Google Git
Sign in
apache / hbase-site / 2e3aaee18b357604e6f6797bafb8e59d3025ccb0 / . / devapidocs / src-html / org / apache / hadoop / hbase / regionserver / wal / SyncFuture.html
blob: 94334da0904fe003f848b3865e8f07ca56d34bc2 [file] [log] [blame]
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<title>Source code</title>
<link rel="stylesheet" type="text/css" href="../../../../../../../stylesheet.css" title="Style">
</head>
<body>
<div class="sourceContainer">
<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.regionserver.wal;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.util.concurrent.ExecutionException;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.util.concurrent.TimeUnit;<a name="line.21"></a>
<span class="sourceLineNo">022</span><a name="line.22"></a>
<span class="sourceLineNo">023</span>import org.apache.hadoop.hbase.exceptions.TimeoutIOException;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>/**<a name="line.26"></a>
<span class="sourceLineNo">027</span> * A Future on a filesystem sync call. It given to a client or 'Handler' for it to wait on till the<a name="line.27"></a>
<span class="sourceLineNo">028</span> * sync completes.<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> * Handlers coming in call append, append, append, and then do a flush/sync of the edits they have<a name="line.30"></a>
<span class="sourceLineNo">031</span> * appended the WAL before returning. Since sync takes a while to complete, we give the Handlers<a name="line.31"></a>
<span class="sourceLineNo">032</span> * back this sync future to wait on until the actual HDFS sync completes. Meantime this sync future<a name="line.32"></a>
<span class="sourceLineNo">033</span> * goes across a queue and is handled by a background thread; when it completes, it finishes up the<a name="line.33"></a>
<span class="sourceLineNo">034</span> * future, the handler get or failed check completes and the Handler can then progress.<a name="line.34"></a>
<span class="sourceLineNo">035</span> * &lt;p&gt;<a name="line.35"></a>
<span class="sourceLineNo">036</span> * This is just a partial implementation of Future; we just implement get and failure.<a name="line.36"></a>
<span class="sourceLineNo">037</span> * &lt;p&gt;<a name="line.37"></a>
<span class="sourceLineNo">038</span> * There is not a one-to-one correlation between dfs sync invocations and instances of this class. A<a name="line.38"></a>
<span class="sourceLineNo">039</span> * single dfs sync call may complete and mark many SyncFutures as done; i.e. we batch up sync calls<a name="line.39"></a>
<span class="sourceLineNo">040</span> * rather than do a dfs sync call every time a Handler asks for it.<a name="line.40"></a>
<span class="sourceLineNo">041</span> * &lt;p&gt;<a name="line.41"></a>
<span class="sourceLineNo">042</span> * SyncFutures are immutable but recycled. Call #reset(long, Span) before use even if it the first<a name="line.42"></a>
<span class="sourceLineNo">043</span> * time, start the sync, then park the 'hitched' thread on a call to #get().<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 SyncFuture {<a name="line.46"></a>
<span class="sourceLineNo">047</span> // Implementation notes: I tried using a cyclicbarrier in here for handler and sync threads<a name="line.47"></a>
<span class="sourceLineNo">048</span> // to coordinate on but it did not give any obvious advantage and some issues with order in which<a name="line.48"></a>
<span class="sourceLineNo">049</span> // events happen.<a name="line.49"></a>
<span class="sourceLineNo">050</span> private static final long NOT_DONE = -1L;<a name="line.50"></a>
<span class="sourceLineNo">051</span><a name="line.51"></a>
<span class="sourceLineNo">052</span> /**<a name="line.52"></a>
<span class="sourceLineNo">053</span> * The transaction id of this operation, monotonically increases.<a name="line.53"></a>
<span class="sourceLineNo">054</span> */<a name="line.54"></a>
<span class="sourceLineNo">055</span> private long txid;<a name="line.55"></a>
<span class="sourceLineNo">056</span><a name="line.56"></a>
<span class="sourceLineNo">057</span> /**<a name="line.57"></a>
<span class="sourceLineNo">058</span> * The transaction id that was set in here when we were marked done. Should be equal or &gt; txnId.<a name="line.58"></a>
