illumos: manual page: pthread_mutex

PTHREAD_MUTEX_INIT(3C) Standard C Library Functions PTHREAD_MUTEX_INIT(3C)

NAME

pthread_mutex_init, pthread_mutex_destroy - initialize or destroy a mutex

SYNOPSIS

#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;
pthread_mutex_t ecmutex = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;
pthread_mutex_t rmutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;

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 initialization, 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.

In cases where error checking mutex attributes are appropriate, the macro
PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP 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
initialized with pthread_mutexattr_init(3C) and its type set to
PTHREAD_MUTEX_ERRORCHECK.

In cases where recursive mutex attributes are appropriate, the macro
PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP 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
initialized with pthread_mutexattr_init(3C) and its type set to
PTHREAD_MUTEX_RECURSIVE.

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_mutexattr_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.

INTERFACE STABILITY