I noticed that when my modem hung up and redialed, my xmpp client was left
sending messages into the void. This will also handle any idle
disconnection issues.
I hope this will be easier to reason about, and less buggy. It was
certianly easier to write!
An immediate benefit is that with a traversable queue of push requests to
select from, the threads can be a lot fairer about choosing which client to
service next.
This will avoid losing any messages received from 1 client when a push
involving another client is running.
Additionally, the handling of push initiation is improved,
it's no longer allowed to run multiples of the same type of push to
the same client.
Still stalls sometimes :(
Observed: With 2 xmpp clients, one would sometimes stop responding
to CanPush messages. Often it was in the middle of a receive-pack
of its own (or was waiting for a failed one to time out).
Now these are always immediately responded to, which is fine; the point
of CanPush is to find out if there's another client out there that's
interested in our push.
Also, in queueNetPushMessage, queue push initiation messages when
we're already running the side of the push they would initiate.
Before, these messages were sent into the netMessagesPush channel,
which was wrong. The xmpp send-pack and receive-pack code discarded
such messages.
This still doesn't make XMPP push 100% robust. In testing, I am seeing
it sometimes try to run two send-packs, or two receive-packs at once
to the same client (probably because the client sent two requests).
Also, I'm seeing rather a lot of cases where it stalls out until it
runs into the 120 second timeout and cancels a push.
And finally, there seems to be a bug in runPush. I have logs that
show it running its setup action, but never its cleanup action.
How is this possible given its use of E.bracket? Either some exception
is finding its way through, or the action somehow stalls forever.
When this happens, one of the 2 clients stops syncing.
Unless the request is for repo uuid we already know. This way, if A1 pairs
with friend B1, and B1 pairs with device B2, then B1 can request A1 pair
with it and no confirmation is needed. (In future, may want to try to do
that automatically, to make a more robust network.)
This may work around google talk's horrible presence handling, in which
clients often don't learn about other clients, at least when using the same
account. This way, every time we start a git push over xmpp, we'll waste
bandwidth asking clients to please try again to identify themselves.
This is not perfect, because on loss of connection, we do not currently
immediately detect it and stop the client. It has to time out, and then
the buddy list will clear.
The NetWatcher should detect disconnects too..
Noticed that, At startup or network reconnect, git push messages were sent,
often before presence info has been gathered, so were not sent to any
buddies.
To fix this, keep track of which buddies have seen such messages,
and when new presence is received from a buddy that has not yet seen it,
resend.
This is done only for push initiation messages, so very little data needs
to be stored.
This fixes the issue mentioned in the last commit.
Turns out just collecting UUID of clients behind a XMPP remote is
insufficient (although I should probably still do it for other reasons),
because a single remote repo might be connected via both XMPP and local
pairing. So a way is needed to know when a push was received from any
client using a given XMPP remote over XMPP, as opposed to via ssh.
Noticed that when pairing, sometimes both sides start to push, and the other
side sends a PushRequest, and the two deadlock, neither doing anything.
(Timeout eventually breaks this.) So, let both run at the same time.
This should help prevent git-annex clients receiving messages that
were intended for normal clients they're sharing the account with.
Changed XMPP protocol use to always send chat messages directed at the
specific client, as the negative priority blocks less directed messages.
It might even work, although nothing yet triggers XMPP pushes.
Also added a set of deferred push messages. Only one push can run at a
time, and unrelated push messages get deferred. The set will never grow
very large, because it only puts two types of messages in there, that
can only vary in the client doing the push.
Maybe the spec allows it, but broadcasting self-directed presence info to
all buddies is just insane.
I had to bring back the IQ messages for self-pairing, while still using
directed presence for other pairing. Ugly.
Testing between Google Talk and prosody, the directed IQ messages
were not received. Google Talk probably only relays them between
clients using the same account.
I first tried even more directed presence, with each client JID being sent
a separate presence, but that didn't work on Google Talk, particularly
it was ignored when one client sent it to another client using the same
account.
So, presence directed at the user@host of the client to pair with. Tested
working between Google Talk and prosody (in both directions), as well
as between two clients with the same account on Google Talk, and
two clients with the same account on prosody.
Only problem with this form of directed presence is that if I also use it
for git pushes, more clients than are interested in a push's data will
receive it. So I may need some better approach, or a hybrid between
directed IQ and directed presence.
