ch3_istartmsgv.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

/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
 *  (C) 2001 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */

#include "mpidi_ch3_impl.h"

static MPID_Request * create_request(MPID_IOV * iov, int iov_count, int iov_offset, int nb)
{
    MPID_Request * sreq;
    int i;
    MPIDI_STATE_DECL(MPID_STATE_CREATE_REQUEST);

    MPIDI_FUNC_ENTER(MPID_STATE_CREATE_REQUEST);
    
    sreq = MPIDI_CH3_Request_create();
    assert(sreq != NULL);
    MPIU_Object_set_ref(sreq, 2);
    sreq->kind = MPID_REQUEST_SEND;
    
    /* memcpy(sreq->ch3.iov, iov, iov_count * sizeof(MPID_IOV)); */
    for (i = 0; i < iov_count; i++)
    {
	sreq->ch3.iov[i] = iov[i];
    }
    if (iov_offset == 0)
    {
	/* memcpy(&sreq->tcp.pkt, iov[0].MPID_IOV_BUF, iov[0].MPID_IOV_LEN); */
	assert(iov[0].MPID_IOV_LEN == sizeof(MPIDI_CH3_Pkt_t));
	sreq->tcp.pkt = *(MPIDI_CH3_Pkt_t *) iov[0].MPID_IOV_BUF;
	sreq->ch3.iov[0].MPID_IOV_BUF = &sreq->tcp.pkt;
    }
    sreq->ch3.iov[iov_offset].MPID_IOV_BUF = 
	(char *) sreq->ch3.iov[iov_offset].MPID_IOV_BUF + nb;
    sreq->ch3.iov[iov_offset].MPID_IOV_LEN -= nb;
    sreq->tcp.iov_offset = iov_offset;
    sreq->ch3.iov_count = iov_count;
    sreq->ch3.ca = MPIDI_CH3_CA_COMPLETE;

    MPIDI_FUNC_EXIT(MPID_STATE_CREATE_REQUEST);
    return sreq;
}

/*
 * MPIDI_CH3_iStartMsgv() attempts to send the message immediately.  If the
 * entire message is successfully sent, then NULL is returned.  Otherwise a
 * request is allocated, the iovec and the first buffer pointed to by the
 * iovec (which is assumed to be a MPIDI_CH3_Pkt_t) are copied into the
 * request, and a pointer to the request is returned.  An error condition also
 * results in a request be allocated and the errror being returned in the
 * status field of the request.
 */

/* XXX - What do we do if MPIDI_CH3_Request_create() returns NULL???  If
   MPIDI_CH3_iStartMsgv() returns NULL, the calling code assumes the request
   completely successfully, but the reality is that we couldn't allocate the
   memory for a request.  This seems like a flaw in the CH3 API. */

/* NOTE - The completion action associated with a request created by
   CH3_iStartMsgv() is alway MPIDI_CH3_CA_COMPLETE.  This implies that
   CH3_iStartMsgv() can only be used when the entire message can be described
   by a single iovec of size MPID_IOV_LIMIT. */
    
#undef FUNCNAME
#define FUNCNAME MPIDI_CH3_iStartMsgv
#undef FCNAME
#define FCNAME MPIDI_QUOTE(FUNCNAME)
MPID_Request * MPIDI_CH3_iStartMsgv(MPIDI_VC * vc, MPID_IOV * iov, int n_iov)
{
    MPID_Request * sreq = NULL;
    MPIDI_STATE_DECL(MPID_STATE_MPIDI_CH3_ISTARTMSGV);
    MPIDI_STATE_DECL(MPID_STATE_WRITEV);

    MPIDI_FUNC_ENTER(MPID_STATE_MPIDI_CH3_ISTARTMSGV);

    MPIDI_DBG_PRINTF((50, FCNAME, "entering"));
    assert(n_iov <= MPID_IOV_LIMIT);
    assert(iov[0].MPID_IOV_LEN <= sizeof(MPIDI_CH3_Pkt_t));

    /* The TCP implementation uses a fixed length header, the size of which is
       the maximum of all possible packet headers */
    iov[0].MPID_IOV_LEN = sizeof(MPIDI_CH3_Pkt_t);
    
    if (vc->tcp.state == MPIDI_CH3I_VC_STATE_CONNECTED) /* MT */
    {
	/* Connection already formed.  If send queue is empty attempt to send
           data, queuing any unsent data. */
	if (MPIDI_CH3I_SendQ_empty(vc)) /* MT */
	{
	    int nb;

	    /* MT - need some signalling to lock down our right to use the
               channel, thus insuring that the progress engine does also try to
               write */
	    do
	    {
		MPIDI_FUNC_ENTER(MPID_STATE_WRITEV);
		nb = writev(vc->tcp.fd, iov, n_iov);
		MPIDI_FUNC_EXIT(MPID_STATE_WRITEV);
	    }
	    while (nb == -1 && errno == EINTR);
	    
	    if (nb > 0)
	    {
		int offset = 0;
    
		while (offset < n_iov)
		{
		    if (nb >= iov[offset].MPID_IOV_LEN)
		    {
			nb -= iov[offset].MPID_IOV_LEN;
			offset++;
		    }
		    else
		    {
			sreq = create_request(iov, n_iov, offset, nb);
			MPIDI_CH3I_SendQ_enqueue_head(vc, sreq);
			MPIDI_CH3I_TCP_post_write(vc, sreq);
			break;
		    }
		}
	    }
	    else if (nb == 0 || errno == EAGAIN ||
		     errno == EWOULDBLOCK || errno == ENOMEM)
	    {
		sreq = create_request(iov, n_iov, 0, 0);
		MPIDI_CH3I_SendQ_enqueue(vc, sreq);
		MPIDI_CH3I_TCP_post_write(vc, sreq);
	    }
	    else
	    {
		sreq = MPIDI_CH3_Request_create();
		assert(sreq != NULL);
		sreq->kind = MPID_REQUEST_SEND;
		sreq->cc = 0;
		/* TODO: Create an appropriate error message based on the value of errno */
		sreq->status.MPI_ERROR = MPI_ERR_INTERN;
	    }
	}
	else
	{
	    sreq = create_request(iov, n_iov, 0, 0);
	    MPIDI_CH3I_SendQ_enqueue(vc, sreq);
	}
    }
    else if (vc->tcp.state == MPIDI_CH3I_VC_STATE_UNCONNECTED)
    {
	/* Form a new connection, queuing the data so it can be sent later. */
	MPIDI_CH3I_TCP_post_connect(vc);
	sreq = create_request(iov, n_iov, 0, 0);
	MPIDI_CH3I_SendQ_enqueue(vc, sreq);
    }
    else if (vc->tcp.state != MPIDI_CH3I_VC_STATE_FAILED)
    {
	/* Unable to send data at the moment, so queue it for later */
	sreq = create_request(iov, n_iov, 0, 0);
	MPIDI_CH3I_SendQ_enqueue(vc, sreq);
    }
    else
    {
	/* Connection failed, so allocate a request and return an error. */
	sreq = MPIDI_CH3_Request_create();
	assert(sreq != NULL);
	sreq->kind = MPID_REQUEST_SEND;
	sreq->cc = 0;
	/* TODO: Create an appropriate error message */
	sreq->status.MPI_ERROR = MPI_ERR_INTERN;
    }
    
    MPIDI_DBG_PRINTF((50, FCNAME, "exiting"));
    MPIDI_FUNC_EXIT(MPID_STATE_MPIDI_CH3_ISTARTMSGV);
    return sreq;
}