/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2005 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */


/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/

#include "ompi_config.h"
#include "opal/util/crc.h"
#include "ompi/constants.h"
#include "ompi/mca/pml/pml.h"
#include "ompi/mca/btl/btl.h"
#include "orte/mca/errmgr/errmgr.h"
#include "ompi/mca/mpool/mpool.h" 
#include "pml_dr.h"
#include "pml_dr_hdr.h"
#include "pml_dr_proc.h"
#include "pml_dr_sendreq.h"
#include "pml_dr_recvreq.h"
#include "ompi/mca/bml/base/base.h"


static int mca_pml_dr_send_request_fini(struct ompi_request_t** request)
{
    mca_pml_dr_send_request_t* sendreq = *(mca_pml_dr_send_request_t**)(request); 
    if(sendreq->req_send.req_base.req_persistent) {
       if(sendreq->req_send.req_base.req_free_called) {
           MCA_PML_DR_FREE(request);
       } else {
           sendreq->req_send.req_base.req_ompi.req_state = OMPI_REQUEST_INACTIVE; 
           /* rewind convertor */
           if(sendreq->req_send.req_bytes_packed) {
               size_t offset = 0;
               ompi_convertor_set_position(&sendreq->req_send.req_convertor, &offset);
           }
           /* if buffered send - release any resources */
           if (sendreq->req_send.req_send_mode == MCA_PML_BASE_SEND_BUFFERED &&
               sendreq->req_send.req_addr != sendreq->req_send.req_base.req_addr) {
               mca_pml_base_bsend_request_fini((ompi_request_t*)sendreq);
           }
       }
    } else {
        MCA_PML_DR_FREE(request);
    }
    return OMPI_SUCCESS;
}

static int mca_pml_dr_send_request_free(struct ompi_request_t** request)
{
    MCA_PML_DR_FREE(request);
    return OMPI_SUCCESS;
}

static int mca_pml_dr_send_request_cancel(struct ompi_request_t* request, int complete)
{
    /* we dont cancel send requests by now */
    return OMPI_SUCCESS;
}

static void mca_pml_dr_send_request_construct(mca_pml_dr_send_request_t* req)
{
    req->req_vfrag0.vf_len = 1;
    req->req_vfrag0.vf_idx = 1;
    req->req_vfrag0.vf_mask = 1;
    req->req_send.req_base.req_type = MCA_PML_REQUEST_SEND;
    req->req_send.req_base.req_ompi.req_fini = mca_pml_dr_send_request_fini;
    req->req_send.req_base.req_ompi.req_free = mca_pml_dr_send_request_free;
    req->req_send.req_base.req_ompi.req_cancel = mca_pml_dr_send_request_cancel;

    OBJ_CONSTRUCT(&req->req_vfrag0, mca_pml_dr_vfrag_t);
    OBJ_CONSTRUCT(&req->req_pending, opal_list_t);
    OBJ_CONSTRUCT(&req->req_retrans, opal_list_t);
    OBJ_CONSTRUCT(&req->req_mutex, opal_mutex_t);
}

static void mca_pml_dr_send_request_destruct(mca_pml_dr_send_request_t* req)
{
    OBJ_DESTRUCT(&req->req_vfrag0);
    OBJ_DESTRUCT(&req->req_pending);
    OBJ_DESTRUCT(&req->req_retrans);
    OBJ_DESTRUCT(&req->req_mutex);
}


OBJ_CLASS_INSTANCE(
    mca_pml_dr_send_request_t,
    mca_pml_base_send_request_t,
    mca_pml_dr_send_request_construct,
    mca_pml_dr_send_request_destruct);

/**
 * Completion of a short message - nothing left to schedule.
 */

void mca_pml_dr_match_completion_cache(
    struct mca_btl_base_module_t* btl,  
    struct mca_btl_base_endpoint_t* ep,
    struct mca_btl_base_descriptor_t* descriptor,
    int status)
{
    mca_pml_dr_send_request_t* sendreq = (mca_pml_dr_send_request_t*)descriptor->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) descriptor->des_context; 

    /* check completion status */
    if(OMPI_SUCCESS != status) {
        /* TSW - FIX */
        opal_output(0, "%s:%d FATAL", __FILE__, __LINE__);
        orte_errmgr.abort();
    }