<span class="sourceLineNo">059</span> * Put this data member into the NOT_DONE state while this class is in use.<a name="line.59"></a>
<span class="sourceLineNo">060</span> */<a name="line.60"></a>
<span class="sourceLineNo">061</span> private long doneTxid;<a name="line.61"></a>
<span class="sourceLineNo">062</span><a name="line.62"></a>
<span class="sourceLineNo">063</span> /**<a name="line.63"></a>
<span class="sourceLineNo">064</span> * If error, the associated throwable. Set when the future is 'done'.<a name="line.64"></a>
<span class="sourceLineNo">065</span> */<a name="line.65"></a>
<span class="sourceLineNo">066</span> private Throwable throwable;<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span> private Thread t;<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span> private boolean forceSync;<a name="line.70"></a>
<span class="sourceLineNo">071</span><a name="line.71"></a>
<span class="sourceLineNo">072</span> /**<a name="line.72"></a>
<span class="sourceLineNo">073</span> * Call this method to clear old usage and get it ready for new deploy.<a name="line.73"></a>
<span class="sourceLineNo">074</span> * @param txid the new transaction id<a name="line.74"></a>
<span class="sourceLineNo">075</span> * @return this<a name="line.75"></a>
<span class="sourceLineNo">076</span> */<a name="line.76"></a>
<span class="sourceLineNo">077</span> synchronized SyncFuture reset(long txid) {<a name="line.77"></a>
<span class="sourceLineNo">078</span> if (t != null &amp;&amp; t != Thread.currentThread()) {<a name="line.78"></a>
<span class="sourceLineNo">079</span> throw new IllegalStateException();<a name="line.79"></a>
<span class="sourceLineNo">080</span> }<a name="line.80"></a>
<span class="sourceLineNo">081</span> t = Thread.currentThread();<a name="line.81"></a>
<span class="sourceLineNo">082</span> if (!isDone()) {<a name="line.82"></a>
<span class="sourceLineNo">083</span> throw new IllegalStateException("" + txid + " " + Thread.currentThread());<a name="line.83"></a>
<span class="sourceLineNo">084</span> }<a name="line.84"></a>
<span class="sourceLineNo">085</span> this.doneTxid = NOT_DONE;<a name="line.85"></a>
<span class="sourceLineNo">086</span> this.txid = txid;<a name="line.86"></a>
<span class="sourceLineNo">087</span> this.throwable = null;<a name="line.87"></a>
<span class="sourceLineNo">088</span> return this;<a name="line.88"></a>
<span class="sourceLineNo">089</span> }<a name="line.89"></a>
<span class="sourceLineNo">090</span><a name="line.90"></a>
<span class="sourceLineNo">091</span> @Override<a name="line.91"></a>
<span class="sourceLineNo">092</span> public synchronized String toString() {<a name="line.92"></a>
<span class="sourceLineNo">093</span> return "done=" + isDone() + ", txid=" + this.txid;<a name="line.93"></a>
<span class="sourceLineNo">094</span> }<a name="line.94"></a>
<span class="sourceLineNo">095</span><a name="line.95"></a>
<span class="sourceLineNo">096</span> synchronized long getTxid() {<a name="line.96"></a>
<span class="sourceLineNo">097</span> return this.txid;<a name="line.97"></a>
<span class="sourceLineNo">098</span> }<a name="line.98"></a>
<span class="sourceLineNo">099</span><a name="line.99"></a>
<span class="sourceLineNo">100</span> synchronized boolean isForceSync() {<a name="line.100"></a>
<span class="sourceLineNo">101</span> return forceSync;<a name="line.101"></a>
<span class="sourceLineNo">102</span> }<a name="line.102"></a>
<span class="sourceLineNo">103</span><a name="line.103"></a>
<span class="sourceLineNo">104</span> synchronized SyncFuture setForceSync(boolean forceSync) {<a name="line.104"></a>
<span class="sourceLineNo">105</span> this.forceSync = forceSync;<a name="line.105"></a>
<span class="sourceLineNo">106</span> return this;<a name="line.106"></a>
<span class="sourceLineNo">107</span> }<a name="line.107"></a>
<span class="sourceLineNo">108</span><a name="line.108"></a>
<span class="sourceLineNo">109</span> /**<a name="line.109"></a>
<span class="sourceLineNo">110</span> * @param txid the transaction id at which this future 'completed'.<a name="line.110"></a>
<span class="sourceLineNo">111</span> * @param t Can be null. Set if we are 'completing' on error (and this 't' is the error).<a name="line.111"></a>
<span class="sourceLineNo">112</span> * @return True if we successfully marked this outstanding future as completed/done. Returns false<a name="line.112"></a>
