TableFunctionExecutionContext.cpp

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/*
 * Copyright 2019 OmniSci, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "QueryEngine/TableFunctions/TableFunctionExecutionContext.h"

#include "Analyzer/Analyzer.h"
#include "QueryEngine/ColumnFetcher.h"
#include "QueryEngine/GpuMemUtils.h"
#include "QueryEngine/TableFunctions/TableFunctionCompilationContext.h"
#include "Shared/Logger.h"

namespace {

template <typename T>
const int8_t* create_literal_buffer(T literal,
                                    const ExecutorDeviceType device_type,
                                    std::vector<std::unique_ptr<char[]>>& literals_owner,
                                    CudaAllocator* gpu_allocator) {
  CHECK_LE(sizeof(T), sizeof(int64_t));  // pad to 8 bytes
  switch (device_type) {
    case ExecutorDeviceType::CPU: {
      literals_owner.emplace_back(std::make_unique<char[]>(sizeof(int64_t)));
      std::memcpy(literals_owner.back().get(), &literal, sizeof(T));
      return reinterpret_cast<const int8_t*>(literals_owner.back().get());
    }
    case ExecutorDeviceType::GPU: {
      CHECK(gpu_allocator);
      const auto gpu_literal_buf_ptr = gpu_allocator->alloc(sizeof(int64_t));
      gpu_allocator->copyToDevice(
          gpu_literal_buf_ptr, reinterpret_cast<int8_t*>(&literal), sizeof(T));
      return gpu_literal_buf_ptr;
    }
  }
  UNREACHABLE();
  return nullptr;
}

size_t get_output_row_count(const TableFunctionExecutionUnit& exe_unit,
                            size_t input_element_count) {
  size_t allocated_output_row_count = 0;
  if (*exe_unit.output_buffer_multiplier) {
    allocated_output_row_count = *exe_unit.output_buffer_multiplier * input_element_count;
  } else {
    throw std::runtime_error(
        "Only row multiplier output buffer configuration is supported for table "
        "functions.");
  }
  return allocated_output_row_count;
}

}  // namespace

ResultSetPtr TableFunctionExecutionContext::execute(
    const TableFunctionExecutionUnit& exe_unit,
    const InputTableInfo& table_info,
    const TableFunctionCompilationContext* compilation_context,
    const ColumnFetcher& column_fetcher,
    const ExecutorDeviceType device_type,
    Executor* executor) {
  CHECK(compilation_context);

  std::vector<std::shared_ptr<Chunk_NS::Chunk>> chunks_owner;
  std::vector<std::unique_ptr<char[]>> literals_owner;

  const int device_id = 0;  // TODO(adb): support multi-gpu table functions
  std::unique_ptr<CudaAllocator> device_allocator;
  if (device_type == ExecutorDeviceType::GPU) {
    auto& data_mgr = executor->catalog_->getDataMgr();
    device_allocator.reset(new CudaAllocator(&data_mgr, device_id));
  }

  std::vector<const int8_t*> col_buf_ptrs;
  ssize_t element_count = -1;
  for (const auto& input_expr : exe_unit.input_exprs) {
    if (auto col_var = dynamic_cast<Analyzer::ColumnVar*>(input_expr)) {
      auto [col_buf, buf_elem_count] = ColumnFetcher::getOneColumnFragment(
          executor,
          *col_var,
          table_info.info.fragments.front(),
          device_type == ExecutorDeviceType::CPU ? Data_Namespace::MemoryLevel::CPU_LEVEL
                                                 : Data_Namespace::MemoryLevel::GPU_LEVEL,
          device_id,
          device_allocator.get(),
          chunks_owner,
          column_fetcher.columnarized_table_cache_);
      if (element_count < 0) {
        element_count = static_cast<ssize_t>(buf_elem_count);
      } else {
        CHECK_EQ(static_cast<ssize_t>(buf_elem_count), element_count);
      }
      col_buf_ptrs.push_back(col_buf);
    } else if (const auto& constant_val = dynamic_cast<Analyzer::Constant*>(input_expr)) {
      // TODO(adb): Unify literal handling with rest of system, either in Codegen or as a
      // separate serialization component
      const auto const_val_datum = constant_val->get_constval();
      const auto& ti = constant_val->get_type_info();
      if (ti.is_fp()) {
        switch (get_bit_width(ti)) {
          case 32:
            col_buf_ptrs.push_back(create_literal_buffer(const_val_datum.floatval,
                                                         device_type,
                                                         literals_owner,
                                                         device_allocator.get()));
            break;
          case 64:
            col_buf_ptrs.push_back(create_literal_buffer(const_val_datum.doubleval,
                                                         device_type,
                                                         literals_owner,
                                                         device_allocator.get()));
            break;
          default:
            UNREACHABLE();
        }
      } else if (ti.is_integer()) {
        switch (get_bit_width(ti)) {
          case 8:
            col_buf_ptrs.push_back(create_literal_buffer(const_val_datum.tinyintval,
                                                         device_type,
                                                         literals_owner,
                                                         device_allocator.get()));
            break;
          case 16:
            col_buf_ptrs.push_back(create_literal_buffer(const_val_datum.smallintval,
                                                         device_type,
                                                         literals_owner,
                                                         device_allocator.get()));
            break;
          case 32:
            col_buf_ptrs.push_back(create_literal_buffer(const_val_datum.intval,
                                                         device_type,
                                                         literals_owner,
                                                         device_allocator.get()));
            break;
          case 64:
            col_buf_ptrs.push_back(create_literal_buffer(const_val_datum.bigintval,
                                                         device_type,
                                                         literals_owner,
                                                         device_allocator.get()));
            break;
          default:
            UNREACHABLE();
        }
      } else {
        throw std::runtime_error("Literal value " + constant_val->toString() +
                                 " is not yet supported.");
      }
    }
  }
  CHECK_EQ(col_buf_ptrs.size(), exe_unit.input_exprs.size());

