pthread_mutexattr_gettype(3C)											     pthread_mutexattr_gettype(3C)

NAME

       pthread_mutexattr_gettype, pthread_mutexattr_settype - get or set mutex type

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]
       #include <pthread.h>

       int pthread_mutexattr_gettype(pthread_mutexattr_t *restrict attr, int *restrict type);

       int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);

       The pthread_mutexattr_gettype() and pthread_mutexattr_settype() functions respectively get and set the mutex type attribute. This attribute
       is set in the type parameter to these functions. The default value of the type attribute is PTHREAD_MUTEX_DEFAULT.

       The type of mutex is contained in the type attribute of the mutex attributes. Valid mutex types include:

       PTHREAD_MUTEX_NORMAL	       This type of mutex does not detect deadlock. A thread attempting to relock this mutex without first unlock-
				       ing it will deadlock. Attempting to unlock a mutex locked by a different thread results in undefined behav-
				       ior. Attempting to unlock an unlocked mutex results in undefined behavior.

       PTHREAD_MUTEX_ERRORCHECK        This type of mutex provides error checking. A thread attempting to relock this mutex without first  unlock-
				       ing it will return with an error. A thread attempting to unlock a mutex that another thread has locked will
				       return with an error. A thread attempting to unlock an unlocked mutex will return with an error.

       PTHREAD_MUTEX_RECURSIVE	       A thread attempting to relock this mutex without first unlocking it will succeed in locking the mutex.  The
				       relocking  deadlock that can occur with mutexes of type PTHREAD_MUTEX_NORMAL cannot occur with this type of
				       mutex. Multiple locks of this mutex require the same number of unlocks to release the mutex before  another
				       thread  can  acquire  the  mutex. A thread attempting to unlock a mutex that another thread has locked will
				       return with an error. A thread attempting to unlock an unlocked mutex will return with an error. This  type
				       of mutex is only supported for mutexes whose process shared attribute is PTHREAD_PROCESS_PRIVATE.

       PTHREAD_MUTEX_DEFAULT	       Attempting  to  recursively lock a mutex of this type results in undefined behavior. Attempting to unlock a
				       mutex of this type that was not locked by the calling thread results in undefined behavior.  Attempting	to
				       unlock  a mutex of this type that is not locked results in undefined behavior. An implementation is allowed
				       to map this mutex to one of the other mutex types.

       Upon successful completion, the pthread_mutexattr_settype() function returns 0. Otherwise, an error number  is  returned  to  indicate  the
       error.

       Upon  successful  completion,  the pthread_mutexattr_gettype() function returns 0 and stores the value of the type attribute of attr in the
       object referenced by the type parameter. Otherwise an error number is returned to indicate the error.

       The pthread_mutexattr_gettype() and pthread_mutexattr_settype() functions will fail if:

       EINVAL	       The value type is invalid.

       The pthread_mutexattr_gettype() and pthread_mutexattr_settype() functions may fail if:

       EINVAL	       The value specified by attr is invalid.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       pthread_cond_timedwait(3C), pthread_cond_wait(3C), attributes(5), standards(5)

       Application should  not	use  a	PTHREAD_MUTEX_RECURSIVE  mutex	with  condition  variables  because  the  implicit  unlock  performed  for
       pthread_cond_wait() or pthread_cond_timedwait() will not actually release the mutex (if it had been locked multiple times). If this occurs,
       no other thread can satisfy the condition of the predicate.

								    23 Mar 2005 				     pthread_mutexattr_gettype(3C)