
/******************************************************************************
 * Copyright (c) NVIDIA CORPORATION.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the NVIDIA CORPORATION nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 ******************************************************************************/

/**
 * @file
 * cub::DeviceSelect::UniqueByKey provides device-wide, parallel operations for selecting unique
 * items by key from sequences of data items residing within device-accessible memory.
 */

#include <cub/config.cuh>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cub/agent/agent_unique_by_key.cuh>
#include <cub/device/dispatch/dispatch_scan.cuh>
#include <cub/device/dispatch/tuning/tuning_unique_by_key.cuh>
#include <cub/util_deprecated.cuh>
#include <cub/util_device.cuh>
#include <cub/util_math.cuh>

#include <iterator>

CUB_NAMESPACE_BEGIN

/******************************************************************************
 * Kernel entry points
 *****************************************************************************/

/**
 * @brief Unique by key kernel entry point (multi-block)
 *
 * @tparam KeyInputIteratorT
 *   Random-access input iterator type for keys
 *
 * @tparam ValueInputIteratorT
 *   Random-access input iterator type for values
 *
 * @tparam KeyOutputIteratorT
 *   Random-access output iterator type for keys
 *
 * @tparam ValueOutputIteratorT
 *   Random-access output iterator type for values
 *
 * @tparam NumSelectedIteratorT
 *   Output iterator type for recording the number of items selected
 *
 * @tparam ScanTileStateT
 *   Tile status interface type
 *
 * @tparam EqualityOpT
 *   Equality operator type
 *
 * @tparam OffsetT
 *   Signed integer type for global offsets
 *
 * @param[in] d_keys_in
 *   Pointer to the input sequence of keys
 *
 * @param[in] d_values_in
 *   Pointer to the input sequence of values
 *
 * @param[out] d_keys_out
 *   Pointer to the output sequence of selected data items
 *
 * @param[out] d_values_out
 *   Pointer to the output sequence of selected data items
 *
 * @param[out] d_num_selected_out
 *   Pointer to the total number of items selected
 *   (i.e., length of @p d_keys_out or @p d_values_out)
 *
 * @param[in] tile_state
 *   Tile status interface
 *
 * @param[in] equality_op
 *   Equality operator
 *
 * @param[in] num_items
 *   Total number of input items
 *   (i.e., length of @p d_keys_in or @p d_values_in)
 *
 * @param[in] num_tiles
 *   Total number of tiles for the entire problem
 *
 * @param[in] vsmem
 *   Memory to support virtual shared memory
 */
template <typename ChainedPolicyT,
          typename KeyInputIteratorT,
          typename ValueInputIteratorT,
          typename KeyOutputIteratorT,
          typename ValueOutputIteratorT,
          typename NumSelectedIteratorT,
          typename ScanTileStateT,
          typename EqualityOpT,
          typename OffsetT>
__launch_bounds__(int(
  cub::detail::vsmem_helper_default_fallback_policy_t<
    typename ChainedPolicyT::ActivePolicy::UniqueByKeyPolicyT,
    AgentUniqueByKey,
    KeyInputIteratorT,
    ValueInputIteratorT,
    KeyOutputIteratorT,
    ValueOutputIteratorT,
    EqualityOpT,
    OffsetT>::agent_policy_t::BLOCK_THREADS))
  CUB_DETAIL_KERNEL_ATTRIBUTES void DeviceUniqueByKeySweepKernel(
    KeyInputIteratorT d_keys_in,
    ValueInputIteratorT d_values_in,
    KeyOutputIteratorT d_keys_out,
    ValueOutputIteratorT d_values_out,
    NumSelectedIteratorT d_num_selected_out,
    ScanTileStateT tile_state,
    EqualityOpT equality_op,
    OffsetT num_items,
    int num_tiles,
    cub::detail::vsmem_t vsmem)
{
  using VsmemHelperT = cub::detail::vsmem_helper_default_fallback_policy_t<
    typename ChainedPolicyT::ActivePolicy::UniqueByKeyPolicyT,
    AgentUniqueByKey,
    KeyInputIteratorT,
    ValueInputIteratorT,
    KeyOutputIteratorT,
    ValueOutputIteratorT,
    EqualityOpT,
    OffsetT>;

  using AgentUniqueByKeyPolicyT = typename VsmemHelperT::agent_policy_t;

