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pthread_cancel(3)
NAME
pthread_cancel - Allows a thread to request a thread to terminate execution
SYNOPSIS
#include <pthread.h>
int pthread_cancel(
pthread_t thread );
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program Interface
PARAMETERS
thread
Thread that receives a cancellation request.
DESCRIPTION
This routine sends a cancellation request to the specified target thread. A
cancellation request is a mechanism by which a calling thread requests the
target thread to terminate as quickly as possible. Issuing a cancellation
request does not guarantee that the target thread will receive or handle
the request.
When the cancellation request is acted on, all active cleanup handler
routines for the target thread are called. When the last cleanup handler
returns, the thread-specific data destructor routines are called for each
thread-specific data key with a destructor and for which the target thread
has a non-NULL value. Finally, the target thread is terminated.
Note that cancellation of the target thread runs asynchronously with
respect to the calling thread's returning from pthread_cancel(3). The
target thread's cancelability state and type determine when or if the
cancellation takes place, as follows:
· The target thread can delay cancellation during critical operations by
setting its cancelability state to PTHREAD_CANCEL_DISABLE.
· Because of communication delays, the calling thread can only rely on
the fact that a cancellation request will eventually become pending in
the target thread (provided that the target thread does not terminate
beforehand).
· The calling thread has no guarantee that a pending cancellation
request will be delivered because delivery is controlled by the target
thread.
When a cancellation request is delivered to a thread, termination
processing is similar to that for pthread_exit(3). For more information
about thread termination, see the discussion of thread termination in
pthread_create(3).
This routine is preferred in implementing an Ada abort statement and any
other language- or software-defined construct for requesting thread
cancellation.
The results of this routine are unpredictable, if the value specified in
thread refers to a thread that does not currently exist.
RETURN VALUES
If an error condition occurs, this routine returns an integer value
indicating the type of error. Possible return values are as follows:
0 Successful completion.
[EINVAL]
The specified thread is invalid.
[ESRCH]
The thread argument does not specify an existing thread.
ERRORS
None
SEE ALSO
Functions: pthread_cleanup_pop(3), pthread_cleanup_push(3),
pthread_create(3), pthread_exit(3), pthread_join(3),
pthread_setcancelstate(3), pthread_setcanceltype(3), pthread_testcancel(3)
Manuals: Guide to DECthreads and Programmer's Guide
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