  CHECK_GE(element_count, ssize_t(0));
  switch (device_type) {
    case ExecutorDeviceType::CPU:
      return launchCpuCode(exe_unit,
                           compilation_context,
                           col_buf_ptrs,
                           static_cast<size_t>(element_count),
                           executor);
    case ExecutorDeviceType::GPU:
      return launchGpuCode(exe_unit,
                           compilation_context,
                           col_buf_ptrs,
                           static_cast<size_t>(element_count),
                           /*device_id=*/0,
                           executor);
  }
  UNREACHABLE();
  return nullptr;
}

ResultSetPtr TableFunctionExecutionContext::launchCpuCode(
    const TableFunctionExecutionUnit& exe_unit,
    const TableFunctionCompilationContext* compilation_context,
    std::vector<const int8_t*>& col_buf_ptrs,
    const size_t elem_count,
    Executor* executor) {
  // setup the inputs
  const auto byte_stream_ptr = reinterpret_cast<const int8_t**>(col_buf_ptrs.data());
  CHECK(byte_stream_ptr);

  // initialize output memory
  QueryMemoryDescriptor query_mem_desc(
      executor, elem_count, QueryDescriptionType::Projection, /*is_table_function=*/true);
  query_mem_desc.setOutputColumnar(true);

  for (size_t i = 0; i < exe_unit.target_exprs.size(); i++) {
    // All outputs padded to 8 bytes
    query_mem_desc.addColSlotInfo({std::make_tuple(8, 8)});
  }

  const auto allocated_output_row_count = get_output_row_count(exe_unit, elem_count);
  auto query_buffers = std::make_unique<QueryMemoryInitializer>(
      exe_unit,
      query_mem_desc,
      /*device_id=*/0,
      ExecutorDeviceType::CPU,
      allocated_output_row_count,
      std::vector<std::vector<const int8_t*>>{col_buf_ptrs},
      std::vector<std::vector<uint64_t>>{{0}},  // frag offsets
      row_set_mem_owner_,
      nullptr,
      executor);

  // setup the output
  int64_t output_row_count = -1;
  auto group_by_buffers_ptr = query_buffers->getGroupByBuffersPtr();
  CHECK(group_by_buffers_ptr);

  // execute
  const auto kernel_element_count = static_cast<int64_t>(elem_count);
  const auto err =
      compilation_context->getFuncPtr()(byte_stream_ptr,
                                        &kernel_element_count,
                                        query_buffers->getGroupByBuffersPtr(),
                                        &output_row_count);
  if (err) {
    throw std::runtime_error("Error executing table function: " + std::to_string(err));
  }
  if (output_row_count < 0) {
    throw std::runtime_error("Table function did not properly set output row count.");
  }

  // Update entry count, it may differ from allocated mem size
  query_buffers->getResultSet(0)->updateStorageEntryCount(output_row_count);

  return query_buffers->getResultSetOwned(0);
}

namespace {
enum {
  ERROR_BUFFER,
  COL_BUFFERS,
  INPUT_ROW_COUNT,
  OUTPUT_BUFFERS,
  OUTPUT_ROW_COUNT,
  KERNEL_PARAM_COUNT,
};
}

ResultSetPtr TableFunctionExecutionContext::launchGpuCode(
    const TableFunctionExecutionUnit& exe_unit,
    const TableFunctionCompilationContext* compilation_context,
    std::vector<const int8_t*>& col_buf_ptrs,
    const size_t elem_count,
    const int device_id,
    Executor* executor) {
#ifdef HAVE_CUDA
  auto& data_mgr = executor->catalog_->getDataMgr();
  auto gpu_allocator = std::make_unique<CudaAllocator>(&data_mgr, device_id);
  CHECK(gpu_allocator);

