NAME¶
pvm_recvf - Redefines the comparison function used to accept messages.
SYNOPSIS¶
C int (*old)() = pvm_recvf( int (*new)( int bufid, int tid, int tag ))
Fortran NOT AVAILABLE
DESCRIPTION¶
The routine
pvm_recvf defines the comparison function to be used by the
pvm_recv, pvm_nrecv, and pvm_probe functions. It is available as a means to
customize PVM message passing. pvm_recvf sets a user supplied comparison
function to evaluate messages for receiving.
recvf returns the old value of the matching function, or 0 if the old function
was the default matcher
pvm_recvf is intended for sophisticated C programmers who understand the
function of such routines (like signal) and who require a receive routine that
can match on more complex message contexts than the default provides.
MATCHING FUNCTION¶
The default comparison function evaluates the source and message tag associated
with all incoming messages.
PARAMETERS¶
- tid
- Integer task identifier of sending process supplied by the user.
- tag
- Integer message tag supplied by the user.
- bufid
- Integer message buffer identifier.
The matching function should return:
Value Action taken
< 0 Return immediately with this error code.
0 Do not pick this message.
1 Pick this message and do not scan the rest.
> 1 Pick this highest ranked message after
scanning them all.
EXAMPLES¶
Implementing message probe with recvf, using our matching function to return
information in a global variable.
#include <pvm3.h>
static int foundit = 0;
static int
foo_match(mid, tid, tag)
int mid;
int tid;
int tag;
{
int t, c;
struct pvmminfo header;
pvm_getminfo(mid, &header);
if ((tid == -1 || tid == header.src) && (tag == -1 || tag == header.tag))
foundit = 1;
return 0;
}
int
probe(src, tag)
{
int (*omatch)();
int cc;
omatch = pvm_recvf(foo_match);
foundit = 0;
if ((cc = pvm_nrecv(src, tag)) < 0)
return cc;
pvm_recvf(omatch);
return foundit;
}
ERRORS¶
No error conditions are returned by
pvm_recvf
SEE ALSO¶
pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_recv(3PVM), pvm_nrecv(3PVM),
pvm_probe(3PVM), pvm_trecv(3PVM)