redis的event处理过程基本流程

这次分析aemain函数主要执行过程，会忽略部分细节处理；

void aeMain(aeEventLoop *eventLoop) {     eventLoop->stop = 0;     while (!eventLoop->stop) {         if (eventLoop->beforesleep != NULL)             eventLoop->beforesleep(eventLoop);         aeProcessEvents(eventLoop, AE_ALL_EVENTS);     }}

这里主要是一个while循环，主要执行函数是eventLoop->beforesleep和aeProcessEvents，本次主要分析aeProcessEvents；关于aeProcessEvents有机会再分析；

int aeProcessEvents(aeEventLoop *eventLoop, int flags){    int processed = 0, numevents;    /* Nothing to do? return ASAP */    if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS)) return 0;    /* Note that we want call select() even if there are no     * file events to process as long as we want to process time     * events, in order to sleep until the next time event is ready     * to fire. */    if (eventLoop->maxfd != -1 ||        ((flags & AE_TIME_EVENTS) && !(flags & AE_DONT_WAIT))) {        int j;        aeTimeEvent *shortest = NULL;        struct timeval tv, *tvp;        if (flags & AE_TIME_EVENTS && !(flags & AE_DONT_WAIT))            shortest = aeSearchNearestTimer(eventLoop);        if (shortest) {            long now_sec, now_ms;            aeGetTime(&now_sec, &now_ms);            tvp = &tv;            /* How many milliseconds we need to wait for the next             * time event to fire? */            long long ms =                (shortest->when_sec - now_sec)*1000 +                shortest->when_ms - now_ms;            if (ms > 0) {                tvp->tv_sec = ms/1000;                tvp->tv_usec = (ms % 1000)*1000;            } else {                tvp->tv_sec = 0;                tvp->tv_usec = 0;            }        } else {            /* If we have to check for events but need to return             * ASAP because of AE_DONT_WAIT we need to set the timeout             * to zero */            if (flags & AE_DONT_WAIT) {                tv.tv_sec = tv.tv_usec = 0;                tvp = &tv;            } else {                /* Otherwise we can block */                tvp = NULL; /* wait forever */            }        }        numevents = aeApiPoll(eventLoop, tvp);        for (j = 0; j < numevents; j++) {            aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];            int mask = eventLoop->fired[j].mask;            int fd = eventLoop->fired[j].fd;            int rfired = 0;    /* note the fe->mask & mask & ... code: maybe an already processed             * event removed an element that fired and we still didn't             * processed, so we check if the event is still valid. */            if (fe->mask & mask & AE_READABLE) {                rfired = 1;                fe->rfileProc(eventLoop,fd,fe->clientData,mask);            }            if (fe->mask & mask & AE_WRITABLE) {                if (!rfired || fe->wfileProc != fe->rfileProc)                    fe->wfileProc(eventLoop,fd,fe->clientData,mask);            }            processed++;        }    }    /* Check time events */    if (flags & AE_TIME_EVENTS)        processed += processTimeEvents(eventLoop);    return processed; /* return the number of processed file/time events */}

本函数最主要部分是aeApiPoll,在它之前的部分是这个函数第二个参数tvp的赋值过程，目的是epoll等待的时间不超过下次time事件的时间；

之后是获取的事件执行对应的读写执行过程；

最后是timeevent的处理；