This patch provides the ability to receive a callback on the completion of a
request. The callback takes place immediately before the request's resources
are released.
This commit provides an interface for accessing and resetting the maximum
number of events in a given period. This information provides better insight
into event queue pressure.
By making BEV_TRIG_DEFER_CALLBACKS equal to BEV_OPT_DEFER_CALLBACKS,
and BEV_TRIG_IGNORE_WATERMARKS disjoint from BEV_OPT_*, we can save a
few operations in bufferevent_run_*, which is critical-path.
"flush" can imply writing something out to a file or connection before
clearing it; "clear" always means "remove". It's also potentially
misleading to say "outdated" here, since the function removes _all_
addresses regardless, not just certain outdated ones.
Also, don't free the lock in this function. Also reindent the function.
As mentioned at https://sourceforge.net/p/levent/bugs/293/
created a small function "evdns_base_flush_outdated_host_addresses" which removes all the previous host addresses, if user wants to clean up the list of hosts can call and use this function.
Defination of this function is part of another patch.
evhttp_write_buffer() used by evhttp_send_reply_chunk() can take callback
executed when (part of) the buffer has been written. Using this callback to
schedule the next chunk avoids buffering large amounts of data in memory.
Basically tcp final handshake looks like this:
(C - client, S - server)
ACK[C] - FIN/ACK[S] - FIN/ACK[S] - ACK [C]
However there are servers, that didn't close connection like this,
while it is still _considered_ as valid, and using libevent http layer
we can do requests to such servers.
Modified handshake:
(C - client, S - server)
ACK[C] - RST/ACK[S] - RST/ACK[S]
And in this case we can't extract IP address from socket, because it is
already closed, and getpeername() will return: "transport endpoint is not connected".
So we need to store address that we are connecting to, after we know it,
and that is what this patch do.
I have reproduced it, however it have some extra packages.
(I will try to fix it)
https://github.com/azat/nfq-examples/blob/master/nfqnl_rst_fin.c
There was actually a bug in the original version of this: it tried to
run the finalizers after (potentially) setting current_base to NULL;
but those finalizers could themselves (potentially) be invoking stuff
that needed to know about the current event_base. So the right time to
do it is _before_ clearing current_base.