<span class="sourceLineNo">113</span> * if this future is already 'done' when this method called.<a name="line.113"></a>
<span class="sourceLineNo">114</span> */<a name="line.114"></a>
<span class="sourceLineNo">115</span> synchronized boolean done(final long txid, final Throwable t) {<a name="line.115"></a>
<span class="sourceLineNo">116</span> if (isDone()) {<a name="line.116"></a>
<span class="sourceLineNo">117</span> return false;<a name="line.117"></a>
<span class="sourceLineNo">118</span> }<a name="line.118"></a>
<span class="sourceLineNo">119</span> this.throwable = t;<a name="line.119"></a>
<span class="sourceLineNo">120</span> if (txid &lt; this.txid) {<a name="line.120"></a>
<span class="sourceLineNo">121</span> // Something badly wrong.<a name="line.121"></a>
<span class="sourceLineNo">122</span> if (throwable == null) {<a name="line.122"></a>
<span class="sourceLineNo">123</span> this.throwable =<a name="line.123"></a>
<span class="sourceLineNo">124</span> new IllegalStateException("done txid=" + txid + ", my txid=" + this.txid);<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> // Mark done.<a name="line.127"></a>
<span class="sourceLineNo">128</span> this.doneTxid = txid;<a name="line.128"></a>
<span class="sourceLineNo">129</span> // Wake up waiting threads.<a name="line.129"></a>
<span class="sourceLineNo">130</span> notify();<a name="line.130"></a>
<span class="sourceLineNo">131</span> return true;<a name="line.131"></a>
<span class="sourceLineNo">132</span> }<a name="line.132"></a>
<span class="sourceLineNo">133</span><a name="line.133"></a>
<span class="sourceLineNo">134</span> boolean cancel(boolean mayInterruptIfRunning) {<a name="line.134"></a>
<span class="sourceLineNo">135</span> throw new UnsupportedOperationException();<a name="line.135"></a>
<span class="sourceLineNo">136</span> }<a name="line.136"></a>
<span class="sourceLineNo">137</span><a name="line.137"></a>
<span class="sourceLineNo">138</span> synchronized long get(long timeoutNs) throws InterruptedException,<a name="line.138"></a>
<span class="sourceLineNo">139</span> ExecutionException, TimeoutIOException {<a name="line.139"></a>
<span class="sourceLineNo">140</span> final long done = System.nanoTime() + timeoutNs;<a name="line.140"></a>
<span class="sourceLineNo">141</span> while (!isDone()) {<a name="line.141"></a>
<span class="sourceLineNo">142</span> wait(1000);<a name="line.142"></a>
<span class="sourceLineNo">143</span> if (System.nanoTime() &gt;= done) {<a name="line.143"></a>
<span class="sourceLineNo">144</span> throw new TimeoutIOException(<a name="line.144"></a>
<span class="sourceLineNo">145</span> "Failed to get sync result after " + TimeUnit.NANOSECONDS.toMillis(timeoutNs)<a name="line.145"></a>
<span class="sourceLineNo">146</span> + " ms for txid=" + this.txid + ", WAL system stuck?");<a name="line.146"></a>
<span class="sourceLineNo">147</span> }<a name="line.147"></a>
<span class="sourceLineNo">148</span> }<a name="line.148"></a>
<span class="sourceLineNo">149</span> if (this.throwable != null) {<a name="line.149"></a>
<span class="sourceLineNo">150</span> throw new ExecutionException(this.throwable);<a name="line.150"></a>
<span class="sourceLineNo">151</span> }<a name="line.151"></a>
<span class="sourceLineNo">152</span> return this.doneTxid;<a name="line.152"></a>
<span class="sourceLineNo">153</span> }<a name="line.153"></a>
<span class="sourceLineNo">154</span><a name="line.154"></a>
<span class="sourceLineNo">155</span> synchronized boolean isDone() {<a name="line.155"></a>
<span class="sourceLineNo">156</span> return this.doneTxid != NOT_DONE;<a name="line.156"></a>
<span class="sourceLineNo">157</span> }<a name="line.157"></a>
<span class="sourceLineNo">158</span><a name="line.158"></a>
<span class="sourceLineNo">159</span> synchronized boolean isThrowable() {<a name="line.159"></a>
<span class="sourceLineNo">160</span> return isDone() &amp;&amp; getThrowable() != null;<a name="line.160"></a>
<span class="sourceLineNo">161</span> }<a name="line.161"></a>
<span class="sourceLineNo">162</span><a name="line.162"></a>
<span class="sourceLineNo">163</span> synchronized Throwable getThrowable() {<a name="line.163"></a>
<span class="sourceLineNo">164</span> return this.throwable;<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>
</pre>
</div>
</body>
</html>