72 lines
1.8 KiB
C++
72 lines
1.8 KiB
C++
#pragma once
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#include <mbgl/actor/mailbox.hpp>
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#include <mbgl/actor/scheduler.hpp>
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#include <array>
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#include <condition_variable>
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#include <mutex>
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#include <queue>
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#include <thread>
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namespace mbgl {
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class ThreadedSchedulerBase : public Scheduler {
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public:
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void schedule(std::function<void()>) override;
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protected:
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ThreadedSchedulerBase() = default;
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~ThreadedSchedulerBase() override;
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void terminate();
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std::thread makeSchedulerThread(size_t index);
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std::queue<std::function<void()>> queue;
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std::mutex mutex;
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std::condition_variable cv;
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bool terminated{false};
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};
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/**
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* @brief ThreadScheduler implements Scheduler interface using a lightweight event loop
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*
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* @tparam N number of threads
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*
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* Note: If N == 1 all scheduled tasks are guaranteed to execute consequently;
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* otherwise, some of the scheduled tasks might be executed in parallel.
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*/
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template <std::size_t N>
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class ThreadedScheduler : public ThreadedSchedulerBase {
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public:
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ThreadedScheduler() {
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for (std::size_t i = 0u; i < N; ++i) {
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threads[i] = makeSchedulerThread(i);
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}
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}
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~ThreadedScheduler() override {
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terminate();
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for (auto& thread : threads) {
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assert(std::this_thread::get_id() != thread.get_id());
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thread.join();
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}
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}
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mapbox::base::WeakPtr<Scheduler> makeWeakPtr() override { return weakFactory.makeWeakPtr(); }
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private:
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std::array<std::thread, N> threads;
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mapbox::base::WeakPtrFactory<Scheduler> weakFactory{this};
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static_assert(N > 0, "Thread count must be more than zero.");
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};
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class SequencedScheduler : public ThreadedScheduler<1> {};
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template <std::size_t extra>
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using ParallelScheduler = ThreadedScheduler<1 + extra>;
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class ThreadPool : public ParallelScheduler<3> {};
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} // namespace mbgl
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