pthread_mutexattr_getprotocol()

Get a mutex's scheduling protocol

Synopsis:

#include <pthread.h>

int pthread_mutexattr_getprotocol( 
            pthread_mutexattr * attr,
            int * protocol );

Arguments:

attr: A pointer to the pthread_mutexattr_t object that you want to get the attribute from.
protocol: A pointer to a location where the function can store the scheduling protocol.

Library:

libc

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

Description:

The pthread_mutexattr_getprotocol() function sets protocol to the current mutex attribute attr's scheduling protocol. The structure pointed to by attr must have been previously created with pthread_mutexattr_init().

The protocol attribute defines the protocol for using mutexes: Currently, protocol may be set to:

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_PRIO_PROTECT: The thread executes at the highest priority or priority ceilings of all the mutexes owned by the thread and initialized with PTHREAD_PRIO_PROTECT, whether other threads are blocked or not.
PTHREAD_PRIO_NONE: Owning the mutex doesn't affect the priority and scheduling of the thread.

A thread holding a PTHREAD_PRIO_INHERIT mutex won't be moved to the tail of the scheduling queue if its original priority is changed (by a call to pthread_schedsetparam(), for example). This remains true if the thread unlocks the PTHREAD_PRIO_INHERIT mutex.

Returns:

EOK: Success.
EINVAL: Invalid mutex attribute attr.

Classification:

POSIX 1003.1 MC1 TPP|TPI

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