    /* attempt to cache the descriptor */
    MCA_BML_BASE_BTL_DES_RETURN( bml_btl, descriptor ); 

    /* signal request completion */
    OPAL_THREAD_LOCK(&ompi_request_lock);
    if(sendreq->req_num_acks == sendreq->req_num_vfrags) {
        MCA_PML_DR_SEND_REQUEST_PML_COMPLETE(sendreq);
    }
    OPAL_THREAD_UNLOCK(&ompi_request_lock);
}

/**
 * Completion of a short message - nothing left to schedule.
 */

void mca_pml_dr_match_completion_free(
    struct mca_btl_base_module_t* btl,  
    struct mca_btl_base_endpoint_t* ep,
    struct mca_btl_base_descriptor_t* descriptor,
    int status)
{
    mca_pml_dr_send_request_t* sendreq = (mca_pml_dr_send_request_t*)descriptor->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) descriptor->des_context; 

    /* check completion status */
    if(OMPI_SUCCESS != status) {
        /* TSW - FIX */
        opal_output(0, "%s:%d FATAL", __FILE__, __LINE__);
        orte_errmgr.abort();
    }

    /* free the descriptor */
    mca_bml_base_free( bml_btl, descriptor ); 

    /* signal request completion */
    OPAL_THREAD_LOCK(&ompi_request_lock);
    if(sendreq->req_num_acks == sendreq->req_num_vfrags) {
        MCA_PML_DR_SEND_REQUEST_PML_COMPLETE(sendreq);
    }
    OPAL_THREAD_UNLOCK(&ompi_request_lock);
}

/*
 *  Completion of the first fragment of a long message that 
 *  requires an acknowledgement
 */
static void mca_pml_dr_rndv_completion(
    mca_btl_base_module_t* btl,
    struct mca_btl_base_endpoint_t* ep,
    struct mca_btl_base_descriptor_t* descriptor,
    int status)
{
    mca_pml_dr_send_request_t* sendreq = (mca_pml_dr_send_request_t*)descriptor->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*)  descriptor->des_context; 
    /* check completion status */
    if(OMPI_SUCCESS != status) {
        /* TSW - FIX */
        opal_output(0, "%s:%d FATAL", __FILE__, __LINE__);
        orte_errmgr.abort();
    }

    /* count bytes of user data actually delivered */
    OPAL_THREAD_LOCK(&ompi_request_lock);
    MCA_PML_DR_SEND_REQUEST_SET_BYTES_DELIVERED(sendreq,descriptor,sizeof(mca_pml_dr_rendezvous_hdr_t));
    OPAL_THREAD_UNLOCK(&ompi_request_lock);

    /* return the descriptor */
    mca_bml_base_free(bml_btl, descriptor); 

    /* advance the request */
    MCA_PML_DR_SEND_REQUEST_ADVANCE(sendreq);

    /* check for pending requests */
    MCA_PML_DR_SEND_REQUEST_PROCESS_PENDING();
}


/**
 * Completion of additional fragments of a large message - may need
 * to schedule additional fragments.
 */

static void mca_pml_dr_frag_completion(
    mca_btl_base_module_t* btl,
    struct mca_btl_base_endpoint_t* ep,
    struct mca_btl_base_descriptor_t* descriptor,
    int status)
{
    mca_pml_dr_send_request_t* sendreq = (mca_pml_dr_send_request_t*)descriptor->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) descriptor->des_context; 
    bool schedule;

    /* check completion status */
    if(OMPI_SUCCESS != status) {
        /* TSW - FIX */
        opal_output(0, "%s:%d FATAL", __FILE__, __LINE__);
        orte_errmgr.abort();
    }

    /* check for request completion */
    OPAL_THREAD_LOCK(&ompi_request_lock);

    /* count bytes of user data actually delivered */
    MCA_PML_DR_SEND_REQUEST_SET_BYTES_DELIVERED(sendreq,descriptor,sizeof(mca_pml_dr_frag_hdr_t));
    if (OPAL_THREAD_ADD_SIZE_T(&sendreq->req_pipeline_depth,-1) == 0 &&
        sendreq->req_bytes_delivered == sendreq->req_send.req_bytes_packed &&
        sendreq->req_num_acks == sendreq->req_num_vfrags) {
        MCA_PML_DR_SEND_REQUEST_PML_COMPLETE(sendreq); 
        schedule = false;
    } else {
        schedule = true;
    }
    OPAL_THREAD_UNLOCK(&ompi_request_lock);
    if(schedule) {
        mca_pml_dr_send_request_schedule(sendreq);
    }

