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https://github.com/mariadb-corporation/mariadb-columnstore-engine.git
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e174696351
EM and PP are most resource-hungry runtimes.
The merge enables to control their cummulative
resource consumption, thread allocation + enables
zero-copy data exchange b/w local EM and PP facilities.
56 lines
1.2 KiB
C++
56 lines
1.2 KiB
C++
#pragma once
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#include <atomic>
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// To be refactored. There are two issues with this implentation.
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// 1. It can be replaced with a lock despite the memory_order_acquire/release mem order. Needs
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// std::atomic_flag instead.
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// 2. https://www.realworldtech.com/forum/?threadid=189711&curpostid=189723
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namespace utils
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{
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inline void getSpinlock(std::atomic<bool>& lock)
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{
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bool _false = false;
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while (!lock.compare_exchange_weak(_false, true, std::memory_order_acquire))
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_false = false;
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}
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inline bool trySpinlock(std::atomic<bool>& lock)
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{
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bool _false = false;
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bool ret = lock.compare_exchange_weak(_false, true, std::memory_order_acquire);
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return ret;
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}
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inline void releaseSpinlock(std::atomic<bool>& lock)
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{
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lock.store(false, std::memory_order_release);
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}
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// c++20 offers a combination of wait/notify methods but
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// I prefer to use a simpler version of uspace spin lock.
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class USpaceSpinLock
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{
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public:
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USpaceSpinLock(std::atomic_flag& flag) : flag_(flag)
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{
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while (flag_.test_and_set(std::memory_order_acquire))
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{
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;
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}
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};
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~USpaceSpinLock()
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{
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release();
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};
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inline void release()
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{
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flag_.clear(std::memory_order_release);
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}
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private:
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std::atomic_flag& flag_;
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};
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} // namespace utils
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