git-annex/Remote/Helper/ExportImport.hs
Joey Hess c1cd402081
make storeKey throw exceptions
When storing content on remote fails, always display a reason why.

Since the Storer used by special remotes already did, this mostly affects
git remotes, but not entirely. For example, if git-lfs failed to connect to
the endpoint, it used to silently return False.
2020-05-13 14:03:00 -04:00

335 lines
12 KiB
Haskell

{- Helper to make remotes support export and import (or not).
-
- Copyright 2017-2019 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE FlexibleInstances, FlexibleContexts #-}
module Remote.Helper.ExportImport where
import Annex.Common
import Types.Remote
import Types.Backend
import Types.Key
import Types.ProposedAccepted
import Backend
import Remote.Helper.Encryptable (isEncrypted)
import qualified Database.Export as Export
import qualified Database.ContentIdentifier as ContentIdentifier
import Annex.Export
import Annex.LockFile
import Annex.SpecialRemote.Config
import Git.Types (fromRef)
import Logs.Export
import Logs.ContentIdentifier (recordContentIdentifier)
import Control.Concurrent.STM
-- | Use for remotes that do not support exports.
class HasExportUnsupported a where
exportUnsupported :: a
instance HasExportUnsupported (ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool) where
exportUnsupported = \_ _ -> return False
instance HasExportUnsupported (ExportActions Annex) where
exportUnsupported = ExportActions
{ storeExport = \_ _ _ _ -> do
warning "store export is unsupported"
return False
, retrieveExport = \_ _ _ _ -> return False
, checkPresentExport = \_ _ -> return False
, removeExport = \_ _ -> return False
, removeExportDirectory = Just $ \_ -> return False
, renameExport = \_ _ _ -> return Nothing
}
-- | Use for remotes that do not support imports.
class HasImportUnsupported a where
importUnsupported :: a
instance HasImportUnsupported (ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool) where
importUnsupported = \_ _ -> return False
instance HasImportUnsupported (ImportActions Annex) where
importUnsupported = ImportActions
{ listImportableContents = return Nothing
, retrieveExportWithContentIdentifier = \_ _ _ _ _ -> return Nothing
, storeExportWithContentIdentifier = \_ _ _ _ _ -> return (Left "import not supported")
, removeExportWithContentIdentifier = \_ _ _ -> return False
, removeExportDirectoryWhenEmpty = Just $ \_ -> return False
, checkPresentExportWithContentIdentifier = \_ _ _ -> return False
}
exportIsSupported :: ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool
exportIsSupported = \_ _ -> return True
importIsSupported :: ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool
importIsSupported = \_ _ -> return True
-- | Prevent or allow exporttree=yes and importtree=yes when
-- setting up a new remote, depending on exportSupported and importSupported.
adjustExportImportRemoteType :: RemoteType -> RemoteType
adjustExportImportRemoteType rt = rt { setup = setup' }
where
setup' st mu cp c gc = do
pc <- either giveup return . parseRemoteConfig c
=<< configParser rt c
let checkconfig supported configured configfield cont =
ifM (supported rt pc gc)
( case st of
Init
| configured pc && isEncrypted pc ->
giveup $ "cannot enable both encryption and " ++ fromProposedAccepted configfield
| otherwise -> cont
Enable oldc -> do
oldpc <- parsedRemoteConfig rt oldc
if configured pc /= configured oldpc
then giveup $ "cannot change " ++ fromProposedAccepted configfield ++ " of existing special remote"
else cont
, if configured pc
then giveup $ fromProposedAccepted configfield ++ " is not supported by this special remote"
else cont
)
checkconfig exportSupported exportTree exportTreeField $
checkconfig importSupported importTree importTreeField $
if importTree pc && not (exportTree pc)
then giveup "cannot enable importtree=yes without also enabling exporttree=yes"
else setup rt st mu cp c gc
-- | Adjust a remote to support exporttree=yes and importree=yes.
--
-- Note that all remotes with importree=yes also have exporttree=yes.
adjustExportImport :: Remote -> RemoteStateHandle -> Annex Remote
adjustExportImport r rs = case getRemoteConfigValue exportTreeField (config r) of
Nothing -> return $ notexport r
Just True -> ifM (isExportSupported r)
( do
exportdbv <- prepexportdb
r' <- isexport exportdbv
if importTree (config r)
then isimport r' exportdbv
else return r'
, return $ notexport r
)
Just False -> return $ notexport r
where
notexport r' = notimport r'
{ exportActions = exportUnsupported
, remotetype = (remotetype r')
{ exportSupported = exportUnsupported
}
}
notimport r' = r'
{ importActions = importUnsupported
, remotetype = (remotetype r')
{ importSupported = importUnsupported
}
}
