/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 The Trustees of the University of Tennessee.
 *                         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 (c) 2007-2018 Los Alamos National Security, LLC.  All rights
 *                         reserved.
 * Copyright (c) 2010      IBM Corporation.  All rights reserved.
 * Copyright (c) 2012-2013 Sandia National Laboratories.  All rights reserved.
 * Copyright (c) 2015 Cisco Systems, Inc.  All rights reserved.
 * Copyright (c) 2017      The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2017-2018 Intel, Inc. All rights reserved.
 * Copyright (c) 2021      Google, LLC. All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */

#include "ompi_config.h"

#include "osc_rdma.h"
#include "osc_rdma_frag.h"
#include "osc_rdma_active_target.h"

#include "mpi.h"
#include "opal/mca/threads/mutex.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/osc/base/base.h"

/**
 * ompi_osc_rdma_pending_post_t:
 *
 * Describes a post operation that was encountered outside it's
 * matching start operation.
 */
struct ompi_osc_rdma_pending_post_t {
    opal_list_item_t super;
    int rank;
};
typedef struct ompi_osc_rdma_pending_post_t ompi_osc_rdma_pending_post_t;

static OBJ_CLASS_INSTANCE(ompi_osc_rdma_pending_post_t, opal_list_item_t, NULL, NULL);

static void ompi_osc_rdma_pending_op_construct (ompi_osc_rdma_pending_op_t *pending_op)
{
    pending_op->op_frag = NULL;
    pending_op->op_buffer = NULL;
    pending_op->op_result = NULL;
    pending_op->op_complete = false;
    pending_op->cbfunc = NULL;
    pending_op->module = NULL;
}

static void ompi_osc_rdma_pending_op_destruct (ompi_osc_rdma_pending_op_t *pending_op)
{
    if (NULL != pending_op->op_frag) {
        ompi_osc_rdma_frag_complete (pending_op->op_frag);
    }

    if (NULL != pending_op->module) {
        (void) opal_atomic_fetch_add_32 (&pending_op->module->pending_ops, -1);
    }

    ompi_osc_rdma_pending_op_construct (pending_op);
}

OBJ_CLASS_INSTANCE(ompi_osc_rdma_pending_op_t, opal_list_item_t,
                   ompi_osc_rdma_pending_op_construct,
                   ompi_osc_rdma_pending_op_destruct);


/**
 * compare_ranks:
 *
 * @param[in] ptra    Pointer to integer item
 * @param[in] ptrb    Pointer to integer item
 *
 * @returns 0 if *ptra == *ptrb
 * @returns -1 if *ptra < *ptrb
 * @returns 1 otherwise
 *
 * This function is used to sort the rank list. It can be removed if
 * groups are always in order.
 */
static int compare_ranks (const void *ptra, const void *ptrb)
{
    int a = *((int *) ptra);
    int b = *((int *) ptrb);

    if (a < b) {
        return -1;
    } else if (a > b) {
        return 1;
    }

    return 0;
}

/**
 * ompi_osc_rdma_get_comm_ranks:
 *
 * @param[in] module    - OSC RDMA module
 * @param[in] sub_group - Group with ranks to translate
 *
 * @returns an array of translated ranks on success or NULL on failure
 *
 * Translate the ranks given in {sub_group} into ranks in the
 * communicator used to create {module}.
 */
static ompi_osc_rdma_peer_t **ompi_osc_rdma_get_peers (ompi_osc_rdma_module_t *module, ompi_group_t *sub_group)
{
    int size = ompi_group_size(sub_group);
    ompi_osc_rdma_peer_t **peers;
    int *ranks1, *ranks2;
    int ret;

    ranks1 = calloc (size, sizeof(int));
    ranks2 = calloc (size, sizeof(int));
    peers = calloc (size, sizeof (ompi_osc_rdma_peer_t *));
    if (NULL == ranks1 || NULL == ranks2 || NULL == peers) {
        free (ranks1);
        free (ranks2);
        free (peers);
        return NULL;
    }

    for (int i = 0 ; i < size ; ++i) {
        ranks1[i] = i;
    }

    ret = ompi_group_translate_ranks (sub_group, size, ranks1, module->comm->c_local_group,
                                      ranks2);
    free (ranks1);
    if (OMPI_SUCCESS != ret) {
        free (ranks2);
        free (peers);
        return NULL;
    }

    qsort (ranks2, size, sizeof (int), compare_ranks);
    for (int i = 0 ; i < size ; ++i) {
        peers[i] = ompi_osc_rdma_module_peer (module, ranks2[i]);
        if (NULL == peers[i]) {
            free (peers);
            peers = NULL;
            break;
        }

