concurrency and status messages when downloading from import

Annex/Drop.hs

@@ -16,7 +16,6 @@ import qualified Remote
 import qualified Command.Drop
 import Command
 import Annex.Wanted
-import Annex.Export
 import Config
 import Annex.Content.Direct
 import qualified Database.Keys

Annex/Export.hs

@@ -13,11 +13,9 @@ import Types
 import Types.Key
 import qualified Git
 import qualified Types.Remote as Remote
-import Config
 import Messages
 import Utility.FileSystemEncoding
 
-import qualified Data.Map as M
 import Control.Applicative
 import Data.Maybe
 import Prelude
@@ -44,9 +42,6 @@ exportKey sha = mk <$> catKey sha
 		, keyChunkNum = Nothing
 		}
 
-exportTree :: Remote.RemoteConfig -> Bool
-exportTree c = fromMaybe False $ yesNo =<< M.lookup "exporttree" c
-
 warnExportConflict :: Remote -> Annex ()
 warnExportConflict r = toplevelWarning True $
 	"Export conflict detected. Different trees have been exported to " ++ 

Annex/Import.hs

@@ -30,6 +30,7 @@ import Annex.Link
 import Annex.LockFile
 import Annex.Content
 import Annex.Export
+import Command
 import Backend
 import Config
 import Types.Key
@@ -44,9 +45,7 @@ import qualified Logs.ContentIdentifier as CIDLog
 
 import Control.Concurrent.STM
 import qualified Data.Map.Strict as M
-
-importTree :: Remote.RemoteConfig -> Bool
-importTree c = fromMaybe False $ yesNo =<< M.lookup "importtree" c
+import qualified Data.Set as S
 
 {- Configures how to build an import tree. -}
 data ImportTreeConfig
@@ -217,20 +216,24 @@ downloadImport remote importtreeconfig importablecontents = do
 	-- importablecontents (eg when it has a history), 
 	-- they will only be downloaded once.
 	cidmap <- liftIO $ newTVarIO M.empty
+	-- When concurrency is enabled, this set is needed to
+	-- avoid two threads both downloading the same content identifier.
+	downloading <- liftIO $ newTVarIO S.empty
 	withExclusiveLock gitAnnexContentIdentifierLock $
 		bracket CIDDb.openDb CIDDb.closeDb $ \db -> do
 			CIDDb.needsUpdateFromLog db
 				>>= maybe noop (CIDDb.updateFromLog db)
-			go cidmap importablecontents db
-	-- TODO really support concurrency; avoid donwloading the same
-	-- ContentIdentifier twice.
+			go cidmap downloading importablecontents db
   where
-	go cidmap (ImportableContents l h) db = do
-		l' <- mapM (download cidmap db) l
+	go cidmap downloading (ImportableContents l h) db = do
+		jobs <- forM l $ \i ->
+			startdownload cidmap downloading db i
+		l' <- liftIO $ forM jobs $
+			either pure (atomically . takeTMVar)
 		if any isNothing l'
 			then return Nothing
 			else do
-				h' <- mapM (\ic -> go cidmap ic db) h
+				h' <- mapM (\ic -> go cidmap downloading ic db) h
 				if any isNothing h'
 					then return Nothing
 					else return $ Just $
@@ -238,9 +241,40 @@ downloadImport remote importtreeconfig importablecontents = do
 							(catMaybes l')
 							(catMaybes h')
 	
-	download cidmap db (loc, (cid, sz)) = getcidkey cidmap db cid >>= \case
-		(k:_) -> return $ Just (loc, k)
-		[] -> checkDiskSpaceToGet tmpkey Nothing $
+	waitstart downloading cid = liftIO $ atomically $ do
+		s <- readTVar downloading
+		if S.member cid s
+			then retry
+			else writeTVar downloading $ S.insert cid s
+	
+	signaldone downloading cid = liftIO $ atomically $ do
+		s <- readTVar downloading
+		writeTVar downloading $ S.delete cid s
+	
+	startdownload cidmap downloading db i@(loc, (cid, _sz)) = getcidkey cidmap db cid >>= \case
+		(k:_) -> return $ Left $ Just (loc, k)
+		[] -> do
+			job <- liftIO $ newEmptyTMVarIO
+			let rundownload = do
+				showStart "import" (fromImportLocation loc)
+				next $ tryNonAsync (download cidmap db i) >>= \case
+					Left e -> next $ do
+						warning (show e)
+						liftIO $ atomically $
+							putTMVar job Nothing
+						return False
+					Right r -> next $ do
+						liftIO $ atomically $
+							putTMVar job r
+						return True
+			commandAction $ bracket_
+				(waitstart downloading cid)
+				(signaldone downloading cid)
+				rundownload
+			return (Right job)
+	
+	download cidmap db (loc, (cid, sz)) =
+		checkDiskSpaceToGet tmpkey Nothing $
 			withTmp tmpkey $ \tmpfile ->
 				Remote.retrieveExportWithContentIdentifier ia loc cid tmpfile (mkkey loc tmpfile) p >>= \case
 					Just k -> tryNonAsync (moveAnnex k tmpfile) >>= \case

