agent
40a3535393
ParallelFor runs a counted loop across a fixed set of threads created up front and hands out indices from an atomic counter, so the calling thread shares the work. A thread-start hook runs once per helper thread.
43 lines
987 B
C++
43 lines
987 B
C++
#pragma once
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#include <atomic>
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#include <condition_variable>
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#include <cstddef>
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#include <functional>
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#include <mutex>
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#include <thread>
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#include <vector>
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namespace tp {
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class ParallelFor {
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public:
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using ThreadStart = std::function<void(size_t index)>;
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explicit ParallelFor(size_t threads, ThreadStart onStart = {});
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~ParallelFor();
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ParallelFor(const ParallelFor&) = delete;
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ParallelFor& operator=(const ParallelFor&) = delete;
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[[nodiscard]] size_t threads() const { return mThreads.size() + 1; }
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void run(size_t count, const std::function<void(size_t index)>& body);
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private:
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void work(size_t generation);
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void drain();
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std::vector<std::thread> mThreads;
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ThreadStart mOnStart;
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std::mutex mMutex;
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std::condition_variable mStart;
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std::condition_variable mDone;
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const std::function<void(size_t)>* mBody = nullptr;
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size_t mCount = 0;
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std::atomic<size_t> mNext{ 0 };
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size_t mBusy = 0;
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size_t mGeneration = 0;
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bool mStopping = false;
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};
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}
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