Get a mutex type
const pthread_mutexattr_t * attr,
int * type );
- A pointer to the pthread_mutexattr_t object that you
want to get the attribute from.
- A pointer to a location where the function can store the type.
Use the -l c option to
to link against this library.
This library is usually included automatically.
The pthread_mutexattr_gettype() function gets the mutex type
from the mutex attribute object attr and stores it
Valid mutex types include:
- No deadlock detection. A thread that attempts to relock this
mutex without first unlocking it deadlocks. Attempts to unlock a mutex locked by
a different thread or attempts to unlock an unlocked mutex result
in undefined behavior.
- Provides error checking.
A thread returns with an error when it attempts to:
- Relock this mutex without first unlocking it.
- Unlock a mutex that another thread has locked.
- Unlock an unlocked mutex.
- A thread that attempts to relock this mutex without first unlocking it succeeds in
locking the mutex. The relocking deadlock that can occur with mutexes of type
PTHREAD_MUTEX_NORMAL can't occur with this mutex type. Multiple locks
of this mutex require the same number of unlocks to release the mutex before
another thread can acquire the mutex. A thread that attempts to unlock a mutex that
another thread has locked, or unlock an unlocked mutex, returns with an error.
- The default value of the type attribute.
Attempts to recursively lock a mutex of this type, or
unlock a mutex of this type that isn't locked by the calling thread, or
unlock a mutex of this type that isn't locked, results in undefined behavior.
- Invalid mutex attribute object attr.
POSIX 1003.1 XSI
An application shouldn't use a PTHREAD_MUTEX_RECURSIVE mutex
with condition variables because the implicit unlock performed for a
may not actually release the mutex (if it's been locked multiple times).
If this happens, no other thread can satisfy the condition of the predicate.