incomplete action to download files from import

Annex/Import.hs

@@ -5,13 +5,16 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
+{-# LANGUAGE BangPatterns #-}
+
 module Annex.Import (
 	RemoteTrackingBranch(..),
 	mkRemoteTrackingBranch,
 	ImportTreeConfig(..),
 	ImportCommitConfig(..),
 	buildImportCommit,
-	buildImportTrees
+	buildImportTrees,
+	downloadImport
 ) where
 
 import Annex.Common
@@ -26,8 +29,14 @@ import qualified Git.Branch
 import qualified Annex
 import Annex.Link
 import Annex.LockFile
+import Utility.Metered
 import Logs.Export
-import Database.Export
+import Logs.ContentIdentifier
+import qualified Database.Export as Export
+import qualified Database.ContentIdentifier as CID
+
+import Control.Concurrent.STM
+import qualified Data.Map.Strict as M
 
 newtype RemoteTrackingBranch = RemoteTrackingBranch
 	{ fromRemoteTrackingBranch :: Ref }
@@ -120,14 +129,14 @@ buildImportCommit remote importtreeconfig importcommitconfig importable =
 
 	updateexportdb importedtree = 
 		withExclusiveLock (gitAnnexExportLock (Remote.uuid remote)) $ do
-			db <- openDb (Remote.uuid remote)
+			db <- Export.openDb (Remote.uuid remote)
 			prevtree <- liftIO $ fromMaybe emptyTree
-				<$> getExportTreeCurrent db
+				<$> Export.getExportTreeCurrent db
 			when (importedtree /= prevtree) $ do
-				updateExportTree db prevtree importedtree
+				Export.updateExportTree db prevtree importedtree
-				liftIO $ recordExportTreeCurrent db importedtree
+				liftIO $ Export.recordExportTreeCurrent db importedtree
 				-- TODO: addExportedLocation etc
-				liftIO $ flushDbQueue db
+			Export.closeDb db
 	
 	updateexportlog importedtree = do
 		old <- getExport (Remote.uuid remote)
@@ -170,3 +179,63 @@ buildImportTrees basetree msubdir importable = History
 		symlink <- calcRepo $ gitAnnexLink relf k
 		linksha <- hashSymlink symlink
 		return $ TreeItem treepath (fromTreeItemType TreeSymlink) linksha
+
+{- Downloads all new ContentIdentifiers. Supports concurrency when enabled.
+ -
+ - If any download fails, the whole thing fails, but it will resume where
+ - it left off.
+ -}
+downloadImport :: Remote -> ImportableContents ContentIdentifier -> Annex (Maybe (ImportableContents Key))
+downloadImport remote importablecontents = do
+	-- This map is used to remember content identifiers that
+	-- were just downloaded, before they have necessarily been
+	-- stored in the database. This way, if the same content
+	-- identifier appears multiple times in the
+	-- importablecontents (eg when it has a history), 
+	-- they will only be downloaded once.
+	cidmap <- liftIO $ newTVarIO M.empty
+	bracket CID.openDb CID.closeDb (go cidmap importablecontents)
+	-- TODO really support concurrency; avoid donwloading the same
+	-- ContentIdentifier twice.
+  where
+	go cidmap (ImportableContents l h) db = do
+		l' <- mapM (download cidmap db) l
+		if any isNothing l'
+			then return Nothing
+			else do
+				h' <- mapM (\ic -> go cidmap ic db) h
+				if any isNothing h'
+					then return Nothing
+					else return $ Just $
+						ImportableContents
+							(catMaybes l')
+							(catMaybes h')
+	
+	download cidmap db (loc, cid) = getcidkey cidmap db cid >>= \case
+		(k:_) -> return $ Just (loc, k)
+		[] -> do
+			-- TODO progresss bar
+			let p = nullMeterUpdate
+			let ia = Remote.importActions remote
+			Remote.retrieveExportWithContentIdentifier ia loc cid mkkey p >>= \case
+				Just k -> do
+					recordcidkey cidmap db cid k
+					return $ Just (loc, k)
+				Nothing -> return Nothing
+	
+	mkkey f = error "TODO"
+
+	getcidkey cidmap db cid = liftIO $
+		CID.getContentIdentifierKeys db (Remote.uuid remote) cid >>= \case
+			[] -> atomically $ do
+				m <- readTVar cidmap
+				-- force lookup inside STM transaction
+				let !v = maybeToList $ M.lookup cid m
+				return v
+			l -> return l
+
+	recordcidkey cidmap db cid k = do
+		liftIO $ atomically $ modifyTVar' cidmap $
+			M.insert cid k
+		liftIO $ CID.recordContentIdentifier db (Remote.uuid remote) cid k
+		recordContentIdentifier (Remote.uuid remote) cid k

Command/Import.hs

@@ -253,11 +253,7 @@ seekRemote remote branch msubdir = allowConcurrentOutput $ do
 	parentcommit <- frombranch Git.Ref.sha
 	let importcommitconfig = ImportCommitConfig parentcommit ManualCommit importmessage
 
-	showStart' "import" (Just (Remote.name remote))
+	importable <- download =<< enumerate
-	-- TODO enumerate and download
-	let importable = ImportableContents [] []
-	showEndOk
-
 	void $ includeCommandAction $
 		commitRemote remote branch tb parentcommit importtreeconfig importcommitconfig importable
   where
@@ -269,6 +265,20 @@ seekRemote remote branch msubdir = allowConcurrentOutput $ do
 		Just v -> return (Just v)
 		Nothing -> inRepo (a branch)
 
+	enumerate = do
+		showStart' "import" (Just (Remote.name remote))
+		Remote.listImportableContents (Remote.importActions remote) >>= \case
+			Nothing -> do
+				showEndFail
+				giveup $ "Unable to list contents of " ++ Remote.name remote
+			Just importable -> do
+				showEndOk
+				return importable
+
+	download importablecontents = downloadImport remote importablecontents >>= \case
+		Nothing -> giveup $ "Failed to import some files from " ++ Remote.name remote ++ ". Re-run command to resume import."
+		Just importable -> return importable
+
 commitRemote :: Remote -> Branch -> RemoteTrackingBranch -> Maybe Sha -> ImportTreeConfig -> ImportCommitConfig -> ImportableContents Key -> CommandStart
 commitRemote remote branch tb parentcommit importtreeconfig importcommitconfig importable = do
 	showStart' "update" (Just $ fromRef $ fromRemoteTrackingBranch tb)

Types/Remote.hs

@@ -258,7 +258,8 @@ data ImportActions a = ImportActions
 		:: ExportLocation
 		-> ContentIdentifier
 		-> (FilePath -> a Key)
-		-- ^ callback that generates a key from the downloaded content
+		-- ^ callback that generates a key from the downloaded content,
+		-- it may rename or delete the file
 		-> MeterUpdate
 		-> a (Maybe Key)
 	-- Exports content to an ExportLocation, and returns the

doc/todo/import_tree.mdwn

@@ -10,6 +10,13 @@ this.
 
 ## implementation notes
 
+* import can run out of disk space. Should listImportableContents 
+  include the size of the file, so that annex.diskreserve can be checked?
+
+* Should retrieveExportWithContentIdentifier have a FilePath parameter,
+  to tell it the file to retrieve to? And if so, would it make sense to
+  have a ContentLocation -> Key, so it can use gitAnnexTmpObjectLocation?
+
 * "git annex import master --from rmt" followed by "git annex import master:sub --from rmt"
   first makes the tracking branch contain only what's in the remote,
   and then grafts what's in the remote into a subdir. Is that the behavior