library/cpp/threading/queue/mpsc_intrusive_unordered.h


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#pragma once 
 
/* 
  Simple almost-wait-free unordered queue for low contention operations. 
 
  It's wait-free for producers. 
  Hanging producer can hide some items from consumer. 
 */ 
 
#include <util/system/types.h> 
 
namespace NThreading { 
    struct TIntrusiveNode { 
        TIntrusiveNode* Next; 
    }; 
 
    class TMPSCIntrusiveUnordered { 
    public: 
        static constexpr ui32 NUMBER_OF_TRIES_FOR_CAS = 3; 
 
        void Push(TIntrusiveNode* node) noexcept; 
        TIntrusiveNode* PopMany() noexcept; 
        TIntrusiveNode* Pop() noexcept; 
 
        void Push(void* node) noexcept { 
            Push(reinterpret_cast<TIntrusiveNode*>(node)); 
        } 

    private: 
        TIntrusiveNode* HeadForCaS = nullptr; 
        TIntrusiveNode* HeadForSwap = nullptr; 
        TIntrusiveNode* NotReadyChain = nullptr; 
        TIntrusiveNode* PopOneQueue = nullptr; 
    }; 
}