1PTHREAD_MUTEX_TIMEDLOCK(3P)POSIX Programmer's ManualPTHREAD_MUTEX_TIMEDLOCK(3P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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13 pthread_mutex_timedlock — lock a mutex
14
16 #include <pthread.h>
17 #include <time.h>
18 int pthread_mutex_timedlock(pthread_mutex_t *restrict mutex,
20 const struct timespec *restrict abstime);
21
23 The pthread_mutex_timedlock() function shall lock the mutex object ref‐
24 erenced by mutex. If the mutex is already locked, the calling thread
25 shall block until the mutex becomes available as in the
26 pthread_mutex_lock() function. If the mutex cannot be locked without
27 waiting for another thread to unlock the mutex, this wait shall be ter‐
28 minated when the specified timeout expires.
29 The timeout shall expire when the absolute time specified by abstime
31 passes, as measured by the clock on which timeouts are based (that is,
32 when the value of that clock equals or exceeds abstime), or if the
33 absolute time specified by abstime has already been passed at the time
34 of the call.
35 The timeout shall be based on the CLOCK_REALTIME clock. The resolution
37 of the timeout shall be the resolution of the clock on which it is
38 based. The timespec data type is defined in the <time.h> header.
39 Under no circumstance shall the function fail with a timeout if the
41 mutex can be locked immediately. The validity of the abstime parameter
42 need not be checked if the mutex can be locked immediately.
43 As a consequence of the priority inheritance rules (for mutexes ini‐
45 tialized with the PRIO_INHERIT protocol), if a timed mutex wait is ter‐
46 minated because its timeout expires, the priority of the owner of the
47 mutex shall be adjusted as necessary to reflect the fact that this
48 thread is no longer among the threads waiting for the mutex.
49 If mutex is a robust mutex and the process containing the owning thread
51 terminated while holding the mutex lock, a call to pthread_mutex_timed‐
52 lock() shall return the error value [EOWNERDEAD]. If mutex is a robust
53 mutex and the owning thread terminated while holding the mutex lock, a
54 call to pthread_mutex_timedlock() may return the error value [EOWN‐
55 ERDEAD] even if the process in which the owning thread resides has not
56 terminated. In these cases, the mutex is locked by the thread but the
57 state it protects is marked as inconsistent. The application should
58 ensure that the state is made consistent for reuse and when that is
59 complete call pthread_mutex_consistent(). If the application is unable
60 to recover the state, it should unlock the mutex without a prior call
61 to pthread_mutex_consistent(), after which the mutex is marked perma‐
62 nently unusable.
63 If mutex does not refer to an initialized mutex object, the behavior is
65 undefined.
66
68 If successful, the pthread_mutex_timedlock() function shall return
69 zero; otherwise, an error number shall be returned to indicate the
70 error.
71
73 The pthread_mutex_timedlock() function shall fail if:
74 EAGAIN The mutex could not be acquired because the maximum number of
76 recursive locks for mutex has been exceeded.
77 EDEADLK
79 The mutex type is PTHREAD_MUTEX_ERRORCHECK and the current
80 thread already owns the mutex.
81 EINVAL The mutex was created with the protocol attribute having the
83 value PTHREAD_PRIO_PROTECT and the calling thread's priority is
84 higher than the mutex' current priority ceiling.
85 EINVAL The process or thread would have blocked, and the abstime param‐
87 eter specified a nanoseconds field value less than zero or
88 greater than or equal to 1000 million.
89 ENOTRECOVERABLE
91 The state protected by the mutex is not recoverable.
92 EOWNERDEAD
94 The mutex is a robust mutex and the process containing the pre‐
95 vious owning thread terminated while holding the mutex lock. The
96 mutex lock shall be acquired by the calling thread and it is up
97 to the new owner to make the state consistent.
98 ETIMEDOUT
100 The mutex could not be locked before the specified timeout
101 expired.
102 The pthread_mutex_timedlock() function may fail if:
104 EDEADLK
106 A deadlock condition was detected.
107 EOWNERDEAD
109 The mutex is a robust mutex and the previous owning thread ter‐
110 minated while holding the mutex lock. The mutex lock shall be
111 acquired by the calling thread and it is up to the new owner to
112 make the state consistent.
113 This function shall not return an error code of [EINTR].
115 The following sections are informative.
117
119 None.
120
122 Applications that have assumed that non-zero return values are errors
123 will need updating for use with robust mutexes, since a valid return
124 for a thread acquiring a mutex which is protecting a currently incon‐
125 sistent state is [EOWNERDEAD]. Applications that do not check the
126 error returns, due to ruling out the possibility of such errors aris‐
127 ing, should not use robust mutexes. If an application is supposed to
128 work with normal and robust mutexes, it should check all return values
129 for error conditions and if necessary take appropriate action.
130
132 Refer to pthread_mutex_lock().
133
135 None.
136
138 pthread_mutex_destroy(), pthread_mutex_lock(), time()
139 The Base Definitions volume of POSIX.1‐2008, Section 4.11, Memory Syn‐
141 chronization, <pthread.h>, <time.h>
142
144 Portions of this text are reprinted and reproduced in electronic form
145 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
146 -- Portable Operating System Interface (POSIX), The Open Group Base
147 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
148 cal and Electronics Engineers, Inc and The Open Group. (This is
149 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
150 event of any discrepancy between this version and the original IEEE and
151 The Open Group Standard, the original IEEE and The Open Group Standard
152 is the referee document. The original Standard can be obtained online
153 at http://www.unix.org/online.html .
154 Any typographical or formatting errors that appear in this page are
156 most likely to have been introduced during the conversion of the source
157 files to man page format. To report such errors, see https://www.ker‐
158 nel.org/doc/man-pages/reporting_bugs.html .
159IEEE/The Open Group 2013 PTHREAD_MUTEX_TIMEDLOCK(3P)