        OBJ_RETAIN(peers[i]);
    }
    free (ranks2);

    return peers;
}

static void ompi_osc_rdma_release_peers (ompi_osc_rdma_peer_t **peers, int npeers)
{
    for (int i = 0 ; i < npeers ; ++i) {
        OBJ_RELEASE(peers[i]);
    }

    free (peers);
}

static void ompi_osc_rdma_handle_post (ompi_osc_rdma_module_t *module, int rank, ompi_osc_rdma_peer_t **peers, int npeers) {
    ompi_osc_rdma_state_t *state = module->state;
    ompi_osc_rdma_pending_post_t *pending_post;

    /* look for the posting peer in the group */
    for (int j = 0 ; j < npeers ; ++j) {
        if (rank == peers[j]->rank) {
            OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_INFO, "got expected post from %d. still expecting posts from %d processes",
                             rank, (int) (npeers - state->num_post_msgs - 1));
            /* an atomic is not really necessary as this function is currently used but it doesn't hurt */
            ompi_osc_rdma_counter_add (&state->num_post_msgs, 1);
            return;
        }
    }

    /* post does not belong to this start epoch. save it for later */
    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_INFO, "got unexpected post from %d . queueing for later", rank);
    pending_post = OBJ_NEW(ompi_osc_rdma_pending_post_t);
    pending_post->rank = rank;
    OPAL_THREAD_SCOPED_LOCK(&module->lock, opal_list_append (&module->pending_posts, &pending_post->super));
}

static void ompi_osc_rdma_check_posts (ompi_osc_rdma_module_t *module)
{
    ompi_osc_rdma_state_t *state = module->state;
    ompi_osc_rdma_sync_t *sync = &module->all_sync;
    int count = 0;

    if (OMPI_OSC_RDMA_SYNC_TYPE_PSCW == sync->type) {
        count = sync->num_peers;
    }

    for (int i = 0 ; i < OMPI_OSC_RDMA_POST_PEER_MAX ; ++i) {
        /* no post at this index (yet) */
        if (0 == state->post_peers[i]) {
            continue;
        }

        ompi_osc_rdma_handle_post (module, state->post_peers[i] - 1, sync->peer_list.peers, count);
        state->post_peers[i] = 0;
    }
}

static int ompi_osc_rdma_post_peer (ompi_osc_rdma_module_t *module, ompi_osc_rdma_peer_t *peer)
{
    uint64_t target = (uint64_t) (intptr_t) peer->state + offsetof (ompi_osc_rdma_state_t, post_index);
    ompi_osc_rdma_lock_t post_index, result, _tmp_value;
    int my_rank = ompi_comm_rank (module->comm);
    int ret;

    if (peer->rank == my_rank) {
        ompi_osc_rdma_handle_post (module, my_rank, NULL, 0);
        return OMPI_SUCCESS;
    }

    /* get a post index */
    if (!ompi_osc_rdma_peer_local_state (peer)) {
        ret = ompi_osc_rdma_lock_btl_fop (module, peer, target, MCA_BTL_ATOMIC_ADD, 1, &post_index, true);
        if (OPAL_UNLIKELY(OMPI_SUCCESS != ret)) {
            return ret;
        }
    } else {
        post_index = ompi_osc_rdma_counter_add ((osc_rdma_atomic_counter_t *) (intptr_t) target, 1) - 1;
    }

    post_index &= OMPI_OSC_RDMA_POST_PEER_MAX - 1;

    target = (uint64_t) (intptr_t) peer->state + offsetof (ompi_osc_rdma_state_t, post_peers) +
        sizeof (osc_rdma_counter_t) * post_index;

    do {
        OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "attempting to post to index %d @ rank %d", (int)post_index, peer->rank);

        _tmp_value = 0;

