man/pthread_cond_timedwait.3

   1 .\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
   2 .\" All rights reserved.
   3 .\"
   4 .\" Redistribution and use in source and binary forms, with or without
   5 .\" modification, are permitted provided that the following conditions
   6 .\" are met:
   7 .\" 1. Redistributions of source code must retain the above copyright
   8 .\"    notice, this list of conditions and the following disclaimer.
   9 .\" 2. Redistributions in binary form must reproduce the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer in the
  11 .\"    documentation and/or other materials provided with the distribution.
  12 .\" 3. Neither the name of the author nor the names of any co-contributors
  13 .\"    may be used to endorse or promote products derived from this software
  14 .\"    without specific prior written permission.
  15 .\"
  16 .\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  17 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  20 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26 .\" SUCH DAMAGE.
  27 .\"
  28 .\" $FreeBSD$
  29 .\"
  30 .Dd May 9, 2010
  31 .Dt PTHREAD_COND_TIMEDWAIT 3
  32 .Os
  33 .Sh NAME
  34 .Nm pthread_cond_timedwait
  35 .Nd "wait on a condition variable for a specific amount of time"
  36 .Sh SYNOPSIS
  37 .In pthread.h
  38 .Ft int
  39 .Fn pthread_cond_timedwait "pthread_cond_t *cond" "pthread_mutex_t *mutex" "const struct timespec *abstime"
  40 .Sh DESCRIPTION
  41 The
  42 .Fn pthread_cond_timedwait
  43 function atomically blocks the current thread waiting on the condition
  44 variable specified by
  45 .Fa cond ,
  46 and releases the mutex specified by
  47 .Fa mutex .
  48 The waiting thread unblocks only after another thread calls
  49 .Xr pthread_cond_signal 3 ,
  50 or
  51 .Xr pthread_cond_broadcast 3
  52 with the same condition variable, or if the system time reaches the
  53 time specified in
  54 .Fa abstime ,
  55 and the current thread reacquires the lock on
  56 .Fa mutex .
  57 .Pp
  58 Values for struct timespec can be obtained by adding the required
  59 time interval to the  the current time obtained using
  60 .Xr gettimeofday 2 .
  61 .Pp
  62 .Fa Note
  63 that struct timeval and struct timespec use different units to specify
  64 the time. Hence, the user should always take care to perform the time unit
  65 conversions accordingly.
  66 .Sh EXAMPLE
  67 .Pp
  68    struct timeval tv;
  69    struct timespec ts;
  70    gettimeofday(&tv, NULL);
  71    ts.tv_sec = tv.tv_sec + 0;
  72    ts.tv_nsec = 0;
  73 .Pp
  74 .Sh RETURN VALUES
  75 If successful, the
  76 .Fn pthread_cond_timedwait
  77 function will return zero.
  78 Otherwise an error number will be returned to
  79 indicate the error.
  80 .Sh ERRORS
  81 The
  82 .Fn pthread_cond_timedwait
  83 function will fail if:
  84 .Bl -tag -width Er
  85 .It Bq Er EINVAL
  86 The value specified by
  87 .Fa cond ,
  88 .Fa mutex
  89 or
  90 .Fa abstime
  91 is invalid.
  92 .It Bq Er ETIMEDOUT
  93 The system time has reached or exceeded the time specified in
  94 .Fa abstime .
  95 .El
  96 .Sh SEE ALSO
  97 .Xr pthread_cond_broadcast 3 ,
  98 .Xr pthread_cond_destroy 3 ,
  99 .Xr pthread_cond_init 3 ,
 100 .Xr pthread_cond_signal 3 ,
 101 .Xr pthread_cond_wait 3 ,
 102 .Xr gettimeofday 2
 103 .Sh STANDARDS
 104 The
 105 .Fn pthread_cond_timedwait
 106 function conforms to
 107 .St -p1003.1-96 .