PTHREAD_RWLOCK_TIMEDR... BSD Library Functions Manual PTHREAD_RWLOCK_TIMEDR...NAMEpthread_rwlock_timedrdlock — acquire a read-write lock for reading or
give up after a specified period
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <pthread.h>
int
pthread_rwlock_timedrdlock(pthread_rwlock_t *rwlock,
const struct timespec *abs_timeout);
DESCRIPTION
This function acquires a read lock on the read-write lock rwlock. How‐
ever, if the lock cannot be acquired without waiting for another thread
to unlock the lock, this wait shall be terminated when abs_timeout
expires.
A thread may hold multiple concurrent read locks. The
pthread_rwlock_unlock(3) function must be called once for each lock
acquired.
If the thread should be interrupted by a signal, the
pthread_rwlock_timedrdlock() function will be automatically restarted
after the thread returns from the signal handler.
The calling thread may deadlock if at the time the call is made it holds
a write lock on rwlock. The results are undefined if this function is
called with an uninitialized read-write lock.
IMPLEMENTATION NOTES
To prevent writer starvation, writers are favored over readers.
RETURN VALUES
If successful, the pthread_rwlock_timedrdlock() function will return
zero. Otherwise, an error number will be returned to indicate the error.
This function shall not return an error code of EINTR.
ERRORS
The pthread_rwlock_timedrdlock() function will fail if:
[ETIMEDOUT] The lock could not be acquired before the specified
timeout expired.
The pthread_rwlock_timedrdlock() function may fail if:
[EAGAIN] The read lock could not be acquired because the maxi‐
mum number of read locks for rwlock would be exceeded.
[EDEADLK] The calling thread already holds a write lock on
rwlock.
[EINVAL] The value specified by rwlock does not refer to an
initialized read-write lock object, or the abs_timeout
nanosecond value is less than zero or greater than or
equal to 1 billion.
SEE ALSOpthread_rwlock_init(3), pthread_rwlock_timedwrlock(3),
pthread_rwlock_unlock(3)STANDARDS
The pthread_rwlock_timedrdlock() function is expected to conform to
ISO/IEC 9945-1:1996 (“POSIX.1”).
HISTORY
The pthread_rwlock_timedrdlock() function first appeared in FreeBSD 5.2.
BSD January 16, 2004 BSD
