add additional debug info about reasons for drops

Assistant/Threads/TransferScanner.hs

@@ -115,12 +115,12 @@ expensiveScan rs = unless onlyweb $ do
 		{- The syncable remotes may have changed since this
 		 - scan began. -}
 		syncrs <- syncDataRemotes <$> getDaemonStatus
+		locs <- liftAnnex $ loggedLocations key
+		present <- liftAnnex $ inAnnex key
+		handleDropsFrom locs syncrs
+			"expensive scan found too many copies of object"
+			present key (Just f) Nothing
 		liftAnnex $ do
-			locs <- loggedLocations key
-			present <- inAnnex key
-
-			handleDropsFrom locs syncrs present key (Just f) Nothing
-
 			let slocs = S.fromList locs
 			let use a = return $ catMaybes $ map (a key slocs) syncrs
 			if present

Assistant/Threads/TransferWatcher.hs

@@ -115,10 +115,14 @@ finishedTransfer :: Transfer -> Maybe TransferInfo -> Assistant ()
 finishedTransfer t (Just info)
 	| transferDirection t == Download =
 		whenM (liftAnnex $ inAnnex $ transferKey t) $ do
-			handleDrops False (transferKey t) (associatedFile info) Nothing
+			dodrops False
 			queueTransfersMatching (/= transferUUID t)
 				"newly received object"
 				Later (transferKey t) (associatedFile info) Upload
-	| otherwise = handleDrops True (transferKey t) (associatedFile info) Nothing
+	| otherwise = dodrops True
+  where
+	dodrops fromhere = handleDrops
+		("drop wanted after " ++ describeTransfer t info)
+		fromhere (transferKey t) (associatedFile info) Nothing
 finishedTransfer _ _ = noop
 

Assistant/Threads/Transferrer.hs

@@ -76,7 +76,9 @@ startTransfer program t info = case (transferRemote info, associatedFile info) o
 			void $ addAlert $ makeAlertFiller True $
 				transferFileAlert direction True file
 			unless isdownload $
-				handleDrops True (transferKey t)
+				handleDrops
+					("object uploaded to " ++ show remote)
+					True (transferKey t)
 					(associatedFile info)
 					(Just remote)
 			recordCommit

Assistant/Threads/Watcher.hs

@@ -254,7 +254,7 @@ onAddSymlink file filestatus = go =<< liftAnnex (Backend.lookupFile file)
 			if present
 				then queueTransfers "new file created" Next key (Just file) Upload
 				else queueTransfers "new or renamed file wanted" Next key (Just file) Download
-			handleDrops present key (Just file) Nothing
+			handleDrops "file renamed" present key (Just file) Nothing
 		| otherwise = noop
 
 onDel :: Handler