int info = pvm_send( int tid, int msgtag ) call pvmfsend( tid, msgtag, info ) int info = pvm_mcast( int *tids, int ntask, int msgtag ) call pvmfmcast( ntask, tids, msgtag, info )
The routine pvm_send() labels the message with an integer identifier msgtag and sends it immediately to the process TID.
The routine pvm_mcast() labels the message with an integer identifier msgtag and broadcasts the message to all tasks specified in the integer array tids (except itself). The tids array is of length ntask.
int info = pvm_psend( int tid, int msgtag,
void *vp, int cnt, int type )
call pvmfpsend( tid, msgtag, xp, cnt, type, info )
The routine pvm_psend() packs and sends an array of the specified datatype to the task identified by TID. The defined datatypes for Fortran are the same as for pvmfpack(). In C the type argument can be any of the following:
PVM_STR PVM_FLOAT PVM_BYTE PVM_CPLX PVM_SHORT PVM_DOUBLE PVM_INT PVM_DCPLX PVM_LONG PVM_UINT PVM_USHORT PVM_ULONG
PVM contains several methods of receiving messages at a task. There is no function matching in PVM, for example, that a pvm_psend must be matched with a pvm_precv. Any of the following routines can be called for any incoming message no matter how it was sent (or multicast).
int bufid = pvm_recv( int tid, int msgtag ) call pvmfrecv( tid, msgtag, bufid )
This blocking receive routine will wait until a message with label msgtag has arrived from TID. A value of -1 in msgtag or TID matches anything (wildcard). It then places the message in a new active receive buffer that is created. The previous active receive buffer is cleared unless it has been saved with a pvm_setrbuf() call.
int bufid = pvm_nrecv( int tid, int msgtag ) call pvmfnrecv( tid, msgtag, bufid )
If the requested message has not arrived, then the nonblocking receive pvm_nrecv() returns bufid = 0. This routine can be called multiple times for the same message to check whether it has arrived, while performing useful work between calls. When no more useful work can be performed, the blocking receive pvm_recv() can be called for the same message. If a message with label msgtag has arrived from TID, pvm_nrecv() places this message in a new active receive buffer (which it creates) and returns the ID of this buffer. The previous active receive buffer is cleared unless it has been saved with a pvm_setrbuf() call. A value of -1 in msgtag or TID matches anything (wildcard).
int bufid = pvm_probe( int tid, int msgtag ) call pvmfprobe( tid, msgtag, bufid )
If the requested message has not arrived, then pvm_probe() returns bufid = 0. Otherwise, it returns a bufid for the message, but does not ``receive'' it. This routine can be called multiple times for the same message to check whether it has arrived, while performing useful work between calls. In addition, pvm_bufinfo() can be called with the returned bufid to determine information about the message before receiving it.
int bufid = pvm_trecv( int tid, int msgtag, struct timeval *tmout ) call pvmftrecv( tid, msgtag, sec, usec, bufid )
PVM also supplies a timeout version of receive. Consider the case where a message is never going to arrive (because of error or failure); the routine pvm_recv would block forever. To avoid such situations, the user may wish to give up after waiting for a fixed amount of time. The routine pvm_trecv() allows the user to specify a timeout period. If the timeout period is set very large, then pvm_trecv acts like pvm_recv. If the timeout period is set to zero, then pvm_trecv acts like pvm_nrecv. Thus, pvm_trecv fills the gap between the blocking and nonblocking receive functions.
int info = pvm_bufinfo( int bufid, int *bytes, int *msgtag, int *tid ) call pvmfbufinfo( bufid, bytes, msgtag, tid, info )
The routine pvm_bufinfo() returns msgtag, source TID, and length in bytes of the message identified by bufid. It can be used to determine the label and source of a message that was received with wildcards specified.
int info = pvm_precv( int tid, int msgtag, void *vp, int cnt,
int type, int *rtid, int *rtag, int *rcnt )
call pvmfprecv( tid, msgtag, xp, cnt, type, rtid, rtag, rcnt, info )
The routine pvm_precv() combines the functions of a blocking receive and unpacking the received buffer. It does not return a bufid. Instead, it returns the actual values of TID, msgtag, and cnt.
int (*old)() = pvm_recvf(int (*new)(int buf, int tid, int tag))
The routine pvm_recvf() modifies the receive context used by the receive functions and can be used to extend PVM. The default receive context is to match on source and message tag. This can be modified to any user-defined comparison function. (See Appendix B for an example of creating a probe function with pvm_recf().) There is no Fortran interface routine for pvm_recvf().