xref: /titanic_44/usr/src/man/man3c/pthread_testcancel.3c (revision a60349c89adffc0902b2353230891d8e7f2b24d9)
te
Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved.
Copyright (c) 2001, the Institute of Electrical and Electronics Engineers, Inc. and The Open Group. All Rights Reserved.
Copyright (c) 2005, Sun Microsystems, Inc. All Rights Reserved.
Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.
The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions 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.
This notice shall appear on any product containing this material.
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
PTHREAD_TESTCANCEL 3C "Mar 23, 2005"
NAME
pthread_testcancel - create cancellation point in the calling thread
SYNOPSIS

cc -mt [ flag... ] file... -lpthread [ library... ]
#include <pthread.h>

void pthread_testcancel(void);
DESCRIPTION

The pthread_testcancel() function forces testing for cancellation. This is useful when you need to execute code that runs for long periods without encountering cancellation points; such as a library routine that executes long-running computations without cancellation points. This type of code can block cancellation for unacceptable long periods of time. One strategy for avoiding blocking cancellation for long periods, is to insert calls to pthread_testcancel() in the long-running computation code and to setup a cancellation handler in the library code, if required.

RETURN VALUES

The pthread_testcancel() function returns void.

ERRORS

The pthread_testcancel() function does not return errors.

EXAMPLES

See cancellation(5) for an example of using pthread_testcancel() to force testing for cancellation and a discussion of cancellation concepts.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Standard
MT-Level MT-Safe
SEE ALSO

Intro(3), pthread_cleanup_pop(3C), pthread_cleanup_push(3C), pthread_exit(3C), pthread_join(3C), pthread_setcancelstate(3C), pthread_setcanceltype(3C), setjmp(3C), attributes(5), cancellation(5), condition(5), standards(5)

NOTES

The pthread_testcancel() function has no effect if cancellation is disabled.

Use pthread_testcancel() with pthread_setcanceltype() called with its canceltype set to PTHREAD_CANCEL_DEFERRED. The pthread_testcancel() function operation is undefined if pthread_setcanceltype() was called with its canceltype argument set to PTHREAD_CANCEL_ASYNCHRONOUS.

It is possible to kill a thread when it is holding a resource, such as lock or allocated memory. If that thread has not setup a cancellation cleanup handler to release the held resource, the application is "cancel-unsafe". See attributes(5) for a discussion of Cancel-Safety, Deferred-Cancel-Safety, and Asynchronous-Cancel-Safety.