"PTHREAD_RWLOCK_DESTROY"(P) 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_rwlock_init.html | 191 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 191 insertions(+) create mode 100644 manual/pthread_rwlock_init.html (limited to 'manual/pthread_rwlock_init.html') diff --git a/manual/pthread_rwlock_init.html b/manual/pthread_rwlock_init.html new file mode 100644 index 0000000..9baa3dc --- /dev/null +++ b/manual/pthread_rwlock_init.html @@ -0,0 +1,191 @@ + + + + + "PTHREAD_RWLOCK_DESTROY"(P) manual page + + + + + + + +

Table of Contents

Name

pthread_rwlock_destroy, pthread_rwlock_init - destroy and +initialize a read-write lock object +

Synopsis

#include <pthread.h> +

pthread_wrlock_t rwlock = +PTHREAD_RWLOCK_INITIALIZER;

int pthread_rwlock_destroy(pthread_rwlock_t *rwlock); +
int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock, +const pthread_rwlockattr_t *restrict attr); +

Description

The pthread_rwlock_destroy function shall destroy the +read-write lock object referenced by rwlock and release any +resources used by the lock. The effect of subsequent use of the lock +is undefined until the lock is reinitialized by another call to +pthread_rwlock_init. An implementation may cause +pthread_rwlock_destroy to set the object referenced by rwlock +to an invalid value. Results are undefined if pthread_rwlock_destroy +is called when any thread holds rwlock. Attempting to destroy +an uninitialized read-write lock results in undefined behavior. +

The pthread_rwlock_init function shall allocate any +resources required to use the read-write lock referenced by rwlock +and initializes the lock to an unlocked state with attributes +referenced by attr. If attr is NULL, the default +read-write lock attributes shall be used; the effect is the same as +passing the address of a default read-write lock attributes object. +Once initialized, the lock can be used any number of times without +being reinitialized. Results are undefined if pthread_rwlock_init +is called specifying an already initialized read-write lock. Results +are undefined if a read-write lock is used without first being +initialized. +

If the pthread_rwlock_init function fails, rwlock +shall not be initialized and the contents of rwlock are +undefined. +

Pthreads-w32 supports statically initialized rwlock +objects using PTHREAD_RWLOCK_INITIALIZER. +An application should still call pthread_rwlock_destroy at +some point to ensure that any resources consumed by the read/write +lock are released.

Only the object referenced by rwlock may be used for +performing synchronization. The result of referring to copies of that +object in calls to pthread_rwlock_destroy , +pthread_rwlock_rdlock , pthread_rwlock_timedrdlock , +pthread_rwlock_timedwrlock , pthread_rwlock_tryrdlock , +pthread_rwlock_trywrlock , pthread_rwlock_unlock , or +pthread_rwlock_wrlock is undefined. +

Pthreads-w32 defines _POSIX_READER_WRITER_LOCKS in +pthread.h as 200112L to indicate that the reader/writer routines are +implemented and may be used.

Return Value

If successful, the pthread_rwlock_destroy and +pthread_rwlock_init functions shall return zero; otherwise, an +error number shall be returned to indicate the error. +

The [EBUSY] and [EINVAL] error checks, if implemented, act as if +they were performed immediately at the beginning of processing for +the function and caused an error return prior to modifying the state +of the read-write lock specified by rwlock. +

Errors

The pthread_rwlock_destroy function may fail if: +

EBUSY +: + The implementation has detected an attempt to destroy the object + referenced by rwlock while it is locked. +
+ EINVAL +: + The value specified by rwlock is invalid. +

+The pthread_rwlock_init function shall fail if: +

EAGAIN +: + The system lacked the necessary resources (other than memory) to + initialize another read-write lock. +
+ ENOMEM +: + Insufficient memory exists to initialize the read-write lock. +; +

+

+The pthread_rwlock_init function may fail if: +

EINVAL +: + The value specified by attr is invalid. +

+These functions shall not return an error code of [EINTR]. +

The following sections are informative. +

Examples

None. +

Application Usage

Applications using these and related read-write lock functions may +be subject to priority inversion, as discussed in the Base +Definitions volume of IEEE Std 1003.1-2001, Section 3.285, +Priority Inversion. +

Rationale

None. +

Future Directions

None. +

Copyright

Portions of this text are reprinted and reproduced in electronic +form from IEEE Std 1003.1, 2003 Edition, Standard for Information +Technology -- Portable Operating System Interface (POSIX), The Open +Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the +Institute of Electrical and Electronics Engineers, Inc and The Open +Group. In the event of any discrepancy between this version and the +original IEEE and The Open Group Standard, the original IEEE and The +Open Group Standard is the referee document. The original Standard +can be obtained online at http://www.opengroup.org/unix/online.html +. +

Modified by Ross Johnson for use with Pthreads-w32.

Table of Contents

Name +
+
Synopsis +
+
Description +
+
Return + Value +
+
Errors +
+
Examples +
+
Application + Usage +
+
Rationale +
+
Future + Directions +
+
See + Also +
+
Copyright +
+

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