forksafe_mutex_trylock()

Arguments:

mutex

A pointer to the forksafe_mutex_t object that you want to try to lock.

Library:

libc, libforksafe_mutex

There are two versions of the forksafe_mutex_*() functions:

• The functions in libc are declared as weak symbols and use a regular mutex, simply calling the corresponding pthread_mutex_*() functions. Use the -l c option to qcc to link against this library. This library is usually included automatically.
• The functions in libforksafe_mutex use a forksafe mutex. Use the -l forksafe_mutex option to qcc to link against this library.

Description:

The forksafe_mutex_trylock() function attempts to lock the forksafe mutex mutex, but doesn't block the calling thread if the mutex is already locked.

For more information about forksafe mutexes, see Using fork() in a multithreaded process in the Processes and Threads chapter of Getting Started with the QNX OS.

Returns:

EOK

Success.

EAGAIN

The mutex couldn't be acquired because the maximum number of recursive locks for mutex has been exceeded.

EBUSY

The mutex was already locked.

EINVAL

One of the following occurred:

• The mutex was created with a protocol attribute of PTHREAD_PRIO_PROTECT, and the calling thread's priority is higher than the mutex's current priority ceiling.
• The mutex is invalid, or it has died.

ENOTRECOVERABLE

The mutex is a robust mutex, and the state that it protects isn't recoverable. All you can do with the mutex is destroy it by calling forksafe_mutex_destroy().

EOWNERDEAD

The mutex is a robust mutex and the process containing the previous owning thread terminated while holding the mutex lock. The calling thread acquires the mutex lock; it's up to the new owner to make the state consistent (see pthread_mutex_consistent()).

Classification:

QNX OS