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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc (build 1.6.0_04) on Tue Feb 19 10:50:42 MST 2008 --><META http-equiv="Content-Type" content="text/html; charset=UTF-8"><TITLE>CachedBufferAllocator (Apache MINA 2.0.0-M1 API Documentation)</TITLE><META NAME="date" CONTENT="2008-02-19"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ if (location.href.indexOf('is-external=true') == -1) { parent.document.title="CachedBufferAllocator (Apache MINA 2.0.0-M1 API Documentation)"; }}</SCRIPT><NOSCRIPT></NOSCRIPT></HEAD><BODY BGCOLOR="white" onload="windowTitle();"><HR><!-- ========= START OF TOP NAVBAR ======= --><A NAME="navbar_top"><!-- --></A><A HREF="#skip-navbar_top" title="Skip navigation links"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/CachedBufferAllocator.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../../org/apache/mina/common/BufferDataException.html" title="class in org.apache.mina.common"><B>PREV CLASS</B></A> <A HREF="../../../../org/apache/mina/common/CloseFuture.html" title="interface in org.apache.mina.common"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../../index.html?org/apache/mina/common/CachedBufferAllocator.html" target="_top"><B>FRAMES</B></A> <A HREF="CachedBufferAllocator.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--></SCRIPT><NOSCRIPT> <A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: NESTED | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">org.apache.mina.common</FONT><BR>Class CachedBufferAllocator</H2><PRE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">java.lang.Object</A> <IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><B>org.apache.mina.common.CachedBufferAllocator</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD><A HREF="../../../../org/apache/mina/common/IoBufferAllocator.html" title="interface in org.apache.mina.common">IoBufferAllocator</A></DD></DL><HR><DL><DT><PRE>public class <B>CachedBufferAllocator</B><DT>extends <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A><DT>implements <A HREF="../../../../org/apache/mina/common/IoBufferAllocator.html" title="interface in org.apache.mina.common">IoBufferAllocator</A></DL></PRE><P>An <A HREF="../../../../org/apache/mina/common/IoBufferAllocator.html" title="interface in org.apache.mina.common"><CODE>IoBufferAllocator</CODE></A> that caches the buffers which are likely to be reused during auto-expansion of the buffers. <p> In <A HREF="../../../../org/apache/mina/common/SimpleBufferAllocator.html" title="class in org.apache.mina.common"><CODE>SimpleBufferAllocator</CODE></A>, the underlying <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio"><CODE>ByteBuffer</CODE></A> of the <A HREF="../../../../org/apache/mina/common/IoBuffer.html" title="class in org.apache.mina.common"><CODE>IoBuffer</CODE></A> is reallocated on its capacity change, which means the newly allocated bigger <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio"><CODE>ByteBuffer</CODE></A> replaces the old small <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio"><CODE>ByteBuffer</CODE></A>. Consequently, the old <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio"><CODE>ByteBuffer</CODE></A> is marked for garbage collection. <p> It's not a problem in most cases as long as the capacity change doesn't happen frequently. However, once it happens too often, it burdens the VM and the cost of filling the newly allocated <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio"><CODE>ByteBuffer</CODE></A> with <code>NUL</code> surpass the cost of accessing the cache. In 2 dual-core Opteron Italy 270 processors, <A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html" title="class in org.apache.mina.common"><CODE>CachedBufferAllocator</CODE></A> outperformed <A HREF="../../../../org/apache/mina/common/SimpleBufferAllocator.html" title="class in org.apache.mina.common"><CODE>SimpleBufferAllocator</CODE></A> in the following situation: <ul> <li>when a 32 bytes buffer is expanded 4 or more times,</li> <li>when a 64 bytes buffer is expanded 4 or more times,</li> <li>when a 128 bytes buffer is expanded 2 or more times,</li> <li>and when a 256 bytes or bigger buffer is expanded 1 or more times.</li> </ul> Please note the observation above is subject to change in a different environment. <p> <A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html" title="class in org.apache.mina.common"><CODE>CachedBufferAllocator</CODE></A> uses <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/ThreadLocal.html?is-external=true" title="class or interface in java.lang"><CODE>ThreadLocal</CODE></A> to store the cached buffer, allocates buffers whose capacity is power of 2 only and provides performance advantage if <A HREF="../../../../org/apache/mina/common/IoBuffer.html#free()"><CODE>IoBuffer.free()</CODE></A> is called properly.<P><P><DL><DT><B>Version:</B></DT> <DD>$Rev: 594400 $, $Date: 2007-11-12 19:49:43 -0700 (Mon, 12 Nov 2007) $</DD><DT><B>Author:</B></DT> <DD>The Apache MINA Project (dev@mina.apache.org)</DD></DL><HR><P><!-- ======== CONSTRUCTOR SUMMARY ======== --><A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>Constructor Summary</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#CachedBufferAllocator()">CachedBufferAllocator</A></B>()</CODE><BR> Creates a new instance with the default parameters (#DEFAULT_MAX_POOL_SIZE and #DEFAULT_MAX_CACHED_BUFFER_SIZE).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#CachedBufferAllocator(int, int)">CachedBufferAllocator</A></B>(int maxPoolSize, int maxCachedBufferSize)</CODE><BR> Creates a new instance.</TD></TR></TABLE> <!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>Method Summary</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../../../org/apache/mina/common/IoBuffer.html" title="class in org.apache.mina.common">IoBuffer</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#allocate(int, boolean)">allocate</A></B>(int requestedCapacity, boolean direct)</CODE><BR> Returns the buffer which is capable of the specified size.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio">ByteBuffer</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#allocateNioBuffer(int, boolean)">allocateNioBuffer</A></B>(int capacity, boolean direct)</CODE><BR> Returns the NIO buffer which is capable of the specified size.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#dispose()">dispose</A></B>()</CODE><BR> Dispose of this allocator.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#getMaxCachedBufferSize()">getMaxCachedBufferSize</A></B>()</CODE><BR> Returns the maximum capacity of a cached buffer.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#getMaxPoolSize()">getMaxPoolSize</A></B>()</CODE><BR> Returns the maximum number of buffers with the same capacity per thread.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../../../org/apache/mina/common/IoBuffer.html" title="class in org.apache.mina.common">IoBuffer</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../../../org/apache/mina/common/CachedBufferAllocator.html#wrap(java.nio.ByteBuffer)">wrap</A></B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio">ByteBuffer</A> nioBuffer)</CODE><BR> Wraps the specified NIO <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/ByteBuffer.html?is-external=true" title="class or interface in java.nio"><CODE>ByteBuffer</CODE></A> into MINA buffer.</TD></TR>⌨️ 快捷键说明
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