51 lines
2.3 KiB
Markdown
51 lines
2.3 KiB
Markdown
Once files are added (or removed or moved), need to send those changes to
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all the other git clones, at both the git level and the key/value level.
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## git syncing
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1. Can use `git annex sync`, which already handles bidirectional syncing.
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When a change is committed, launch the part of `git annex sync` that pushes
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out changes. **done**; changes are pushed out to all remotes in parallel
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1. Watch `.git/refs/remotes/` for changes (which would be pushed in from
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another node via `git annex sync`), and run the part of `git annex sync`
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that merges in received changes, and follow it by the part that pushes out
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changes (sending them to any other remotes).
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[The watching can be done with the existing inotify code! This avoids needing
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any special mechanism to notify a remote that it's been synced to.]
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**done**
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1. Periodically retry pushes that failed. **done** (every half an hour)
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1. Also, detect if a push failed due to not being up-to-date, pull,
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and repush. **done**
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2. Use a git merge driver that adds both conflicting files,
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so conflicts never break a sync. **done**
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3. Investigate the XMPP approach like dvcs-autosync does, or other ways of
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signaling a change out of band.
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4. Add a hook, so when there's a change to sync, a program can be run
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and do its own signaling.
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## misc todo
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* --debug will show often unnecessary work being done. Optimise.
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* It would be nice if, when a USB drive is connected,
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syncing starts automatically. Use dbus on Linux?
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## data syncing
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There are two parts to data syncing. First, map the network and second,
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decide what to sync when.
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Mapping the network can reuse code in `git annex map`. Once the map is
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built, we want to find paths through the network that reach all nodes
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eventually, with the least cost. This is a minimum spanning tree problem,
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except with a directed graph, so really a Arborescence problem.
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With the map, we can determine which nodes to push new content to. Then we
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need to control those data transfers, sending to the cheapest nodes first,
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and with appropriate rate limiting and control facilities.
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This probably will need lots of refinements to get working well.
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## other considerations
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This assumes the network is connected. It's often not, so the
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[[cloud]] needs to be used to bridge between LANs.
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