1PROBE(3PVM)                     PVM Version 3.4                    PROBE(3PVM)
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NAME

6       pvm_probe - Check if message has arrived.
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SYNOPSIS

10       C    int bufid = pvm_probe( int tid, int msgtag )
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12       Fortran   call pvmfprobe( tid, msgtag, bufid )
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PARAMETERS

16       tid     Integer  task  identifier  of  sending  process supplied by the
17               user.
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19       msgtag  Integer message tag supplied by the user.  msgtag should be  >=
20               0.
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22       bufid   Integer  returning  the  value of the new active receive buffer
23               identifier.  Values less than zero indicate an error.
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DESCRIPTION

27       The routine pvm_probe checks to see if a message with label msgtag  has
28       arrived  from tid.  If a matching message has arrived pvm_probe returns
29       a buffer identifier in bufid.  This bufid can be used with  pvm_bufinfo
30       to  determine  information  about  the  message  such as its source and
31       length.
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33       If the requested message has not arrived, then pvm_probe returns with a
34       0 in bufid.  If some error occurs bufid will be < 0.
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36       A  -1 in msgtag or tid matches anything.  This allows the user the fol‐
37       lowing options.  If tid = -1 and msgtag is defined by  the  user,  then
38       pvm_probe  will  accept a message from any process which has a matching
39       msgtag.  If msgtag = -1 and tid is defined by the user, then  pvm_probe
40       will accept any message that is sent from process tid.  If tid = -1 and
41       msgtag = -1, then pvm_probe will accept any message from any process.
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43       pvm_probe can be called multiple times to check if a given message  has
44       arrived  yet.  After  the  message has arrived, pvm_recv must be called
45       before the message can be unpacked into the  user's  memory  using  the
46       unpack routines.
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EXAMPLES

50       C:
51            tid = pvm_parent();
52            msgtag = 4 ;
53            arrived = pvm_probe( tid, msgtag );
54            if ( arrived )
55                 info = pvm_bufinfo( arrived, &len, &tag, &tid );
56            else
57                 /* go do other computing */
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59       Fortran:
60            CALL PVMFPROBE( -1, 4, ARRIVED )
61            IF ( ARRIVED .GT. 0 ) THEN
62                 CALL PVMFBUFINFO( ARRIVED, LEN, TAG, TID, INFO )
63            ELSE
64       *         GO DO USEFUL WORK
65            ENDIF
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ERRORS

69       These error conditions can be returned by pvm_probe.
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71       PvmBadParam
72              giving an invalid tid value or msgtag.
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74       PvmSysErr
75              pvmd not responding.
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SEE ALSO

78       pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_nrecv(3PVM), pvm_recv(3PVM),
79       pvm_unpack(3PVM)
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83                                30 August, 1993                    PROBE(3PVM)
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