TRECV(3PVM)							  PVM Version 3.4						       TRECV(3PVM)

NAME

       pvm_trecv - Receive with timeout.

SYNOPSIS

       C    #include <sys/time.h>
	    int bufid = pvm_trecv( int tid, int msgtag, struct timeval *tmout )

       Fortran	 call pvmftrecv( tid, msgtag, sec, usec, bufid )

PARAMETERS

       tid     Integer to match task identifier of sending process.

       msgtag  Integer to match message tag; should be >= 0.

       tmout   (or sec and usec) Time to wait before returning without a message.

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

DESCRIPTION

       The  routine  pvm_trecv	blocks the process until a message with label msgtag has arrived from tid.  pvm_trecv then places the message in a
       new active receive buffer, also clearing the current receive buffer.  If no matching message arrives within  the  specified  waiting  time,
       pvm_trecv returns without a message.

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

       In C, the tmout fields tv_sec and tv_usec specify how long pvm_trecv will wait without returning a matching message.  In Fortran, two sepa-
       rate parameters, sec and usec are passed.  With both set to zero, pvm_trecv behaves the same as pvm_nrecv, which is to probe  for  messages
       and return immediately even if none are matched.  In C, passing a null pointer in tmout makes pvm_trecv act like pvm_recv, that is, it will
       wait indefinitely.  In Fortran, setting sec to -1 has the same effect.

       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_trecv is successful, bufid will be the new active receive buffer identifier.  If no message is received, pvm_trecv  returns  0.	If
       some error occurs then bufid will be < 0.

       Once pvm_trecv returns, the data in the message can be unpacked into the user's memory using the unpack routines.

EXAMPLES

       C:
	    struct timeval tmout;

	    tid = pvm_parent();
	    msgtag = 4 ;
	    tmout.tv_sec = 60;
	    tmout.tv_usec = 0;
	    if ((bufid = pvm_trecv( tid, msgtag, &tmout )) > 0) {
		 pvm_upkint( tid_array, 10, 1 );
		 pvm_upkint( problem_size, 1, 1 );
		 pvm_upkfloat( input_array, 100, 1 );
	    }

       Fortran:
	    CALL PVMFTRECV( -1, 4, 60, 0, BUFID )
	    IF (BUFID .EQ. 0) GO TO 666
	    CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO )
	    CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO )
       666  CONTINUE

ERRORS

       These error conditions can be returned by pvm_trecv

       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_recv(3PVM), pvm_unpack(3PVM), pvm_probe(3PVM), pvm_send(3PVM), pvm_mcast(3PVM)

								 8 February, 1994						       TRECV(3PVM)