        /* try to post. if the value isn't 0 then another rank is occupying this index */
        if (!ompi_osc_rdma_peer_local_state (peer)) {
            ret = ompi_osc_rdma_lock_btl_cswap (module, peer, target, 0, 1 + (int64_t) my_rank, &result);
            if (OPAL_UNLIKELY(OMPI_SUCCESS != ret)) {
                return ret;
            }
        } else {
            result = !ompi_osc_rdma_lock_compare_exchange ((osc_rdma_atomic_counter_t *) target, &_tmp_value,
                                                           1 + (osc_rdma_counter_t) my_rank);
        }

        if (OPAL_LIKELY(0 == result)) {
            break;
        }

        /* prevent circular wait by checking for post messages received */
        ompi_osc_rdma_check_posts (module);

        /* zzzzzzzzzzzzz */
        nanosleep (&(struct timespec) {.tv_sec = 0, .tv_nsec = 100}, NULL);
    } while (1);

    return OMPI_SUCCESS;
}

int ompi_osc_rdma_post_atomic (ompi_group_t *group, int mpi_assert, ompi_win_t *win)
{
    ompi_osc_rdma_module_t *module = GET_MODULE(win);
    ompi_osc_rdma_peer_t **peers;
    ompi_osc_rdma_state_t *state = module->state;
    int ret = OMPI_SUCCESS;

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "post: %p, %d, %s", (void*) group, mpi_assert, win->w_name);

    /* check if we are already in a post epoch */
    if (module->pw_group) {
        return OMPI_ERR_RMA_SYNC;
    }

    /* save the group */
    OBJ_RETAIN(group);

    OPAL_THREAD_LOCK(&module->lock);

    /* ensure we're not already in a post */
    if (NULL != module->pw_group) {
        OPAL_THREAD_UNLOCK(&(module->lock));
        return OMPI_ERR_RMA_SYNC;
    }
    module->pw_group = group;

    /* Update completion counter.  Can't have received any completion
       messages yet; complete won't send a completion header until
       we've sent a post header. */
    state->num_complete_msgs = 0;
    OPAL_THREAD_UNLOCK(&module->lock);

    if ((mpi_assert & MPI_MODE_NOCHECK) || 0 == ompi_group_size (group)) {
        return OMPI_SUCCESS;
    }

    /* translate group ranks into the communicator */
    peers = ompi_osc_rdma_get_peers (module, module->pw_group);
    if (OPAL_UNLIKELY(NULL == peers)) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "sending post messages");

    /* send a hello counter to everyone in group */
    for (int i = 0 ; i < ompi_group_size(module->pw_group) ; ++i) {
        ret = ompi_osc_rdma_post_peer (module, peers[i]);
        if (OPAL_UNLIKELY(OMPI_SUCCESS != ret)) {
            break;
        }
    }

    ompi_osc_rdma_release_peers (peers, ompi_group_size(module->pw_group));

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "post complete");

    return ret;
}

int ompi_osc_rdma_start_atomic (ompi_group_t *group, int mpi_assert, ompi_win_t *win)
{
    ompi_osc_rdma_module_t *module = GET_MODULE(win);
    ompi_osc_rdma_pending_post_t *pending_post, *next;
    ompi_osc_rdma_state_t *state = module->state;
    ompi_osc_rdma_sync_t *sync = &module->all_sync;
    int group_size = ompi_group_size (group);

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "start: %p, %d, %s", (void*) group, mpi_assert,
                     win->w_name);

    OPAL_THREAD_LOCK(&module->lock);

    /* check if we are already in an access epoch */
    if (ompi_osc_rdma_access_epoch_active (module)) {
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_ERR_RMA_SYNC;
    }

    /* mark all procs in this group as being in an access epoch */
    sync->num_peers = ompi_group_size (group);
    sync->sync.pscw.group = group;

    /* haven't processed any post messages yet */
    state->num_post_msgs = 0;

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "start group size %d", sync->num_peers);

    sync->type = OMPI_OSC_RDMA_SYNC_TYPE_PSCW;

    if (0 == ompi_group_size (group)) {
        /* nothing more to do. this is an empty start epoch */
        sync->peer_list.peers = NULL;
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_SUCCESS;
    }

    opal_atomic_wmb ();

    /* prevent us from entering a passive-target, fence, or another pscw access epoch until
     * the matching complete is called */
    sync->epoch_active = true;

