NAME

       pvm_probe - Check if message has arrived.

SYNOPSIS

       C    int bufid = pvm_probe( int tid, int msgtag )

       Fortran   call pvmfprobe( tid, msgtag, bufid )

PARAMETERS

       tid     Integer task identifier of sending process supplied by the user.

       msgtag  Integer message tag supplied by the user.  msgtag should be >= 0.

       bufid   Integer  returning  the value of the new active receive buffer identifier.  Values
               less than zero indicate an error.

DESCRIPTION

       The routine pvm_probe checks to see if a message with label msgtag has arrived  from  tid.
       If  a  matching  message has arrived pvm_probe returns a buffer identifier in bufid.  This
       bufid can be used with pvm_bufinfo to determine information about the message such as  its
       source and length.

       If  the  requested  message has not arrived, then pvm_probe returns with a 0 in bufid.  If
       some error occurs bufid will be < 0.

       A -1 in msgtag or tid matches anything.  This allows the user the following  options.   If
       tid  = -1 and msgtag is defined by the user, then pvm_probe will accept a message from any
       process which has a matching msgtag.  If msgtag = -1 and tid is defined by the user,  then
       pvm_probe will accept any message that is sent from process tid.  If tid = -1 and msgtag =
       -1, then pvm_probe will accept any message from any process.

       pvm_probe can be called multiple times to check if a given message has arrived yet.  After
       the  message  has arrived, pvm_recv must be called before the message can be unpacked into
       the user's memory using the unpack routines.

EXAMPLES

       C:
            tid = pvm_parent();
            msgtag = 4 ;
            arrived = pvm_probe( tid, msgtag );
            if ( arrived )
                 info = pvm_bufinfo( arrived, &len, &tag, &tid );
            else
                 /* go do other computing */

       Fortran:
            CALL PVMFPROBE( -1, 4, ARRIVED )
            IF ( ARRIVED .GT. 0 ) THEN
                 CALL PVMFBUFINFO( ARRIVED, LEN, TAG, TID, INFO )
            ELSE
       *         GO DO USEFUL WORK
            ENDIF

ERRORS

       These error conditions can be returned by pvm_probe.

       PvmBadParam
              giving an invalid tid value or msgtag.

       PvmSysErr
              pvmd not responding.

SEE ALSO

       pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_nrecv(3PVM), pvm_recv(3PVM), pvm_unpack(3PVM)

                                         30 August, 1993                              PROBE(3PVM)