/*
 * Copyright (C) by Argonne National Laboratory
 *     See COPYRIGHT in top-level directory
 */

#include "mpiimpl.h"

/*
=== BEGIN_MPI_T_CVAR_INFO_BLOCK ===

cvars:
    - name        : MPIR_CVAR_ISCAN_INTRA_ALGORITHM
      category    : COLLECTIVE
      type        : enum
      default     : auto
      class       : none
      verbosity   : MPI_T_VERBOSITY_USER_BASIC
      scope       : MPI_T_SCOPE_ALL_EQ
      description : |-
        Variable to select allgather algorithm
        auto - Internal algorithm selection (can be overridden with MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based algorithms
        sched_smp                  - Force smp algorithm
        sched_recursive_doubling   - Force recursive doubling algorithm
        gentran_recursive_doubling - Force generic transport recursive doubling algorithm

    - name        : MPIR_CVAR_ISCAN_DEVICE_COLLECTIVE
      category    : COLLECTIVE
      type        : boolean
      default     : true
      class       : none
      verbosity   : MPI_T_VERBOSITY_USER_BASIC
      scope       : MPI_T_SCOPE_ALL_EQ
      description : >-
        This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iscan will
        allow the device to override the MPIR-level collective
        algorithms.  The device might still call the MPIR-level
        algorithms manually.  If set to false, the device-override
        will be disabled.

=== END_MPI_T_CVAR_INFO_BLOCK ===
*/

/* -- Begin Profiling Symbol Block for routine MPI_Iscan */
#if defined(HAVE_PRAGMA_WEAK)
#pragma weak MPI_Iscan = PMPI_Iscan
#elif defined(HAVE_PRAGMA_HP_SEC_DEF)
#pragma _HP_SECONDARY_DEF PMPI_Iscan  MPI_Iscan
#elif defined(HAVE_PRAGMA_CRI_DUP)
#pragma _CRI duplicate MPI_Iscan as PMPI_Iscan
#elif defined(HAVE_WEAK_ATTRIBUTE)
int MPI_Iscan(const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype, MPI_Op op,
              MPI_Comm comm, MPI_Request * request)
    __attribute__ ((weak, alias("PMPI_Iscan")));
#endif
/* -- End Profiling Symbol Block */

/* Define MPICH_MPI_FROM_PMPI if weak symbols are not supported to build
   the MPI routines */
#ifndef MPICH_MPI_FROM_PMPI
#undef MPI_Iscan
#define MPI_Iscan PMPI_Iscan


int MPIR_Iscan_allcomm_auto(const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
                            MPI_Op op, MPIR_Comm * comm_ptr, MPIR_Request ** request)
{
    int mpi_errno = MPI_SUCCESS;

    MPIR_Csel_coll_sig_s coll_sig = {
        .coll_type = MPIR_CSEL_COLL_TYPE__ISCAN,
        .comm_ptr = comm_ptr,

        .u.iscan.sendbuf = sendbuf,
        .u.iscan.recvbuf = recvbuf,
        .u.iscan.count = count,
        .u.iscan.datatype = datatype,
        .u.iscan.op = op,
    };

    MPII_Csel_container_s *cnt = MPIR_Csel_search(comm_ptr->csel_comm, coll_sig);
    MPIR_Assert(cnt);

    switch (cnt->id) {
        case MPII_CSEL_CONTAINER_TYPE__ALGORITHM__MPIR_Iscan_intra_sched_auto:
            MPII_SCHED_WRAPPER(MPIR_Iscan_intra_sched_auto, comm_ptr, request, sendbuf, recvbuf,
                               count, datatype, op);
            break;

        case MPII_CSEL_CONTAINER_TYPE__ALGORITHM__MPIR_Iscan_intra_sched_recursive_doubling:
            MPII_SCHED_WRAPPER(MPIR_Iscan_intra_sched_recursive_doubling, comm_ptr, request,
                               sendbuf, recvbuf, count, datatype, op);
            break;

        case MPII_CSEL_CONTAINER_TYPE__ALGORITHM__MPIR_Iscan_intra_sched_smp:
            MPII_SCHED_WRAPPER(MPIR_Iscan_intra_sched_smp, comm_ptr, request, sendbuf, recvbuf,
                               count, datatype, op);
            break;

        case MPII_CSEL_CONTAINER_TYPE__ALGORITHM__MPIR_Iscan_intra_gentran_recursive_doubling:
            mpi_errno =
                MPIR_Iscan_intra_gentran_recursive_doubling(sendbuf, recvbuf, count, datatype, op,
                                                            comm_ptr, request);
            break;

        default:
            MPIR_Assert(0);
    }

  fn_exit:
    return mpi_errno;
  fn_fail:
    goto fn_exit;
}

int MPIR_Iscan_intra_sched_auto(const void *sendbuf, void *recvbuf, int count,
                                MPI_Datatype datatype, MPI_Op op, MPIR_Comm * comm_ptr,
                                MPIR_Sched_t s)
{
    int mpi_errno = MPI_SUCCESS;