    /* return the descriptor */
    mca_bml_base_free(bml_btl, descriptor);

    /* check for pending requests */
    MCA_PML_DR_SEND_REQUEST_PROCESS_PENDING();
}



/**
 *  Buffer the entire message and mark as complete.
 */

int mca_pml_dr_send_request_start_buffered(
    mca_pml_dr_send_request_t* sendreq,
    mca_bml_base_btl_t* bml_btl,
    size_t size)
{
    mca_btl_base_descriptor_t* descriptor;
    mca_btl_base_segment_t* segment;
    mca_pml_dr_hdr_t* hdr;
    struct iovec iov;
    unsigned int iov_count;
    size_t max_data;
    int32_t free_after;
    int rc;

    /* allocate descriptor */
    mca_bml_base_alloc(bml_btl, &descriptor, sizeof(mca_pml_dr_rendezvous_hdr_t) + size);
    if(NULL == descriptor) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    } 
    segment = descriptor->des_src;

    /* pack the data into the BTL supplied buffer */
    iov.iov_base = (void*)((unsigned char*)segment->seg_addr.pval + 
             sizeof(mca_pml_dr_rendezvous_hdr_t));
    iov.iov_len = size;
    iov_count = 1;
    max_data = size;
    if((rc = ompi_convertor_pack(
        &sendreq->req_send.req_convertor,
        &iov,
        &iov_count,
        &max_data,
        &free_after)) < 0) {
        mca_bml_base_free(bml_btl, descriptor);
        return rc;
    }

    /* update lengths */
    segment->seg_len = sizeof(mca_pml_dr_rendezvous_hdr_t) + max_data;
    sendreq->req_send_offset = max_data;
    sendreq->req_vfrag0.vf_size = max_data;

    descriptor->des_cbfunc = mca_pml_dr_rndv_completion;
    descriptor->des_flags |= MCA_BTL_DES_FLAGS_PRIORITY;
    descriptor->des_cbdata = sendreq;

    /* buffer the remainder of the message */
    rc = mca_pml_base_bsend_request_alloc((ompi_request_t*)sendreq);
    if(OMPI_SUCCESS != rc) {
        mca_bml_base_free(bml_btl, descriptor);
        return rc;
    }

    iov.iov_base = (void*)(((unsigned char*)sendreq->req_send.req_addr) + sendreq->req_send_offset);
    iov.iov_len = max_data = sendreq->req_send.req_bytes_packed - sendreq->req_send_offset;

    if((rc = ompi_convertor_pack(
            &sendreq->req_send.req_convertor,
            &iov,
            &iov_count,
            &max_data,
            &free_after)) < 0) {
            mca_bml_base_free(bml_btl, descriptor);
            return rc;
    }

    /* build rendezvous header */
    hdr = (mca_pml_dr_hdr_t*)segment->seg_addr.pval;
    hdr->hdr_common.hdr_flags = 0;
    hdr->hdr_common.hdr_csum = 0;
    hdr->hdr_common.hdr_type = MCA_PML_DR_HDR_TYPE_RNDV;
    hdr->hdr_match.hdr_vid = sendreq->req_vfrag0.vf_id;
    hdr->hdr_match.hdr_ctx = sendreq->req_send.req_base.req_comm->c_contextid;
    hdr->hdr_match.hdr_src = sendreq->req_send.req_base.req_comm->c_my_rank;
    hdr->hdr_match.hdr_tag = sendreq->req_send.req_base.req_tag;
    hdr->hdr_match.hdr_seq = sendreq->req_send.req_base.req_sequence;
    hdr->hdr_match.hdr_csum = sendreq->req_send.req_convertor.checksum;
    hdr->hdr_match.hdr_src_req.pval = sendreq;
    hdr->hdr_rndv.hdr_msg_length = sendreq->req_send.req_bytes_packed;
    hdr->hdr_common.hdr_csum = opal_csum(hdr, sizeof(mca_pml_dr_rendezvous_hdr_t));

    /* re-init convertor for packed data */
    ompi_convertor_prepare_for_send(
            &sendreq->req_send.req_convertor,
            sendreq->req_send.req_datatype,
            sendreq->req_send.req_count,
            sendreq->req_send.req_addr);