  // Thread block type for selecting data from input tiles
  using AgentUniqueByKeyT = typename VsmemHelperT::agent_t;

  // Static shared memory allocation
  __shared__ typename VsmemHelperT::static_temp_storage_t static_temp_storage;

  // Get temporary storage
  typename AgentUniqueByKeyT::TempStorage& temp_storage =
    VsmemHelperT::get_temp_storage(static_temp_storage, vsmem, (blockIdx.x * gridDim.y) + blockIdx.y);

  // Process tiles
  AgentUniqueByKeyT(temp_storage, d_keys_in, d_values_in, d_keys_out, d_values_out, equality_op, num_items)
    .ConsumeRange(num_tiles, tile_state, d_num_selected_out);

  // If applicable, hints to discard modified cache lines for vsmem
  VsmemHelperT::discard_temp_storage(temp_storage);
}

/******************************************************************************
 * Dispatch
 ******************************************************************************/

/**
 * @brief Utility class for dispatching the appropriately-tuned kernels for DeviceSelect
 *
 * @tparam KeyInputIteratorT
 *   Random-access input iterator type for keys
 *
 * @tparam ValueInputIteratorT
 *   Random-access input iterator type for values
 *
 * @tparam KeyOutputIteratorT
 *   Random-access output iterator type for keys
 *
 * @tparam ValueOutputIteratorT
 *   Random-access output iterator type for values
 *
 * @tparam NumSelectedIteratorT
 *   Output iterator type for recording the number of items selected
 *
 * @tparam EqualityOpT
 *   Equality operator type
 *
 * @tparam OffsetT
 *   Signed integer type for global offsets
 */
template <typename KeyInputIteratorT,
          typename ValueInputIteratorT,
          typename KeyOutputIteratorT,
          typename ValueOutputIteratorT,
          typename NumSelectedIteratorT,
          typename EqualityOpT,
          typename OffsetT,
          typename SelectedPolicy = DeviceUniqueByKeyPolicy<KeyInputIteratorT, ValueInputIteratorT>>
struct DispatchUniqueByKey : SelectedPolicy
{
    /******************************************************************************
     * Types and constants
     ******************************************************************************/

    enum
    {
        INIT_KERNEL_THREADS = 128,
    };

    // The input key and value type
    using KeyT = typename std::iterator_traits<KeyInputIteratorT>::value_type;
    using ValueT = typename std::iterator_traits<ValueInputIteratorT>::value_type;

    // Tile status descriptor interface type
    using ScanTileStateT = ScanTileState<OffsetT>;

    /// Device-accessible allocation of temporary storage.  When NULL, the required allocation size
    /// is written to `temp_storage_bytes` and no work is done.
    void *d_temp_storage;

    /// Reference to size in bytes of `d_temp_storage` allocation
    size_t &temp_storage_bytes;

    /// Pointer to the input sequence of keys
    KeyInputIteratorT d_keys_in;

    /// Pointer to the input sequence of values
    ValueInputIteratorT d_values_in;

    /// Pointer to the output sequence of selected data items
    KeyOutputIteratorT d_keys_out;

    /// Pointer to the output sequence of selected data items
    ValueOutputIteratorT d_values_out;

    /// Pointer to the total number of items selected
    /// (i.e., length of @p d_keys_out or @p d_values_out)
    NumSelectedIteratorT d_num_selected_out;

    /// Equality operator
    EqualityOpT equality_op;

    /// Total number of input items (i.e., length of @p d_keys_in or @p d_values_in)
    OffsetT num_items;

    /// **[optional]** CUDA stream to launch kernels within.  Default is stream<sub>0</sub>.
    cudaStream_t stream;

