cassandra-server

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">  <html lang="en"> <head>  <title>OpOrder (apache-cassandra API)</title> <meta name="date" content="2014-09-07"> <link rel="stylesheet" type="text/css" href="../../../../../stylesheet.css" title="Style"> </head> <body> <script type="text/javascript"> </script> <noscript> <div>JavaScript is disabled on your browser.</div> </noscript>  <div class="topNav"><a name="navbar_top">  </a><a href="#skip-navbar_top" title="Skip navigation links"></a><a name="navbar_top_firstrow">  </a> <ul class="navList" title="Navigation"> <li><a href="../../../../../overview-summary.html">Overview</a></li> <li><a href="package-summary.html">Package</a></li> <li class="navBarCell1Rev">Class</li> <li><a href="class-use/OpOrder.html">Use</a></li> <li><a href="package-tree.html">Tree</a></li> <li><a href="../../../../../deprecated-list.html">Deprecated</a></li> <li><a href="../../../../../index-all.html">Index</a></li> <li><a href="../../../../../help-doc.html">Help</a></li> </ul> </div> <div class="subNav"> <ul class="navList"> <li>Prev Class</li> <li><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Barrier.html" title="class in org.apache.cassandra.utils.concurrent"><span class="strong">Next Class</span></a></li> </ul> <ul class="navList"> <li><a href="../../../../../index.html?org/apache/cassandra/utils/concurrent/OpOrder.html" target="_top">Frames</a></li> <li><a href="OpOrder.html" target="_top">No Frames</a></li> </ul> <ul class="navList" id="allclasses_navbar_top"> <li><a href="../../../../../allclasses-noframe.html">All Classes</a></li> </ul> <div> <script type="text/javascript"> </script> </div> <div> <ul class="subNavList"> <li>Summary: </li> <li><a href="#nested_class_summary">Nested</a> | </li> <li>Field | </li> <li><a href="#constructor_summary">Constr</a> | </li> <li><a href="#method_summary">Method</a></li> </ul> <ul class="subNavList"> <li>Detail: </li> <li>Field | </li> <li><a href="#constructor_detail">Constr</a> | </li> <li><a href="#method_detail">Method</a></li> </ul> </div> <a name="skip-navbar_top">  </a></div>   <div class="header"> <div class="subTitle">org.apache.cassandra.utils.concurrent</div> <h2 title="Class OpOrder" class="title">Class OpOrder</h2> </div> <div class="contentContainer"> <ul class="inheritance"> <li>java.lang.Object</li> <li> <ul class="inheritance"> <li>org.apache.cassandra.utils.concurrent.OpOrder</li> </ul> </li> </ul> <div class="description"> <ul class="blockList"> <li class="blockList"> <hr> <br> <pre>public class <span class="strong">OpOrder</span> extends java.lang.Object</pre> <div class="block"><p>A class for providing synchronization between producers and consumers that do not communicate directly with each other, but where the consumers need to process their work in contiguous batches. In particular this is useful for both CommitLog and Memtable where the producers (writing threads) are modifying a structure that the consumer (flush executor) only batch syncs, but needs to know what 'position' the work is at for co-ordination with other processes, <p>The typical usage is something like: <pre> public final class ExampleShared { final OpOrder order = new OpOrder(); volatile SharedState state; static class SharedState { volatile Barrier barrier; // ... } public void consume() { SharedState state = this.state; state.setReplacement(new State()) state.doSomethingToPrepareForBarrier(); state.barrier = order.newBarrier(); // seal() MUST be called after newBarrier() else barrier.isAfter() // will always return true, and barrier.await() will fail state.barrier.issue(); // wait for all producer work started prior to the barrier to complete state.barrier.await(); // change the shared state to its replacement, as the current state will no longer be used by producers this.state = state.getReplacement(); state.doSomethingWithExclusiveAccess(); } public void produce() { try (Group opGroup = order.start()) { SharedState s = state; while (s.barrier != null && !s.barrier.isAfter(opGroup)) s = s.getReplacement(); s.doProduceWork(); } } } </pre></div> </li> </ul> </div> <div class="summary"> <ul class="blockList"> <li class="blockList">  <ul class="blockList"> <li class="blockList"><a name="nested_class_summary">  </a> <h3>Nested Class Summary</h3> <table class="overviewSummary" border="0" cellpadding="3" cellspacing="0" summary="Nested Class Summary table, listing nested classes, and an explanation"> <caption><span>Nested Classes</span><span class="tabEnd"> </span></caption> <tr> <th class="colFirst" scope="col">Modifier and Type</th> <th class="colLast" scope="col">Class and Description</th> </tr> <tr class="altColor"> <td class="colFirst"><code>class </code></td> <td class="colLast"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Barrier.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Barrier</a></strong></code> <div class="block">This class represents a synchronisation point providing ordering guarantees on operations started against the enclosing OpOrder.</div> </td> </tr> <tr class="rowColor"> <td class="colFirst"><code>static class </code></td> <td class="colLast"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Group.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Group</a></strong></code> <div class="block">Represents a group of identically ordered operations, i.e.