Section: POSIX Programmer's Manual (3P)
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.
--- lock a read-write lock for reading
int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rwlock,
const struct timespec *restrict abstime);
function shall apply a read lock to the read-write lock referenced by
as in the
function. However, if the lock cannot be acquired without waiting 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
passes, as measured by the clock on which timeouts are based (that is,
when the value of that clock equals or exceeds
or if the absolute time specified by
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
data type is defined in the
header. Under no circumstances shall the function fail with a timeout
if the lock can be acquired immediately. The validity of the
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
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
The results are undefined if this function is called with an
uninitialized read-write lock.
function shall return zero if the lock for reading on the read-write
lock object referenced by
is acquired. Otherwise, an error number shall be returned to indicate
function shall fail if:
The lock could not be acquired before the specified timeout expired.
function may fail if:
The read lock could not be acquired because the maximum number of read
locks for lock would be exceeded.
A deadlock condition was detected or the calling thread already holds a
write lock on
nanosecond value is less than zero or greater than or equal to 1000
This function shall not return an error code of
The following sections are informative.
Applications using this function may be subject to priority inversion,
as discussed in the Base Definitions volume of POSIX.1-2008,
, Priority Inversion.
If an implementation detects that the value specified by the
does not refer to an initialized read-write lock object, it is
recommended that the function should fail and report an
The Base Definitions volume of POSIX.1-2008,
Section 3.287, Priority Inversion,
Section 4.11, Memory Synchronization,
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
Electrical 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
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