THR_JOIN(3C) Standard C Library Functions THR_JOIN(3C)

NAME

thr_join - wait for thread termination

SYNOPSIS

cc -mt [ flag... ] file...[ library... ]
#include <thread.h>

int thr_join(thread_t thread, thread_t *departed, void **status);

DESCRIPTION

The thr_join() function suspends processing of the calling thread
until the target thread completes. The thread argument must be a
member of the current process and cannot be a detached thread. See
thr_create(3C).


If two or more threads wait for the same thread to complete, all will
suspend processing until the thread has terminated, and then one
thread will return successfully and the others will return with an
error of ESRCH. The thr_join() function will not block processing of
the calling thread if the target thread has already terminated.


If a thr_join() call returns successfully with a non-null status
argument, the value passed to thr_exit(3C) by the terminating thread
will be placed in the location referenced by status.


If the target thread ID is 0, thr_join() finds and returns the
status of a terminated undetached thread in the process. If no such
thread exists, it suspends processing of the calling thread until a
thread for which no other thread is waiting enters that state, at
which time it returns successfully, or until all other threads in the
process are either daemon threads or threads waiting in thr_join(),
in which case it returns EDEADLK. See NOTES.


If departed is not NULL, it points to a location that is set to the
ID of the terminated thread if thr_join() returns successfully.

RETURN VALUES

If successful, thr_join() returns 0. Otherwise, an error number is
returned to indicate the error.

ERRORS

EDEADLK
A joining deadlock would occur, such as when a thread
attempts to wait for itself, or the calling thread is
waiting for any thread to exit and only daemon threads or
waiting threads exist in the process.


ESRCH
No undetached thread could be found corresponding to the
given thread ID.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | MT-Safe |
+---------------+-----------------+

SEE ALSO

thr_create(3C), thr_exit(3C), wait(3C), attributes(7), standards(7)

NOTES

Using thr_join(3C) in the following syntax,

while (thr_join(0, NULL, NULL) == 0);


will wait for the termination of all non-daemon threads, excluding
threads that are themselves waiting in thr_join().

March 27, 2000 THR_JOIN(3C)