    /* request is complete at mpi level */
    OPAL_THREAD_LOCK(&ompi_request_lock);
    MCA_PML_DR_SEND_REQUEST_MPI_COMPLETE(sendreq);
    OPAL_THREAD_UNLOCK(&ompi_request_lock);

    /* send */
    rc = mca_bml_base_send(bml_btl, descriptor, MCA_BTL_TAG_PML);
    if(OMPI_SUCCESS != rc) {
        mca_bml_base_free(bml_btl, descriptor );
    }
    return rc;
}


/**
 *  BTL requires "specially" allocated memory. Request a segment that
 *  is used for initial hdr and any eager data.
 */

int mca_pml_dr_send_request_start_copy(
    mca_pml_dr_send_request_t* sendreq,
    mca_bml_base_btl_t* bml_btl,
    size_t size)
{
    mca_btl_base_descriptor_t* descriptor;
    mca_btl_base_segment_t* segment;
    mca_pml_dr_hdr_t* hdr;
    struct iovec iov;
    unsigned int iov_count;
    size_t max_data;
    int32_t free_after;
    int rc;

    /* allocate descriptor */
    mca_bml_base_alloc(bml_btl, &descriptor, sizeof(mca_pml_dr_match_hdr_t) + size);
    if(NULL == descriptor) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    } 
    segment = descriptor->des_src;

    /* pack the data into the supplied buffer */
    iov.iov_base = (void*)((unsigned char*)segment->seg_addr.pval + sizeof(mca_pml_dr_match_hdr_t));
    iov.iov_len = size;
    iov_count = 1;
    max_data = size;
    if((rc = ompi_convertor_pack(
            &sendreq->req_send.req_convertor,
            &iov,
            &iov_count,
            &max_data,
            &free_after)) < 0) {
            mca_bml_base_free(bml_btl, descriptor);
            return rc;
    }

    /* build match header */
    hdr = (mca_pml_dr_hdr_t*)segment->seg_addr.pval;
    hdr->hdr_common.hdr_flags = 0;
    hdr->hdr_common.hdr_csum = 0;
    hdr->hdr_common.hdr_type = MCA_PML_DR_HDR_TYPE_MATCH;
    hdr->hdr_match.hdr_ctx = sendreq->req_send.req_base.req_comm->c_contextid;
    hdr->hdr_match.hdr_src = sendreq->req_send.req_base.req_comm->c_my_rank;
    hdr->hdr_match.hdr_tag = sendreq->req_send.req_base.req_tag;
    hdr->hdr_match.hdr_seq = sendreq->req_send.req_base.req_sequence;
    hdr->hdr_match.hdr_csum = sendreq->req_send.req_convertor.checksum;
    hdr->hdr_common.hdr_csum = opal_csum(hdr, sizeof(mca_pml_dr_match_hdr_t));

    /* update lengths */
    segment->seg_len = sizeof(mca_pml_dr_match_hdr_t) + max_data;
    sendreq->req_send_offset = max_data;
    sendreq->req_vfrag0.vf_size = max_data;

    /* short message */
    descriptor->des_cbfunc = mca_pml_dr_match_completion_free;
    descriptor->des_flags |= MCA_BTL_DES_FLAGS_PRIORITY;
    descriptor->des_cbdata = sendreq;

    /* signal request completion */
    OPAL_THREAD_LOCK(&ompi_request_lock);
    MCA_PML_DR_SEND_REQUEST_MPI_COMPLETE(sendreq);
    OPAL_THREAD_UNLOCK(&ompi_request_lock);

    /* send */
    rc = mca_bml_base_send(bml_btl, descriptor, MCA_BTL_TAG_PML);
    if(OMPI_SUCCESS != rc) {
        mca_bml_base_free(bml_btl, descriptor );
    } 
    return rc;
}

/**
 *  BTL can send directly from user buffer so allow the BTL
 *  to prepare the segment list.
 */

int mca_pml_dr_send_request_start_prepare(
    mca_pml_dr_send_request_t* sendreq,
    mca_bml_base_btl_t* bml_btl,
    size_t size)
{
    mca_btl_base_descriptor_t* descriptor;
    mca_btl_base_segment_t* segment;
    mca_pml_dr_hdr_t* hdr;
    int rc;

