pthreads/pthread_cond_timedwait.3

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  30 .Dd July 28, 1998
  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 .Fd #include <pthread.h>
  38 .Ft int
  39 .Fo pthread_cond_timedwait
  40 .Fa "pthread_cond_t *restrict cond"
  41 .Fa "pthread_mutex_t *restrict mutex"
  42 .Fa "const struct timespec *restrict abstime"
  43 .Fc
  44 .Sh DESCRIPTION
  45 The
  46 .Fn pthread_cond_timedwait
  47 function atomically blocks the current thread waiting on the condition
  48 variable specified by
  49 .Fa cond
  50 and unblocks the mutex specified by
  51 .Fa mutex .
  52 The waiting thread unblocks only after another thread calls
  53 .Xr pthread_cond_signal 3 ,
  54 or
  55 .Xr pthread_cond_broadcast 3
  56 with the same condition variable, or if the system time reaches the
  57 time specified in
  58 .Fa abstime ,
  59 and the current thread reacquires the lock on
  60 .Fa mutex .
  61 .Pp
  62 Values for struct timespec can be obtained by adding the required
  63 time interval to the  the current time obtained using
  64 .Xr gettimeofday 2 .
  65 .Pp
  66 .Fa Note
  67 that struct timeval and struct timespec use different units to specify
  68 the time. Hence, the user should always take care to perform the time unit
  69 conversions accordingly.
  70 .Sh EXAMPLE
  71 .Pp
  72    struct timeval tv;
  73    struct timespec ts;
  74    gettimeofday(&tv, NULL);
  75    ts.tv_sec = tv.tv_sec + 0;
  76    ts.tv_nsec = 0;
  77 .Pp
  78 .Sh RETURN VALUES
  79 If successful, the
  80 .Fn pthread_cond_timedwait
  81 function will return zero.
  82 Otherwise, an error number will be returned to
  83 indicate the error.
  84 .Sh ERRORS
  85 .Fn pthread_cond_timedwait
  86 will fail if:
  87 .Bl -tag -width Er
  88 .It Bq Er EINVAL
  89 The value specified by
  90 .Fa cond ,
  91 .Fa mutex
  92 or
  93 .Fa abstime
  94 is invalid.
  95 .It Bq Er ETIMEDOUT
  96 The system time has reached or exceeded the time specified in
  97 .Fa abstime .
  98 .El
  99 .Sh SEE ALSO
 100 .Xr pthread_cond_broadcast 3 ,
 101 .Xr pthread_cond_destroy 3 ,
 102 .Xr pthread_cond_init 3 ,
 103 .Xr pthread_cond_signal 3 ,
 104 .Xr pthread_cond_wait 3 ,
 105 .Xr gettimeofday 2
 106 .Sh STANDARDS
 107 .Fn pthread_cond_timedwait
 108 conforms to
 109 .St -p1003.1-96 .