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tis_setcancelstate

Section: C Library Functions (3)
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NAME

tis_setcancelstate - Changes the calling thread's cancelability state.  

LIBRARY

Standard C Library (libc.so, libc.a)  

SYNOPSIS

#include <tis.h>

int tis_setcancelstate(
                      int      state,
                      int      *oldstate);  

STANDARDS

None  

PARAMETERS

State of general cancelability to set for the calling thread. Valid state values are as follows: PTHREAD_CANCEL_ENABLE PTHREAD_CANCEL_DISABLE Receives the value of the calling thread's previous cancelability state.  

DESCRIPTION

This routine sets the calling thread's cancelability state to the value specified in the state argument and returns the calling thread's previous cancelability state in the location referenced by the oldstate argument.

When a thread's cancelability state is set to PTHREAD_CANCEL_DISABLE, a cancelation request cannot be delivered to the thread, even if a cancelable routine is called or asynchronous cancelability is enabled.

When a thread is created, its default cancelability state is PTHREAD_CANCEL_ENABLE. When this routine is called prior to loading threads, the cancelability state propagates to the initial thread in the executing program.  

Possible Problems When Disabling Cancelability

The most important use of a cancelation request is to ensure that indefinite wait operations are terminated. For example, a thread waiting on some network connection, which might take days to respond (or might never respond), should be made cancelable.

When a thread's cancelability state is disabled, no routine called within that thread is cancelable. As a result, the user is unable to cancel the operation. When disabling cancelability, be sure that no long waits can occur or that it is necessary for other reasons to defer cancelation requests around that particular region of code.

 

RETURN VALUES

On successful completion, this routine returns the calling thread's previous cancelability state in the oldstate argument.

If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The specified state is not PTHREAD_CANCEL_ENABLE or PTHREAD_CANCEL_DISABLE.  

ERRORS

None  

RELATED INFORMATION

Functions: tis_testcancel(3)

Manuals: Guide to DECthreads and Programmer's Guide

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Index

NAME
LIBRARY
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
Possible Problems When Disabling Cancelability
RETURN VALUES
ERRORS
RELATED INFORMATION

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Time: 02:42:05 GMT, October 02, 2010