pthread_cond_timedwait.3   [plain text]

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.\" $FreeBSD: src/lib/libc_r/man/pthread_cond_timedwait.3,v 1.8.2.6 2001/08/17 15:42:51 ru Exp $
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.Dd July 28, 1998
.Dt PTHREAD_COND_TIMEDWAIT 3
.Os
.Sh NAME
.Nm pthread_cond_timedwait
.Nd "wait on a condition variable for a specific amount of time"
.Sh SYNOPSIS
.Fd #include <pthread.h>
.Ft int
.Fo pthread_cond_timedwait
.Fa "pthread_cond_t *restrict cond"
.Fa "pthread_mutex_t *restrict mutex"
.Fa "const struct timespec *restrict abstime"
.Fc
.Sh DESCRIPTION
The
.Fn pthread_cond_timedwait
function atomically blocks the current thread waiting on the condition
variable specified by
.Fa cond
and unblocks the mutex specified by
.Fa mutex .
The waiting thread unblocks only after another thread calls
.Xr pthread_cond_signal 3 ,
or
.Xr pthread_cond_broadcast 3
with the same condition variable, or if the system time reaches the
time specified in
.Fa abstime ,
and the current thread reacquires the lock on
.Fa mutex .
.Pp 
Values for struct timespec can be obtained by adding the required
time interval to the  the current time obtained using 
.Xr gettimeofday 2 .
.Pp
.Fa Note 
that struct timeval and struct timespec use different units to specify
the time. Hence, the user should always take care to perform the time unit 
conversions accordingly.
.Sh EXAMPLE
.Pp
   struct timeval tv;
   struct timespec ts;
   gettimeofday(&tv, NULL);
   ts.tv_sec = tv.tv_sec + 0;
   ts.tv_nsec = 0;
.Pp
.Sh RETURN VALUES
If successful, the
.Fn pthread_cond_timedwait
function will return zero.
Otherwise, an error number will be returned to
indicate the error.
.Sh ERRORS
.Fn pthread_cond_timedwait
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value specified by
.Fa cond ,
.Fa mutex
or
.Fa abstime
is invalid.
.It Bq Er ETIMEDOUT
The system time has reached or exceeded the time specified in
.Fa abstime .
.El
.Sh SEE ALSO
.Xr pthread_cond_broadcast 3 ,
.Xr pthread_cond_destroy 3 ,
.Xr pthread_cond_init 3 ,
.Xr pthread_cond_signal 3 ,
.Xr pthread_cond_wait 3 ,
.Xr gettimeofday 2
.Sh STANDARDS
.Fn pthread_cond_timedwait
conforms to
.St -p1003.1-96 .