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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>pthread_mutex_init</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_007_1432"> </a>NAME</h4><blockquote>pthread_mutex_init, pthread_mutex_destroy - initialise or destroy a mutex</blockquote><h4><a name = "tag_000_007_1433"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="pthread.h.html">pthread.h</a>>int pthread_mutex_init(pthread_mutex_t *<i>mutex</i>, const pthread_mutexattr_t *<i>attr</i>);int pthread_mutex_destroy(pthread_mutex_t *<i>mutex</i>);pthread_mutex_t <i>mutex</i> = PTHREAD_MUTEX_INITIALIZER;</code></pre></blockquote><h4><a name = "tag_000_007_1434"> </a>DESCRIPTION</h4><blockquote>The<i>pthread_mutex_init()</i>function initialises the mutex referenced by<i>mutex</i>with attributes specifiedby<i>attr</i>.If<i>attr</i>is NULL,the default mutex attributes are used; the effect is the same aspassing the address of a default mutex attributes object.Upon successful initialisation, the state of the mutex becomesinitialised and unlocked.<p>Attempting to initialise an already initialisedmutex results inundefined behaviour.<p>The<i>pthread_mutex_destroy()</i>function destroys the mutex object referenced by<i>mutex</i>;the mutex object becomes, in effect, uninitialised.An implementation may cause<i>pthread_mutex_destroy()</i>to set the object referenced by<i>mutex</i>to an invalid value.A destroyed mutex objectcan be re-initialised using<i>pthread_mutex_init()</i>;the results of otherwise referencing the object after it has been destroyedare undefined.<p>It is safe to destroy an initialised mutex that is unlocked.Attempting to destroy a locked mutex results inundefined behaviour.<p>In cases where default mutex attributes are appropriate,the macro PTHREAD_MUTEX_INITIALIZERcan be used to initialise mutexes that are statically allocated.The effect is equivalent to dynamic initialisation by a call to<i>pthread_mutex_init()</i>with parameter<i>attr</i>specified as NULL,except that no error checks are performed.</blockquote><h4><a name = "tag_000_007_1435"> </a>RETURN VALUE</h4><blockquote>If successful, the<i>pthread_mutex_init()</i>and<i>pthread_mutex_destroy()</i>functions return zero.Otherwise, an error number is returned to indicate the error.The [EBUSY] and [EINVAL] error checks, if implemented,act as if they were performed immediatelyat the beginning of processing for the functionand cause an error returnprior to modifying the state of the mutex specified by<i>mutex</i>.</blockquote><h4><a name = "tag_000_007_1436"> </a>ERRORS</h4><blockquote>The <i>pthread_mutex_init()</i>function will fail if:<dl compact><dt>[EAGAIN]<dd>The system lacked the necessary resources (other than memory)to initialise another mutex.<dt>[ENOMEM]<dd>Insufficient memory exists to initialise the mutex.<dt>[EPERM]<dd>The caller does not have the privilege to perform the operation.</dl><p>The<i>pthread_mutex_init()</i>function may fail if:<dl compact><dt>[EBUSY]<dd>The implementation has detected an attemptto re-initialise the object referenced by<i>mutex</i>,a previously initialised, butnot yet destroyed, mutex.<dt>[EINVAL]<dd>The value specified by<i>attr</i>is invalid.</dl><p>The<i>pthread_mutex_destroy()</i>function may fail if:<dl compact><dt>[EBUSY]<dd>The implementation has detected an attempt to destroythe object referenced by<i>mutex</i>while it is locked or referenced(for example, while being used in a<i><a href="pthread_cond_wait.html">pthread_cond_wait()</a></i>or<i><a href="pthread_cond_timedwait.html">pthread_cond_timedwait()</a></i>)by another thread.<dt>[EINVAL]<dd>The value specified by<i>mutex</i>is invalid.</dl><p>These functions will not return an error code of [EINTR].</blockquote><h4><a name = "tag_000_007_1437"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_1438"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_1439"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_1440"> </a>SEE ALSO</h4><blockquote><i><a href="pthread_mutex_getprioceiling.html">pthread_mutex_getprioceiling()</a></i>,<i><a href="pthread_mutex_lock.html">pthread_mutex_lock()</a></i>,<i><a href="pthread_mutex_unlock.html">pthread_mutex_unlock()</a></i>,<i><a href="pthread_mutex_setprioceiling.html">pthread_mutex_setprioceiling()</a></i>,<i><a href="pthread_mutex_trylock.html">pthread_mutex_trylock()</a></i>,<i><a href="pthread_mutexattr_getpshared.html">pthread_mutexattr_getpshared()</a></i>,<i><a href="pthread_mutexattr_setpshared.html">pthread_mutexattr_setpshared()</a></i>,<i><a href="pthread.h.html"><pthread.h></a></i>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from the POSIX Threads Extension (1003.1c-1995)</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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