Pthread_cond_timedwait Error Codes

the interface may not be implemented on Linux. Name pthread_cond_timedwait, pthread_cond_wait - wait on a condition Synopsis #include int pthread_cond_timedwait(pthread_cond_t *restrict cond, pthread_mutex_t *restrict mutex, const struct pthread_cond_timedwait example timespec *restrict abstime); int pthread_cond_wait(pthread_cond_t *restrict cond, pthread_mutex_t *restrict mutex); Description The

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pthread_cond_timedwait() and pthread_cond_wait() functions shall block on a condition variable. They shall be called with mutex locked by the pthread_cond_timedwait return value calling thread or undefined behavior results. These functions atomically release mutex and cause the calling thread to block on the condition variable cond; atomically here means "atomically with respect to access by pthread_cond_timedwait timeout another thread to the mutex and then the condition variable". That is, if another thread is able to acquire the mutex after the about-to-block thread has released it, then a subsequent call to pthread_cond_broadcast() or pthread_cond_signal() in that thread shall behave as if it were issued after the about-to-block thread has blocked. Upon successful return, the mutex shall have been locked and shall

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be owned by the calling thread. When using condition variables there is always a Boolean predicate involving shared variables associated with each condition wait that is true if the thread should proceed. Spurious wakeups from the pthread_cond_timedwait() or pthread_cond_wait() functions may occur. Since the return from pthread_cond_timedwait() or pthread_cond_wait() does not imply anything about the value of this predicate, the predicate should be re-evaluated upon such return. The effect of using more than one mutex for concurrent pthread_cond_timedwait() or pthread_cond_wait() operations on the same condition variable is undefined; that is, a condition variable becomes bound to a unique mutex when a thread waits on the condition variable, and this (dynamic) binding shall end when the wait returns. A condition wait (whether timed or not) is a cancellation point. When the cancelability enable state of a thread is set to PTHREAD_CANCEL_DEFERRED, a side effect of acting upon a cancellation request while in a condition wait is that the mutex is (in effect) re-acquired before calling the first cancellation cleanup handler. The effect is as if the thread were unblocked, allowed to execute up to the point of returning

conditions Synopsis #include pthread_cond_t cond = PTHREAD_COND_INITIALIZER; int pthread_cond_init(pthread_cond_t *cond, pthread_condattr_t *cond_attr); int pthread_cond_signal(pthread_cond_t *cond); int pthread_cond_broadcast(pthread_cond_t *cond); int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex); int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, const struct timespec *abstime); int pthread_cond_destroy(pthread_cond_t *cond); Description A condition (short https://www.sourceware.org/pthreads-win32/manual/pthread_cond_init.html for ‘‘condition variable’’) is a synchronization device that allows threads to suspend execution and relinquish the processors until some predicate on shared data is satisfied. The basic operations on conditions are: http://man7.org/linux/man-pages/man3/pthread_cond_timedwait.3p.html signal the condition (when the predicate becomes true), and wait for the condition, suspending the thread execution until another thread signals the condition. A condition variable must always be associated pthread_cond_timedwait example with a mutex, to avoid the race condition where a thread prepares to wait on a condition variable and another thread signals the condition just before the first thread actually waits on it. pthread_cond_init initializes the condition variable cond, using the condition attributes specified in cond_attr, or default attributes if cond_attr is NULL. Variables of type pthread_cond_t can also be initialized statically, pthread_cond_timedwait error codes using the constant PTHREAD_COND_INITIALIZER. In the Pthreads-w32 implementation, an application should still call pthread_cond_destroy at some point to ensure that any resources consumed by the condition variable are released. pthread_cond_signal restarts one of the threads that are waiting on the condition variable cond. If no threads are waiting on cond, nothing happens. If several threads are waiting on cond, exactly one is restarted, but it is not specified which. pthread_cond_broadcast restarts all the threads that are waiting on the condition variable cond. Nothing happens if no threads are waiting on cond. pthread_cond_wait atomically unlocks the mutex (as per pthread_unlock_mutex) and waits for the condition variable cond to be signalled. The thread execution is suspended and does not consume any CPU time until the condition variable is signalled. The mutex must be locked by the calling thread on entrance to pthread_cond_wait. Before returning to the calling thread, pthread_cond_wait re-acquires mutex (as per pthread_lock_mutex). Unlocking the mutex and suspending on the condition variable is done atomically. Thus, if all threads always acquire the mutex before signalling the condition, this guarantees that the condition cannot be

ManualTHREAD_COND_TIMEDWAIT(3P) PROLOG top 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 top pthread_cond_timedwait, pthread_cond_wait — wait on a condition SYNOPSIS top #include int pthread_cond_timedwait(pthread_cond_t *restrict cond, pthread_mutex_t *restrict mutex, const struct timespec *restrict abstime); int pthread_cond_wait(pthread_cond_t *restrict cond, pthread_mutex_t *restrict mutex); DESCRIPTION top The pthread_cond_timedwait() and pthread_cond_wait() functions shall block on a condition variable. The application shall ensure that these functions are called with mutex locked by the calling thread; otherwise, an error (for PTHREAD_MUTEX_ERRORCHECK and robust mutexes) or undefined behavior (for other mutexes) results. These functions atomically release mutex and cause the calling thread to block on the condition variable cond; atomically here means ``atomically with respect to access by another thread to the mutex and then the condition variable''. That is, if another thread is able to acquire the mutex after the about-to-block thread has released it, then a subsequent call to pthread_cond_broadcast() or pthread_cond_signal() in that thread shall behave as if it were issued after the about-to-block thread has blocked. Upon successful return, the mutex shall have been locked and shall be owned by the calling thread. If mutex is a robust mutex where an owner terminated while holding the lock and the state is recoverable, the mutex shall be acquired even though the function returns an error code. When using condition variables there is always a Boolean predicate involving shared variables associated with each condition wait that is true if