git-annex/CmdLine/Batch.hs
Joey Hess e72ec8b9b2
add back git-annex branch read cache
The cache was removed way back in 2012,
commit 3417c55189

Then I forgot I had removed it! I remember clearly multiple times when I
thought, "this reads the same data twice, but the cache will avoid that
being very expensive".

The reason it was removed was it messed up the assistant noticing when
other processes made changes. That same kind of problem has recently
been addressed when adding the optimisation to avoid reading the journal
unnecessarily.

Indeed, enableInteractiveJournalAccess is run in just the
right places, so can just piggyback on it to know when it's not safe
to use the cache.
2020-07-06 12:22:33 -04:00

121 lines
3.7 KiB
Haskell

{- git-annex batch commands
-
- Copyright 2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module CmdLine.Batch where
import Annex.Common
import Types.Command
import CmdLine.Action
import CmdLine.GitAnnex.Options
import Options.Applicative
import Limit
import Types.FileMatcher
import Annex.BranchState
data BatchMode = Batch BatchFormat | NoBatch
data BatchFormat = BatchLine | BatchNull
parseBatchOption :: Parser BatchMode
parseBatchOption = go
<$> switch
( long "batch"
<> help "enable batch mode"
)
<*> switch
( short 'z'
<> help "null delimited batch input"
)
where
go True False = Batch BatchLine
go True True = Batch BatchNull
go False _ = NoBatch
-- A batchable command can run in batch mode, or not.
-- In batch mode, one line at a time is read, parsed, and a reply output to
-- stdout. In non batch mode, the command's parameters are parsed and
-- a reply output for each.
batchable :: (opts -> String -> Annex Bool) -> Parser opts -> CmdParamsDesc -> CommandParser
batchable handler parser paramdesc = batchseeker <$> batchparser
where
batchparser = (,,)
<$> parser
<*> parseBatchOption
<*> cmdParams paramdesc
batchseeker (opts, NoBatch, params) =
mapM_ (go NoBatch opts) params
batchseeker (opts, batchmode@(Batch fmt), _) =
batchInput fmt (pure . Right) (go batchmode opts)
go batchmode opts p =
unlessM (handler opts p) $
batchBadInput batchmode
-- bad input is indicated by an empty line in batch mode. In non batch
-- mode, exit on bad input.
batchBadInput :: BatchMode -> Annex ()
batchBadInput NoBatch = liftIO exitFailure
batchBadInput (Batch _) = liftIO $ putStrLn ""
-- Reads lines of batch mode input, runs a parser, and passes the result
-- to the action.
--
-- Note that if the batch input includes a worktree filename, it should
-- be converted to relative. Normally, filename parameters are passed
-- through git ls-files, which makes them relative, but batch mode does
-- not use that, and absolute worktree files are likely to cause breakage.
batchInput :: BatchFormat -> (String -> Annex (Either String a)) -> (a -> Annex ()) -> Annex ()
batchInput fmt parser a = go =<< batchLines fmt
where
go [] = return ()
go (l:rest) = do
either parseerr a =<< parser l
go rest
parseerr s = giveup $ "Batch input parse failure: " ++ s
batchLines :: BatchFormat -> Annex [String]
batchLines fmt = do
enableInteractiveBranchAccess
liftIO $ splitter <$> getContents
where
splitter = case fmt of
BatchLine -> lines
BatchNull -> splitc '\0'
-- Runs a CommandStart in batch mode.
--
-- The batch mode user expects to read a line of output, and it's up to the
-- CommandStart to generate that output as it succeeds or fails to do its
-- job. However, if it stops without doing anything, it won't generate
-- any output, so in that case, batchBadInput is used to provide the caller
-- with an empty line.
batchCommandAction :: CommandStart -> Annex ()
batchCommandAction a = maybe (batchBadInput (Batch BatchLine)) (const noop)
=<< callCommandAction' a
-- Reads lines of batch input and passes the filepaths to a CommandStart
-- to handle them.
--
-- Absolute filepaths are converted to relative.
--
-- File matching options are not checked.
batchStart :: BatchFormat -> (FilePath -> CommandStart) -> Annex ()
batchStart fmt a = batchInput fmt (Right <$$> liftIO . relPathCwdToFile) $
batchCommandAction . a
-- Like batchStart, but checks the file matching options
-- and skips non-matching files.
batchFilesMatching :: BatchFormat -> (FilePath -> CommandStart) -> Annex ()
batchFilesMatching fmt a = do
matcher <- getMatcher
batchStart fmt $ \f ->
let f' = toRawFilePath f
in ifM (matcher $ MatchingFile $ FileInfo f' f')
( a f
, return Nothing
)