diff options
Diffstat (limited to 'Assistant/ScanRemotes.hs')
| -rw-r--r-- | Assistant/ScanRemotes.hs | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/Assistant/ScanRemotes.hs b/Assistant/ScanRemotes.hs index 05b2a2ca9..2362bd9b4 100644 --- a/Assistant/ScanRemotes.hs +++ b/Assistant/ScanRemotes.hs @@ -26,10 +26,14 @@ newScanRemoteMap = atomically newEmptyTMVar getScanRemote :: ScanRemoteMap -> IO Remote getScanRemote v = atomically $ do m <- takeTMVar v - let newest = Prelude.head $ reverse $ - map fst $ sortBy (compare `on` snd) $ M.toList m - putTMVar v $ M.delete newest m - return newest + let l = reverse $ map fst $ sortBy (compare `on` snd) $ M.toList m + case l of + [] -> retry -- should never happen + (newest:_) -> do + let m' = M.delete newest m + unless (M.null m') $ + putTMVar v m' + return newest {- Adds new remotes that need scanning to the map. -} addScanRemotes :: ScanRemoteMap -> [Remote] -> IO () |