1PTHREAD_RWLOCK_TRYWRLOCK(3P)POSIX Programmer's ManuaPlTHREAD_RWLOCK_TRYWRLOCK(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_rwlock_trywrlock, pthread_rwlock_wrlock — lock a read-write
14 lock object for writing
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17 #include <pthread.h>
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19 int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
20 int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
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23 The pthread_rwlock_trywrlock() function shall apply a write lock like
24 the pthread_rwlock_wrlock() function, with the exception that the func‐
25 tion shall fail if any thread currently holds rwlock (for reading or
26 writing).
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28 The pthread_rwlock_wrlock() function shall apply a write lock to the
29 read-write lock referenced by rwlock. The calling thread acquires the
30 write lock if no other thread (reader or writer) holds the read-write
31 lock rwlock. Otherwise, the thread shall block until it can acquire
32 the lock. The calling thread may deadlock if at the time the call is
33 made it holds the read-write lock (whether a read or write lock).
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35 Implementations may favor writers over readers to avoid writer starva‐
36 tion.
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38 Results are undefined if any of these functions are called with an
39 uninitialized read-write lock.
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41 If a signal is delivered to a thread waiting for a read-write lock for
42 writing, upon return from the signal handler the thread resumes waiting
43 for the read-write lock for writing as if it was not interrupted.
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46 The pthread_rwlock_trywrlock() function shall return zero if the lock
47 for writing on the read-write lock object referenced by rwlock is
48 acquired. Otherwise, an error number shall be returned to indicate the
49 error.
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51 If successful, the pthread_rwlock_wrlock() function shall return zero;
52 otherwise, an error number shall be returned to indicate the error.
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55 The pthread_rwlock_trywrlock() function shall fail if:
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57 EBUSY The read-write lock could not be acquired for writing because it
58 was already locked for reading or writing.
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60 The pthread_rwlock_wrlock() function may fail if:
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62 EDEADLK
63 A deadlock condition was detected or the current thread already
64 owns the read-write lock for writing or reading.
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66 These functions shall not return an error code of [EINTR].
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68 The following sections are informative.
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71 None.
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74 Applications using these functions may be subject to priority inver‐
75 sion, as discussed in the Base Definitions volume of POSIX.1‐2008, Sec‐
76 tion 3.287, Priority Inversion.
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79 If an implementation detects that the value specified by the rwlock
80 argument to pthread_rwlock_trywrlock() or pthread_rwlock_wrlock() does
81 not refer to an initialized read-write lock object, it is recommended
82 that the function should fail and report an [EINVAL] error.
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85 None.
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88 pthread_rwlock_destroy(), pthread_rwlock_rdlock(), pthread_rwlock_time‐
89 drdlock(), pthread_rwlock_timedwrlock(), pthread_rwlock_unlock()
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91 The Base Definitions volume of POSIX.1‐2008, Section 3.287, Priority
92 Inversion, Section 4.11, Memory Synchronization, <pthread.h>
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95 Portions of this text are reprinted and reproduced in electronic form
96 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
97 -- Portable Operating System Interface (POSIX), The Open Group Base
98 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
99 cal and Electronics Engineers, Inc and The Open Group. (This is
100 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
101 event of any discrepancy between this version and the original IEEE and
102 The Open Group Standard, the original IEEE and The Open Group Standard
103 is the referee document. The original Standard can be obtained online
104 at http://www.unix.org/online.html .
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106 Any typographical or formatting errors that appear in this page are
107 most likely to have been introduced during the conversion of the source
108 files to man page format. To report such errors, see https://www.ker‐
109 nel.org/doc/man-pages/reporting_bugs.html .
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113IEEE/The Open Group 2013 PTHREAD_RWLOCK_TRYWRLOCK(3P)