    /* translate the group ranks into the communicator */
    sync->peer_list.peers = ompi_osc_rdma_get_peers (module, group);
    if (NULL == sync->peer_list.peers) {
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    /* save the group */
    OBJ_RETAIN(group);

    if (!(mpi_assert & MPI_MODE_NOCHECK)) {
        /* look through list of pending posts */
        OPAL_LIST_FOREACH_SAFE(pending_post, next, &module->pending_posts, ompi_osc_rdma_pending_post_t) {
            for (int i = 0 ; i < group_size ; ++i) {
                ompi_osc_rdma_peer_t *peer = sync->peer_list.peers[i];

                if (pending_post->rank == peer->rank) {
                    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "found queued post from %d. still expecting posts "
                                     "from %d processes", peer->rank, (int) (group_size - state->num_post_msgs - 1));
                    opal_list_remove_item (&module->pending_posts, &pending_post->super);
                    OBJ_RELEASE(pending_post);
                    ompi_osc_rdma_counter_add (&state->num_post_msgs, 1);
                    break;
                }
            }
        }

        /* wait for all post messages to arrive */
        while (state->num_post_msgs != group_size) {
            OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "waiting for post messages. have %d of %d",
                             (int) state->num_post_msgs, group_size);
            ompi_osc_rdma_check_posts (module);
            ompi_osc_rdma_progress (module);
        }
    } else {
        state->num_post_msgs = group_size;
    }

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "start complete");

    OPAL_THREAD_UNLOCK(&module->lock);
    return OMPI_SUCCESS;
}

int ompi_osc_rdma_complete_atomic (ompi_win_t *win)
{
    ompi_osc_rdma_module_t *module = GET_MODULE(win);
    ompi_osc_rdma_sync_t *sync = &module->all_sync;
    ompi_osc_rdma_peer_t **peers;
    ompi_group_t *group;
    int group_size;
    int ret __opal_attribute_unused__;

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "complete: %s", win->w_name);

    OPAL_THREAD_LOCK(&module->lock);
    if (0 == sync->num_peers) {
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_SUCCESS;
    }

    if (OMPI_OSC_RDMA_SYNC_TYPE_PSCW != sync->type) {
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_ERR_RMA_SYNC;
    }

    /* phase 1 cleanup sync object */
    group = sync->sync.pscw.group;
    group_size = sync->num_peers;
    sync->type = OMPI_OSC_RDMA_SYNC_TYPE_NONE;
    sync->epoch_active = false;

    peers = sync->peer_list.peers;
    if (NULL == peers) {
        OPAL_THREAD_UNLOCK(&(module->lock));
        return OMPI_SUCCESS;
    }

    OBJ_RELEASE(group);

    sync->peer_list.peers = NULL;

    OPAL_THREAD_UNLOCK(&(module->lock));

    ompi_osc_rdma_sync_rdma_complete (sync);

    /* for each process in the group increment their number of complete messages */
    for (int i = 0 ; i < group_size ; ++i) {
        ompi_osc_rdma_peer_t *peer = peers[i];
        intptr_t target = (intptr_t) peer->state + offsetof (ompi_osc_rdma_state_t, num_complete_msgs);

        if (!ompi_osc_rdma_peer_local_state (peer)) {
            ret = ompi_osc_rdma_lock_btl_op (module, peer, target, MCA_BTL_ATOMIC_ADD, 1, true);
            assert (OMPI_SUCCESS == ret);
        } else {
            (void) ompi_osc_rdma_counter_add ((osc_rdma_atomic_counter_t *) target, 1);
        }
    }

    /* release our reference to peers in this group */
    ompi_osc_rdma_release_peers (peers, group_size);

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "complete complete");

    return OMPI_SUCCESS;
}

int ompi_osc_rdma_wait_atomic (ompi_win_t *win)
{
    ompi_osc_rdma_module_t *module = GET_MODULE(win);
    ompi_osc_rdma_state_t *state = module->state;
    ompi_group_t *group;
    int group_size;

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "wait: %s", win->w_name);

    OPAL_THREAD_LOCK(&module->lock);
    if (NULL == module->pw_group) {
        OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_INFO, "no matching post");
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_ERR_RMA_SYNC;
    }

    group_size = ompi_group_size (module->pw_group);
    OPAL_THREAD_UNLOCK(&module->lock);

