pthread_mutexattr

Synopsis:

#include <pthread.h>

int pthread_mutexattr_init( pthread_mutexattr_t* attr );

Arguments:

attr: A pointer to the pthread_mutexattr_t object that you want to initialize.

Library:

libc

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

Description:

The pthread_mutexattr_init() function initializes the attributes in the mutex attribute object attr to their default values. After calling this function, you can use the pthread_mutexattr_* family of functions to make any changes to the attributes:

Attribute	Default	Get	Set
Priority ceiling	None	pthread_mutexattr_getprioceiling()	pthread_mutexattr_setprioceiling()
Protocol	PTHREAD_PRIO_INHERIT	pthread_mutexattr_getprotocol()	pthread_mutexattr_setprotocol()
Process-shared	PTHREAD_PROCESS_PRIVATE	pthread_mutexattr_getpshared()	pthread_mutexattr_setpshared()
Recursiveness	PTHREAD_RECURSIVE_DISABLE	pthread_mutexattr_getrecursive()	pthread_mutexattr_setrecursive()
Robustness	PTHREAD_MUTEX_STALLED	pthread_mutexattr_getrobust()	pthread_mutexattr_setrobust()
Type	PTHREAD_MUTEX_DEFAULT	pthread_mutexattr_gettype()	pthread_mutexattr_settype()
Wake-up	PTHREAD_WAKEUP_DISABLE	pthread_mutexattr_getwakeup_np()	pthread_mutexattr_setwakeup_np()

The default values include:

PTHREAD_PRIO_INHERIT: When a thread is blocking higher-priority threads by locking one or more mutexes with this attribute, the thread's priority is raised to that of the highest priority thread waiting on the PTHREAD_PRIO_INHERIT mutex.
PTHREAD_RECURSIVE_DISABLE: Threads can't recursively lock a mutex; any thread that tries to lock an already locked mutex becomes blocked.

Note: Robust mutexes, mutexes with priority ceilings, and those using SyncMutexEvent() use more system resources than other mutexes.

After initializing a mutex attribute object, you can use it to initialize one or more mutexes by calling pthread_mutex_init().

Returns:

EOK: Success.
ENOMEM: Insufficient memory to initialize mutex attribute object attr.

Classification:

POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes