refactor the restage runner

Sponsored-by: Dartmouth College's DANDI project

1 files changed, 51 insertions, 0 deletions

diff --git a/Logs/Restage.hs b/Logs/Restage.hs
new file mode 100644
index 0000000000..75bba857c9
--- /dev/null
+++ b/Logs/Restage.hs
@@ -0,0 +1,51 @@
+{- git-annex restage log file
+ -
+ - Copyright 2022 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU AGPL version 3 or higher.
+ -}
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Logs.Restage where
+
+import Annex.Common
+import Git.FilePath
+import Logs.File
+
+import qualified Data.ByteString.Lazy as L
+
+-- | Log a file whose pointer needs to be restaged in git.
+-- The content of the file may not be a pointer, if it is populated with
+-- the annex content. The InodeCache is used to verify that the file
+-- still contains the content, and it's still safe to restage its pointer.
+writeRestageLog :: TopFilePath -> InodeCache -> Annex ()
+writeRestageLog f ic = do
+	logf <- fromRepo gitAnnexRestageLog
+	lckf <- fromRepo gitAnnexRestageLock
+	appendLogFile logf lckf $ L.fromStrict $
+		encodeBS (showInodeCache ic) <> ":" <> getTopFilePath f
+
+-- | Streams the content of the restage log, and then empties the log at
+-- the end.
+--
+-- If the action is interrupted or throws an exception, the log file is
+-- left unchanged.
+--
+-- Locking is used to prevent new items being added to the log while this
+-- is running.
+streamSmudged :: (TopFilePath -> InodeCache -> Annex ()) -> Annex ()
+streamSmudged a = do
+	logf <- fromRepo gitAnnexRestageLog
+	lckf <- fromRepo gitAnnexRestageLock
+	streamLogFile (fromRawFilePath logf) lckf $ \l -> 
+		case parse l of
+			Nothing -> noop
+			Just (k, f) -> a f ic
+  where
+	parse l = 
+		let (ics, f) = separate (== ':') l
+		in do
+			ic <- readInodeCache ics
+			return (asTopFilePath (toRawFilePath f), ic)
+