pthread_testcancel()--Create Cancellation Point
Syntax
#include <pthread.h>
void pthread_testcancel(void);
Threadsafe: Yes Signal Safe: No
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The
pthread_testcancel
() function creates a cancellation point in the calling thread. If cancelability is currently disabled, this function has no effect. For more information on cancelability, see Thread cancellation APIs.
When cancelability is disabled, all cancels are held pending in the target thread until the thread changes the cancelability. When cancelability is deferred, all cancels are held pending in the target thread until the thread changes the cancelability, calls a function that is a cancellation point, or calls pthread_testcancel(), thus creating a cancellation point. When cancelability is asynchronous, all cancels are acted upon immediately, interrupting the thread with its processing.
You should not use asynchronous thread cancellation via the PTHREAD_CANCEL_ASYNCHRONOUS option of pthread_setcanceltype(). See the common user errors section of this document for more information.
- #define _MULTI_THREADED
- #include <pthread.h>
- #include <stdio.h>
- #include "check.h"
-
- void cleanupHandler(void *parm) {
- printf("Inside cancellation cleanup handler/n");
- }
-
- void *threadfunc(void *parm)
- {
- unsigned int i=0;
- int rc=0, oldState=0;
- printf("Entered secondary thread/n");
- pthread_cleanup_push(cleanupHandler, NULL);
- rc = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldState);
- checkResults("pthread_setcancelstate()/n", rc);
-
- sleep(2);
- while (1) {
- printf("Secondary thread is now looping/n");
- ++i;
- sleep(1);
-
-
-
- pthread_testcancel();
- if (i == 5) {
- printf("Cancel state set to ENABLE/n");
- rc = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,&oldState);
- checkResults("pthread_setcancelstate(2)/n", rc);
-
-
- }
- }
- pthread_cleanup_pop(0);
- return NULL;
- }
-
- int main(int argc, char **argv)
- {
- pthread_t thread;
- int rc=0;
- void *status=NULL;
-
- printf("Enter Testcase - %s/n", argv[0]);
-
-
- printf("Create thread using the NULL attributes/n");
- rc = pthread_create(&thread, NULL, threadfunc, NULL);
- checkResults("pthread_create(NULL)/n", rc);
-
- sleep(1);
- printf("Cancel the thread/n");
- rc = pthread_cancel(thread);
- checkResults("pthread_cancel()/n", rc);
-
- rc = pthread_join(thread, &status);
- if (status != PTHREAD_CANCELED) {
- printf("Thread returned unexpected result!/n");
- exit(1);
- }
- printf("Main completed/n");
- return 0;
- }
Output:
Enter Testcase - QP0WTEST/TPTESTC0
Create thread using the NULL attributes
Entered secondary thread
Cancel the thread
Secondary thread is now looping
Secondary thread is now looping
Secondary thread is now looping
Secondary thread is now looping
Secondary thread is now looping
Cancel state set to ENABLE
Secondary thread is now looping
Inside cancellation cleanup handler
Main completed
(stevenliyong) |