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__THRSLEEP(3)            BSD Library Functions Manual            __THRSLEEP(3)

NAME
     __thrsleep, __thrwakeup -- userspace thread sleep and wakeup

SYNOPSIS
     #include <&lt;sys/time.h>&gt;

     int
     __thrsleep(const volatile void *id, clockid_t clock_id,
         const struct timespec *abstime, void *lock, const int *abort);

     int
     __thrwakeup(const volatile void *id, int count);

DESCRIPTION
     The __thrsleep() and __thrwakeup() functions provide thread sleep and
     wakeup primitives with which synchronization primitives such as mutexes
     and condition variables can be implemented.  __thrsleep() blocks the
     calling thread on the abstract ``wait channel'' identified by the id
     argument until another thread calls __thrwakeup() with the same id value.
     If the abstime argument is not NULL, then it specifies an absolute time,
     measured against the clock_id clock, after which __thrsleep() should time
     out and return.  If the specified time is in the past then __thrsleep()
     will return immediately without blocking.

     The lock argument, if not NULL, points to a locked spinlock that will be
     unlocked by __thrsleep() atomically with respect to calls to
     __thrwakeup(), such that if another thread locks the spinlock before
     calling __thrwakeup() with the same id, then the thread that called
     __thrsleep() will be eligible for being woken up and unblocked.

     The abort argument, if not NULL, points to an int that will be examined
     after unlocking the spinlock pointed to by lock and immediately before
     blocking.  If that int is non-zero then __thrsleep() will immediately
     return EINTR without blocking.  This provides a mechanism for a signal
     handler to keep a call to __thrsleep() from blocking, even if the signal
     is delivered immediately before the call.

     The __thrwakeup() function unblocks one or more threads that are sleeping
     on the wait channel identified by id.  The number of threads unblocked is
     specified by the count argument, except that if zero is specified then
     all threads sleeping on that id are unblocked.

RETURN VALUES
     __thrsleep() will return zero if woken by a matching call to
     __thrwakeup(), otherwise an error number will be returned to indicate the
     error.

     __thrwakeup() will return zero if at least one matching call to
     __thrsleep() was unblocked, otherwise an error number will be returned to
     indicate the error.

ERRORS
     __thrsleep() and __thrwakeup() will fail if:

     [EINVAL]           The ident argument is NULL.

     In addition, __thrsleep() may return one of the following errors:

     [EWOULDBLOCK]      The time specified by the abstime and clock_id argu-
                        ments was reached.

     [EINTR]            A signal arrived or the abort argument pointed to a
                        non-zero value.

     [EINVAL]           The clock_id argument is neither CLOCK_REALTIME nor
                        CLOCK_MONOTONIC.

     __thrwakeup() may return the following error:

     [ESRCH]            No threads calling __thrsleep() with the same id were
                        found.

SEE ALSO
     pthread_cond_wait(3), pthread_mutex_lock(3), tsleep(9)

STANDARDS
     The __thrsleep() and __thrwakeup() functions are specific to OpenBSD and
     should not be used in portable applications.

HISTORY
     The thrsleep() and thrwakeup() syscalls appeared in OpenBSD 3.9.  The
     clock_id and abstime arguments were added in OpenBSD 4.9.  The functions
     were renamed to __thrsleep() and __thrwakeup() and the abort argument was
     added in OpenBSD 5.1

AUTHORS
     The thrsleep() and thrwakeup() syscalls were created by Ted Unangst
     <tedu@OpenBSD.org>.  This manual page was written by Philip Guenther
     <guenther@OpenBSD.org>.

BSD                              July 16, 2013                             BSD