pthread_mutexattr_gettype(3C)				   Standard C Library Functions 			     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);

DESCRIPTION

       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  unlocking
				   it  will  deadlock.	Attempting  to	unlock a mutex locked by a different thread results in undefined behavior.
				   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 unlocking 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.

RETURN VALUES

       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.

ERRORS

       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.

ATTRIBUTES

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

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

SEE ALSO

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

NOTES

       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.

SunOS 5.11							    23 Mar 2005 				     pthread_mutexattr_gettype(3C)