    /* prepare descriptor */
    mca_bml_base_prepare_src(
            bml_btl, 
            NULL,
            &sendreq->req_send.req_convertor,
            sizeof(mca_pml_dr_match_hdr_t),
            &size,
            &descriptor);
    if(NULL == descriptor) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    } 
    segment = descriptor->des_src;

    /* build match header */
    hdr = (mca_pml_dr_hdr_t*)segment->seg_addr.pval;
    hdr->hdr_common.hdr_flags = 0;
    hdr->hdr_common.hdr_csum = 0;
    hdr->hdr_common.hdr_type = MCA_PML_DR_HDR_TYPE_MATCH;
    hdr->hdr_match.hdr_ctx = sendreq->req_send.req_base.req_comm->c_contextid;
    hdr->hdr_match.hdr_src = sendreq->req_send.req_base.req_comm->c_my_rank;
    hdr->hdr_match.hdr_tag = sendreq->req_send.req_base.req_tag;
    hdr->hdr_match.hdr_seq = sendreq->req_send.req_base.req_sequence;
    hdr->hdr_match.hdr_csum = sendreq->req_send.req_convertor.checksum;
    hdr->hdr_common.hdr_csum = opal_csum(hdr, sizeof(mca_pml_dr_match_hdr_t));

    /* short message */
    descriptor->des_cbfunc = mca_pml_dr_match_completion_free;
    descriptor->des_flags |= MCA_BTL_DES_FLAGS_PRIORITY;
    descriptor->des_cbdata = sendreq;
       
    /* update lengths */
    sendreq->req_send_offset = size;
    sendreq->req_vfrag0.vf_size = size;

    /* send */
    rc = mca_bml_base_send(bml_btl, descriptor, MCA_BTL_TAG_PML); 
    if(OMPI_SUCCESS != rc) {
        mca_bml_base_free(bml_btl, descriptor );
    }
    return rc;
}


/**
 *  Rendezvous is required. Eager send up to
 *  the btls eager limit.
 */

int mca_pml_dr_send_request_start_rndv(
    mca_pml_dr_send_request_t* sendreq,
    mca_bml_base_btl_t* bml_btl,
    size_t size,
    int flags)
{
    mca_btl_base_descriptor_t* des;
    mca_btl_base_segment_t* segment;
    mca_pml_dr_hdr_t* hdr;
    int rc;

    /* prepare descriptor */
    if(size == 0) {
        mca_bml_base_alloc(
                           bml_btl, 
                           &des, 
                           sizeof(mca_pml_dr_rendezvous_hdr_t)
                           ); 
    } else {
        mca_bml_base_prepare_src(
                                 bml_btl, 
                                 NULL,
                                 &sendreq->req_send.req_convertor,
                                 sizeof(mca_pml_dr_rendezvous_hdr_t),
                                 &size,
                                 &des);
    }

    if(NULL == des) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    } 
    segment = des->des_src;

    /* build hdr */
    hdr = (mca_pml_dr_hdr_t*)segment->seg_addr.pval;
    hdr->hdr_common.hdr_flags = flags;
    hdr->hdr_common.hdr_type = MCA_PML_DR_HDR_TYPE_RNDV;
    hdr->hdr_match.hdr_ctx = sendreq->req_send.req_base.req_comm->c_contextid;
    hdr->hdr_match.hdr_src = sendreq->req_send.req_base.req_comm->c_my_rank;
    hdr->hdr_match.hdr_tag = sendreq->req_send.req_base.req_tag;
    hdr->hdr_match.hdr_seq = sendreq->req_send.req_base.req_sequence;
    hdr->hdr_match.hdr_src_req.pval = sendreq;
    hdr->hdr_rndv.hdr_msg_length = sendreq->req_send.req_bytes_packed;

    /* first fragment of a long message */
    des->des_flags |= MCA_BTL_DES_FLAGS_PRIORITY;
    des->des_cbdata = sendreq;
    des->des_cbfunc = mca_pml_dr_rndv_completion;
    sendreq->req_send_offset = size;
    sendreq->req_vfrag0.vf_size = size;

    /* send */
    rc = mca_bml_base_send(bml_btl, des, MCA_BTL_TAG_PML);
    if(OMPI_SUCCESS != rc) {
        mca_bml_base_free(bml_btl, des );
    }
    return rc;
}


