NAME

       pthread_tryjoin_np, pthread_timedjoin_np - try to join with a terminated thread

LIBRARY

       POSIX threads library (libpthread, -lpthread)

SYNOPSIS

       #define _GNU_SOURCE             /* See feature_test_macros(7) */
       #include <pthread.h>

       int pthread_tryjoin_np(pthread_t thread, void **retval);
       int pthread_timedjoin_np(pthread_t thread, void **retval,
                                const struct timespec *abstime);

DESCRIPTION

       These  functions  operate  in  the same way as pthread_join(3), except for the differences
       described on this page.

       The pthread_tryjoin_np() function performs a nonblocking  join  with  the  thread  thread,
       returning  the  exit  status  of the thread in *retval.  If thread has not yet terminated,
       then instead of blocking, as is done by pthread_join(3), the call returns an error.

       The pthread_timedjoin_np() function performs a join-with-timeout.  If thread has  not  yet
       terminated,  then  the  call  blocks  until a maximum time, specified in abstime, measured
       against the CLOCK_REALTIME clock.  If the timeout expires before  thread  terminates,  the
       call  returns  an  error.   The abstime argument is a timespec(3) structure, specifying an
       absolute time measured since the Epoch (see time(2)).

RETURN VALUE

       On success, these functions return 0; on error, they return an error number.

ERRORS

       These functions can fail with the same errors  as  pthread_join(3).   pthread_tryjoin_np()
       can in addition fail with the following error:

       EBUSY  thread had not yet terminated at the time of the call.

       pthread_timedjoin_np() can in addition fail with the following errors:

       EINVAL abstime value is invalid (tv_sec is less than 0 or tv_nsec is greater than 1e9).

       ETIMEDOUT
              The call timed out before thread terminated.

       pthread_timedjoin_np() never returns the error EINTR.

VERSIONS

       These functions were added in glibc 2.3.3.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │pthread_tryjoin_np(), pthread_timedjoin_np()                   │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       These  functions  are  nonstandard GNU extensions; hence the suffix "_np" (nonportable) in
       the names.

BUGS

       The pthread_timedjoin_np() function measures time by  internally  calculating  a  relative
       sleep  interval  that  is  then  measured against the CLOCK_MONOTONIC clock instead of the
       CLOCK_REALTIME clock.  Consequently, the timeout is unaffected by discontinuous changes to
       the CLOCK_REALTIME clock.

EXAMPLES

       The following code waits to join for up to 5 seconds:

           struct timespec ts;
           int s;

           ...

           if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
               /* Handle error */
           }

           ts.tv_sec += 5;

           s = pthread_timedjoin_np(thread, NULL, &ts);
           if (s != 0) {
               /* Handle error */
           }

SEE ALSO

       clock_gettime(2), pthread_exit(3), pthread_join(3), timespec(3), pthreads(7)