git-annex/Command/NumCopies.hs

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{- git-annex command
-
- Copyright 2014 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Command.NumCopies where
import Command
import qualified Annex
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import Annex.NumCopies
cmd :: Command
cmd = noMessages $ command "numcopies" SectionSetup
"configure desired number of copies"
paramNumber (withParams seek)
seek :: CmdParams -> CommandSeek
seek = withWords (commandAction . start)
start :: [String] -> CommandStart
start [] = startGet
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start [s] = case readish s of
Nothing -> giveup $ "Bad number: " ++ s
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Just n
| n > 0 -> startSet n
| n == 0 -> ifM (Annex.getState Annex.force)
( startSet n
, giveup "Setting numcopies to 0 is very unsafe. You will lose data! If you really want to do that, specify --force."
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)
| otherwise -> giveup "Number cannot be negative!"
start _ = giveup "Specify a single number."
startGet :: CommandStart
startGet = startingCustomOutput (ActionItemOther Nothing) $ next $ do
v <- getGlobalNumCopies
case v of
Just n -> liftIO $ putStrLn $ show $ fromNumCopies n
Nothing -> do
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liftIO $ putStrLn "global numcopies is not set"
old <- deprecatedNumCopies
case old of
Nothing -> liftIO $ putStrLn "(default is 1)"
Just n -> liftIO $ putStrLn $ "(deprecated git config annex.numcopies is set to " ++ show (fromNumCopies n) ++ " locally)"
return True
startSet :: Int -> CommandStart
startSet n = startingUsualMessages "numcopies" ai si $ do
make CommandStart return a StartMessage The goal is to be able to run CommandStart in the main thread when -J is used, rather than unncessarily passing it off to a worker thread, which incurs overhead that is signficant when the CommandStart is going to quickly decide to stop. To do that, the message it displays needs to be displayed in the worker thread, after the CommandStart has run. Also, the change will mean that CommandStart will no longer necessarily run with the same Annex state as CommandPerform. While its docs already said it should avoid modifying Annex state, I audited all the CommandStart code as part of the conversion. (Note that CommandSeek already sometimes runs with a different Annex state, and that has not been a source of any problems, so I am not too worried that this change will lead to breakage going forward.) The only modification of Annex state I found was it calling allowMessages in some Commands that default to noMessages. Dealt with that by adding a startCustomOutput and a startingUsualMessages. This lets a command start with noMessages and then select the output it wants for each CommandStart. One bit of breakage: onlyActionOn has been removed from commands that used it. The plan is that, since a StartMessage contains an ActionItem, when a Key can be extracted from that, the parallel job runner can run onlyActionOn' automatically. Then commands won't need to worry about this detail. Future work. Otherwise, this was a fairly straightforward process of making each CommandStart compile again. Hopefully other behavior changes were mostly avoided. In a few cases, a command had a CommandStart that called a CommandPerform that then called showStart multiple times. I have collapsed those down to a single start action. The main command to perhaps suffer from it is Command.Direct, which used to show a start for each file, and no longer does. Another minor behavior change is that some commands used showStart before, but had an associated file and a Key available, so were changed to ShowStart with an ActionItemAssociatedFile. That will not change the normal output or behavior, but --json output will now include the key. This should not break it for anyone using a real json parser.
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setGlobalNumCopies $ NumCopies n
next $ return True
where
ai = ActionItemOther (Just $ show n)
si = SeekInput [show n]