NAME¶
pvm_recv - Receive a message.
SYNOPSIS¶
C int bufid = pvm_recv( int tid, int msgtag )
Fortran call pvmfrecv( 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 returns the value of the new active receive buffer identifier.
Values less than zero indicate an error.
DESCRIPTION¶
The routine
pvm_recv blocks the process until a message with label
msgtag has arrived from
tid. pvm_recv then places the message in
a new
active receive buffer, which also clears the current receive
buffer.
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_recv will accept a message from any process which has a matching msgtag.
If msgtag = -1 and tid is defined by the user, then pvm_recv will accept any
message that is sent from process tid. If tid = -1 and msgtag = -1, then
pvm_recv will accept any message from any process.
The PVM model guarantees the following about message order. If task 1 sends
message A to task 2, then task 1 sends message B to task 2, message A will
arrive at task 2 before message B. Moreover, if both messages arrive before
task 2 does a receive, then a wildcard receive will always return message A.
If pvm_recv is successful,
bufid will be the value of the new active
receive buffer identifier. If some error occurs then
bufid will be <
0.
pvm_recv is blocking which means the routine waits until a message matching the
user specified tid and msgtag values arrives at the local pvmd. If the message
has already arrived then pvm_recv returns immediately with the message.
Once pvm_recv returns, the data in the message can be unpacked into the user's
memory using the unpack routines.
EXAMPLES¶
C:
tid = pvm_parent();
msgtag = 4 ;
bufid = pvm_recv( tid, msgtag );
info = pvm_upkint( tid_array, 10, 1 );
info = pvm_upkint( problem_size, 1, 1 );
info = pvm_upkfloat( input_array, 100, 1 );
Fortran:
CALL PVMFRECV( -1, 4, BUFID )
CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO )
CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO )
ERRORS¶
These error conditions can be returned by
pvm_recv
- PvmBadParam
- giving an invalid tid value, or msgtag < -1.
- PvmSysErr
- pvmd not responding.
SEE ALSO¶
pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_nrecv(3PVM), pvm_unpack(3PVM),
pvm_probe(3PVM), pvm_send(3PVM), pvm_mcast(3PVM)