/**
 *  Schedule pipeline of send descriptors for the given request,
 *  using send protocol.
 */

int mca_pml_dr_send_request_schedule(mca_pml_dr_send_request_t* sendreq)
{ 
    /*
     * Only allow one thread in this routine for a given request.
     * However, we cannot block callers on a mutex, so simply keep track
     * of the number of times the routine has been called and run through
     * the scheduling logic once for every call.
    */
    
    mca_bml_base_endpoint_t* bml_endpoint = sendreq->req_endpoint;
    if(OPAL_THREAD_ADD32(&sendreq->req_lock,1) == 1) {
        do {
            /* allocate remaining bytes to BTLs */
            size_t bytes_remaining = sendreq->req_send.req_bytes_packed - sendreq->req_send_offset;
            while(bytes_remaining > 0 && 
                  sendreq->req_pipeline_depth < mca_pml_dr.send_pipeline_depth) {
                
                mca_pml_dr_frag_hdr_t* hdr;
                mca_btl_base_descriptor_t* des;
                mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_next(&bml_endpoint->btl_send); 
                mca_pml_dr_vfrag_t* vfrag = sendreq->req_vfrag;
                size_t size = bytes_remaining;
                size_t offset = sendreq->req_send_offset - vfrag->vf_offset;
                int rc;

                /* do we need to allocate a new vfrag */
                if(vfrag->vf_size == offset) {
                    MCA_PML_DR_VFRAG_ALLOC(vfrag,rc);
                    if(NULL == vfrag) {
                        OPAL_THREAD_LOCK(&mca_pml_dr.lock);
                        opal_list_append(&mca_pml_dr.send_pending, (opal_list_item_t*)sendreq);
                        OPAL_THREAD_UNLOCK(&mca_pml_dr.lock);
                        break;
                    }
                    MCA_PML_DR_SEND_REQUEST_VFRAG_INIT(sendreq,bml_endpoint,bytes_remaining,vfrag);
                    offset = 0;
                    sendreq->req_num_vfrags++;
                }

                /* makes sure that we don't exceed vfrag size */
                if (size > vfrag->vf_max_send_size) {
                    size = vfrag->vf_max_send_size;
                }
                if (size > vfrag->vf_size - offset) {
                    size = vfrag->vf_size - offset;
                }

                /* pack into a descriptor */
                ompi_convertor_set_position(&sendreq->req_send.req_convertor, &sendreq->req_send_offset);
                mca_bml_base_prepare_src(
                                         bml_btl, 
                                         NULL, 
                                         &sendreq->req_send.req_convertor,
                                         sizeof(mca_pml_dr_frag_hdr_t),
                                         &size,
                                         &des
                                         );
                if(des == NULL) {
                    OPAL_THREAD_LOCK(&mca_pml_dr.lock);
                    opal_list_append(&mca_pml_dr.send_pending, (opal_list_item_t*)sendreq);
                    OPAL_THREAD_UNLOCK(&mca_pml_dr.lock);
                    break;
                }
                des->des_cbfunc = mca_pml_dr_frag_completion;
                des->des_cbdata = sendreq;

                /* setup header */
                hdr = (mca_pml_dr_frag_hdr_t*)des->des_src->seg_addr.pval;
                hdr->hdr_common.hdr_flags = 0;
                hdr->hdr_common.hdr_csum = 0;
                hdr->hdr_common.hdr_type = MCA_PML_DR_HDR_TYPE_FRAG;
                hdr->hdr_vid = vfrag->vf_id;
                hdr->hdr_vlen = vfrag->vf_len;
                hdr->hdr_frag_idx = vfrag->vf_idx;
                hdr->hdr_frag_csum = sendreq->req_send.req_convertor.checksum;
                hdr->hdr_frag_offset = sendreq->req_send_offset;
                hdr->hdr_src_req.pval = sendreq;
                hdr->hdr_dst_req = sendreq->req_vfrag0.vf_recv;
                hdr->hdr_common.hdr_csum = opal_csum(hdr, sizeof(mca_pml_dr_frag_hdr_t));

                /* update state */
                vfrag->vf_idx++;
                sendreq->req_send_offset += size;
                OPAL_THREAD_ADD_SIZE_T(&sendreq->req_pipeline_depth,1);

                /* start vfrag watchdog timer */
                MCA_PML_DR_VFRAG_WDOG_START(vfrag);

