/*
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* =====================================================================================
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*
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* Filename: robust.h
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*
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* Description:
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*
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* Version: 1.0
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* Created: 2021年04月27日 10时04分29秒
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* Revision: none
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* Compiler: gcc
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*
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* Author: Li Chao (), lichao@aiotlink.com
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* Organization:
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*
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* =====================================================================================
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*/
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#ifndef ROBUST_Q31RCWYU
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#define ROBUST_Q31RCWYU
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#include "bh_util.h"
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#include "log.h"
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#include <atomic>
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#include <chrono>
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#include <unistd.h>
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namespace robust
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{
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// atomic queue, length is 1.
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// lowest bit is used for data flag, 63 bit for data.
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class AtomicQ63
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{
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public:
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typedef int64_t Data;
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AtomicQ63() { memset(this, 0, sizeof(*this)); }
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bool push(const Data d, bool try_more = false)
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{
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auto cur = buf.load();
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return Empty(cur) && buf.compare_exchange_strong(cur, Enc(d));
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}
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bool pop(Data &d, bool try_more = false)
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{
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Data cur = buf.load();
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bool r = !Empty(cur) && buf.compare_exchange_strong(cur, 0);
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if (r) { d = Dec(cur); }
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return r;
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}
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private:
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static inline bool Empty(const Data d) { return (d & 1) == 0; } // lowest bit 1 means data ok.
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static inline Data Enc(const Data d) { return (d << 1) | 1; } // lowest bit 1 means data ok.
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static inline Data Dec(const Data d) { return d >> 1; } // lowest bit 1 means data ok.
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typedef std::atomic<Data> AData;
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static_assert(sizeof(Data) == sizeof(AData));
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AData buf;
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};
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// atomic request-reply process, one cycle a time.
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class AtomicReqRep
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{
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public:
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typedef int64_t Data;
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typedef std::function<Data(const Data)> Handler;
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bool ClientRequest(const Data request, Data &reply);
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bool ServerProcess(Handler onReq);
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AtomicReqRep() :
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data_(0), timestamp_(now()) {}
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private:
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enum State {
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eStateFree,
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eStateRequest,
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eStateReply
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};
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static int GetState(Data d) { return d & MaskBits(3); }
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static Data Encode(Data d, State st) { return (d << 3) | st; }
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static Data Decode(Data d) { return d >> 3; }
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typedef std::chrono::steady_clock steady_clock;
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typedef steady_clock::duration Duration;
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static Duration now() { return steady_clock::now().time_since_epoch(); }
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bool DataCas(Data expected, Data val) { return data_.compare_exchange_strong(expected, val); }
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std::atomic<Data> data_;
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std::atomic<Duration> timestamp_;
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};
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} // namespace robust
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#endif // end of include guard: ROBUST_Q31RCWYU
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