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "waiting on complete message. have %d of %d",
                     (int) state->num_complete_msgs, group_size);

    while (group_size != state->num_complete_msgs) {
        ompi_osc_rdma_progress (module);
        opal_atomic_mb ();
    }

    OPAL_THREAD_LOCK(&module->lock);
    group = module->pw_group;
    module->pw_group = NULL;
    OPAL_THREAD_UNLOCK(&module->lock);

    OBJ_RELEASE(group);

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "wait complete");

    return OMPI_SUCCESS;
}


int ompi_osc_rdma_test_atomic (ompi_win_t *win, int *flag)
{
    ompi_osc_rdma_module_t *module = GET_MODULE(win);
    ompi_osc_rdma_state_t *state = module->state;
    ompi_group_t *group;
    int group_size;

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "test: %s", win->w_name);

    OPAL_THREAD_LOCK(&module->lock);
    if (NULL == module->pw_group) {
        OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_INFO, "no matching post");
        OPAL_THREAD_UNLOCK(&module->lock);
        return OMPI_ERR_RMA_SYNC;
    }

    group_size = ompi_group_size (module->pw_group);

    *flag = (group_size == state->num_complete_msgs);
    OPAL_THREAD_UNLOCK(&module->lock);

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "checking on complete message. have %d of %d",
                     (int) state->num_complete_msgs, group_size);

    if (!*flag) {
        ompi_osc_rdma_progress (module);
        return OMPI_SUCCESS;
    }

    state->num_complete_msgs = 0;

    OPAL_THREAD_LOCK(&(module->lock));
    group = module->pw_group;
    module->pw_group = NULL;
    OPAL_THREAD_UNLOCK(&(module->lock));

    OBJ_RELEASE(group);

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "test complete. returning flag: true");

    return OMPI_SUCCESS;
}

int ompi_osc_rdma_fence_atomic (int mpi_assert, ompi_win_t *win)
{
    ompi_osc_rdma_module_t *module = GET_MODULE(win);
    int ret = OMPI_SUCCESS;

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "fence: %d, %s", mpi_assert, win->w_name);

    /* can't enter an active target epoch while a lock is active */
    if (ompi_osc_rdma_in_passive_epoch (module) || module->pw_group) {
        OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_INFO, "can not start fence epoch due to conflicting epoch");
        return OMPI_ERR_RMA_SYNC;
    }

    /* NTH: locking here isn't really needed per-se but it may make user synchronization errors more
     * predictable. if the user is using RMA correctly then there will be no contention on this lock. */
    OPAL_THREAD_LOCK(&module->lock);

    /* active sends are now active (we will close the epoch if NOSUCCEED is specified) */
    if (0 == (mpi_assert & MPI_MODE_NOSUCCEED)) {
        module->all_sync.type = OMPI_OSC_RDMA_SYNC_TYPE_FENCE;
        module->all_sync.num_peers = ompi_comm_size (module->comm);
        /* NTH: should add a fast access array for peers here later. for now just use the
         * hash table. */
    }

    /* technically it is possible to enter a lock epoch (which will close the fence epoch) if
     * no communication has occurred. this flag will be set to true on the next put, get,
     * accumulate, etc if no other synchronization call is made. <sarcasm> yay fence </sarcasm> */
    module->all_sync.epoch_active = false;

    /* there really is no practical difference between NOPRECEDE and the normal case. in both cases there
     * may be local stores that will not be visible as they should if we do not barrier. since that is the
     * case there is no optimization for NOPRECEDE */

    ompi_osc_rdma_sync_rdma_complete (&module->all_sync);

    /* ensure all writes to my memory are complete (both local stores, and RMA operations) */
    ret = module->comm->c_coll->coll_barrier(module->comm, module->comm->c_coll->coll_barrier_module);

    if (mpi_assert & MPI_MODE_NOSUCCEED) {
        /* as specified in MPI-3 p 438 3-5 the fence can end an epoch. it isn't explicitly
         * stated that MPI_MODE_NOSUCCEED ends the epoch but it is a safe assumption. */
        module->all_sync.type = OMPI_OSC_RDMA_SYNC_TYPE_NONE;
    }

    OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "fence complete");

    OPAL_THREAD_UNLOCK(&module->lock);

    return ret;
}
