We used to use the needs_reinit flag in struct eventop to indicate
whether an event backend had shared state across a fork(), and
therefore would require us to construct a new event backend. But
when we realized that the signal notification fds and the thread
notification fds would always be shared across forks, we stopped
looking at it.
This patch restores the old behavior so that poll, select, and
win32select don't need to do a linear scan over all pending
fds/signals when they do a reinit. Their life is hard enough
already.
Previously, event_reinit required a bunch of really dubious hacks,
and violated a lot of abstraction barriers to mess around with lists
of internal events and "pretend" to re-add them.
The new (and fairly well commented!) implementation tries to be much
smarter, by isolating the changes as much as possible to the backend
state, and minimizing the amount of abstraction violations.
Specifically, we now use event_del() to remove events we want to
remove, rather than futzing around with queues in event_reinit().
To avoid bogus calls to evsel->del(), we temporarily replace evsel
with a null-object stub.
Also, we now push the responsibility for calling evsel->add() down
into the evmap code, so that we don't actually need to unlink and
re-link all of our events.
While re-adding all the events, event_reinit() could add a signal
event, which could then cause evsig_add() to add the
base->sig.ev_signal event. Later on its merry path through
base->eventqueue, event_reinit() would find that same event and give
it to event_io_add a second time. This would make the ev_io_next
list for that fd become circular. Ouch!
Some people use event_base_once(EV_TIMEOUT) to make a callback get
called "immediately". But this is pretty roundabout: it uses the
timeout heap to immediately put the event onto the active queue, when
it could just use event_active. Additionally, it can lead to
surprising re-ordering behavior.
This patch changes event_base_once so it bypasses event_add() and
called event_active() directly on a pure-timeout event with an empty
timeout.
I thought we'd fixed the cases where this could come up, but
apparently having an event_base_break() happen while processing
signal events could get us in trouble.
Found by Remi Gacogne. Sourceforge issue 3451433 .
This function is particularly useful for selectively increasing
the accuracy of the cached time value in 'base' during callbacks
that take a long time to execute.
This function has no effect if the base is currently not in its
event loop or if timeval caching is disabled via EVENT_BASE_FLAG_NO_CACHE_TIME.
Add a zero check to the function `event_mm_malloc_',
i.e. simply return NULL if the sz argument is zero.
On failure, set errno to ENOMEM and return NULL.
Add a zero check to the function `event_mm_calloc_',
i.e. simply return NULL if either argument is zero.
Also add an unsigned integer multiplication check, and if an integer
overflow would occur, set errno to ENOMEM and return NULL.
On failure, set errno to ENOMEM and return NULL.
Add a NULL check to the function `event_mm_strdup_',
i.e. set errno to EINVAL and return NULL.
Also add an unsigned integer addition check, and if an integer
overflow would occur, set errno to ENOMEM and return NULL.
If a memory allocation error occurs, again set errno to ENOMEM
and return NULL.
Add unit tests to `test/regress_util.c'.
Since we're computing the time after each callback, we might as well
update the time cache (if we're using it) and use monotonic time (if
we've got that).
Conflicts:
event.c
The conflicts were with the 21_faster_timeout_adj branch, which
added a "reinsert" function that needed to get renamed to
"reinsert_timeout". Also, some of the code that 21_split_functions
changes got removed by 21_faster_timeout_adj.
event_base_free(NULL) means "free the current event base".
Previously, it would assert if there was no 'current' base. Now it
just warns and returns.
Reported by Gilad Benjamini
Previously, we did stuff like
if (!lock)
EVTHREAD_ALLOC_LOCK(lock,0);
for the evsig base global lock, the arc4random lock, and the debug_map
lock. But that's potentially racy! Instead, we move the
responisiblity for global lock initialization to the functions where
we set up the lock callbacks.
(Rationale: We already require that you set up the locking callbacks
before you create any event_base, and that you do so exatly once.)
For now, we'll only check for gettimeofday jumps once every 5 seconds.
Let's see how that works.
This reverts commit 5209fadfd07af3f3379ac607582c37933b33e044.
