81 lines
2.4 KiB
C
81 lines
2.4 KiB
C
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <atomic>
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#include <cstddef>
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#include <memory>
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#include <vector>
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#include <folly/executors/SoftRealTimeExecutor.h>
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#include <folly/executors/ThreadPoolExecutor.h>
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#include <folly/synchronization/LifoSem.h>
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namespace folly {
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/**
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* `EDFThreadPoolExecutor` is a `SoftRealTimeExecutor` that implements
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* the earliest-deadline-first scheduling policy.
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*/
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class EDFThreadPoolExecutor : public SoftRealTimeExecutor,
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public ThreadPoolExecutor {
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public:
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class Task;
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class TaskQueue;
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static constexpr uint64_t kEarliestDeadline = 0;
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static constexpr uint64_t kLatestDeadline =
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std::numeric_limits<uint64_t>::max();
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explicit EDFThreadPoolExecutor(
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std::size_t numThreads,
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std::shared_ptr<ThreadFactory> threadFactory =
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std::make_shared<NamedThreadFactory>("EDFThreadPool"));
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~EDFThreadPoolExecutor() override;
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using ThreadPoolExecutor::add;
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void add(Func f) override;
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void add(Func f, uint64_t deadline) override;
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void add(Func f, std::size_t total, uint64_t deadline);
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void add(std::vector<Func> fs, uint64_t deadline);
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folly::Executor::KeepAlive<> deadlineExecutor(uint64_t deadline);
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protected:
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void threadRun(ThreadPtr thread) override;
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void stopThreads(std::size_t numThreads) override;
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std::size_t getPendingTaskCountImpl() const override final;
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private:
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bool shouldStop();
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std::shared_ptr<Task> take();
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std::unique_ptr<TaskQueue> taskQueue_;
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LifoSem sem_;
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std::atomic<int> threadsToStop_{0};
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// All operations performed on `numIdleThreads_` explicitly specify memory
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// ordering of `std::memory_order_seq_cst`. This is due to `numIdleThreads_`
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// performing Dekker's algorithm with `numItems` prior to consumer threads
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// (workers) wait on `sem_`.
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std::atomic<std::size_t> numIdleThreads_{0};
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};
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} // namespace folly
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