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pthread_mutex_init(3) [osf1 man page]

pthread_mutex_init(3)					     Library Functions Manual					     pthread_mutex_init(3)

pthread_mutex_init - Initializes a mutex. LIBRARY
DECthreads POSIX 1003.1c Library ( SYNOPSIS
#include <pthread.h> int pthread_mutex_init( pthread_mutex_t *mutex, const pthread_mutexattr_t *attr); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: IEEE Std 1003.1c-1995, POSIX System Application Program Interface PARAMETERS
Mutex to be initialized. Mutex attributes object that defines the characteristics of the mutex to be initialized. DESCRIPTION
This routine initializes a mutex with the attributes specified by the mutex attributes object specified in the attr argument. A mutex is a synchronization object that allows multiple threads to serialize their access to shared data. The mutex is initialized and set to the unlocked state. If attr is set to NULL, the default mutex attributes are used. The pthread_mutex- attr_settype(3) routine can be used to specify the type of mutex that is created (normal, recursive, or errorcheck). Use the PTHREAD_MUTEX_INITIALIZER macro to statically initialize a mutex without calling this routine. Statically initialized mutexes need not be destroyed using pthread_mutex_destroy(3). Use this macro as follows: pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER Only normal mutexes can be statically initialized. A mutex is a resource of the process, not part of any particular thread. A mutex is neither destroyed nor unlocked automatically when any thread exits. If a mutex is allocated on a stack, static initializers cannot be used on the mutex. RETURN VALUES
If an error condition occurs, this routine returns an integer value indicating the type of error, the mutex is not initialized, and the contents of mutex are undefined. Possible return values are as follows: Successful completion. The system lacks the necessary resources to initialize the mutex. The implementation has detected an attempt to reinitialize the mutex (a previously initialized, but not yet destroyed mutex). The value specified by mutex is not a valid mutex. Insufficient memory exists to initialize the mutex. The caller does not have privileges to perform the operation. ERRORS
Functions: pthread_mutexattr_init(3), pthread_mutexattr_gettype(3), pthread_mutexattr_settype(3), pthread_mutex_lock(3), pthread_mutex_try- lock(3), pthread_mutex_unlock(3) Manuals: Guide to DECthreads and Programmer's Guide delim off pthread_mutex_init(3)

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pthread_mutex_init(3C)					   Standard C Library Functions 				    pthread_mutex_init(3C)

pthread_mutex_init, pthread_mutex_destroy - initialize or destroy a mutex SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ] #include <pthread.h> int pthread_mutex_init(pthread_mutex_t *restrict mutex, const pthread_mutexattr_t *restrict attr); int pthread_mutex_destroy(pthread_mutex_t *mutex); pthread_mutex_t mutex= PTHREAD_MUTEX_INITIALIZER; DESCRIPTION
The pthread_mutex_init() function initializes the mutex referenced by mutex with attributes specified by attr. If attr is NULL, the default mutex attributes are used; the effect is the same as passing the address of a default mutex attributes object. Upon successful ini- tialization, the state of the mutex becomes initialized and unlocked. Except for robust mutexes, attempting to initialize an already initialized mutex results in undefined behavior. The pthread_mutex_destroy() function destroys the mutex object referenced by mutex; the mutex object becomes, in effect, uninitialized. A destroyed mutex object can be re-initialized using pthread_mutex_init(); the results of otherwise referencing the object after it has been destroyed are undefined. It is safe to destroy an initialized mutex that is unlocked. Attempting to destroy a locked mutex results in undefined behavior. In cases where default mutex attributes are appropriate, the macro PTHREAD_MUTEX_INITIALIZER can be used to initialize mutexes that are statically allocated. The effect is equivalent to dynamic initialization by a call to pthread_mutex_init() with parameter attr specified as NULL, except that no error checks are performed. RETURN VALUES
If successful, the pthread_mutex_init() and pthread_mutex_destroy() functions return 0. Otherwise, an error number is returned to indicate the error. ERRORS
The pthread_mutex_init() function will fail if: EAGAIN The system lacked the necessary resources (other than memory) to initialize another mutex. EBUSY An attempt was detected to re-initialize a robust mutex previously initialized but not yet destroyed. See pthread_mutex- attr_setrobust(3C). EINVAL An attempt was detected to re-initialize a robust mutex previously initialized with a different set of attributes. See pthread_mutexattr_setrobust(3C). ENOMEM Insufficient memory exists to initialize the mutex. EPERM The caller does not have the privilege to perform the operation. The pthread_mutex_init() function may fail if: EBUSY An attempt was detected to re-initialize the object referenced by mutex, a mutex previously initialized but not yet destroyed. EINVAL The value specified by attr or mutex is invalid. The pthread_mutex_destroy() function may fail if: EBUSY An attempt was detected to destroy the object referenced by mutex while it is locked or referenced (for example, while being used in a pthread_cond_wait(3C) or pthread_cond_timedwait(3C)) by another thread. EINVAL The value specified by mutex 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_wait(3C), pthread_mutex_lock(3C), pthread_mutexattr_setprioceiling(3C), pthread_mutexattr_setprotocol(3C), pthread_mutex- attr_setpshared(3C), pthread_mutexattr_setrobust(3C), pthread_mutexattr_settype(3C), attributes(5), mutex(5), standards(5) SunOS 5.11 11 Nov 2008 pthread_mutex_init(3C)
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