    /**
     * @param[in] d_temp_storage
     *   Device-accessible allocation of temporary storage.
     *   When NULL, the required allocation size is written to
     *   `temp_storage_bytes` and no work is done.
     *
     * @tparam temp_storage_bytes
     *   [in,out] Reference to size in bytes of `d_temp_storage` allocation
     *
     * @param[in] d_keys_in
     *   Pointer to the input sequence of keys
     *
     * @param[in] d_values_in
     *   Pointer to the input sequence of values
     *
     * @param[out] d_keys_out
     *   Pointer to the output sequence of selected data items
     *
     * @param[out] d_values_out
     *   Pointer to the output sequence of selected data items
     *
     * @param[out] d_num_selected_out
     *   Pointer to the total number of items selected
     *   (i.e., length of @p d_keys_out or @p d_values_out)
     *
     * @param[in] equality_op
     *   Equality operator
     *
     * @param[in] num_items
     *   Total number of input items (i.e., length of @p d_keys_in or @p d_values_in)
     *
     * @param[in] stream
     *   **[optional]** CUDA stream to launch kernels within.
     *   Default is stream<sub>0</sub>.
     */
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE DispatchUniqueByKey(void *d_temp_storage,
                                                             size_t &temp_storage_bytes,
                                                             KeyInputIteratorT d_keys_in,
                                                             ValueInputIteratorT d_values_in,
                                                             KeyOutputIteratorT d_keys_out,
                                                             ValueOutputIteratorT d_values_out,
                                                             NumSelectedIteratorT d_num_selected_out,
                                                             EqualityOpT equality_op,
                                                             OffsetT num_items,
                                                             cudaStream_t stream)
        : d_temp_storage(d_temp_storage)
        , temp_storage_bytes(temp_storage_bytes)
        , d_keys_in(d_keys_in)
        , d_values_in(d_values_in)
        , d_keys_out(d_keys_out)
        , d_values_out(d_values_out)
        , d_num_selected_out(d_num_selected_out)
        , equality_op(equality_op)
        , num_items(num_items)
        , stream(stream)
    {}

    CUB_DETAIL_RUNTIME_DEBUG_SYNC_IS_NOT_SUPPORTED
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE
    DispatchUniqueByKey(
        void*                   d_temp_storage,
        size_t&                 temp_storage_bytes,
        KeyInputIteratorT       d_keys_in,
        ValueInputIteratorT     d_values_in,
        KeyOutputIteratorT      d_keys_out,
        ValueOutputIteratorT    d_values_out,
        NumSelectedIteratorT    d_num_selected_out,
        EqualityOpT             equality_op,
        OffsetT                 num_items,
        cudaStream_t            stream,
        bool                    debug_synchronous
    ):
        d_temp_storage(d_temp_storage),
        temp_storage_bytes(temp_storage_bytes),
        d_keys_in(d_keys_in),
        d_values_in(d_values_in),
        d_keys_out(d_keys_out),
        d_values_out(d_values_out),
        d_num_selected_out(d_num_selected_out),
        equality_op(equality_op),
        num_items(num_items),
        stream(stream)
    {
      CUB_DETAIL_RUNTIME_DEBUG_SYNC_USAGE_LOG
    }


    /******************************************************************************
     * Dispatch entrypoints
     ******************************************************************************/

    template <typename ActivePolicyT, typename InitKernel, typename ScanKernel>
    CUB_RUNTIME_FUNCTION _CCCL_HOST  _CCCL_FORCEINLINE
    cudaError_t Invoke(InitKernel init_kernel, ScanKernel scan_kernel)
    {
        using Policy = typename ActivePolicyT::UniqueByKeyPolicyT;

        using VsmemHelperT = cub::detail::vsmem_helper_default_fallback_policy_t<
          Policy,
          AgentUniqueByKey,
          KeyInputIteratorT,
          ValueInputIteratorT,
          KeyOutputIteratorT,
          ValueOutputIteratorT,
          EqualityOpT,
          OffsetT>;

        cudaError error = cudaSuccess;
        do
        {
            // Get device ordinal
            int device_ordinal;
            error = CubDebug(cudaGetDevice(&device_ordinal));
            if (cudaSuccess != error)
            {
              break;
            }

            // Number of input tiles
            constexpr auto block_threads    = VsmemHelperT::agent_policy_t::BLOCK_THREADS;
            constexpr auto items_per_thread = VsmemHelperT::agent_policy_t::ITEMS_PER_THREAD;
            int tile_size                   = block_threads * items_per_thread;
            int num_tiles                   = static_cast<int>(cub::DivideAndRoundUp(num_items, tile_size));
            const auto vsmem_size          = num_tiles * VsmemHelperT::vsmem_per_block;

            // Specify temporary storage allocation requirements
            size_t allocation_sizes[2] = {0, vsmem_size};

