Avoid websocket disconnects by sending pings

[orottier]

re issue botman/driver-slack#13, I've taken a bit different approach than the POC in the issue discussion, let me know what you think.
I'll run this over the weekend, let's see if it actually works :)

usage (botman):

$loop->addPeriodicTimer(60, function () use ($botman) {
    $timeout = 2.0;
    $botman->getClient()->checkConnection($timeout);
});

[mpociot]

@orottier Thank you for the PR. Did you have a chance to try this out?

[orottier]

I did actually!

The websocket did not disconnect for 9 days, which is better than the typical 2/3 days (needs more statistics, I know). However the client stopped receiving pongs at some point but it did not trigger a reconnect. Looking at the code, I'm probably not catching the Timeout properly
->otherwise(function (Timer\TimeoutException $error) { has a wrong namespace

and since it's wrapped in another promise I think the Exception does not propagate or something. I'll fix that and add some more logging, to be continued.

[orottier]

It's been a wild ride Marcel

• I borked one VM by var_dumping an error which filled the whole disk
• I failed to reproduce the timeouts because apparently the inner loop interval is 5 seconds
• I tried to trigger the timeout by sleeping before resolving promises but of course PHP is not async at all so the whole event loop sleeps
• I fixed the inside of the TimeOut handler, somehow the error never propagated back up

The bot has consistently stopped receiving pongs after three/four days. I'm running again with the updated code and will let you know if it finally works ;)

[orottier]

Good news! The websocket connection dropped over the weekend, but was detected by this code and successfully reconnected. :)

I guess we are good to go, but maybe you want to consider building the ping pong in the botman lib, instead of now asking the user to put in their own code

$loop->addPeriodicTimer(60, function () use ($botman) {
    $timeout = 2.0;
    $botman->getClient()->checkConnection($timeout);
});

[simensen]

I could definitely use something like this. Are we close to being able to merge this? :)

[Carpenter0100]

@mpociot Is it possible to merge this? I have the same (issue).

[orottier]

Hi, I've rebased on the current master. @mpociot it would be great if you could merge and tag.

To summarize, this lets the slack client listen for pings. If it does not receive a pong before $timeout, the websocket will reconnect. It's up to the client to actually initiate the pings via

$loop->addPeriodicTimer(60, function () use ($botman) {
    $timeout = 2.0;
    $botman->getClient()->checkConnection($timeout);
});

[mpociot]

Thank you very much for the work on this @orottier !

[guycalledseven]

Thank you! Can somebody please push this to packagist.org?
composer still sees v1.1 as latest composer show mpociot/slack-client --all:

versions : dev-master, * 1.1, 1.0, 0.3.4, 0.3.3, 0.3.2, 0.3.1, 0.3.0, 0.2.10, 0.2.9, 0.2.8, 0.2.7, 0.2.6, v0.2.5, v0.2.4, v0.2.3, v0.2.2, v0.2.1, v0.2.0, v0.1.1, v0.1.0