                /* initiate send - note that this may complete before the call returns */
                rc = mca_bml_base_send( bml_btl, des, MCA_BTL_TAG_PML);
                
                if(rc == OMPI_SUCCESS) {
                    bytes_remaining -= size;
                } else {
                    sendreq->req_send_offset -= size;
                    OPAL_THREAD_ADD_SIZE_T(&sendreq->req_pipeline_depth,-1);
                    mca_bml_base_free(bml_btl,des);
                    OPAL_THREAD_LOCK(&mca_pml_dr.lock);
                    opal_list_append(&mca_pml_dr.send_pending, (opal_list_item_t*)sendreq);
                    OPAL_THREAD_UNLOCK(&mca_pml_dr.lock);
                    break;
                }
                mca_pml_dr_progress(); 
            }

            /*
             * VFrags w/ nacks or that timed out
             */
            while(opal_list_get_size(&sendreq->req_retrans) &&
                  sendreq->req_pipeline_depth < mca_pml_dr.send_pipeline_depth) {
                mca_pml_dr_vfrag_t* vfrag = (mca_pml_dr_vfrag_t*)opal_list_get_first(&sendreq->req_retrans);

                /*
                 * Retransmit fragments that have not been acked.
                 */
                while(vfrag->vf_idx < vfrag->vf_len && 
                      sendreq->req_pipeline_depth < mca_pml_dr.send_pipeline_depth) {
                    if(((1 << vfrag->vf_idx) & vfrag->vf_ack) == 0) {
                        mca_bml_base_btl_t* bml_btl = mca_bml_base_btl_array_get_next(&bml_endpoint->btl_send); 
                        mca_pml_dr_frag_hdr_t* hdr;
                        mca_btl_base_descriptor_t* des;
                        size_t offset = vfrag->vf_offset + (vfrag->vf_max_send_size * vfrag->vf_idx);
                        size_t size;
                        int rc;

                        if(vfrag->vf_idx == vfrag->vf_len - 1) {
                            size = vfrag->vf_size - offset;
                        } else {
                            size = vfrag->vf_max_send_size;
                        }

                        /* pack into a descriptor */
                        ompi_convertor_set_position(&sendreq->req_send.req_convertor, &offset);
                        mca_bml_base_prepare_src(
                                                 bml_btl, 
                                                 NULL, 
                                                 &sendreq->req_send.req_convertor,
                                                 sizeof(mca_pml_dr_frag_hdr_t),
                                                 &size,
                                                 &des
                                                 );
                        if(des == NULL) {
                            OPAL_THREAD_LOCK(&mca_pml_dr.lock);
                            opal_list_append(&mca_pml_dr.send_pending, (opal_list_item_t*)sendreq);
                            OPAL_THREAD_UNLOCK(&mca_pml_dr.lock);
                            break;
                        }
                        des->des_cbfunc = mca_pml_dr_frag_completion;
                        des->des_cbdata = sendreq;

                        /* setup header */
                        hdr = (mca_pml_dr_frag_hdr_t*)des->des_src->seg_addr.pval;
                        hdr->hdr_common.hdr_flags = 0;
                        hdr->hdr_common.hdr_csum = 0;
                        hdr->hdr_common.hdr_type = MCA_PML_DR_HDR_TYPE_FRAG;
                        hdr->hdr_vid = vfrag->vf_id;
                        hdr->hdr_vlen = vfrag->vf_len;
                        hdr->hdr_frag_idx = vfrag->vf_idx;
                        hdr->hdr_frag_csum = sendreq->req_send.req_convertor.checksum;
                        hdr->hdr_frag_offset = sendreq->req_send_offset;
                        hdr->hdr_src_req.pval = sendreq;
                        hdr->hdr_dst_req = sendreq->req_vfrag0.vf_recv;
                        hdr->hdr_common.hdr_csum = opal_csum(hdr, sizeof(mca_pml_dr_frag_hdr_t));

                        /* update state */
                        vfrag->vf_idx++;
                        sendreq->req_send_offset += size;
                        OPAL_THREAD_ADD_SIZE_T(&sendreq->req_pipeline_depth,1);

                        /* start vfrag watchdog timer */
                        MCA_PML_DR_VFRAG_WDOG_START(vfrag);

