PTHREAD_MUTEXATTR(3) manual page

From 41f88a82b33cdb357c83b582381232733ed2d039 Mon Sep 17 00:00:00 2001 From: rpj Date: Thu, 5 May 2005 14:18:27 +0000 Subject: '' --- manual/pthread_mutexattr_init.html | 155 +++++++++++++++++++++++++++++++++++++ 1 file changed, 155 insertions(+) create mode 100644 manual/pthread_mutexattr_init.html (limited to 'manual/pthread_mutexattr_init.html') diff --git a/manual/pthread_mutexattr_init.html b/manual/pthread_mutexattr_init.html new file mode 100644 index 0000000..3ab5a09 --- /dev/null +++ b/manual/pthread_mutexattr_init.html @@ -0,0 +1,155 @@ + + + + + PTHREAD_MUTEXATTR(3) manual page + + + + + + + +

Table of Contents

Name

pthread_mutexattr_init, pthread_mutexattr_destroy, +pthread_mutexattr_settype, pthread_mutexattr_gettype - mutex creation +attributes +

Synopsis

#include <pthread.h> +

int pthread_mutexattr_init(pthread_mutexattr_t *attr); +

int pthread_mutexattr_destroy(pthread_mutexattr_t *attr); +

int pthread_mutexattr_settype(pthread_mutexattr_t *attr, +int type); +

int pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, +int *type); +

int pthread_mutexattr_setkind_np(pthread_mutexattr_t *attr, +int type); +

int pthread_mutexattr_getkind_np(const pthread_mutexattr_t +*attr, int *type); +

Description

Mutex attributes can be specified at mutex creation time, by +passing a mutex attribute object as second argument to +pthread_mutex_init(3) . +Passing NULL is equivalent to passing a mutex attribute object +with all attributes set to their default values. +

pthread_mutexattr_init initializes the mutex attribute +object attr and fills it with default values for the +attributes. +

pthread_mutexattr_destroy destroys a mutex attribute +object, which must not be reused until it is reinitialized.

The following mutex types are supported:

PTHREAD_MUTEX_NORMAL - for +‘‘fast’’ mutexes.

PTHREAD_MUTEX_RECURSIVE - for +‘‘recursive’’ mutexes.

PTHREAD_MUTEX_ERRORCHECK - for +‘‘error checking’’ mutexes.

The mutex type determines what happens if a thread attempts to +lock a mutex it already owns with pthread_mutex_lock(3) +. If the mutex is of the “normal” or “fast” type, +pthread_mutex_lock(3) +simply suspends the calling thread forever. If the mutex is of the +‘‘error checking’’ type, pthread_mutex_lock(3) +returns immediately with the error code EDEADLK. If the mutex +is of the ‘‘recursive’’ type, the call to +pthread_mutex_lock(3) +returns immediately with a success return code. The number of times +the thread owning the mutex has locked it is recorded in the mutex. +The owning thread must call pthread_mutex_unlock(3) +the same number of times before the mutex returns to the unlocked +state. +

The default mutex type is PTHREAD_MUTEX_NORMAL

Pthreads-w32 also recognises the following equivalent types +that are used by Linux:

PTHREAD_MUTEX_FAST_NP +– equivalent to PTHREAD_MUTEX_NORMAL

PTHREAD_MUTEX_RECURSIVE_NP

PTHREAD_MUTEX_ERRORCHECK_NP

pthread_mutexattr_settype sets the mutex type attribute in +attr to the value specified by type. +

pthread_mutexattr_gettype retrieves the current value of +the mutex kind attribute in attr and stores it in the location +pointed to by type. +

Pthreads-w32 also recognises the following equivalent +functions that are used in Linux:

pthread_mutexattr_setkind_np is an alias for +pthread_mutexattr_settype. +

pthread_mutexattr_getkind_np is +an alias for pthread_mutexattr_gettype. +

Return Value

pthread_mutexattr_init, pthread_mutexattr_destroy +and pthread_mutexattr_gettype always return 0. +

pthread_mutexattr_settype returns 0 on success and a +non-zero error code on error. +

Errors

On error, pthread_mutexattr_settype returns the following +error code: +

EINVAL +: + type is none of:
PTHREAD_MUTEX_NORMAL, + PTHREAD_MUTEX_FAST_NP,
PTHREAD_MUTEX_RECURSIVE, + PTHREAD_MUTEX_RECURSIVE_NP,
PTHREAD_MUTEX_ERRORCHECK, + PTHREAD_MUTEX_ERRORCHECK_NP +

+Author

Xavier Leroy <Xavier.Leroy@inria.fr> +

Modified by Ross Johnson for use with Pthreads-w32.

Notes

For speed, Pthreads-w32 never checks the thread ownership +of mutexes of type PTHREAD_MUTEX_NORMAL (or +PTHREAD_MUTEX_FAST_NP) when performing operations on the +mutex. It is therefore possible for one thread to lock such a mutex +and another to unlock it.

When developing code, it is a +common precaution to substitute the error checking type, and drop in +the normal type for release if the extra performance is required.

Table of Contents

Name +
+
Synopsis +
+
Description +
+
Return + Value +
+
Errors +
+
Author +
+
See + Also
+
Notes
+

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