/*
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* =====================================================================================
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*
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* Filename: robust.cpp
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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19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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#include "robust.h"
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#include <chrono>
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#include <thread>
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namespace robust
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{
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namespace
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{
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static_assert(sizeof(steady_clock::duration) == sizeof(int64_t));
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static_assert(sizeof(RobustReqRep) == 24);
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static_assert(sizeof(Mutex) == 8);
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static_assert(sizeof(CircularBuffer<int>) == 48);
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auto Now() { return steady_clock::now().time_since_epoch(); }
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const steady_clock::duration kIoTimeout = 10ms;
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const steady_clock::duration kIoExpire = 100ms;
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void Yield() { std::this_thread::sleep_for(10us); }
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} // namespace
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void QuickSleep()
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{
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Yield();
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}
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bool RobustReqRep::StateCas(State exp, State val)
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{
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bool r = state_.compare_exchange_strong(exp, val);
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return r ? (timestamp_.store(Now()), true) : false;
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}
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int RobustReqRep::ClientReadReply(Msg &reply)
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{
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auto end_time = Now() + kIoTimeout;
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int done = false;
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do {
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if (StateCas(eServerWriteEnd, eClientReadBegin)) {
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Read(reply);
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done = StateCas(eClientReadBegin, eClientReadEnd);
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if (done) { break; }
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}
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Yield();
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} while (Now() < end_time);
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return done ? eSuccess : eTimeout;
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}
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int RobustReqRep::ClientWriteRequest(const Msg &request)
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{
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if (request.size() > capacity_) {
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return eSizeError;
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}
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auto end_time = Now() + kIoTimeout;
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bool done = false;
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do {
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if (StateCas(eStateReady, eClientWriteBegin)) {
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Write(request);
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done = StateCas(eClientWriteBegin, eClientWriteEnd);
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if (done) { break; }
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}
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Yield();
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} while (Now() < end_time);
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return done ? eSuccess : eTimeout;
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}
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int RobustReqRep::ServerReadRequest(Msg &request)
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{
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bool done = false;
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if (StateCas(eClientWriteEnd, eServerReadBegin)) {
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Read(request);
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done = StateCas(eServerReadBegin, eServerReadEnd);
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} else {
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auto old = state_.load();
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if (old != eStateReady && timestamp_.load() + kIoExpire < Now()) {
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StateCas(old, eStateReady);
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}
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}
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return done ? eSuccess : eTimeout;
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}
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int RobustReqRep::ServerWriteReply(const Msg &reply)
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{
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if (reply.size() > capacity_) {
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return eSizeError;
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}
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// no need to loop write, either success or timeout.
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bool done = false;
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if (StateCas(eServerReadEnd, eServerWriteBegin)) {
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Write(reply);
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done = StateCas(eServerWriteBegin, eServerWriteEnd);
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}
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return done ? eSuccess : eTimeout;
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}
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} // namespace robust
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