| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| **/ |
| |
| #ifndef QUICKSTEP_QUERY_EXECUTION_WORK_ORDER_SELECTION_POLICY_HPP_ |
| #define QUICKSTEP_QUERY_EXECUTION_WORK_ORDER_SELECTION_POLICY_HPP_ |
| |
| #include <cstddef> |
| #include <stack> |
| #include <queue> |
| |
| #include "utility/Macros.hpp" |
| |
| #include "glog/logging.h" |
| |
| namespace quickstep { |
| |
| /** \addtogroup QueryExecution |
| * @{ |
| */ |
| |
| /** |
| * @brief Base class for a policy to select work orders for query execution. |
| **/ |
| class WorkOrderSelectionPolicy { |
| public: |
| /** |
| * @brief Whether there is an available work order for execution. |
| * |
| * @return True if a work order is available. Otherwise, false. |
| **/ |
| virtual bool hasWorkOrder() const = 0; |
| |
| /** |
| * @brief Add work order. |
| * |
| * @param operator_index The operator index for added work order. |
| **/ |
| virtual void addWorkOrder(const std::size_t operator_index) = 0; |
| |
| /** |
| * @brief Choose the operator index for next workorder execution based on the policy. |
| * |
| * @return The operator index chosen for next workorder execution. |
| **/ |
| virtual std::size_t getOperatorIndexForNextWorkOrder() = 0; |
| |
| protected: |
| /** |
| * @brief Constructor. |
| **/ |
| WorkOrderSelectionPolicy() {} |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(WorkOrderSelectionPolicy); |
| }; |
| |
| /** |
| * @brief Choose the next work order in a first-in-first-out manner. |
| **/ |
| class FifoWorkOrderSelectionPolicy final : public WorkOrderSelectionPolicy { |
| public: |
| /** |
| * @brief Constructor. |
| **/ |
| FifoWorkOrderSelectionPolicy() = default; |
| |
| bool hasWorkOrder() const override { |
| return !work_orders_.empty(); |
| } |
| |
| void addWorkOrder(const std::size_t operator_index) override { |
| work_orders_.push(operator_index); |
| } |
| |
| std::size_t getOperatorIndexForNextWorkOrder() override { |
| DCHECK(hasWorkOrder()); |
| const std::size_t operator_index = work_orders_.front(); |
| work_orders_.pop(); |
| |
| return operator_index; |
| } |
| |
| private: |
| std::queue<std::size_t> work_orders_; |
| |
| DISALLOW_COPY_AND_ASSIGN(FifoWorkOrderSelectionPolicy); |
| }; |
| |
| /** |
| * @brief Choose the next work order in a last-in-first-out manner. |
| **/ |
| class LifoWorkOrderSelectionPolicy final : public WorkOrderSelectionPolicy { |
| public: |
| /** |
| * @brief Constructor. |
| **/ |
| LifoWorkOrderSelectionPolicy() = default; |
| |
| bool hasWorkOrder() const override { |
| return !work_orders_.empty(); |
| } |
| |
| void addWorkOrder(const std::size_t operator_index) override { |
| work_orders_.push(operator_index); |
| } |
| |
| std::size_t getOperatorIndexForNextWorkOrder() override { |
| DCHECK(hasWorkOrder()); |
| const std::size_t operator_index = work_orders_.top(); |
| work_orders_.pop(); |
| |
| return operator_index; |
| } |
| |
| private: |
| std::stack<std::size_t> work_orders_; |
| |
| DISALLOW_COPY_AND_ASSIGN(LifoWorkOrderSelectionPolicy); |
| }; |
| |
| /** @} */ |
| |
| } // namespace quickstep |
| |
| #endif // QUICKSTEP_QUERY_EXECUTION_WORK_ORDER_SELECTION_POLICY_HPP_ |