This is not part of the regression tests, since running it necessarily
takes a while. There is a new test-ratelim test; run it with '-h'
for an argument to see its options.
The fairness algorithms are not the best, not every bufferevent type
is supported, and some of the locking tricks here are simply absurd.
Still, this code should be a good first step.
Note that we've made two subtle mistakes: we are supposed to suffix
any non-released version with "-dev", and we're supposed to use the
last byte of the numeric version to indicate whether we have done this.
For example, when 2.0.4-alpha is released, its numeric versin will be
0x 02 00 04 00. As soon as we tag it, we will change the version in
the git repository to 2.0.4-alpha-dev, whose numeric version will be
0x 02 00 04 01 or something.
There are lots of things we do internally in bufferevents to indicate
"the user would like this operation to happen, but we aren't going to
try until some other condition goes away." Our logic here has gotten
entirely too complicated.
This patch tries to fix that by adding the idea of 'suspend flags' for
read and write. To say "don't bother reading or writing until
condition X no longer holds," bufferevent_suspend_read/write(bev,
BEV_SUSPEND_X). When X no longer holds, call
bufferevent_unsuspend_read/write(bev, BEV_SUSPEND_X).
Right now, only the read-watermark logic uses this.
William's original commit message:
Valgrind complains on startup because kq_init passes to kevent only
a partially initialized structure. The code doesn't expect kevent
to look at .fflags, .udata, or .data, I suppose, because it merely
tickles the kernel looking for an error response. But perhaps
that's unwarranted chuminess (notwithstanding that it's checking
for an OS X bug), and needless noise nonetheless.
There were a couple of places in the code where we manually kept lock
counts to make sure we never accessed resources without holding a
lock, and that we never released a lock we didn't have. The
lock-debugging code already puts counts on _every_ lock when lock
debugging is enabled, so there is no need to keep these counts around
otherwise. This patch rewrites the ASSERT_FOO_LOCKED macros to all
use a common EVLOCK_ASSERT_LOCKED().
We also teach the lock debugging code to keep track of who exactly
holds each lock, so that EVLOCK_ASSERT_LOCKED() means "locked by this
thread."
Original message:
evdns contains a bug related to thread lock.
enable thread lock by evthread_use_pthreads() will cause successive
evdns_base_resolve_ipv4() (and other resolve functions i think) to
hang on EVDNS_LOCK(base) after one or several successful call to
evdns_base_resolve_ipv4().
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.
Previously, there was no good way to request different kinds of lock
(say, read/write vs writeonly or recursive vs nonrecursive), or for a
lock function to signal failure (which would be important for a
trylock mode).
This patch revises the lock API to be a bit more useful. The older
lock calls are still supported for now.
We also add a debugging mode to catch common errors in using the
locking APIs.
It turns out that kqueue_dealloc wasn't calling evsig_dealloc()
(because it doesn't use the main signal handler logic) so the sh_old
array was leaking.
This patch also introduces a fix in evsig_dealloc() where we set
the sh_old array to NULL when we free it, so that main/fork can pass.
