track exported files in a sqlite database

Went with a separate db per export remote, rather than a single export
database. Mostly because there will probably not be a lot of separate
export remotes, and it might be convenient to be able to delete a given
remote's export database.

This commit was supported by the NSF-funded DataLad project.

Annex/Locations.hs

@@ -36,6 +36,7 @@ module Annex.Locations (
 	gitAnnexFsckDbDir,
 	gitAnnexFsckDbLock,
 	gitAnnexFsckResultsLog,
+	gitAnnexExportDbDir,
 	gitAnnexScheduleState,
 	gitAnnexTransferDir,
 	gitAnnexCredsDir,
@@ -290,6 +291,15 @@ gitAnnexFsckDbLock u r = gitAnnexFsckDir u r </> "fsck.lck"
 gitAnnexFsckResultsLog :: UUID -> Git.Repo -> FilePath
 gitAnnexFsckResultsLog u r = gitAnnexDir r </> "fsckresults" </> fromUUID u
 
+{- .git/annex/export/uuid/ is used to store information about
+ - exports to special remotes. -}
+gitAnnexExportDir :: UUID -> Git.Repo -> FilePath
+gitAnnexExportDir u r = gitAnnexDir r </> "export" </> fromUUID u
+
+{- Directory containing database used to record export info. -}
+gitAnnexExportDbDir :: UUID -> Git.Repo -> FilePath
+gitAnnexExportDbDir u r = gitAnnexExportDir u r </> "db"
+
 {- .git/annex/schedulestate is used to store information about when
  - scheduled jobs were last run. -}
 gitAnnexScheduleState :: Git.Repo -> FilePath

Command/Export.hs

@@ -21,6 +21,7 @@ import Annex.Content
 import Annex.CatFile
 import Logs.Location
 import Logs.Export
+import Database.Export
 import Messages.Progress
 import Utility.Tmp
 
@@ -81,6 +82,8 @@ seek o = do
 	when (length old > 1) $
 		warning "Export conflict detected. Different trees have been exported to the same special remote. Resolving.."
 	
+	db <- openDb (uuid r)
+	
 	-- First, diff the old and new trees and delete all changed
 	-- files in the export. Every file that remains in the export will
 	-- have the content from the new treeish.
@@ -89,7 +92,7 @@ seek o = do
 	forM_ old $ \oldtreesha -> do
 		(diff, cleanup) <- inRepo $
 			Git.DiffTree.diffTreeRecursive oldtreesha new
-		seekActions $ pure $ map (startUnexport r) diff
+		seekActions $ pure $ map (startUnexport r db) diff
 		void $ liftIO cleanup
 
 	-- Waiting until now to record the export guarantees that,
@@ -102,12 +105,13 @@ seek o = do
 
 	-- Export everything that is not yet exported.
 	(l, cleanup') <- inRepo $ Git.LsTree.lsTree new
-	seekActions $ pure $ map (startExport r) l
+	seekActions $ pure $ map (startExport r db) l
 	void $ liftIO cleanup'
 
-startExport :: Remote -> Git.LsTree.TreeItem -> CommandStart
+startExport :: Remote -> ExportHandle -> Git.LsTree.TreeItem -> CommandStart
-startExport r ti = do
+startExport r db ti = do
 	ek <- exportKey (Git.LsTree.sha ti)
+	liftIO $ addExportLocation db (asKey ek) loc
 	stopUnless (notElem (uuid r) <$> loggedLocations (asKey ek)) $ do
 		showStart "export" f
 		next $ performExport r ek (Git.LsTree.sha ti) loc
@@ -144,11 +148,12 @@ cleanupExport r ek = do
 	logChange (asKey ek) (uuid r) InfoPresent
 	return True
 
