📄 semaphore.html
字号:
<!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 1.4.2_03) on Mon May 31 21:03:10 EDT 2004 -->
<TITLE>
Semaphore (DbUnit 2.1 API)
</TITLE>
<META NAME="keywords" CONTENT="org.dbunit.util.concurrent.Semaphore class">
<LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../stylesheet.css" TITLE="Style">
<SCRIPT type="text/javascript">
function windowTitle()
{
parent.document.title="Semaphore (DbUnit 2.1 API)";
}
</SCRIPT>
</HEAD>
<BODY BGCOLOR="white" onload="windowTitle();">
<!-- ========= 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=3 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/Semaphore.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/dbunit/util/concurrent/Puttable.html" title="interface in org.dbunit.util.concurrent"><B>PREV CLASS</B></A>
<A HREF="../../../../org/dbunit/util/concurrent/SemaphoreControlledChannel.html" title="class in org.dbunit.util.concurrent"><B>NEXT CLASS</B></A></FONT></TD>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
<A HREF="../../../../index.html" target="_top"><B>FRAMES</B></A>
<A HREF="Semaphore.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 | <A HREF="#field_summary">FIELD</A> | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD>
<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
DETAIL: <A HREF="#field_detail">FIELD</A> | <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.dbunit.util.concurrent</FONT>
<BR>
Class Semaphore</H2>
<PRE>
java.lang.Object
<IMG SRC="../../../../resources/inherit.gif" ALT="extended by"><B>org.dbunit.util.concurrent.Semaphore</B>
</PRE>
<DL>
<DT><B>All Implemented Interfaces:</B> <DD><A HREF="../../../../org/dbunit/util/concurrent/Sync.html" title="interface in org.dbunit.util.concurrent">Sync</A></DD>
</DL>
<HR>
<DL>
<DT>public class <B>Semaphore</B><DT>extends java.lang.Object<DT>implements <A HREF="../../../../org/dbunit/util/concurrent/Sync.html" title="interface in org.dbunit.util.concurrent">Sync</A></DL>
<P>
Base class for counting semaphores. Conceptually, a semaphore maintains a set of permits. Each acquire() blocks if necessary until a permit is available, and then takes it. Each release adds a permit. However, no actual permit objects are used; the Semaphore just keeps a count of the number available and acts accordingly. <p> A semaphore initialized to 1 can serve as a mutual exclusion lock. <p> Different implementation subclasses may provide different ordering guarantees (or lack thereof) surrounding which threads will be resumed upon a signal. <p> The default implementation makes NO guarantees about the order in which threads will acquire permits. It is often faster than other implementations. <p> <b>Sample usage.</b> Here is a class that uses a semaphore to help manage access to a pool of items. <pre> class Pool { static final MAX_AVAILABLE = 100; private final Semaphore available = new Semaphore(MAX_AVAILABLE); public Object getItem() throws InterruptedException { // no synch available.acquire(); return getNextAvailableItem(); } public void putItem(Object x) { // no synch if (markAsUnused(x)) available.release(); } // Not a particularly efficient data structure; just for demo protected Object[] items = ... whatever kinds of items being managed protected boolean[] used = new boolean[MAX_AVAILABLE]; protected synchronized Object getNextAvailableItem() { for (int i = 0; i < MAX_AVAILABLE; ++i) { if (!used[i]) { used[i] = true; return items[i]; } } return null; // not reached } protected synchronized boolean markAsUnused(Object item) { for (int i = 0; i < MAX_AVAILABLE; ++i) { if (item == items[i]) { if (used[i]) { used[i] = false; return true; } else return false; } } return false; } }</pre> <p>[<a href="http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html"> Introduction to this package. </a>]
<P>
<P>
<HR>
<P>
<!-- ======== NESTED CLASS SUMMARY ======== -->
<!-- =========== FIELD SUMMARY =========== -->
<A NAME="field_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=2><FONT SIZE="+2">
<B>Field Summary</B></FONT></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>protected long</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/dbunit/util/concurrent/Semaphore.html#permits_">permits_</A></B></CODE>
<BR>
current number of available permits</TD>
</TR>
</TABLE>
<A NAME="fields_inherited_from_class_org.dbunit.util.concurrent.Sync"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TD><B>Fields inherited from interface org.dbunit.util.concurrent.<A HREF="../../../../org/dbunit/util/concurrent/Sync.html" title="interface in org.dbunit.util.concurrent">Sync</A></B></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_CENTURY">ONE_CENTURY</A>, <A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_DAY">ONE_DAY</A>, <A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_HOUR">ONE_HOUR</A>, <A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_MINUTE">ONE_MINUTE</A>, <A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_SECOND">ONE_SECOND</A>, <A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_WEEK">ONE_WEEK</A>, <A HREF="../../../../org/dbunit/util/concurrent/Sync.html#ONE_YEAR">ONE_YEAR</A></CODE></TD>
</TR>
</TABLE>
<!-- ======== CONSTRUCTOR SUMMARY ======== -->
<A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=2><FONT SIZE="+2">
<B>Constructor Summary</B></FONT></TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><B><A HREF="../../../../org/dbunit/util/concurrent/Semaphore.html#Semaphore(long)">Semaphore</A></B>(long initialPermits)</CODE>
<BR>
Create a Semaphore with the given initial number of permits.</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">
<TD COLSPAN=2><FONT SIZE="+2">
<B>Method Summary</B></FONT></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/dbunit/util/concurrent/Semaphore.html#acquire()">acquire</A></B>()</CODE>
<BR>
Wait until a permit is available, and take one</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> boolean</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/dbunit/util/concurrent/Semaphore.html#attempt(long)">attempt</A></B>(long msecs)</CODE>
<BR>
Wait at most msecs millisconds for a permit.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> long</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../org/dbunit/util/concurrent/Semaphore.html#permits()">permits</A></B>()</CODE>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -