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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>pthread_cancel</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="pthread_cancel"></a> <a name="tag_03_513"></a><!-- pthread_cancel --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_513_01"></a>NAME</h4><blockquote>pthread_cancel - cancel execution of a thread</blockquote><h4><a name="tag_03_513_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('THR')">THR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/pthread.h.html">pthread.h</a>><br><br> int pthread_cancel(pthread_t</tt> <i>thread</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_513_03"></a>DESCRIPTION</h4><blockquote><p>The <i>pthread_cancel</i>() function shall request that <i>thread</i> be canceled. The target thread's cancelability state andtype determines when the cancellation takes effect. When the cancellation is acted on, the cancellation cleanup handlers for<i>thread</i> shall be called. When the last cancellation cleanup handler returns, the thread-specific data destructor functionsshall be called for <i>thread</i>. When the last destructor function returns, <i>thread</i> shall be terminated.</p><p>The cancellation processing in the target thread shall run asynchronously with respect to the calling thread returning from<i>pthread_cancel</i>().</p></blockquote><h4><a name="tag_03_513_04"></a>RETURN VALUE</h4><blockquote><p>If successful, the <i>pthread_cancel</i>() function shall return zero; otherwise, an error number shall be returned to indicatethe error.</p></blockquote><h4><a name="tag_03_513_05"></a>ERRORS</h4><blockquote><p>The <i>pthread_cancel</i>() function may fail if:</p><dl compact><dt>[ESRCH]</dt><dd>No thread could be found corresponding to that specified by the given thread ID.</dd></dl><p>The <i>pthread_cancel</i>() function shall not return an error code of [EINTR].</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_513_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_513_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_513_08"></a>RATIONALE</h4><blockquote><p>Two alternative functions were considered for sending the cancellation notification to a thread. One would be to define a newSIGCANCEL signal that had the cancellation semantics when delivered; the other was to define the new <i>pthread_cancel</i>()function, which would trigger the cancellation semantics.</p><p>The advantage of a new signal was that so much of the delivery criteria were identical to that used when trying to deliver asignal that making cancellation notification a signal was seen as consistent. Indeed, many implementations implement cancellationusing a special signal. On the other hand, there would be no signal functions that could be used with this signal except <a href="../functions/pthread_kill.html"><i>pthread_kill</i>()</a>, and the behavior of the delivered cancellation signal would be unlikeany previously existing defined signal.</p><p>The benefits of a special function include the recognition that this signal would be defined because of the similar deliverycriteria and that this is the only common behavior between a cancellation request and a signal. In addition, the cancellationdelivery mechanism does not have to be implemented as a signal. There are also strong, if not stronger, parallels with languageexception mechanisms than with signals that are potentially obscured if the delivery mechanism is visibly closer to signals.</p><p>In the end, it was considered that as there were so many exceptions to the use of the new signal with existing signals functionsit would be misleading. A special function has resolved this problem. This function was carefully defined so that an implementationwishing to provide the cancellation functions on top of signals could do so. The special function also means that implementationsare not obliged to implement cancellation with signals.</p></blockquote><h4><a name="tag_03_513_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_513_10"></a>SEE ALSO</h4><blockquote><p><a href="pthread_exit.html"><i>pthread_exit</i>()</a> , <a href="pthread_cond_timedwait.html"><i>pthread_cond_timedwait</i>()</a> , <a href="pthread_join.html"><i>pthread_join</i>()</a> , <ahref="pthread_setcancelstate.html"><i>pthread_setcancelstate</i>()</a> , the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/pthread.h.html"><i><pthread.h></i></a></p></blockquote><h4><a name="tag_03_513_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 5. Included for alignment with the POSIX Threads Extension.</p></blockquote><h4><a name="tag_03_513_12"></a>Issue 6</h4><blockquote><p>The <i>pthread_cancel</i>() function is marked as part of the Threads option.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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