用C++模拟异步编程

<code class="lang-cpp">// coroutine.cpp : 定义控制台应用程序的入口点。
//
                                 
#include "stdafx.h"
                                 
#include <stdio.h>
#include <windows.h>
#include <queue>
#include <tuple>
                                 
using namespace std;
                                 
struct CoContext;
typedef void (*CoRoutine)(CoContext*);
                                 
queue<pair<int, cocontext*>> resumequeue;
                                 
struct CoContext {
    CoContext(
        CoRoutine pfunc, INT_PTR resume1 = 0, INT_PTR resume2 = 0, INT_PTR resume3 = 0,
        CoContext* resumecontext = NULL, int resumetick = 1, bool finished = false)
        : pfunc(pfunc), resume1(resume1), resume2(resume2), resume3(resume3),
        resumecontext(resumecontext), resumetick(resumetick), finished(finished)
    {
        // 构造函数
    }
    CoRoutine pfunc;
    INT_PTR resume1;
    INT_PTR resume2;
    INT_PTR resume3;
    CoContext *resumecontext;
    int resumetick;
    bool finished;
};
                                 
void pushcontext(int tick, CoContext *ctx)
{
    resumequeue.push(pair<int, cocontext*>(tick, ctx));
}
                                 
void coroutine1(CoContext *ctx);
                                 
int main()
{
    CoContext *ctx = new CoContext(coroutine1);
    pushcontext(1, ctx);
                                 
    while (1)
    {
        if (!resumequeue.empty() && --resumequeue.front().first <= 0)         {             cocontext *ctx="resumequeue.front().second;"             if (ctx->finished)
            {
                if (ctx->resumecontext)
                    pushcontext(ctx->resumetick, ctx->resumecontext);
                else
                    delete ctx; // 此处存在问题，见06-01更新说明
            }
            else
            {
                ctx->pfunc(ctx);
            }
            resumequeue.pop();
        }
        Sleep(1);
    }
    return 0;
}
                                 
////////////////////////////////////////////////////////////
// 两个异步函数
// coroutine1调用coroutine2
// coroutine2返回coroutine1但仍在工作（这里以空等来模拟）
// coroutine1设置coroutine2的恢复点为自己，并等待（返回消息循环）
// coroutine2工作完成，设置finished标志
// 消息循环检测到了finished标志，恢复coroutine1的状态
// coroutine1恢复以后删除coroutine2的状态
// coroutine1完成并返回消息循环
// 消息循环检测到了finished标志，由于恢复点为空，将删除它的状态
                                 
void coroutine2(CoContext *ctx)
{
    if (ctx->resume1 == 1) goto resume1; // 跳到恢复点
                                 
    // 空等待1000ms
    printf("just suspend 200 ticks\n");
    ctx->resume1 = 1;
    return pushcontext(200, ctx);
resume1:
    printf("after suspend 200 ticks\n");
                                 
    // 处理完成并返回
    printf("set finished\n");
    ctx->finished = true;
    return pushcontext(1, ctx);
}
                                 
void coroutine1(CoContext *ctx)
{
    if (ctx->resume1 == 1) goto resume1; // 跳到恢复点
                                 
    // 调用异步函数
    printf("before calling\n");
    CoContext *ctx2 = new CoContext(coroutine2);
    coroutine2(ctx2);
    printf("after calling\n");
                                 
    // 等待await
    printf("before awaiting\n");
    ctx2->resumecontext = ctx;
    ctx2->resumetick = 1;
    ctx->resume1 = 1;
    ctx->resume2 = (INT_PTR)ctx2;
    return;
resume1:
    delete (CoContext*)ctx->resume2;
    printf("after awaiting\n");
                                     
    // 处理完成并返回
    printf("set finished\n"); 
    ctx->finished = true;
    return pushcontext(1, ctx);
}</=></int,></pair<int,></tuple></queue></windows.h></stdio.h></code>

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