Assistant/DaemonStatus.hs

@@ -19,8 +19,8 @@ import Logs.Trust
 import Utility.TimeStamp
 import qualified Remote
 import qualified Types.Remote as Remote
+import Config
 import Config.DynamicConfig
-import Annex.Export
 
 import Control.Concurrent.STM
 import System.Posix.Types

Command/Import.hs

@@ -261,7 +261,7 @@ seekRemote remote branch msubdir = allowConcurrentOutput $ do
 	parentcommit <- fromtrackingbranch Git.Ref.sha
 	let importcommitconfig = ImportCommitConfig parentcommit ManualCommit importmessage
 
-	importable <- download importtreeconfig =<< enumerate
+	importable <- download importtreeconfig =<< listcontents
 	void $ includeCommandAction $
 		commitRemote remote branch tb parentcommit importtreeconfig importcommitconfig importable
   where
@@ -271,8 +271,8 @@ seekRemote remote branch msubdir = allowConcurrentOutput $ do
 
 	fromtrackingbranch a = inRepo $ a (fromRemoteTrackingBranch tb)
 
-	enumerate = do
-		showStart' "import" (Just (Remote.name remote))
+	listcontents = do
+		showStart' "list" (Just (Remote.name remote))
 		Remote.listImportableContents (Remote.importActions remote) >>= \case
 			Nothing -> do
 				showEndFail

Config.hs

@@ -94,6 +94,12 @@ setRemoteIgnore r b = setConfig (remoteConfig r "ignore") (Git.Config.boolConfig
 setRemoteBare :: Git.Repo -> Bool -> Annex ()
 setRemoteBare r b = setConfig (remoteConfig r "bare") (Git.Config.boolConfig b)
 
+exportTree :: Remote.RemoteConfig -> Bool
+exportTree c = fromMaybe False $ yesNo =<< M.lookup "exporttree" c
+
+importTree :: Remote.RemoteConfig -> Bool
+importTree c = fromMaybe False $ yesNo =<< M.lookup "importtree" c
+
 isBareRepo :: Annex Bool
 isBareRepo = fromRepo Git.repoIsLocalBare
 

Remote/External.hs

@@ -20,7 +20,6 @@ import Git.Config (isTrue, boolConfig)
 import Git.Env
 import Remote.Helper.Special
 import Remote.Helper.ExportImport
-import Annex.Export
 import Remote.Helper.ReadOnly
 import Remote.Helper.Messages
 import Utility.Metered

Remote/Helper/ExportImport.hs

@@ -18,7 +18,6 @@ import Remote.Helper.Encryptable (isEncrypted)
 import qualified Database.Export as Export
 import qualified Database.ContentIdentifier as ContentIdentifier
 import Annex.Export
-import Annex.Import
 import Annex.LockFile
 import Config
 import Git.Types (fromRef)

Remote/S3.hs

@@ -39,7 +39,6 @@ import Control.Concurrent.STM.TVar
 import Annex.Common
 import Types.Remote
 import Types.Export
-import Annex.Export
 import qualified Git
 import Config
 import Config.Cost

doc/todo/import_tree.mdwn

@@ -13,8 +13,7 @@ this.
 * Need to support annex-tracking-branch configuration, which documentation
   says makes git-annex sync and assistant do imports.
 
-* git-annex import needs to say when it's downloading files, display
-  progress bars, and support concurrent downloads.
+* progress bars when downloading from import
 
 * When on an adjusted unlocked branch, need to import the files unlocked.
   Also, the tracking branch code needs to know about such branches,