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(5) 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(5), standards(5)

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)