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Event loop: call after sleep() only from top level.

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In general we do not want before/after sleep() callbacks to be called
when we re-enter the event loop, since those calls are only designed in
order to perform operations every main iteration of the event loop, and
re-entering is often just a way to incrementally serve clietns with
error messages or other auxiliary operations. However, if we call the
callbacks, we are then forced to think at before/after sleep callbacks
as re-entrant, which is much harder without any good need.

However here there was also a clear bug: beforeSleep() was actually
never called when re-entering the event loop. But the new afterSleep()
callback was. This is broken and in this instance re-entering
afterSleep() caused a modules GIL dead lock.
This commit is contained in:
antirez 2017-07-11 00:13:52 +02:00
parent 11182a1a58
commit 54e4bbeabd
2 changed files with 4 additions and 2 deletions
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5
src/ae.c
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@ -344,6 +344,7 @@ static int processTimeEvents(aeEventLoop *eventLoop) {
* if flags has AE_FILE_EVENTS set, file events are processed.
* if flags has AE_TIME_EVENTS set, time events are processed.
* if flags has AE_DONT_WAIT set the function returns ASAP until all
* if flags has AE_CALL_AFTER_SLEEP set, the aftersleep callback is called.
* the events that's possible to process without to wait are processed.
*
* The function returns the number of events processed. */
@ -403,7 +404,7 @@ int aeProcessEvents(aeEventLoop *eventLoop, int flags)
numevents = aeApiPoll(eventLoop, tvp);
/* After sleep callback. */
if (eventLoop->aftersleep != NULL)
if (eventLoop->aftersleep != NULL && flags & AE_CALL_AFTER_SLEEP)
eventLoop->aftersleep(eventLoop);
for (j = 0; j < numevents; j++) {
@ -460,7 +461,7 @@ void aeMain(aeEventLoop *eventLoop) {
while (!eventLoop->stop) {
if (eventLoop->beforesleep != NULL)
eventLoop->beforesleep(eventLoop);
aeProcessEvents(eventLoop, AE_ALL_EVENTS);
aeProcessEvents(eventLoop, AE_ALL_EVENTS|AE_CALL_AFTER_SLEEP);
}
}

1
src/ae.h
View File

@ -46,6 +46,7 @@
#define AE_TIME_EVENTS 2
#define AE_ALL_EVENTS (AE_FILE_EVENTS|AE_TIME_EVENTS)
#define AE_DONT_WAIT 4
#define AE_CALL_AFTER_SLEEP 8
#define AE_NOMORE -1
#define AE_DELETED_EVENT_ID -1