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26 .Dt PTHREAD_RWLOCK_TIMEDRDLOCK 3
29 .Nm pthread_rwlock_timedrdlock
30 .Nd "acquire a read-write lock for reading or give up after a specified period"
36 .Fn pthread_rwlock_timedrdlock "pthread_rwlock_t *restrict rwlock" "const struct timespec *restrict abs_timeout"
38 This function acquires a read lock on the read-write lock
40 However, if the lock cannot be
41 acquired without waiting for another thread to
43 this wait shall be terminated when
47 A thread may hold multiple concurrent read locks.
49 .Xr pthread_rwlock_unlock 3
50 function must be called once for each lock acquired.
52 If the thread should be interrupted by a signal,
54 .Fn pthread_rwlock_timedrdlock
55 function will be automatically restarted after the thread returns from
58 The calling thread may deadlock if
59 at the time the call is made it holds a write lock on
61 The results are undefined if this function is called with
62 an uninitialized read-write lock.
63 .Sh IMPLEMENTATION NOTES
64 To prevent writer starvation, writers are favored over readers.
67 .Fn pthread_rwlock_timedrdlock
68 function will return zero.
69 Otherwise, an error number will be returned to indicate the error.
71 This function shall not return an error code of
75 .Fn pthread_rwlock_timedrdlock
76 function will fail if:
79 The lock could not be acquired before the specified timeout expired.
83 .Fn pthread_rwlock_timedrdlock
87 The read lock could not be
88 acquired because the maximum number of read locks for
92 The calling thread already holds a write lock on
95 The value specified by
97 does not refer to an initialized read-write lock object,
100 nanosecond value is less than zero or
101 greater than or equal to 1 billion.
104 .Xr pthread_rwlock_init 3 ,
105 .Xr pthread_rwlock_timedwrlock 3 ,
106 .Xr pthread_rwlock_unlock 3
109 .Fn pthread_rwlock_timedrdlock
110 function is expected to conform to
114 .Fn pthread_rwlock_timedrdlock
115 function first appeared in