irecv_tcp.c

刚才是说明 现在是安装程序在 LINUX环境下进行编程的MPICH安装文件

err = MPI_SUCCESS;
/* Error checking */
...
request_ptr = MPID_Request_recv_FOA( tag, rank, comm_ptr, &found );
/* FOA ensures that the request is not busy when it is returned if found, and
   is busy if not found.  FOA is really ``Find and remove or allocate and 
   insert'' */
if (found) {
    if (request_ptr->eager.ptr) {
        /* This is the eager case; all data is available */
        /* This requires FOA to wait while receiving data (busy).  The
           assumption is that eager messages will be relatively short */
        /* Check for Truncation */
        msg_size = request_ptr->status.count;
        if (count * datatype->size < msg_size ) {
            err = MPID_Err_create_code( MPI_ERR_TRUNCATE, 0, 0, 
					msg_size, count*datatype->size );
            request_ptr->status.count = count * datatype->size;
        }
        if (datatype->is_contig) 
            MPID_Memcpy( buffer, request_ptr->eager.ptr, 
			 request_ptr->status.count );
        else {
            int location = 0;  /* start from the beginning of eager.ptr */
            MPID_Unpack( buffer, count, datatype, 
			 request_ptr->eager.ptr, &location, 
			 request_ptr->status.count, request_ptr->msg_format );
        }
        /* release eager.ptr (includes flow control) */
        MPID_EagerFree( rank, comm_ptr, request_ptr->eager.ptr, msg_size );
        MPID_MemWrite_ordered( request_ptr->xfer_completed, 1 );
    }
    else {
         /* This is the rendezvous case */
         MPID_Hid_ok_to_send_t *packet;
         struct iovec vector[1];

	 /* First, set up to unpack the data when it starts to arrive */
	 request_ptr->buf.ptr      = buffer;
	 request_ptr->buf.count    = count;
	 request_ptr->buf.datatype = datatype;
	 MPID_Datatype_incr(datatype,1);
	 MPID_Comm_incr(comm_ptr,1);

	 /* Now, send the request to deliver the data */
         packet = (MPID_Hid_ok_to_send_t *)&request_ptr.packet;
         vector[0].iov_base = &packet;
         vector[0].iov_len  = sizeof(MPID_Hid_ok_to_send_t);
         packet->recv_request_id = request_ptr->self;
         packet->send_request_id = request_ptr->rndv.sender_id;
         packet->kind            = MPID_Hid_ok_to_send;
         packet->len             = sizeof(MPID_Hid_ok_to_send_t);
         MPID_Rhcv_tcp( request_ptr->status.MPI_SOURCE, comm_ptr,
                        MPID_Hid_ok_to_send, vector, 1, NULL );
    }
}
else {
    /* Unmatched.  Attach the user's datatype/buffer. 
       When this receive is matched, the communication agent will
       use that information to save the data into the user's buffer
       The tag, communicator, and source rank are already saved (by FOA) */ 
    request_ptr->buf.ptr      = buffer;
    request_ptr->buf.count    = count;
    request_ptr->buf.datatype = datatype;
    request_ptr->buf.comm_ptr = comm_ptr;
    MPID_Datatype_incr(datatype,1);
    MPID_Comm_incr(comm_ptr,1);
    MPID_MemWrite_ordered(request_ptr->busy,0);
}
/* The MPI_Request is the index of the MPID_Request in the MPID_Request
   array; this is saved in the self field */
*request = request_ptr->self;
return err;