    if (comm_ptr->hierarchy_kind == MPIR_COMM_HIERARCHY_KIND__PARENT) {
        mpi_errno = MPIR_Iscan_intra_sched_smp(sendbuf, recvbuf, count, datatype, op, comm_ptr, s);
    } else {
        mpi_errno =
            MPIR_Iscan_intra_sched_recursive_doubling(sendbuf, recvbuf, count, datatype, op,
                                                      comm_ptr, s);
    }

    return mpi_errno;
}

int MPIR_Iscan_impl(const void *sendbuf, void *recvbuf, int count,
                    MPI_Datatype datatype, MPI_Op op, MPIR_Comm * comm_ptr, MPIR_Request ** request)
{
    int mpi_errno = MPI_SUCCESS;

    *request = NULL;

    /* If the user picks one of the transport-enabled algorithms, branch there
     * before going down to the MPIR_Sched-based algorithms. */
    /* TODO - Eventually the intention is to replace all of the
     * MPIR_Sched-based algorithms with transport-enabled algorithms, but that
     * will require sufficient performance testing and replacement algorithms. */
    switch (MPIR_CVAR_ISCAN_INTRA_ALGORITHM) {
        case MPIR_CVAR_ISCAN_INTRA_ALGORITHM_gentran_recursive_doubling:
            mpi_errno =
                MPIR_Iscan_intra_gentran_recursive_doubling(sendbuf, recvbuf, count,
                                                            datatype, op, comm_ptr, request);
            break;

        case MPIR_CVAR_ISCAN_INTRA_ALGORITHM_sched_recursive_doubling:
            MPII_SCHED_WRAPPER(MPIR_Iscan_intra_sched_recursive_doubling, comm_ptr, request,
                               sendbuf, recvbuf, count, datatype, op);
            break;

        case MPIR_CVAR_ISCAN_INTRA_ALGORITHM_sched_smp:
            MPII_SCHED_WRAPPER(MPIR_Iscan_intra_sched_smp, comm_ptr, request,
                               sendbuf, recvbuf, count, datatype, op);
            break;

        case MPIR_CVAR_ISCAN_INTRA_ALGORITHM_sched_auto:
            MPII_SCHED_WRAPPER(MPIR_Iscan_intra_sched_auto, comm_ptr, request, sendbuf, recvbuf,
                               count, datatype, op);
            break;

        case MPIR_CVAR_ISCAN_INTRA_ALGORITHM_auto:
            mpi_errno =
                MPIR_Iscan_allcomm_auto(sendbuf, recvbuf, count, datatype, op, comm_ptr, request);
            break;

        default:
            MPIR_Assert(0);
    }

    MPIR_ERR_CHECK(mpi_errno);

  fn_exit:
    return mpi_errno;
  fn_fail:
    goto fn_exit;
}

int MPIR_Iscan(const void *sendbuf, void *recvbuf, int count,
               MPI_Datatype datatype, MPI_Op op, MPIR_Comm * comm_ptr, MPIR_Request ** request)
{
    int mpi_errno = MPI_SUCCESS;
    void *in_recvbuf = recvbuf;
    void *host_sendbuf;
    void *host_recvbuf;

    MPIR_Coll_host_buffer_alloc(sendbuf, recvbuf, count, datatype, &host_sendbuf, &host_recvbuf);
    if (host_sendbuf)
        sendbuf = host_sendbuf;
    if (host_recvbuf)
        recvbuf = host_recvbuf;

    if ((MPIR_CVAR_DEVICE_COLLECTIVES == MPIR_CVAR_DEVICE_COLLECTIVES_all) ||
        ((MPIR_CVAR_DEVICE_COLLECTIVES == MPIR_CVAR_DEVICE_COLLECTIVES_percoll) &&
         MPIR_CVAR_ISCAN_DEVICE_COLLECTIVE)) {
        mpi_errno = MPID_Iscan(sendbuf, recvbuf, count, datatype, op, comm_ptr, request);
    } else {
        mpi_errno = MPIR_Iscan_impl(sendbuf, recvbuf, count, datatype, op, comm_ptr, request);
    }

    MPIR_Coll_host_buffer_swap_back(host_sendbuf, host_recvbuf, in_recvbuf, count, datatype,
                                    *request);

    return mpi_errno;
}

#endif /* MPICH_MPI_FROM_PMPI */

/*@
MPI_Iscan - Computes the scan (partial reductions) of data on a collection of
            processes in a nonblocking way

Input Parameters:
+ sendbuf - starting address of the send buffer (choice)
. count - number of elements in input buffer (non-negative integer)
. datatype - data type of elements of input buffer (handle)
. op - operation (handle)
- comm - communicator (handle)