            // Bytes needed for tile status descriptors
            error = CubDebug(ScanTileStateT::AllocationSize(num_tiles, allocation_sizes[0]));
            if (cudaSuccess != error)
            {
                break;
            }

            // Compute allocation pointers into the single storage blob (or compute the necessary size of the blob)
            void *allocations[2] = {NULL, NULL};

            error = CubDebug(
              AliasTemporaries(d_temp_storage, temp_storage_bytes, allocations, allocation_sizes));
            if (cudaSuccess != error)
            {
                break;
            }

            if (d_temp_storage == NULL)
            {
                // Return if the caller is simply requesting the size of the storage allocation
                break;
            }

            // Construct the tile status interface
            ScanTileStateT tile_state;
            error = CubDebug(tile_state.Init(num_tiles, allocations[0], allocation_sizes[0]));
            if (cudaSuccess != error)
            {
                break;
            }

            // Log init_kernel configuration
            num_tiles = CUB_MAX(1, num_tiles);
            int init_grid_size = cub::DivideAndRoundUp(num_tiles, INIT_KERNEL_THREADS);

            #ifdef CUB_DETAIL_DEBUG_ENABLE_LOG
            _CubLog("Invoking init_kernel<<<%d, %d, 0, %lld>>>()\n", init_grid_size, INIT_KERNEL_THREADS, (long long) stream);
            #endif

            // Invoke init_kernel to initialize tile descriptors
            THRUST_NS_QUALIFIER::cuda_cub::launcher::triple_chevron(
                init_grid_size, INIT_KERNEL_THREADS, 0, stream
            ).doit(init_kernel, tile_state, num_tiles, d_num_selected_out);

            // Check for failure to launch
            error = CubDebug(cudaPeekAtLastError());
            if (cudaSuccess != error)
            {
                break;
            }

            // Sync the stream if specified to flush runtime errors
            error = CubDebug(detail::DebugSyncStream(stream));
            if (cudaSuccess != error)
            {
              break;
            }

            // Return if empty problem
            if (num_items == 0) break;

            // Get max x-dimension of grid
            int max_dim_x;
            error =
              CubDebug(cudaDeviceGetAttribute(&max_dim_x, cudaDevAttrMaxGridDimX, device_ordinal));
            if (cudaSuccess != error)
            {
                break;
            }

            // Get grid size for scanning tiles
            dim3 scan_grid_size;
            scan_grid_size.z = 1;
            scan_grid_size.y = cub::DivideAndRoundUp(num_tiles, max_dim_x);
            scan_grid_size.x = CUB_MIN(num_tiles, max_dim_x);

            // Log select_if_kernel configuration
            #ifdef CUB_DETAIL_DEBUG_ENABLE_LOG
            {
              // Get SM occupancy for unique_by_key_kernel
              int scan_sm_occupancy;
              error = CubDebug(MaxSmOccupancy(scan_sm_occupancy, // out
                                              scan_kernel,
                                              block_threads));
              if (cudaSuccess != error)
              {
                break;
              }

              _CubLog("Invoking unique_by_key_kernel<<<{%d,%d,%d}, %d, 0, "
                      "%lld>>>(), %d items per thread, %d SM occupancy\n",
                      scan_grid_size.x,
                      scan_grid_size.y,
                      scan_grid_size.z,
                      block_threads,
                      (long long)stream,
                      items_per_thread,
                      scan_sm_occupancy);
            }
            #endif

            // Invoke select_if_kernel
            error =
              THRUST_NS_QUALIFIER::cuda_cub::launcher::triple_chevron(scan_grid_size, block_threads, 0, stream)
                .doit(scan_kernel,
                      d_keys_in,
                      d_values_in,
                      d_keys_out,
                      d_values_out,
                      d_num_selected_out,
                      tile_state,
                      equality_op,
                      num_items,
                      num_tiles,
                      cub::detail::vsmem_t{allocations[1]});

            // Check for failure to launch
            error = CubDebug(error);
            if (cudaSuccess != error)
            {
              break;
            }

            // Sync the stream if specified to flush runtime errors
            error = CubDebug(detail::DebugSyncStream(stream));
            if (cudaSuccess != error)
            {
              break;
            }
        }
        while(0);

        return error;
    }

    template <typename ActivePolicyT>
    CUB_RUNTIME_FUNCTION _CCCL_HOST  _CCCL_FORCEINLINE
    cudaError_t Invoke()
    {
        using MaxPolicyT = typename DispatchUniqueByKey::MaxPolicy;

