I've convinced myself that nothing in DaemonStatus can deadlock,
as it always keepts the TMVar full. That was the only reason it was in the
Annex monad.
This is a way to send a notification to a set of clients, any of which can be
blocked waiting for a new notification to arrive. A complication is that any
number of clients may be be dead, and we don't want stale notifications for
those clients to pile up and leak memory.
It took me 3 tries to find the solution, which turns out to be simple: An array
of SampleVars, one per client. Using SampleVars means that clients only see the
most recent notification, but when the notification is just "the assistant's
state changed somehow; display a refreshed rendering of it", that's sufficient.
This avoids forking another process, avoids polling, fixes a race,
and avoids a rare forkProcess thread hang that I saw once time
when starting the webapp.
Had to switch to toWaiAppPlain to avoid a seeming bug in toWaiApp;
chromium only received a partial copy of jquery. Always the same length
each time, which makes me think it's a bug in the compression, although
a bug in the autohead middleware is also a possibility.
Anyway, there's little need for compression for a local webapp. Not wasting
time compressing things is probably a net gain.
Similarly, I've not worried about minifying this yet. Although that would
avoid bloating the git-annex binary quite so much.
Very happy to have a reusable autoUpdate widget that can make any Yesod
widget automatically refresh!
Also added support for non-javascript browsers, falling back to meta
refresh.
Also, the home page is now rendered with the webapp status on it, before
any refreshing is done.
