"PTHREAD_RWLOCK_TRYWRLOCK"(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_wrlock.html | 151 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 151 insertions(+) create mode 100644 manual/pthread_rwlock_wrlock.html (limited to 'manual/pthread_rwlock_wrlock.html') diff --git a/manual/pthread_rwlock_wrlock.html b/manual/pthread_rwlock_wrlock.html new file mode 100644 index 0000000..33ee766 --- /dev/null +++ b/manual/pthread_rwlock_wrlock.html @@ -0,0 +1,151 @@ + + + + + "PTHREAD_RWLOCK_TRYWRLOCK"(P) manual page + + + + + + + +

Table of Contents

Name

pthread_rwlock_trywrlock, pthread_rwlock_wrlock - lock a +read-write lock object for writing +

Synopsis

#include <pthread.h> +

int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock); +
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock); + +

Description

The pthread_rwlock_trywrlock function shall apply a write +lock like the pthread_rwlock_wrlock function, with the +exception that the function shall fail if any thread currently holds +rwlock (for reading or writing). +

The pthread_rwlock_wrlock function shall apply a write lock +to the read-write lock referenced by rwlock. The calling +thread acquires the write lock if no other thread (reader or writer) +holds the read-write lock rwlock. Otherwise, the thread shall +block until it can acquire the lock. The calling thread may deadlock +if at the time the call is made it holds the read-write lock (whether +a read or write lock). +

Pthreads-win32 does not prefer either writers or readers in +acquiring the lock – all threads enter a single prioritised FIFO +queue. While this may not be optimally efficient for some +applications, it does ensure that one type does not starve the other.

Results are undefined if any of these functions are called with an +uninitialized read-write lock. +

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

The pthread_rwlock_trywrlock function shall return zero if +the lock for writing on the read-write lock object referenced by +rwlock is acquired. Otherwise, an error number shall be +returned to indicate the error. +

If successful, the pthread_rwlock_wrlock function shall +return zero; otherwise, an error number shall be returned to indicate +the error. +

Errors

The pthread_rwlock_trywrlock function shall fail if: +

EBUSY +: + The read-write lock could not be acquired for writing because it was + already locked for reading or writing. +

+The pthread_rwlock_trywrlock and pthread_rwlock_wrlock +functions may fail if: +

EINVAL +: + The value specified by rwlock does not refer to an + initialized read-write lock object. +

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

The following sections are informative. +

Examples

None. +

Application Usage

Applications using these 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 +
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Synopsis +
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Description +
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Return + Value +
+
Errors +
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Examples +
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Application + Usage +
+
Rationale +
+
Future + Directions +
+
See + Also +
+
Copyright +
+

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