Output Parameters:
+ recvbuf - starting address of the receive buffer (choice)
- request - communication request (handle)

.N ThreadSafe

.N Fortran

.N Errors
@*/
int MPI_Iscan(const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
              MPI_Op op, MPI_Comm comm, MPI_Request * request)
{
    int mpi_errno = MPI_SUCCESS;
    MPIR_Comm *comm_ptr = NULL;
    MPIR_Request *request_ptr = NULL;
    MPIR_FUNC_TERSE_STATE_DECL(MPID_STATE_MPI_ISCAN);

    MPID_THREAD_CS_ENTER(GLOBAL, MPIR_THREAD_GLOBAL_ALLFUNC_MUTEX);
    MPIR_FUNC_TERSE_ENTER(MPID_STATE_MPI_ISCAN);

    /* Validate parameters, especially handles needing to be converted */
#ifdef HAVE_ERROR_CHECKING
    {
        MPID_BEGIN_ERROR_CHECKS;
        {
            MPIR_ERRTEST_DATATYPE(datatype, "datatype", mpi_errno);
            MPIR_ERRTEST_COUNT(count, mpi_errno);
            MPIR_ERRTEST_OP(op, mpi_errno);
            MPIR_ERRTEST_COMM(comm, mpi_errno);

            /* TODO more checks may be appropriate */
        }
        MPID_END_ERROR_CHECKS;
    }
#endif /* HAVE_ERROR_CHECKING */

    /* Convert MPI object handles to object pointers */
    MPIR_Comm_get_ptr(comm, comm_ptr);

    /* Validate parameters and objects (post conversion) */
#ifdef HAVE_ERROR_CHECKING
    {
        MPID_BEGIN_ERROR_CHECKS;
        {
            MPIR_Comm_valid_ptr(comm_ptr, mpi_errno, FALSE);
            if (mpi_errno != MPI_SUCCESS)
                goto fn_fail;

            MPIR_ERRTEST_COMM_INTRA(comm_ptr, mpi_errno);
            if (!HANDLE_IS_BUILTIN(datatype)) {
                MPIR_Datatype *datatype_ptr = NULL;
                MPIR_Datatype_get_ptr(datatype, datatype_ptr);
                MPIR_Datatype_valid_ptr(datatype_ptr, mpi_errno);
                if (mpi_errno != MPI_SUCCESS)
                    goto fn_fail;
                MPIR_Datatype_committed_ptr(datatype_ptr, mpi_errno);
                if (mpi_errno != MPI_SUCCESS)
                    goto fn_fail;
            }

            if (!HANDLE_IS_BUILTIN(op)) {
                MPIR_Op *op_ptr = NULL;
                MPIR_Op_get_ptr(op, op_ptr);
                MPIR_Op_valid_ptr(op_ptr, mpi_errno);
            } else {
                mpi_errno = (*MPIR_OP_HDL_TO_DTYPE_FN(op)) (datatype);
            }
            if (mpi_errno != MPI_SUCCESS)
                goto fn_fail;

            MPIR_ERRTEST_ARGNULL(request, "request", mpi_errno);

            if (sendbuf != MPI_IN_PLACE && count != 0)
                MPIR_ERRTEST_ALIAS_COLL(sendbuf, recvbuf, mpi_errno);
            /* TODO more checks may be appropriate (counts, in_place, etc) */
        }
        MPID_END_ERROR_CHECKS;
    }
#endif /* HAVE_ERROR_CHECKING */

    /* ... body of routine ...  */

    mpi_errno = MPIR_Iscan(sendbuf, recvbuf, count, datatype, op, comm_ptr, &request_ptr);
    MPIR_ERR_CHECK(mpi_errno);

    /* create a complete request, if needed */
    if (!request_ptr)
        request_ptr = MPIR_Request_create_complete(MPIR_REQUEST_KIND__COLL);
    /* return the handle of the request to the user */
    *request = request_ptr->handle;

    /* ... end of body of routine ... */

  fn_exit:
    MPIR_FUNC_TERSE_EXIT(MPID_STATE_MPI_ISCAN);
    MPID_THREAD_CS_EXIT(GLOBAL, MPIR_THREAD_GLOBAL_ALLFUNC_MUTEX);
    return mpi_errno;

  fn_fail:
    /* --BEGIN ERROR HANDLING-- */
#ifdef HAVE_ERROR_CHECKING
    {
        mpi_errno =
            MPIR_Err_create_code(mpi_errno, MPIR_ERR_RECOVERABLE, __func__, __LINE__, MPI_ERR_OTHER,
                                 "**mpi_iscan", "**mpi_iscan %p %p %d %D %O %C %p", sendbuf,
                                 recvbuf, count, datatype, op, comm, request);
    }
#endif
    mpi_errno = MPIR_Err_return_comm(comm_ptr, __func__, mpi_errno);
    goto fn_exit;
    /* --END ERROR HANDLING-- */
}
