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Re: http2 connection keepalive broken


On Mon, Apr 30, 2018 at 12:06 PM, Stefan Eissing
<stefan.eissing@xxxxxxxxxxxxx> wrote:
>
>> Am 30.04.2018 um 12:00 schrieb Yann Ylavic <ylavic.dev@xxxxxxxxx>:
>>
>> There nothing wrong with returning CONN_STATE_WRITE_COMPLETION here
>> like before, CONN_STATE_HANDLER is wrong though.
>> So the previous code with s/CONN_STATE_HANDLER/CONN_STATE_LINGER/
>> should restore the behaviour I think.
>
> Will give it a try. However, I had already keepalive tests in the http2
> test suite, but those do not fail. So, mpm_event's behaviour on when
> it ditches idle connections is not really clear to me and other tests I
> do not know of.

Do the tests check for e.g. 1s (linger) vs 5s (keepalive) timeout?

>
> Basically, I am a bit frustrated by mpm_event and its non-documentation.
> Maybe I missed the documents that explain how its different states actually work?

I can try a formal documentation with a bit of my own idle time :)
Meanwhile, this comment in process_socket() is the only one I'm aware of:

    /*
     * The process_connection hooks above should set the connection state
     * appropriately upon return, for event MPM to either:
     * - do lingering close (CONN_STATE_LINGER),
     * - wait for readability of the next request with respect to the keepalive
     *   timeout (state CONN_STATE_CHECK_REQUEST_LINE_READABLE),
     * - wait for read/write-ability of the underlying socket with respect to
     *   its timeout by setting c->clogging_input_filters to 1 and the sense
     *   to CONN_SENSE_WANT_READ/WRITE (state CONN_STATE_WRITE_COMPLETION),
     * - keep flushing the output filters stack in nonblocking mode, and then
     *   if required wait for read/write-ability of the underlying socket with
     *   respect to its own timeout (state CONN_STATE_WRITE_COMPLETION); since
     *   completion at some point may require reads (e.g. SSL_ERROR_WANT_READ),
     *   an output filter can also set the sense to CONN_SENSE_WANT_READ at any
     *   time for event MPM to do the right thing,
     * - suspend the connection (SUSPENDED) such that it now interracts with
     *   the MPM through suspend/resume_connection() hooks, and/or registered
     *   poll callbacks (PT_USER), and/or registered timed callbacks triggered
     *   by timer events.
     * If a process_connection hook returns an error or no hook sets the state
     * to one of the above expected value, we forcibly close the connection w/
     * CONN_STATE_LINGER.  This covers the cases where no process_connection
     * hook executes (DECLINED), or one returns OK w/o touching the state (i.e.
     * CONN_STATE_READ_REQUEST_LINE remains after the call) which can happen
     * with third-party modules not updated to work specifically with event MPM
     * while this was expected to do lingering close unconditionally with
     * worker or prefork MPMs for instance.
     */

We can do better...