        // Ensure kernels are instantiated.
        return Invoke<ActivePolicyT>(
            DeviceCompactInitKernel<ScanTileStateT, NumSelectedIteratorT>,
            DeviceUniqueByKeySweepKernel<
                MaxPolicyT,
                KeyInputIteratorT,
                ValueInputIteratorT,
                KeyOutputIteratorT,
                ValueOutputIteratorT,
                NumSelectedIteratorT,
                ScanTileStateT,
                EqualityOpT,
                OffsetT>
        );
    }

    /**
     * @brief Internal dispatch routine
     *
     * @param[in] d_temp_storage
     *   Device-accessible allocation of temporary storage.
     *   When NULL, the required allocation size is written to
     *   `temp_storage_bytes` and no work is done.
     *
     * @param[in,out] &temp_storage_bytes
     *   Reference to size in bytes of `d_temp_storage` allocation
     *
     * @param[in] d_keys_in
     *   Pointer to the input sequence of keys
     *
     * @param[in] d_values_in
     *   Pointer to the input sequence of values
     *
     * @param[out] d_keys_out
     *   Pointer to the output sequence of selected data items
     *
     * @param[out] d_values_out
     *   Pointer to the output sequence of selected data items
     *
     * @param[out] d_num_selected_out
     *   Pointer to the total number of items selected
     *   (i.e., length of @p d_keys_out or @p d_values_out)
     *
     * @param[in] equality_op
     *   Equality operator
     *
     * @param[in] num_items
     *   Total number of input items (i.e., the length of @p d_in)
     *
     * @param[in] stream
     *   **[optional]** CUDA stream to launch kernels within.
     *   Default is stream<sub>0</sub>.
     */
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE static cudaError_t
    Dispatch(void *d_temp_storage,
             size_t &temp_storage_bytes,
             KeyInputIteratorT d_keys_in,
             ValueInputIteratorT d_values_in,
             KeyOutputIteratorT d_keys_out,
             ValueOutputIteratorT d_values_out,
             NumSelectedIteratorT d_num_selected_out,
             EqualityOpT equality_op,
             OffsetT num_items,
             cudaStream_t stream)
    {
        using MaxPolicyT = typename DispatchUniqueByKey::MaxPolicy;

        cudaError_t error;
        do
        {
            // Get PTX version
            int ptx_version = 0;
            error = CubDebug(PtxVersion(ptx_version));
            if (cudaSuccess != error)
            {
                break;
            }

            // Create dispatch functor
            DispatchUniqueByKey dispatch(
                d_temp_storage,
                temp_storage_bytes,
                d_keys_in,
                d_values_in,
                d_keys_out,
                d_values_out,
                d_num_selected_out,
                equality_op,
                num_items,
                stream);

            // Dispatch to chained policy
            error = CubDebug(MaxPolicyT::Invoke(ptx_version, dispatch));
            if (cudaSuccess != error)
            {
                break;
            }
        }
        while (0);

        return error;
    }

    CUB_DETAIL_RUNTIME_DEBUG_SYNC_IS_NOT_SUPPORTED
    CUB_RUNTIME_FUNCTION _CCCL_FORCEINLINE
    static cudaError_t Dispatch(
        void*                   d_temp_storage,
        size_t                  &temp_storage_bytes,
        KeyInputIteratorT       d_keys_in,
        ValueInputIteratorT     d_values_in,
        KeyOutputIteratorT      d_keys_out,
        ValueOutputIteratorT    d_values_out,
        NumSelectedIteratorT    d_num_selected_out,
        EqualityOpT             equality_op,
        OffsetT                 num_items,
        cudaStream_t            stream,
        bool                    debug_synchronous)
    {
      CUB_DETAIL_RUNTIME_DEBUG_SYNC_USAGE_LOG

      return Dispatch(d_temp_storage,
                      temp_storage_bytes,
                      d_keys_in,
                      d_values_in,
                      d_keys_out,
                      d_values_out,
                      d_num_selected_out,
                      equality_op,
                      num_items,
                      stream);
    }
};

CUB_NAMESPACE_END
