45 lines
2.2 KiB
Text
45 lines
2.2 KiB
Text
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Started implementing [[transfer_control]]. Although I'm currently calling
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the configuration for it "preferred content expressions". (What a mouthful!)
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I was mostly able to reuse the Limit code (used to handle parameters like
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--not --in otherrepo), so it can already build Matchers for preferred content
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expressions in my little Domain Specific Language.
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Preferred content expressions can be edited with `git annex vicfg`, which
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checks that they parse properly.
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The plan is that the first place to use them is not going to be inside the
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assistant, but in commands that use the `--auto` parameter, which will use
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them as an additional constraint, in addition to the numcopies setting
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already used. Once I get it working there, I'll add it to the assistant.
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Let's say a repo has a preferred content setting of
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"(not copies=trusted:2) and (not in=usbdrive)"
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* `git annex get --auto` will get files that have less than 2 trusted
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copies, and are not in the usb drive.
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* `git annex drop --auto` will drop files that have 2 or more trusted
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copies, and are not in the usb drive (assuming numcopies allows dropping
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them of course).
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* `git annex copy --auto --to thatrepo` run from another repo
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will only copy files that have less than 2 trusted copies. (And if that
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was run on the usb drive, it'd never copy anything!)
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There is a complication here.. What if the repo with that preferred content
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setting is itself trusted? Then when it gets a file, its number of
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trusted copies increases, which will make it be dropped again. :-/
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This is a nuance that the numcopies code already deals with, but it's
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much harder to deal with it in these complicated expressions. I need to think
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about this; the three ideas I'm working on are:
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1. Leave it to whoever/whatever writes these expressions to write ones
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that avoid such problems. Which is ok if I'm the only one writing
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pre-canned ones, in practice..
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2. Transform expressions into ones that avoid such problems. (For example,
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replace "not copies=trusted:2" with "not (copies=trusted:2 or (in=here and
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trusted=here and copies=trusted:3))"
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3. Have some of the commands (mostly drop I think) pretend the drop
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has already happened, and check if it'd then want to get the file back
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again.
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