92 lines
2.7 KiB
Haskell
92 lines
2.7 KiB
Haskell
{- git repository command queue
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-
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- Copyright 2010 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Git.Queue (
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Queue,
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empty,
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add,
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size,
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full,
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flush
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) where
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import qualified Data.Map as M
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import System.IO
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import System.Cmd.Utils
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import Data.String.Utils
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import Control.Monad (forM_)
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import Utility
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import Git
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{- An action to perform in a git repository. The file to act on
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- is not included, and must be able to be appended after the params. -}
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data Action = Action {
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getSubcommand :: String,
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getParams :: [CommandParam]
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} deriving (Show, Eq, Ord)
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{- A queue of actions to perform (in any order) on a git repository,
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- with lists of files to perform them on. This allows coalescing
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- similar git commands. -}
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data Queue = Queue Int (M.Map Action [FilePath])
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deriving (Show, Eq)
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{- A recommended maximum size for the queue, after which it should be
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- run.
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-
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- 10240 is semi-arbitrary. If we assume git filenames are between 10 and
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- 255 characters long, then the queue will build up between 100kb and
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- 2550kb long commands. The max command line length on linux is somewhere
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- above 20k, so this is a fairly good balance -- the queue will buffer
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- only a few megabytes of stuff and a minimal number of commands will be
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- run by xargs. -}
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maxSize :: Int
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maxSize = 10240
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{- Constructor for empty queue. -}
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empty :: Queue
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empty = Queue 0 M.empty
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{- Adds an action to a queue. -}
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add :: Queue -> String -> [CommandParam] -> [FilePath] -> Queue
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add (Queue n m) subcommand params files = Queue (n + 1) m'
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where
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action = Action subcommand params
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-- There are probably few items in the map, but there
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-- can be a lot of files per item. So, optimise adding
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-- files.
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m' = M.insertWith' const action fs m
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fs = files ++ M.findWithDefault [] action m
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{- Number of items in a queue. -}
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size :: Queue -> Int
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size (Queue n _) = n
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{- Is a queue large enough that it should be flushed? -}
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full :: Queue -> Bool
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full (Queue n _) = n > maxSize
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{- Runs a queue on a git repository. -}
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flush :: Repo -> Queue -> IO Queue
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flush repo (Queue _ m) = do
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forM_ (M.toList m) $ uncurry $ runAction repo
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return empty
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{- Runs an Action on a list of files in a git repository.
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-
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- Complicated by commandline length limits.
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-
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- Intentionally runs the command even if the list of files is empty;
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- this allows queueing commands that do not need a list of files. -}
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runAction :: Repo -> Action -> [FilePath] -> IO ()
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runAction repo action files =
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pOpen WriteToPipe "xargs" ("-0":"git":params) feedxargs
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where
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params = toCommand $ gitCommandLine repo
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(Param (getSubcommand action):getParams action)
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feedxargs h = hPutStr h $ join "\0" files
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