                        /* initiate send - note that this may complete before the call returns */
                        rc = mca_bml_base_send( bml_btl, des, MCA_BTL_TAG_PML);
                        
                        if(rc == OMPI_SUCCESS) {
                            bytes_remaining -= size;
                        } else {
                            vfrag->vf_idx--;
                            OPAL_THREAD_ADD_SIZE_T(&sendreq->req_pipeline_depth,-1);
                            mca_bml_base_free(bml_btl,des);
                            OPAL_THREAD_LOCK(&mca_pml_dr.lock);
                            opal_list_append(&mca_pml_dr.send_pending, (opal_list_item_t*)sendreq);
                            OPAL_THREAD_UNLOCK(&mca_pml_dr.lock);
                            break;
                        }
                    }
                    vfrag->vf_idx++;
                }

                /* move from retrans to pending list */
                if(vfrag->vf_idx == vfrag->vf_len) {
                    OPAL_THREAD_LOCK(&sendreq->req_mutex);
                    opal_list_remove_item(&sendreq->req_retrans, (opal_list_item_t*)vfrag);
                    opal_list_append(&sendreq->req_pending, (opal_list_item_t*)vfrag);
                    OPAL_THREAD_UNLOCK(&sendreq->req_mutex);
                }
            }
        } while (OPAL_THREAD_ADD32(&sendreq->req_lock,-1) > 0);
    }
    return OMPI_SUCCESS;
} 


/**
 *  Acknowledgment of vfrag
 */
void mca_pml_dr_send_request_acked(
    mca_pml_dr_send_request_t* sendreq,
    mca_pml_dr_ack_hdr_t* ack)
{
    if(ack->hdr_common.hdr_flags & MCA_PML_DR_HDR_FLAGS_MATCH) {
        sendreq->req_vfrag0.vf_recv = ack->hdr_dst_req;
        MCA_PML_DR_SEND_REQUEST_ADVANCE(sendreq);
    } else {
        mca_pml_dr_vfrag_t* vfrag;
        MCA_PML_DR_SEND_REQUEST_VFRAG_PENDING(sendreq, ack, vfrag);
        if(NULL == vfrag) {
            return;
        }

        /* add in acknowledged fragments */
        vfrag->vf_ack |= ack->hdr_vmask;

        /* have all fragments w/in this vfrag been acked? */
        if((vfrag->vf_ack & vfrag->vf_mask) == vfrag->vf_mask) {
 
            /* return vfrag */
            if (vfrag != &sendreq->req_vfrag0) {
                MCA_PML_DR_VFRAG_RETURN(vfrag);
            }

            /* are we done with this request */
            OPAL_THREAD_LOCK(&ompi_request_lock);
            sendreq->req_num_acks++;
            if(sendreq->req_bytes_delivered == sendreq->req_send.req_bytes_packed &&
               sendreq->req_num_acks == sendreq->req_num_vfrags) {
               MCA_PML_DR_SEND_REQUEST_PML_COMPLETE(sendreq);
            }
            OPAL_THREAD_UNLOCK(&ompi_request_lock);

        } else {
            /* retransmit missing fragments */
            OPAL_THREAD_LOCK(&sendreq->req_mutex);
            vfrag->vf_idx = 0;
            opal_list_append(&sendreq->req_retrans, (opal_list_item_t*)vfrag);
            OPAL_THREAD_UNLOCK(&sendreq->req_mutex);
            mca_pml_dr_send_request_schedule(sendreq);
        }
    }
}


void mca_pml_dr_send_request_nacked(
    mca_pml_dr_send_request_t* sendreq,
    mca_pml_dr_ack_hdr_t* ack)
{
    mca_pml_dr_vfrag_t* vfrag;
    MCA_PML_DR_SEND_REQUEST_VFRAG_PENDING(sendreq, ack, vfrag);
    if(NULL == vfrag) {
        return;
    }

    /* removed nacked bits from acknowledged fragments */
    vfrag->vf_idx = 0;
    vfrag->vf_ack &= ~ack->hdr_vmask;

    /* retransmit missing fragments */
    OPAL_THREAD_LOCK(&sendreq->req_mutex);
    opal_list_append(&sendreq->req_retrans, (opal_list_item_t*)vfrag);
    OPAL_THREAD_UNLOCK(&sendreq->req_mutex);
    mca_pml_dr_send_request_schedule(sendreq);
}