The logic here is a little complex, since epoll_add must used called exactly
when no events were previously set, epoll_mod must be used when any events
were previously set, and epoll_del only called when the removing all events.
Previously, our default lock model kind of assumed that every lock was
potentially a read-write lock. This was a poor choice, since
read-write locks are far more expensive than regular locks, and so the
lock API should only use them when we can actually take advantage of
them. Neither our pthreads or win32 lock implementation provided rw
locks.
Now that we have a way (not currently used!) to indicate that we
really want a read-write lock, we shouldn't actually say "lock this
for reading" or "lock this for writing" unless we mean it.
I've gone through everything that it declared to see where it was used,
and it seems that we probably don't need it anywhere.
Here's what it declared, and why I think we're okay dropping it.
o struct timeval {}
(Used all over, and we can't really get away with declaring it ourselves;
we need the same definition the system uses. If we can't find struct
timeval, we're pretty much sunk.)
o struct timespec {}
(Used in event.c, evdns.c, kqueue.c, evport.c. Of these,
kqueue.c and event.c include sys/_time.h. event.c conditions its use on
_EVENT_HAVE_CLOCK_GETTIME, and kqueue() only works if timespec is defined.)
o TIMEVAL_TO_TIMESPEC
(Used in kqueue.c, but every place with kqueue has sys/time.h)
o struct timezone {}
(event2/util.h has a forward declaration; only evutil.c references it and
doesn't look at its contents.)
o timerclear, timerisset, timercmp, timeradd, timersub
(Everything now uses the evutil_timer* variants.)
o ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF, struct itemerval
(These are only used in test/regress.c, which does not include _time.h)
o CLOCK_REALTIME
(Only used in evdns.c, which does not include _time.h)
o TIMESPEC_TO_TIMEVAL
o DST_*
o timespecclear, timespecisset, timespeccmp, timespecadd, timespecsub
o struct clockinfo {}
o CLOCK_VIRTUAL, CLOCK_PROF
o TIMER_RELTIME, TIMER_ABSTIME
(unused)
svn:r1494
This is harder than it sounds, since we need to make sure to
release the lock around the key call to the kernel (e.g.,
select, epoll_wait, kevent), AND we need to make sure that
none of the fields that are used in that call are touched by
anything that might be running concurrently in another
thread. I managed to do this pretty well for everything but
poll(). With poll, I needed to introduce a copy of the
event_set structure.
This patch also fixes a bug in win32.c where we called
realloc() instead of mm_realloc().
svn:r1450
We do this by not allocating the maximum epoll_event array for the epoll
backend at startup. Instead, we start out accepting 32 events at a time, and
double the array's size when it seems that the OS is generating events faster
than we're requesting them. This saves up to 374K per epoll-based
event_base. Resolves bug 2839240.
svn:r1428
a) this is 2009
b) niels and nick have been comaintainers for a while
c) saying "all rights reserved" when you then go on to explicitly
disclaim some rights is sheer cargo-cultism.
svn:r1065
Fix for epoll-on-linux bug (#1908866) where timeout values over (LONG_MAX-999)/HZ) (35 for me, or maybe 6 hours 50 min for some people, or maybe 3 hours 25 minutes for a special few) get treated as "wait forever". This actually deserves to be fixed in the kernel, but even if it is we will need to support Linux versions with this bug.
svn:r709
