Gilad Benjamini noted that we check the error code for deleting a
write-timeout event twice, and the read timeout not at all. This
shouldn't be a bit problem, since it's really hard for a delete to
fail on a timeout-only event, but it's worth fixing.
Fixes bug 3046787
When we freed a bufferevent that was in a rate-limiting group and
blocked on IO, the process of freeing it caused it to get removed
from the group. But removing the bufferevent from the group made
its limits get removed, which could make it get un-suspended and in
turn cause its events to get re-added. Since we would then
immediately _free_ the events, this would result in dangling
pointers.
Fixes bug 3041007.
Although bufferevent operations are threadsafe, sometimes you need
to make sure that a few operations on a single bufferevent will all
be executed with nothing intervening. That's what these functions
are for.
We were saying
mm_free(bufev - bufev->be_ops->mem_offset);
when we should have said
mm_free(((char*)bufev) - bufev->be_ops->mem_offset);
In other words, if mem_offset had ever been nonzero, then instead of
backing up mem_offset bytes to find the thing we were supposed to free, we
would have backed up mem_offset*sizeof(struct bufferevent) bytes, and freed
something completely crazy.
Spotted thanks to a conversation with Jardel Weyrich
The different bufferevent implementations had different behavior for
their timeouts. Some of them kept re-triggering the timeouts
indefinitely; some disabled the event immediately the first time a
timeout triggered. Some of them made the timeouts only count when
the bufferevent was actively trying to read or write; some did not.
The new behavior is modeled after old socket bufferevents, since
they were here first and their behavior is relatively sane.
Basically, each timeout disables the bufferevent's corresponding
read or write operation when it fires. Timeouts are stopped
whenever we suspend writing or reading, and reset whenever we
unsuspend writing or reading. Calling bufferevent_enable resets a
timeout, as does changing the timeout value.
This should end the family of bugs where we call bufferevent_free()
while a pending callback is holding a reference on the bufferevent,
and the callback tries to invoke the user callbacks before it releases
its own final reference.
This means that bufferevent_decref() is now a separate function from
bufferevent_free().
I don't expect that many users will be so religious about calling
unassign, but we need to be so that it's at least possible to use
debug mode without eating memory.
Most of these should be unable to fail, since adding a timeout
generally always works. Still, it's better not to try to be "too
smart for our own good here."
There are some remaining event_add() calls that I didn't add checks
for; I've marked those with "XXXX" comments.
In many places throughout the code, we called _bufferevent_run_eventcb
without checking whether the eventcb was actually set. This would
work fine when the bufferevent's callbacks were deferred, but
otherwise the code would segfault. Strangely, we always remembered to
check before calling the _bufferevent_run_{read,write}cb functions.
To prevent similar errors in the future, all of
_buferevent_run_{read,write,event}cb now check to make sure the
callback is actually set before invoking or deferring the callback.
This patch also removes the now-redundant checks for {read,write}cb.
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.
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.
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.
This patch from Chris Davis saves some callback depth, and adds proper
ref-counting to bufferevents when there's a deferred evbuffer callback
inflight. It could use a couple more comments to really nail down what
its invariants are.
svn:r1543
This code adds a new Bufferevent type that is only compiled when the
openssl library is present. It supports using an SSL object and an
event alert mechanism, which can either be an fd or an underlying
bufferevent.
There is still more work to do: the unit tests are incomplete, and we
need to support flush and shutdown much better. Sometimes events are
generated needlessly: this will hose performance.
There's a new encrypting proxy in sample/le-proxy.c.
This code has only been tested on OSX, and nowhere else.
svn:r1382
Rationale: we hold a lock on the bufferevent when its callbacks are
executing, so we need to release the lock afterwards. But the
callback might free the bufferevent, so unless we're holding a
reference on the bufferevent, the lock might not be there for us to
release.
svn:r1347
This fixes part of bug 2800642, I believe, though there is still a
general race condition in multithreaded use of events that we need to
think about.
svn:r1337
Paired and asynchronous bufferevents didn't do timeouts, and filtering
bufferevents gave them funny semantics. Now they all should all work
in a way consistent with what socket bufferevents do now: a [read/write]
timeout triggers if [reading/writing] is enabled, and if the timeout is
set, and the right amount of time passes without any data getting
[added to the input buffer/drained from the output buffer].
svn:r1314
Previously, set_flags() would replace all previous user-visible flags.
Now it just sets the flags, and there is a clear_flags() function to
clear other flags.
svn:r1293
OpenSSL uses something like this to implement get/set access for
properties on its BIOs, so that it doesn't need to add a pair of
get/set functions to the vtable struct for every new abstract property
it provides an accessor for.
Doing this lets us make bufferevent_setfd abstract, and implement an
abstract bufferevent_getfd.
svn:r1284
This is a bit of an interface doozy, but it's really needed in order
to be able to document this stuff without apologizing it. This patch
does the following renamings:
evbuffercb -> bufferevent_data_cb
everrorcb -> bufferevent_event_cb
EVBUFFER_(READ,WRITE,...) -> BEV_EVENT_(...)
EVBUFFER_(INPUT,OUTPUT) -> bufferevent_get_(input,output)
All the old names are available in event2/bufferevent_compat.h
svn:r1283
This way we don't expose more of a bufferevent than we need to. One
motivation is to make it easier to automatically get deferred callbacks
with a bufferevent without exposing the deferred_cb structure.
svn:r1169
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
