> return true;</span> |
| <span class="source-line-no">115</span><span id="line-115"> }</span> |
| <span class="source-line-no">116</span><span id="line-116"> return false;</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"> private void waitForFetchToFinish() throws InterruptedException {</span> |
| <span class="source-line-no">120</span><span id="line-120"> synchronized (fetchInProgress) {</span> |
| <span class="source-line-no">121</span><span id="line-121"> while (fetchInProgress.get()) {</span> |
| <span class="source-line-no">122</span><span id="line-122"> // We don't want the fetches to block forever, for example if there are bugs</span> |
| <span class="source-line-no">123</span><span id="line-123"> // of missing notifications.</span> |
| <span class="source-line-no">124</span><span id="line-124"> fetchInProgress.wait(MAX_FETCH_TIMEOUT_MS);</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"> /**</span> |
| <span class="source-line-no">130</span><span id="line-130"> * Fetches the ClusterId from FS if it is not cached locally. Atomically updates the cached copy</span> |
| <span class="source-line-no">131</span><span id="line-131"> * and is thread-safe. Optimized to do a single fetch when there are multiple threads are trying</span> |
| <span class="source-line-no">132</span><span id="line-132"> * get from a clean cache.</span> |
| <span class="source-line-no">133</span><span id="line-133"> * @return ClusterId by reading from FileSystem or null in any error case or cluster ID does not</span> |
| <span class="source-line-no">134</span><span id="line-134"> * exist on the file system or if the server initiated a tear down.</span> |
| <span class="source-line-no">135</span><span id="line-135"> */</span> |
| <span class="source-line-no">136</span><span id="line-136"> public String getFromCacheOrFetch() {</span> |
| <span class="source-line-no">137</span><span id="line-137"> if (server.isStopping() || server.isStopped()) {</span> |
| <span class="source-line-no">138</span><span id="line-138"> return null;</span> |
| <span class="source-line-no">139</span><span id="line-139"> }</span> |
| <span class="source-line-no">140</span><span id="line-140"> String id = getClusterId();</span> |
| <span class="source-line-no">141</span><span id="line-141"> if (id != null) {</span> |
| <span class="source-line-no">142</span><span id="line-142"> return id;</span> |
| <span class="source-line-no">143</span><span id="line-143"> }</span> |
| <span class="source-line-no">144</span><span id="line-144"> if (!attemptFetch()) {</span> |
| <span class="source-line-no">145</span><span id="line-145"> // A fetch is in progress.</span> |
| <span class="source-line-no">146</span><span id="line-146"> try {</span> |
| <span class="source-line-no">147</span><span id="line-147"> waitForFetchToFinish();</span> |
| <span class="source-line-no">148</span><span id="line-148"> } catch (InterruptedException e) {</span> |
| <span class="source-line-no">149</span><span id="line-149"> // pass and return whatever is in the cache.</span> |
| <span class="source-line-no">150</span><span id="line-150"> }</span> |
| <span class="source-line-no">151</span><span id="line-151"> }</span> |
| <span class="source-line-no">152</span><span id="line-152"> return getClusterId();</span> |
| <span class="source-line-no">153</span><span id="line-153"> }</span> |
| <span class="source-line-no">154</span><span id="line-154"></span> |
| <span class="source-line-no">155</span><span id="line-155"> public int getCacheStats() {</span> |
| <span class="source-line-no">156</span><span id="line-156"> return cacheMisses.get();</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> |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| </pre> |
| </div> |
| </main> |
| </body> |
| </html> |
