好吧，神马都init好了，loop毕竟是个环呐，在哪跑起来呢，ok，他是ev_run的工作：
int ev_run (EV_P_ int flags)
{
#if EV_FEATURE_API
++loop_depth;
#endif assert (("libev: ev_loop recursion during release detected", loop_done != EVBREAK_RECURSE)); loop_done = EVBREAK_CANCEL; EV_INVOKE_PENDING; /* in case we recurse, ensure ordering stays nice and clean */ do
{
#if EV_VERIFY >= 2
ev_verify (EV_A);
#endif #ifndef _WIN32
if (expect_false (curpid)) /* penalise the forking check even more */
if (expect_false (getpid () != curpid))
{
curpid = getpid ();
postfork = ;
}
#endif #if EV_FORK_ENABLE
/* we might have forked, so queue fork handlers */
if (expect_false (postfork))
if (forkcnt)
{
queue_events (EV_A_ (W *)forks, forkcnt, EV_FORK);
EV_INVOKE_PENDING;
}
#endif #if EV_PREPARE_ENABLE
/* queue prepare watchers (and execute them) */
if (expect_false (preparecnt))
{
queue_events (EV_A_ (W *)prepares, preparecnt, EV_PREPARE);
EV_INVOKE_PENDING;
}
#endif if (expect_false (loop_done))
break; /* we might have forked, so reify kernel state if necessary */
if (expect_false (postfork))
loop_fork (EV_A); /* update fd-related kernel structures */
fd_reify (EV_A); /* calculate blocking time */
{
ev_tstamp waittime = .;
ev_tstamp sleeptime = .; /* remember old timestamp for io_blocktime calculation */
ev_tstamp prev_mn_now = mn_now; /* update time to cancel out callback processing overhead */
time_update (EV_A_ 1e100); /* from now on, we want a pipe-wake-up */
pipe_write_wanted = ; ECB_MEMORY_FENCE; /* make sure pipe_write_wanted is visible before we check for potential skips */ if (expect_true (!(flags & EVRUN_NOWAIT || idleall || !activecnt || pipe_write_skipped)))
{
waittime = MAX_BLOCKTIME; if (timercnt)
{
ev_tstamp to = ANHE_at (timers [HEAP0]) - mn_now;
if (waittime > to) waittime = to;
} #if EV_PERIODIC_ENABLE
if (periodiccnt)
{
ev_tstamp to = ANHE_at (periodics [HEAP0]) - ev_rt_now;
if (waittime > to) waittime = to;
}
#endif /* don't let timeouts decrease the waittime below timeout_blocktime */
if (expect_false (waittime < timeout_blocktime))
waittime = timeout_blocktime; /* at this point, we NEED to wait, so we have to ensure */
/* to pass a minimum nonzero value to the backend */
if (expect_false (waittime < backend_mintime))
waittime = backend_mintime; /* extra check because io_blocktime is commonly 0 */
if (expect_false (io_blocktime))
{
sleeptime = io_blocktime - (mn_now - prev_mn_now); if (sleeptime > waittime - backend_mintime)
sleeptime = waittime - backend_mintime; if (expect_true (sleeptime > .))
