1PTHREAD_RWLOCK_TIMEDRDLOCK(3PPO)SIX Programmer's ManPuTaHlREAD_RWLOCK_TIMEDRDLOCK(3P)
2
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.
10
12 pthread_rwlock_timedrdlock - lock a read-write lock for reading
13
15 #include <pthread.h>
16 #include <time.h>
17 int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rwlock,
19 const struct timespec *restrict abs_timeout);
20
23 The pthread_rwlock_timedrdlock() function shall apply a read lock to
24 the read-write lock referenced by rwlock as in the
25 pthread_rwlock_rdlock() function. However, if the lock cannot be
26 acquired without waiting for other threads to unlock the lock, this
27 wait shall be terminated when the specified timeout expires. The time‐
28 out shall expire when the absolute time specified by abs_timeout
29 passes, as measured by the clock on which timeouts are based (that is,
30 when the value of that clock equals or exceeds abs_timeout), or if the
31 absolute time specified by abs_timeout has already been passed at the
32 time of the call.
33 If the Timers option is supported, the timeout shall be based on the
35 CLOCK_REALTIME clock. If the Timers option is not supported, the time‐
36 out shall be based on the system clock as returned by the time() func‐
37 tion. The resolution of the timeout shall be the resolution of the
38 clock on which it is based. The timespec data type is defined in the
39 <time.h> header. Under no circumstances shall the function fail with a
40 timeout if the lock can be acquired immediately. The validity of the
41 abs_timeout parameter need not be checked if the lock can be immedi‐
42 ately acquired.
43 If a signal that causes a signal handler to be executed is delivered to
45 a thread blocked on a read-write lock via a call to
46 pthread_rwlock_timedrdlock(), upon return from the signal handler the
47 thread shall resume waiting for the lock as if it was not interrupted.
48 The calling thread may deadlock if at the time the call is made it
50 holds a write lock on rwlock. The results are undefined if this func‐
51 tion is called with an uninitialized read-write lock.
52
54 The pthread_rwlock_timedrdlock() function shall return zero if the lock
55 for reading on the read-write lock object referenced by rwlock is
56 acquired. Otherwise, an error number shall be returned to indicate the
57 error.
58
60 The pthread_rwlock_timedrdlock() function shall fail if:
61 ETIMEDOUT
63 The lock could not be acquired before the specified timeout
64 expired.
65 The pthread_rwlock_timedrdlock() function may fail if:
68 EAGAIN The read lock could not be acquired because the maximum number
70 of read locks for lock would be exceeded.
71 EDEADLK
73 The calling thread already holds a write lock on rwlock.
74 EINVAL The value specified by rwlock does not refer to an initialized
76 read-write lock object, or the abs_timeout nanosecond value is
77 less than zero or greater than or equal to 1000 million.
78 This function shall not return an error code of [EINTR].
81 The following sections are informative.
83
85 None.
86
88 Applications using this function may be subject to priority inversion,
89 as discussed in the Base Definitions volume of IEEE Std 1003.1-2001,
90 Section 3.285, Priority Inversion.
91 The pthread_rwlock_timedrdlock() function is part of the Threads and
93 Timeouts options and need not be provided on all implementations.
94
96 None.
97
99 None.
100
102 pthread_rwlock_destroy(), pthread_rwlock_rdlock(),
103 pthread_rwlock_timedwrlock(), pthread_rwlock_tryrdlock(),
104 pthread_rwlock_trywrlock(), pthread_rwlock_unlock(),
105 pthread_rwlock_wrlock(), the Base Definitions volume of
106 IEEE Std 1003.1-2001, <pthread.h>, <time.h>
107
109 Portions of this text are reprinted and reproduced in electronic form
110 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
111 -- Portable Operating System Interface (POSIX), The Open Group Base
112 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
113 Electrical and Electronics Engineers, Inc and The Open Group. In the
114 event of any discrepancy between this version and the original IEEE and
115 The Open Group Standard, the original IEEE and The Open Group Standard
116 is the referee document. The original Standard can be obtained online
117 at http://www.opengroup.org/unix/online.html .
118IEEE/The Open Group 2003 PTHREAD_RWLOCK_TIMEDRDLOCK(3P)