/*
 * =====================================================================================
 *
 *       Filename:  robust.cpp
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  2021年04月27日 10时04分19秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Li Chao (), lichao@aiotlink.com
 *   Organization:  
 *
 * =====================================================================================
 */
#include "robust.h"
#include <thread>

using namespace std::chrono;
using namespace std::chrono_literals;

namespace
{
void yield() { std::this_thread::sleep_for(10us); }
} // namespace

namespace robust
{

bool AtomicReqRep::ClientRequest(const Data request, Data &reply)
{
	auto end_time = now() + 3s;
	do {
		Data cur = data_.load();
		if (GetState(cur) == eStateFree &&
		    DataCas(cur, Encode(request, eStateRequest))) {
			do {
				yield();
				cur = data_.load();
				if (GetState(cur) == eStateReply) {
					DataCas(cur, Encode(0, eStateFree));
					reply = Decode(cur);
					return true;
				}
			} while (now() < end_time);
		}
		yield();
	} while (now() < end_time);
	return false;
}

bool AtomicReqRep::ServerProcess(Handler onReq)
{
	Data cur = data_.load();
	switch (GetState(cur)) {
	case eStateRequest:
		if (DataCas(cur, Encode(onReq(Decode(cur)), eStateReply))) {
			timestamp_ = now();
			return true;
		}
		break;
	case eStateReply:
		if (timestamp_.load() + 3s < now()) {
			DataCas(cur, Encode(0, eStateFree));
		}
		break;
	case eStateFree:
	default: break;
	}
	return false;
}
} // namespace robust