When an automatic upgrade completes, or when the user clicks on the upgrade
button in one webapp, but also has it open in another browser window/tab,
we have a problem: The current web server is going to stop running in
minutes, but there is no way to send a redirect to the web browser to the
new url.
To solve this, used long polling, so the webapp is always listening for
urls it should redirect to. This allows globally redirecting every open
webapp. Works great! Tested with 2 web browsers with 2 tabs each.
May be useful for other purposes later too, dunno.
The overhead is 2 http requests per page load in the webapp. Due to yesod's
speed, this does not seem to noticibly delay it. Only 1 of the requests
could possibly block the page load, the other is async.
A while ago I added code to support recent versions of shakespeare-js,
(commit fe11b3a940). But it seems that resulted
in quoting of all strings inserted into javascript files, which means it's
now impossible to do the type of metaprogramming that longpolling.julius
relied on. I have found another way to accomplish the same thing without
needing to generate unique function names. Hopefully it's portable.
Opinion of shakespeare-js now at rock bottom. One of these days, this
needs to be redone to use Fay.