  std::vector<CUdeviceptr> kernel_params(KERNEL_PARAM_COUNT, 0);
  // setup the inputs
  auto byte_stream_ptr = gpu_allocator->alloc(col_buf_ptrs.size() * sizeof(int64_t));
  gpu_allocator->copyToDevice(byte_stream_ptr,
                              reinterpret_cast<int8_t*>(col_buf_ptrs.data()),
                              col_buf_ptrs.size() * sizeof(int64_t));
  kernel_params[COL_BUFFERS] = reinterpret_cast<CUdeviceptr>(byte_stream_ptr);

  kernel_params[INPUT_ROW_COUNT] =
      reinterpret_cast<CUdeviceptr>(gpu_allocator->alloc(sizeof(elem_count)));
  gpu_allocator->copyToDevice(reinterpret_cast<int8_t*>(kernel_params[INPUT_ROW_COUNT]),
                              reinterpret_cast<const int8_t*>(&elem_count),
                              sizeof(elem_count));

  kernel_params[ERROR_BUFFER] =
      reinterpret_cast<CUdeviceptr>(gpu_allocator->alloc(sizeof(int32_t)));

  // initialize output memory
  QueryMemoryDescriptor query_mem_desc(
      executor, elem_count, QueryDescriptionType::Projection, /*is_table_function=*/true);
  query_mem_desc.setOutputColumnar(true);

  for (size_t i = 0; i < exe_unit.target_exprs.size(); i++) {
    // All outputs padded to 8 bytes
    query_mem_desc.addColSlotInfo({std::make_tuple(8, 8)});
  }
  const auto allocated_output_row_count = get_output_row_count(exe_unit, elem_count);
  auto query_buffers = std::make_unique<QueryMemoryInitializer>(
      exe_unit,
      query_mem_desc,
      device_id,
      ExecutorDeviceType::GPU,
      allocated_output_row_count,
      std::vector<std::vector<const int8_t*>>{col_buf_ptrs},
      std::vector<std::vector<uint64_t>>{{0}},  // frag offsets
      row_set_mem_owner_,
      gpu_allocator.get(),
      executor);

  // setup the output
  int64_t output_row_count = -1;
  kernel_params[OUTPUT_ROW_COUNT] =
      reinterpret_cast<CUdeviceptr>(gpu_allocator->alloc(sizeof(int64_t*)));
  gpu_allocator->copyToDevice(reinterpret_cast<int8_t*>(kernel_params[OUTPUT_ROW_COUNT]),
                              reinterpret_cast<int8_t*>(&output_row_count),
                              sizeof(output_row_count));

  auto group_by_buffers_ptr = query_buffers->getGroupByBuffersPtr();
  CHECK(group_by_buffers_ptr);

  const unsigned block_size_x = executor->blockSize();
  const unsigned block_size_y = 1;
  const unsigned block_size_z = 1;
  const unsigned grid_size_x = executor->gridSize();
  const unsigned grid_size_y = 1;
  const unsigned grid_size_z = 1;

  auto gpu_output_buffers = query_buffers->setupTableFunctionGpuBuffers(
      query_mem_desc, device_id, block_size_x, grid_size_x);
  kernel_params[OUTPUT_BUFFERS] = reinterpret_cast<CUdeviceptr>(gpu_output_buffers.first);

  // execute
  CHECK_EQ(static_cast<size_t>(KERNEL_PARAM_COUNT), kernel_params.size());

  std::vector<void*> param_ptrs;
  for (auto& param : kernel_params) {
    param_ptrs.push_back(&param);
  }

  // Get cu func
  const auto gpu_context = compilation_context->getGpuCode();
  CHECK(gpu_context);
  const auto native_code = gpu_context->getNativeCode(device_id);
  auto cu_func = static_cast<CUfunction>(native_code.first);
  checkCudaErrors(cuLaunchKernel(cu_func,
                                 grid_size_x,
                                 grid_size_y,
                                 grid_size_z,
                                 block_size_x,
                                 block_size_y,
                                 block_size_z,
                                 0,  // shared mem bytes
                                 nullptr,
                                 &param_ptrs[0],
                                 nullptr));
  // TODO(adb): read errors

  // read output row count from GPU
  int64_t new_output_row_count = -1;
  gpu_allocator->copyFromDevice(
      reinterpret_cast<int8_t*>(&new_output_row_count),
      reinterpret_cast<int8_t*>(kernel_params[OUTPUT_ROW_COUNT]),
      sizeof(int64_t));
  if (new_output_row_count < 0) {
    new_output_row_count = allocated_output_row_count;
  }

  // Update entry count, it may differ from allocated mem size
  query_buffers->getResultSet(0)->updateStorageEntryCount(new_output_row_count);

  // Copy back to CPU storage
  query_buffers->copyGroupByBuffersFromGpu(&data_mgr,
                                           query_mem_desc,
                                           new_output_row_count,
                                           gpu_output_buffers,
                                           nullptr,
                                           block_size_x,
                                           grid_size_x,
                                           device_id,
                                           false);

  return query_buffers->getResultSetOwned(0);
#else
  UNREACHABLE();
  return nullptr;
#endif
}