SyncCondvarSignal(), SyncCondvarSignal_r()

Wake up any threads that are blocked on a synchronization object

Synopsis:

#include <sys/neutrino.h>

int SyncCondvarSignal( sync_t* sync,
                       int broadcast );

int SyncCondvarSignal_r( sync_t* sync,
                         int broadcast );

Arguments:

sync

A pointer to a sync_t for the synchronization object. You must have initialized this argument by calling SyncTypeCreate() or statically initialized it with the manifest PTHREAD_COND_INITIALIZER.

broadcast

Zero if you want to make ready to run the thread with the highest priority that's been waiting the longest, or nonzero if you want to make all waiting threads ready.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The SyncCondvarSignal() and SyncCondvarSignal_r() kernel calls wake up one or all threads that are blocked on the synchronization object sync.

These functions are similar, except in the way they indicate errors. See the Returns section for details.

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Instead of using these kernel calls directly, consider calling pthread_cond_broadcast() or pthread_cond_signal().

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In all cases, each awakened thread attempts to reacquire the controlling mutex passed in SyncCondvarWait() before control is returned to the thread. If the mutex is already locked when the kernel attempts to lock it, the thread becomes blocked on the mutex until it's unlocked.

Blocking states

These calls don't block.

Returns:

The only difference between these functions is the way they indicate errors:

SyncCondvarSignal()

If an error occurs, the function returns -1 and sets errno. Any other value returned indicates success.

SyncCondvarSignal_r()

EOK is returned on success. This function does NOT set errno. If an error occurs, any value in the Errors section may be returned.

Errors:

EFAULT

A fault occurred when the kernel tried to access sync.

EINVAL

The synchronization ID specified in sync doesn't exist.

Classification:

QNX Neutrino

See also:

pthread_cond_broadcast(), pthread_cond_signal(), pthread_cond_wait(), SyncCondvarWait()