📄 pthread_rwlock_destroy.html
字号:
<!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_rwlock_destroy</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="pthread_rwlock_destroy"></a> <a name="tag_03_555"></a><!-- pthread_rwlock_destroy --> <!--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_555_01"></a>NAME</h4><blockquote>pthread_rwlock_destroy, pthread_rwlock_init - destroy and initialize a read-write lock object</blockquote><h4><a name="tag_03_555_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_rwlock_destroy(pthread_rwlock_t *</tt><i>rwlock</i><tt>);<br> int pthread_rwlock_init(pthread_rwlock_t *restrict</tt> <i>rwlock</i><tt>,<br> const pthread_rwlockattr_t *restrict</tt> <i>attr</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_555_03"></a>DESCRIPTION</h4><blockquote><p>The <i>pthread_rwlock_destroy</i>() function shall destroy the read-write lock object referenced by <i>rwlock</i> and releaseany resources used by the lock. The effect of subsequent use of the lock is undefined until the lock is reinitialized by anothercall to <i>pthread_rwlock_init</i>(). An implementation may cause <i>pthread_rwlock_destroy</i>() to set the object referenced by<i>rwlock</i> to an invalid value. Results are undefined if <i>pthread_rwlock_destroy</i>() is called when any thread holds<i>rwlock</i>. Attempting to destroy an uninitialized read-write lock results in undefined behavior.</p><p>The <i>pthread_rwlock_init</i>() function shall allocate any resources required to use the read-write lock referenced by<i>rwlock</i> and initializes the lock to an unlocked state with attributes referenced by <i>attr</i>. If <i>attr</i> is NULL, thedefault read-write lock attributes shall be used; the effect is the same as passing the address of a default read-write lockattributes object. Once initialized, the lock can be used any number of times without being reinitialized. Results are undefined if<i>pthread_rwlock_init</i>() is called specifying an already initialized read-write lock. Results are undefined if a read-writelock is used without first being initialized.</p><p>If the <i>pthread_rwlock_init</i>() function fails, <i>rwlock</i> shall not be initialized and the contents of <i>rwlock</i> areundefined.</p><p>Only the object referenced by <i>rwlock</i> may be used for performing synchronization. The result of referring to copies ofthat object in calls to <i>pthread_rwlock_destroy</i>(), <a href="../functions/pthread_rwlock_rdlock.html"><i>pthread_rwlock_rdlock</i>()</a>, <a href="../functions/pthread_rwlock_timedrdlock.html"><i>pthread_rwlock_timedrdlock</i>()</a>, <a href="../functions/pthread_rwlock_timedwrlock.html"><i>pthread_rwlock_timedwrlock</i>()</a>, <a href="../functions/pthread_rwlock_tryrdlock.html"><i>pthread_rwlock_tryrdlock</i>()</a>, <a href="../functions/pthread_rwlock_trywrlock.html"><i>pthread_rwlock_trywrlock</i>()</a>, <a href="../functions/pthread_rwlock_unlock.html"><i>pthread_rwlock_unlock</i>()</a>, or <a href="../functions/pthread_rwlock_wrlock.html"><i>pthread_rwlock_wrlock</i>()</a> is undefined.</p></blockquote><h4><a name="tag_03_555_04"></a>RETURN VALUE</h4><blockquote><p>If successful, the <i>pthread_rwlock_destroy</i>() and <i>pthread_rwlock_init</i>() functions shall return zero; otherwise, anerror number shall be returned to indicate the error.</p><p>The [EBUSY] and [EINVAL] error checks, if implemented, act as if they were performed immediately at the beginning of processingfor the function and caused an error return prior to modifying the state of the read-write lock specified by <i>rwlock</i>.</p></blockquote><h4><a name="tag_03_555_05"></a>ERRORS</h4><blockquote><p>The <i>pthread_rwlock_destroy</i>() function may fail if:</p><dl compact><dt>[EBUSY]</dt><dd>The implementation has detected an attempt to destroy the object referenced by <i>rwlock</i> while it is locked.</dd><dt>[EINVAL]</dt><dd>The value specified by <i>rwlock</i> is invalid.</dd></dl><p>The <i>pthread_rwlock_init</i>() function shall fail if:</p><dl compact><dt>[EAGAIN]</dt><dd>The system lacked the necessary resources (other than memory) to initialize another read-write lock.</dd><dt>[ENOMEM]</dt><dd>Insufficient memory exists to initialize the read-write lock.</dd><dt>[EPERM]</dt><dd>The caller does not have the privilege to perform the operation.</dd></dl><p>The <i>pthread_rwlock_init</i>() function may fail if:</p><dl compact><dt>[EBUSY]</dt><dd>The implementation has detected an attempt to reinitialize the object referenced by <i>rwlock</i>, a previously initialized butnot yet destroyed read-write lock.</dd><dt>[EINVAL]</dt><dd>The value specified by <i>attr</i> is invalid.</dd></dl><p>These functions 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_555_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_555_07"></a>APPLICATION USAGE</h4><blockquote><p>Applications using these and related read-write lock functions may be subject to priority inversion, as discussed in the BaseDefinitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap03.html#tag_03_285">Section 3.285, PriorityInversion</a>.</p></blockquote><h4><a name="tag_03_555_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_555_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_555_10"></a>SEE ALSO</h4><blockquote><p><a href="pthread_rwlock_rdlock.html"><i>pthread_rwlock_rdlock</i>()</a> , <a href="pthread_rwlock_timedrdlock.html"><i>pthread_rwlock_timedrdlock</i>()</a> , <a href="pthread_rwlock_timedwrlock.html"><i>pthread_rwlock_timedwrlock</i>()</a> , <a href="pthread_rwlock_tryrdlock.html"><i>pthread_rwlock_tryrdlock</i>()</a> , <a href="pthread_rwlock_trywrlock.html"><i>pthread_rwlock_trywrlock</i>()</a> , <a href="pthread_rwlock_unlock.html"><i>pthread_rwlock_unlock</i>()</a> , <a href="pthread_rwlock_wrlock.html"><i>pthread_rwlock_wrlock</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <ahref="../basedefs/pthread.h.html"><i><pthread.h></i></a></p></blockquote><h4><a name="tag_03_555_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 5.</p></blockquote><h4><a name="tag_03_555_12"></a>Issue 6</h4><blockquote><p>The following changes are made for alignment with IEEE Std 1003.1j-2000:</p><ul><li><p>The margin code in the SYNOPSIS is changed to THR to indicate that the functionality is now part of the Threads option(previously it was part of the Read-Write Locks option in IEEE Std 1003.1j-2000 and also part of the XSI extension). Theinitializer macro is also deleted from the SYNOPSIS.</p></li><li><p>The DESCRIPTION is updated as follows:</p><ul><li><p>It explicitly notes allocation of resources upon initialization of a read-write lock object.</p></li><li><p>A paragraph is added specifying that copies of read-write lock objects may not be used.</p></li></ul></li><li><p>An [EINVAL] error is added to the ERRORS section for <i>pthread_rwlock_init</i>(), indicating that the <i>rwlock</i> value isinvalid.</p></li><li><p>The SEE ALSO section is updated.</p></li></ul><p>The <b>restrict</b> keyword is added to the <i>pthread_rwlock_init</i>() prototype for alignment with the ISO/IEC 9899:1999standard.</p><p>IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/45 is applied, adding APPLICATION USAGE relating to priorityinversion.</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
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 + -