</div> </td> </tr> </table> </li> </ul>  <ul class="blockList"> <li class="blockList"><a name="constructor_summary">  </a> <h3>Constructor Summary</h3> <table class="overviewSummary" border="0" cellpadding="3" cellspacing="0" summary="Constructor Summary table, listing constructors, and an explanation"> <caption><span>Constructors</span><span class="tabEnd"> </span></caption> <tr> <th class="colOne" scope="col">Constructor and Description</th> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.html#OpOrder()">OpOrder</a></strong>()</code> </td> </tr> </table> </li> </ul>  <ul class="blockList"> <li class="blockList"><a name="method_summary">  </a> <h3>Method Summary</h3> <table class="overviewSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> <caption><span>Methods</span><span class="tabEnd"> </span></caption> <tr> <th class="colFirst" scope="col">Modifier and Type</th> <th class="colLast" scope="col">Method and Description</th> </tr> <tr class="altColor"> <td class="colFirst"><code>void</code></td> <td class="colLast"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.html#awaitNewBarrier()">awaitNewBarrier</a></strong>()</code> </td> </tr> <tr class="rowColor"> <td class="colFirst"><code><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Group.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Group</a></code></td> <td class="colLast"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.html#getCurrent()">getCurrent</a></strong>()</code> </td> </tr> <tr class="altColor"> <td class="colFirst"><code><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Barrier.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Barrier</a></code></td> <td class="colLast"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.html#newBarrier()">newBarrier</a></strong>()</code> <div class="block">Creates a new barrier.</div> </td> </tr> <tr class="rowColor"> <td class="colFirst"><code><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Group.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Group</a></code></td> <td class="colLast"><code><strong><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.html#start()">start</a></strong>()</code> <div class="block">Start an operation against this OpOrder.</div> </td> </tr> </table> <ul class="blockList"> <li class="blockList"><a name="methods_inherited_from_class_java.lang.Object">  </a> <h3>Methods inherited from class java.lang.Object</h3> <code>clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait</code></li> </ul> </li> </ul> </li> </ul> </div> <div class="details"> <ul class="blockList"> <li class="blockList">  <ul class="blockList"> <li class="blockList"><a name="constructor_detail">  </a> <h3>Constructor Detail</h3> <a name="OpOrder()">  </a> <ul class="blockListLast"> <li class="blockList"> <h4>OpOrder</h4> <pre>public OpOrder()</pre> </li> </ul> </li> </ul>  <ul class="blockList"> <li class="blockList"><a name="method_detail">  </a> <h3>Method Detail</h3> <a name="start()">  </a> <ul class="blockList"> <li class="blockList"> <h4>start</h4> <pre>public <a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Group.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Group</a> start()</pre> <div class="block">Start an operation against this OpOrder. Once the operation is completed Ordered.close() MUST be called EXACTLY once for this operation.</div> <dl><dt><span class="strong">Returns:</span></dt><dd>the Ordered instance that manages this OpOrder</dd></dl> </li> </ul> <a name="newBarrier()">  </a> <ul class="blockList"> <li class="blockList"> <h4>newBarrier</h4> <pre>public <a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Barrier.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Barrier</a> newBarrier()</pre> <div class="block">Creates a new barrier. The barrier is only a placeholder until barrier.issue() is called on it, after which all new operations will start against a new Group that will not be accepted by barrier.isAfter(), and barrier.await() will return only once all operations started prior to the issue have completed.</div> <dl><dt><span class="strong">Returns:</span></dt><dd></dd></dl> </li> </ul> <a name="getCurrent()">  </a> <ul class="blockList"> <li class="blockList"> <h4>getCurrent</h4> <pre>public <a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Group.html" title="class in org.apache.cassandra.utils.concurrent">OpOrder.Group</a> getCurrent()</pre> </li> </ul> <a name="awaitNewBarrier()">  </a> <ul class="blockListLast"> <li class="blockList"> <h4>awaitNewBarrier</h4> <pre>public void awaitNewBarrier()</pre> </li> </ul> </li> </ul> </li> </ul> </div> </div>   <div class="bottomNav"><a name="navbar_bottom">  </a><a href="#skip-navbar_bottom" title="Skip navigation links"></a><a name="navbar_bottom_firstrow">  </a> <ul class="navList" title="Navigation"> <li><a href="../../../../../overview-summary.html">Overview</a></li> <li><a href="package-summary.html">Package</a></li> <li class="navBarCell1Rev">Class</li> <li><a href="class-use/OpOrder.html">Use</a></li> <li><a href="package-tree.html">Tree</a></li> <li><a href="../../../../../deprecated-list.html">Deprecated</a></li> <li><a href="../../../../../index-all.html">Index</a></li> <li><a href="../../../../../help-doc.html">Help</a></li> </ul> </div> <div class="subNav"> <ul class="navList"> <li>Prev Class</li> <li><a href="../../../../../org/apache/cassandra/utils/concurrent/OpOrder.Barrier.html" title="class in org.apache.cassandra.utils.concurrent"><span class="strong">Next Class</span></a></li> </ul> <ul class="navList"> <li><a href="../../../../../index.html?org/apache/cassandra/utils/concurrent/OpOrder.html" target="_top">Frames</a></li> <li><a href="OpOrder.html" target="_top">No Frames</a></li> </ul> <ul class="navList" id="allclasses_navbar_bottom"> <li><a href="../../../../../allclasses-noframe.html">All Classes</a></li> </ul> <div> <script type="text/javascript"> </script> </div> <div> <ul class="subNavList"> <li>Summary: </li> <li><a href="#nested_class_summary">Nested</a> | </li> <li>Field | </li> <li><a href="#constructor_summary">Constr</a> | </li> <li><a href="#method_summary">Method</a></li> </ul> <ul class="subNavList"> <li>Detail: </li> <li>Field | </li> <li><a href="#constructor_detail">Constr</a> | </li> <li><a href="#method_detail">Method</a></li> </ul> </div> <a name="skip-navbar_bottom">  </a></div>  <p class="legalCopy"><small>Copyright © 2014 The Apache Software Foundation</small></p> </body> </html>