blog for the day

doc/design/assistant/blog/day_61__network_connection_detection.mdwn

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+Today, added a thread that deals with recovering when there's been a loss
+of network connectivity. When the network's down, the normal immediate
+syncing of changes of course doesn't work. So this thread detects when the
+network comes back up, and does a pull+push to network remotes, and
+triggers scanning for file content that needs to be transferred.
+
+I used dbus again, to detect events generated by both network-manager and
+wicd when they've sucessfully brought an interface up. Or, if they're not
+available, it polls every 30 minutes.
+
+When the network comes up, in addition to the git pull+push, it also
+currently does a full scan of the repo to find files whose contents
+need to be transferred to get fully back into sync.
+
+I think it'll be ok for some git pulls and pushes to happen when
+moving to a new network, or resuming a laptop (or every 30 minutes when
+resorting to polling). But the transfer scan is currently really too heavy
+to be appropriate to do every time in those situations. I have an idea for
+avoiding that scan when the remote's git-annex branch has not changed. But
+I need to refine it, to handle cases like this:
+
+1. a new remote is added
+2. file contents start being transferred to (or from it)
+3. the network is taken down
+4. all the queued transfers fail
+5. the network comes back up
+6. the transfer scan needs to know the remote was not all in sync
+   before #3, and so should do a full scan despite the git-annex branch
+   not having changed
+
+---
+
+Doubled the ram in my netbook, which I use for all development. Yesod needs
+rather a lot of ram to compile and link, and this should make me quite a
+lot more productive. I was struggling with OOM killing bits of chromium
+during my last week of development.