git-annex/Command/Get.hs
Joey Hess 436f107715
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.
2019-06-06 17:13:54 -04:00

116 lines
3.6 KiB
Haskell

{- git-annex command
-
- Copyright 2010, 2013 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Command.Get where
import Command
import qualified Remote
import Annex.Content
import Annex.Transfer
import Annex.NumCopies
import Annex.Wanted
import qualified Command.Move
cmd :: Command
cmd = withGlobalOptions [jobsOption, jsonOptions, jsonProgressOption, annexedMatchingOptions] $
command "get" SectionCommon
"make content of annexed files available"
paramPaths (seek <$$> optParser)
data GetOptions = GetOptions
{ getFiles :: CmdParams
, getFrom :: Maybe (DeferredParse Remote)
, autoMode :: Bool
, keyOptions :: Maybe KeyOptions
, batchOption :: BatchMode
}
optParser :: CmdParamsDesc -> Parser GetOptions
optParser desc = GetOptions
<$> cmdParams desc
<*> optional (parseRemoteOption <$> parseFromOption)
<*> parseAutoOption
<*> optional (parseIncompleteOption <|> parseKeyOptions <|> parseFailedTransfersOption)
<*> parseBatchOption
seek :: GetOptions -> CommandSeek
seek o = allowConcurrentOutput $ do
from <- maybe (pure Nothing) (Just <$$> getParsed) (getFrom o)
let go = whenAnnexed $ start o from
case batchOption o of
Batch fmt -> batchFilesMatching fmt go
NoBatch -> withKeyOptions (keyOptions o) (autoMode o)
(commandAction . startKeys from)
(withFilesInGit (commandAction . go))
=<< workTreeItems (getFiles o)
start :: GetOptions -> Maybe Remote -> FilePath -> Key -> CommandStart
start o from file key = start' expensivecheck from key afile ai
where
afile = AssociatedFile (Just file)
ai = mkActionItem (key, afile)
expensivecheck
| autoMode o = numCopiesCheck file key (<)
<||> wantGet False (Just key) afile
| otherwise = return True
startKeys :: Maybe Remote -> (Key, ActionItem) -> CommandStart
startKeys from (key, ai) = checkFailedTransferDirection ai Download $
start' (return True) from key (AssociatedFile Nothing) ai
start' :: Annex Bool -> Maybe Remote -> Key -> AssociatedFile -> ActionItem -> CommandStart
start' expensivecheck from key afile ai =
stopUnless (not <$> inAnnex key) $ stopUnless expensivecheck $
case from of
Nothing -> go $ perform key afile
Just src ->
stopUnless (Command.Move.fromOk src key) $
go $ Command.Move.fromPerform src Command.Move.RemoveNever key afile
where
go = starting "get" ai
perform :: Key -> AssociatedFile -> CommandPerform
perform key afile = stopUnless (getKey key afile) $
next $ return True -- no cleanup needed
{- Try to find a copy of the file in one of the remotes,
- and copy it to here. -}
getKey :: Key -> AssociatedFile -> Annex Bool
getKey key afile = getKey' key afile =<< Remote.keyPossibilities key
getKey' :: Key -> AssociatedFile -> [Remote] -> Annex Bool
getKey' key afile = dispatch
where
dispatch [] = do
showNote "not available"
showlocs
return False
dispatch remotes = notifyTransfer Download afile $ \witness -> do
ok <- pickRemote remotes $ \r -> ifM (probablyPresent r)
( docopy r witness
, return False
)
if ok
then return ok
else do
Remote.showTriedRemotes remotes
showlocs
return False
showlocs = Remote.showLocations False key []
"No other repository is known to contain the file."
-- This check is to avoid an ugly message if a remote is a
-- drive that is not mounted.
probablyPresent r
| Remote.hasKeyCheap r =
either (const False) id <$> Remote.hasKey r key
| otherwise = return True
docopy r witness = getViaTmp (Remote.retrievalSecurityPolicy r) (RemoteVerify r) key $ \dest ->
download (Remote.uuid r) key afile stdRetry
(\p -> do
showAction $ "from " ++ Remote.name r
Remote.retrieveKeyFile r key afile dest p
) witness