redis源码--processTimeEvents时间事件

/* Process time events */static int processTimeEvents(aeEventLoop *eventLoop) { int processed = 0; aeTimeEvent *te; long long maxId; time_t now = time(NULL); /* If the system clock is moved to the future, and then set back to the * right value, time events may be delayed in a random way. Often this * means that scheduled operations will not be performed soon enough. * * Here we try to detect system clock skews, and force all the time * events to be processed ASAP when this happens: the idea is that * processing events earlier is less dangerous than delaying them * indefinitely, and practice suggests it is. */ if (now < eventLoop->lastTime) { te = eventLoop->timeEventHead; while(te) { te->when_sec = 0; te = te->next; } } eventLoop->lastTime = now; te = eventLoop->timeEventHead; maxId = eventLoop->timeEventNextId-1; while(te) { long now_sec, now_ms; long long id; if (te->id > maxId) { te = te->next; continue; } aeGetTime(&now_sec, &now_ms); if (now_sec > te->when_sec || (now_sec == te->when_sec && now_ms >= te->when_ms)) { int retval; id = te->id; retval = te->timeProc(eventLoop, id, te->clientData); processed++; /* After an event is processed our time event list may * no longer be the same, so we restart from head. * Still we make sure to don't process events registered * by event handlers itself in order to don't loop forever. * To do so we saved the max ID we want to handle. * * FUTURE OPTIMIZATIONS: * Note that this is NOT great algorithmically. Redis uses * a single time event so it's not a problem but the right * way to do this is to add the new elements on head, and * to flag deleted elements in a special way for later * deletion (putting references to the nodes to delete into * another linked list). */ if (retval != AE_NOMORE) { aeAddMillisecondsToNow(retval,&te->when_sec,&te->when_ms); } else { aeDeleteTimeEvent(eventLoop, id); } te = eventLoop->timeEventHead; } else { te = te->next; } } return processed;}