pushed checkPresent exception handling out of Remote implementations

I tend to prefer moving toward explicit exception handling, not away from
it, but in this case, I think there are good reasons to let checkPresent
throw exceptions:

1. They can all be caught in one place (Remote.hasKey), and we know
   every possible exception is caught there now, which we didn't before.
2. It simplified the code of the Remotes. I think it makes sense for
   Remotes to be able to be implemented without needing to worry about
   catching exceptions inside them. (Mostly.)
3. Types.StoreRetrieve.Preparer can only work on things that return a
   Bool, which all the other relevant remote methods already did.
   I do not see a good way to generalize that type; my previous attempts
   failed miserably.
This commit is contained in:
Joey Hess 2014-08-06 13:45:19 -04:00
parent 781833b16f
commit b4cf22a388
24 changed files with 167 additions and 163 deletions

View file

@ -50,8 +50,8 @@ gen r _ c gc =
retrieveKeyFile = downloadKey,
retrieveKeyFileCheap = downloadKeyCheap,
removeKey = dropKey,
hasKey = checkKey,
hasKeyCheap = False,
checkPresent = checkKey,
checkPresentCheap = False,
whereisKey = Just getUrls,
remoteFsck = Nothing,
repairRepo = Nothing,
@ -98,12 +98,12 @@ dropKey k = do
mapM_ (setUrlMissing k) =<< getUrls k
return True
checkKey :: Key -> Annex (Either String Bool)
checkKey :: Key -> Annex Bool
checkKey key = do
us <- getUrls key
if null us
then return $ Right False
else return =<< checkKey' key us
then return False
else either error return =<< checkKey' key us
checkKey' :: Key -> [URLString] -> Annex (Either String Bool)
checkKey' key us = firsthit us (Right False) $ \u -> do
let (u', downloader) = getDownloader u