pthread_setcancelstate(3T)

NAME

pthread_setcancelstate(), pthread_setcanceltype() — set and retrieve current thread's cancelability state or type.

SYNOPSIS

#include <pthread.h>

int pthread_setcancelstate( 
   int state, 
   int *oldstate 
); 

int pthread_setcanceltype( 
   int type, 
   int *oldtype 
); 

PARAMETERS

state: Value to which the cancelability state of the calling thread is to be set.
oldstate: Pointer to the location where the old cancelability state of the calling thread will be returned.
type: Value to which the cancelability type of the calling thread is to be set.
oldtype: Pointer to the location where the old cancelability type of the calling thread will be returned.

DESCRIPTION

pthread_setcancelstate() atomically sets the calling thread's cancelability state to the value in state and returns the previous cancelability state in oldstate. The legal values for state are:

PTHREAD_CANCEL_DISABLE: Disable cancelability for the calling thread. Cancellation requests against the calling thread are held pending.
PTHREAD_CANCEL_ENABLE: Enable cancelability for the calling thread. Cancellation requests against the calling thread may be acted upon. When a pending cancellation request will be acted upon depends on the thread's cancelability type.

By default, a thread's cancelability state is set to PTHREAD_CANCEL_ENABLE when it is created.

pthread_setcanceltype() atomically sets the calling thread's cancelability type to the value in type and returns the previous cancelability type in oldtype. The legal values for type are:

PTHREAD_CANCEL_ASYNCHRONOUS: New or pending cancellation requests against the calling thread may be acted upon at any time (if cancellation is enabled for the calling thread).
PTHREAD_CANCEL_DEFERRED: Cancellation requests for the calling thread are held pending until a cancellation point is reached.

A thread's cancelability type is set to PTHREAD_CANCEL_DEFERRED when it is created.

If a thread's cancelability state is disabled, the setting of the thread's cancelability type has no immediate effect. All cancellation requests are held pending. However, once cancelability is enabled again, the new type will be in effect.

RETURN VALUE

Upon successful completion, pthread_setcancelstate() and pthread_setcanceltype() return zero. Otherwise, an error number is returned to indicate the error (the errno variable is not set).

ERRORS

For each of the following conditions, if the condition is detected, the pthread_setcancelstate() and pthread_setcanceltype() functions return the corresponding error number:

[EINVAL]: state contains an invalid value.
[EINVAL]: type contains an invalid value.

NOTES

Only functions that are async-cancel safe should be called from a thread that is asynchronously cancelable.

AUTHOR

pthread_setcancelstate() and pthread_setcanceltype() were derived from the IEEE POSIX P1003.1c standard.

STANDARDS CONFORMANCE

pthread_setcancelstate(): POSIX 1003.1c.
pthread_setcanceltype(): POSIX 1003.1c.