{
ev_sleep (sleeptime);
waittime -= sleeptime;
}
}
} #if EV_FEATURE_API
++loop_count;
#endif
assert ((loop_done = EVBREAK_RECURSE, )); /* assert for side effect */
backend_poll (EV_A_ waittime);
assert ((loop_done = EVBREAK_CANCEL, )); /* assert for side effect */ pipe_write_wanted = ; /* just an optimisation, no fence needed */ ECB_MEMORY_FENCE_ACQUIRE;
if (pipe_write_skipped)
{
assert (("libev: pipe_w not active, but pipe not written", ev_is_active (&pipe_w)));
ev_feed_event (EV_A_ &pipe_w, EV_CUSTOM);
} /* update ev_rt_now, do magic */
time_update (EV_A_ waittime + sleeptime);
} /* queue pending timers and reschedule them */
timers_reify (EV_A); /* relative timers called last */
#if EV_PERIODIC_ENABLE
periodics_reify (EV_A); /* absolute timers called first */
#endif #if EV_IDLE_ENABLE
/* queue idle watchers unless other events are pending */
idle_reify (EV_A);
#endif #if EV_CHECK_ENABLE
/* queue check watchers, to be executed first */
if (expect_false (checkcnt))
queue_events (EV_A_ (W *)checks, checkcnt, EV_CHECK);
#endif EV_INVOKE_PENDING;
}
while (expect_true (
activecnt
&& !loop_done
&& !(flags & (EVRUN_ONCE | EVRUN_NOWAIT))
)); if (loop_done == EVBREAK_ONE)
loop_done = EVBREAK_CANCEL; #if EV_FEATURE_API
--loop_depth;
#endif return activecnt;
}
看到了那么多ifdef有木有想shi的赶脚，尼玛。对于win32下，我们来精简下，哈哈：
int
ev_run (EV_P_ int flags)
{
assert (("libev: ev_loop recursion during release detected", loop_done != EVBREAK_RECURSE)); loop_done = EVBREAK_CANCEL;
//激活已经pending的事件
EV_INVOKE_PENDING; /* in case we recurse, ensure ordering stays nice and clean */ do
{
if (expect_false (curpid)) /* penalise the forking check even more */
if (expect_false (getpid () != curpid))
{
curpid = getpid ();
postfork = ;
} if (expect_false (loop_done))
break; /* update fd-related kernel structures */
fd_reify (EV_A);//把更改的事件进行更新 /* calculate blocking time */
{
ev_tstamp waittime = .;
ev_tstamp sleeptime = .; /* remember old timestamp for io_blocktime calculation */
ev_tstamp prev_mn_now = mn_now; /* update time to cancel out callback processing overhead */
time_update (EV_A_ 1e100); /* from now on, we want a pipe-wake-up */
pipe_write_wanted = ; ECB_MEMORY_FENCE; /* make sure pipe_write_wanted is visible before we check for potential skips */ if (expect_true (!(flags & EVRUN_NOWAIT || idleall || !activecnt || pipe_write_skipped)))
{
waittime = MAX_BLOCKTIME; if (timercnt)
{
ev_tstamp to = ANHE_at (timers [HEAP0]) - mn_now;
if (waittime > to) waittime = to;
} /* don't let timeouts decrease the waittime below timeout_blocktime */
if (expect_false (waittime < timeout_blocktime))
waittime = timeout_blocktime; /* at this point, we NEED to wait, so we have to ensure */
/* to pass a minimum nonzero value to the backend */
if (expect_false (waittime < backend_mintime))
waittime = backend_mintime; /* extra check because io_blocktime is commonly 0 */
if (expect_false (io_blocktime))
{
sleeptime = io_blocktime - (mn_now - prev_mn_now); if (sleeptime > waittime - backend_mintime)
sleeptime = waittime - backend_mintime; if (expect_true (sleeptime > .))
{
ev_sleep (sleeptime); //以上这么大一堆，都是在计算必要的sleep事件，其实就是阻塞嘛
waittime -= sleeptime;
}
}
} assert ((loop_done = EVBREAK_RECURSE, )); /* assert for side effect */
backend_poll (EV_A_ waittime);//这里开始调用上层封装的epool,select进行轮询，收集pending事件
assert ((loop_done = EVBREAK_CANCEL, )); /* assert for side effect */ pipe_write_wanted = ; /* just an optimisation, no fence needed */ ECB_MEMORY_FENCE_ACQUIRE;
if (pipe_write_skipped)
{
assert (("libev: pipe_w not active, but pipe not written", ev_is_active (&pipe_w)));
ev_feed_event (EV_A_ &pipe_w, EV_CUSTOM);
} /* update ev_rt_now, do magic */
time_update (EV_A_ waittime + sleeptime);
} /* queue pending timers and reschedule them */
timers_reify (EV_A); /* relative timers called last *///对pending的timer事件进行收集 EV_INVOKE_PENDING; //遍历所有pending事件
}
while (expect_true (
activecnt
&& !loop_done
&& !(flags & (EVRUN_ONCE | EVRUN_NOWAIT))
)); if (loop_done == EVBREAK_ONE)
loop_done = EVBREAK_CANCEL; return activecnt;
}
所有总结下，ev_run是libev的核心，
他主要做了五件事情：
1.更新更改的FD事件
2.进行必要的sleep
3.backend_poll收集pending的IO事件
4.收集pending的timer事件
5.调用所有pending的事件
ok，就是这样了！但是还有很多细节啊，尼玛代码之虐心，非比寻常啊！