Fix rsync special remote to work when -Jn is used for concurrent uploads.

Remote/Rsync.hs

@@ -39,6 +39,7 @@ import Logs.Transfer
 import Types.Creds
 import Types.Key (isChunkKey)
 import Annex.DirHashes
+import Utility.Tmp
 
 import qualified Data.Map as M
 
@@ -252,16 +253,8 @@ sendParams = ifM crippledFileSystem
  - up trees for rsync. -}
 withRsyncScratchDir :: (FilePath -> Annex a) -> Annex a
 withRsyncScratchDir a = do
-	p <- liftIO getPID
 	t <- fromRepo gitAnnexTmpObjectDir
-	createAnnexDirectory t
-	let tmp = t </> "rsynctmp" </> show p
-	nuke tmp
-	liftIO $ createDirectoryIfMissing True tmp
-	nuke tmp `after` a tmp
-  where
-	nuke d = liftIO $ whenM (doesDirectoryExist d) $
-		removeDirectoryRecursive d
+	withTmpDirIn t "rsynctmp" a
 
 rsyncRetrieve :: RsyncOpts -> Key -> FilePath -> Maybe MeterUpdate -> Annex Bool
 rsyncRetrieve o k dest meterupdate =

debian/changelog

@@ -1,6 +1,8 @@
 git-annex (5.20150728) UNRELEASED; urgency=medium
 
   * webapp: Support enabling known gitlab.com remotes.
+  * Fix rsync special remote to work when -Jn is used for concurrent
+    uploads.
 
  -- Joey Hess <id@joeyh.name>  Mon, 27 Jul 2015 15:57:07 -0400
 

doc/bugs/rsync_remote_with_-J2_fails.mdwn

@@ -53,3 +53,5 @@ Repo config:
 	annex-uuid = f05581cc-7236-41ed-9db8-49424f863307
 
 """]]
+
+> [[fixed|done]] --[[Joey]]

doc/bugs/rsync_remote_with_-J2_fails/comment_1_793bbc86b495dda0328c35cb5abe4fad._comment

@@ -0,0 +1,13 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2015-07-30T17:18:24Z"
+ content="""
+The -J1 is a red herring; there's no progress output for -J modes, so the
+whole transfer runs quietly there.
+
+The -J2 failure is because the rsync special remote implementation uses a
+local scratch directory which is supposed to be empty. But, since it uses
+the pid of the process to create the directory name, concurrently transfers
+will use the same scratch directory and so interfere with one-another.
+"""]]