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)