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PTHREAD_RWLOCK_TIMEDRDLOCK(POSIX Programmer's MaPTHREAD_RWLOCK_TIMEDRDLOCK(3P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAME
pthread_rwlock_timedrdlock -- lock a read-write lock for reading
SYNOPSIS
#include <pthread.h>
#include <time.h>
int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rwlock,
const struct timespec *restrict abstime);
DESCRIPTION
The pthread_rwlock_timedrdlock() function shall apply a read lock to
the read-write lock referenced by rwlock as in the pthread_rwlock_rd-
lock() function. However, if the lock cannot be acquired without wait-
ing for other threads to unlock the lock, this wait shall be terminated
when the specified timeout expires. The timeout shall expire when the
absolute time specified by abstime passes, as measured by the clock on
which timeouts are based (that is, when the value of that clock equals
or exceeds abstime), or if the absolute time specified by abstime has
already been passed at the time of the call.
The timeout shall be based on the CLOCK_REALTIME clock. The resolution
of the timeout shall be the resolution of the CLOCK_REALTIME clock. The
timespec data type is defined in the <time.h> header. Under no circum-
stances shall the function fail with a timeout if the lock can be ac-
quired immediately. The validity of the abstime parameter need not be
checked if the lock can be immediately acquired.
If a signal that causes a signal handler to be executed is delivered to
a thread blocked on a read-write lock via a call to
pthread_rwlock_timedrdlock(), upon return from the signal handler the
thread shall resume waiting for the lock as if it was not interrupted.
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 func-
tion is called with an uninitialized read-write lock.
RETURN VALUE
The pthread_rwlock_timedrdlock() function shall return zero if the lock
for reading on the read-write lock object referenced by rwlock is ac-
quired. Otherwise, an error number shall be returned to indicate the
error.
ERRORS
The pthread_rwlock_timedrdlock() function shall fail if:
ETIMEDOUT
The lock could not be acquired before the specified timeout ex-
pired.
The pthread_rwlock_timedrdlock() function may fail if:
EAGAIN The read lock could not be acquired because the maximum number
of read locks for lock would be exceeded.
EDEADLK
A deadlock condition was detected or the calling thread already
holds a write lock on rwlock.
EINVAL The abstime nanosecond value is less than zero or greater than
or equal to 1000 million.
This function shall not return an error code of [EINTR].
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
Applications using this function may be subject to priority inversion,
as discussed in the Base Definitions volume of POSIX.1-2008, Section
3.287, Priority Inversion.
RATIONALE
If an implementation detects that the value specified by the rwlock ar-
gument to pthread_rwlock_timedrdlock() does not refer to an initialized
read-write lock object, it is recommended that the function should fail
and report an [EINVAL] error.
FUTURE DIRECTIONS
None.
SEE ALSO
pthread_rwlock_destroy(), pthread_rwlock_rdlock(),
pthread_rwlock_timedwrlock(), pthread_rwlock_trywrlock(),
pthread_rwlock_unlock()
The Base Definitions volume of POSIX.1-2008, Section 3.287, Priority
Inversion, Section 4.11, Memory Synchronization, <pthread.h>, <time.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker-
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 PTHREAD_RWLOCK_TIMEDRDLOCK(3P)
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