-startUnexport :: Remote -> Git.DiffTree.DiffTreeItem -> CommandStart
+startUnexport :: Remote -> ExportHandle -> Git.DiffTree.DiffTreeItem -> CommandStart
-startUnexport r diff
+startUnexport r db diff
 	| Git.DiffTree.srcsha diff /= nullSha = do
 		showStart "unexport" f
 		oldk <- exportKey (Git.DiffTree.srcsha diff)
+		liftIO $ removeExportLocation db (asKey oldk) loc
 		next $ performUnexport r oldk loc
 	| otherwise = stop
   where

Database/Export.hs

@@ -0,0 +1,85 @@
+{- Sqlite database used for exports to special remotes.
+ -
+ - Copyright 2017 Joey Hess <id@joeyh.name>
+ -:
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE QuasiQuotes, TypeFamilies, TemplateHaskell #-}
+{-# LANGUAGE OverloadedStrings, GADTs, FlexibleContexts #-}
+{-# LANGUAGE MultiParamTypeClasses, GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE RankNTypes #-}
+
+module Database.Export (
+	ExportHandle,
+	openDb,
+	closeDb,
+	addExportLocation,
+	removeExportLocation,
+	getExportLocation,
+	ExportedId,
+) where
+
+import Database.Types
+import qualified Database.Queue as H
+import Database.Init
+import Annex.Locations
+import Annex.Common hiding (delete)
+import Types.Remote (ExportLocation(..))
+
+import Database.Persist.TH
+import Database.Esqueleto hiding (Key)
+
+data ExportHandle = ExportHandle H.DbQueue
+
+share [mkPersist sqlSettings, mkMigrate "migrateExport"] [persistLowerCase|
+Exported
+  key IKey
+  file SFilePath
+  KeyFileIndex key file
+  UniqueKey key
+|]
+
+{- Opens the database, creating it if it doesn't exist yet. -}
+openDb :: UUID -> Annex ExportHandle
+openDb u = do
+	dbdir <- fromRepo (gitAnnexExportDbDir u)
+	let db = dbdir </> "db"
+	unlessM (liftIO $ doesFileExist db) $ do
+		initDb db $ void $
+			runMigrationSilent migrateExport
+	h <- liftIO $ H.openDbQueue db "exported"
+	return $ ExportHandle h
+
+closeDb :: ExportHandle -> Annex ()
+closeDb (ExportHandle h) = liftIO $ H.closeDbQueue h
+
+queueDb :: ExportHandle -> SqlPersistM () -> IO ()
+queueDb (ExportHandle h) = H.queueDb h checkcommit
+  where
+	-- commit queue after 1000 changes
+	checkcommit sz _lastcommittime
+		| sz > 1000 = return True
+		| otherwise = return False
+
+addExportLocation :: ExportHandle -> Key -> ExportLocation -> IO ()
+addExportLocation h k (ExportLocation f) = queueDb h $ 
+	void $ insertUnique $ Exported (toIKey k) (toSFilePath f)
+
+removeExportLocation :: ExportHandle -> Key -> ExportLocation -> IO ()
+removeExportLocation h k (ExportLocation f) = queueDb h $
+	delete $ from $ \r -> do
+		where_ (r ^. ExportedKey ==. val ik &&. r ^. ExportedFile ==. val ef)
+  where
+	ik = toIKey k
+	ef = toSFilePath f
+
+{- Doesn't know about recently queued changes. -}
+getExportLocation :: ExportHandle -> Key -> IO [ExportLocation]
+getExportLocation (ExportHandle h) k = H.queryDbQueue h $ do
+	l <- select $ from $ \r -> do
+		where_ (r ^. ExportedKey ==. val ik)
+		return (r ^. ExportedFile)
+	return $ map (ExportLocation . fromSFilePath . unValue) l
+  where
+	ik = toIKey k

git-annex.cabal

@@ -787,6 +787,7 @@ Executable git-annex
     Config.GitConfig
     Creds
     Crypto
+    Database.Export
     Database.Fsck
     Database.Handle
     Database.Init