isimport r' exportdbv = do
ciddbv <- prepciddb
let keycids k = do
db <- getciddb ciddbv
liftIO $ ContentIdentifier.getContentIdentifiers db rs k
let checkpresent k loc =
checkPresentExportWithContentIdentifier
(importActions r')
k loc
=<< keycids k
return $ r'
{ exportActions = (exportActions r')
{ storeExport = \f k loc p -> do
db <- getciddb ciddbv
exportdb <- getexportdb exportdbv
oldks <- liftIO $ Export.getExportTreeKey exportdb loc
oldcids <- liftIO $ concat
<$> mapM (ContentIdentifier.getContentIdentifiers db rs) oldks
storeExportWithContentIdentifier (importActions r') f k loc oldcids p >>= \case
Left err -> do
warning err
return False
Right newcid -> do
withExclusiveLock gitAnnexContentIdentifierLock $ do
liftIO $ ContentIdentifier.recordContentIdentifier db rs newcid k
liftIO $ ContentIdentifier.flushDbQueue db
recordContentIdentifier rs newcid k
return True
, removeExport = \k loc ->
removeExportWithContentIdentifier (importActions r') k loc
=<< keycids k
, removeExportDirectory = removeExportDirectoryWhenEmpty (importActions r')
-- renameExport is optional, and the
-- remote's implementation may
-- lose modifications to the file
-- (by eg copying and then deleting)
-- so don't use it
, renameExport = \_ _ _ -> return Nothing
, checkPresentExport = checkpresent
}
, checkPresent = if appendonly r'
then checkPresent r'
else \k -> anyM (checkpresent k)
=<< getexportlocs exportdbv k
, getInfo = do
is <- getInfo r'
return (is++[("import", "yes")])
}
isexport dbv = return $ r
-- Storing a key on an export could be implemented,
-- but it would perform unncessary work
-- when another repository has already stored the
-- key, and the local repository does not know
-- about it. To avoid unnecessary costs, don't do it.
{ storeKey = \_ _ _ ->
giveup "remote is configured with exporttree=yes; use `git-annex export` to store content on it"
-- Keys can be retrieved using retrieveExport,
-- but since that retrieves from a path in the
-- remote that another writer could have replaced
-- with content not of the requested key,
-- the content has to be strongly verified.
--
-- appendonly remotes have a key/value store,
-- so don't need to use retrieveExport. However,
-- fall back to it if retrieveKeyFile fails.
, retrieveKeyFile = \k af dest p ->
let retrieveexport = retrieveKeyFileFromExport dbv k af dest p
in if appendonly r
then do
ret@(ok, _v) <- retrieveKeyFile r k af dest p
if ok
then return ret
else retrieveexport
else retrieveexport
, retrieveKeyFileCheap = if appendonly r
then retrieveKeyFileCheap r
else \_ _ _ -> return False
-- Removing a key from an export would need to
-- change the tree in the export log to not include
-- the file. Otherwise, conflicts when removing
-- files would not be dealt with correctly.
-- There does not seem to be a good use case for
-- removing a key from an export in any case.
, removeKey = \_k -> do
warning "dropping content from an export is not supported; use `git annex export` to export a tree that lacks the files you want to remove"
return False
-- Can't lock content on exports, since they're
-- not key/value stores, and someone else could
-- change what's exported to a file at any time.
--
-- (except for appendonly remotes)
, lockContent = if appendonly r
then lockContent r
else Nothing
-- Check if any of the files a key was exported to
-- are present. This doesn't guarantee the export
-- contains the right content, which is why export
-- remotes are untrusted.
--
-- (but appendonly remotes work the same as any
-- non-export remote)
, checkPresent = if appendonly r
then checkPresent r
else \k -> anyM (checkPresentExport (exportActions r) k)
=<< getexportlocs dbv k
-- checkPresent from an export is more expensive
-- than otherwise, so not cheap. Also, this
-- avoids things that look at checkPresentCheap and
-- silently skip non-present files from behaving
-- in confusing ways when there's an export
-- conflict.
, checkPresentCheap = False
, mkUnavailable = return Nothing
, getInfo = do
ts <- map fromRef . exportedTreeishes
<$> getExport (uuid r)
is <- getInfo r
return (is++[("export", "yes"), ("exportedtree", unwords ts)])
}
prepciddb = do
lcklckv <- liftIO newEmptyTMVarIO
dbtv <- liftIO newEmptyTMVarIO
return (dbtv, lcklckv)
prepexportdb = do
lcklckv <- liftIO newEmptyTMVarIO
dbv <- liftIO newEmptyTMVarIO
exportinconflict <- liftIO $ newTVarIO False
return (dbv, lcklckv, exportinconflict)
-- Only open the database once it's needed.
getciddb (dbtv, lcklckv) =
liftIO (atomically (tryReadTMVar dbtv)) >>= \case
Just db -> return db
-- let only one thread take the lock
Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
( do
db <- ContentIdentifier.openDb
ContentIdentifier.needsUpdateFromLog db >>= \case
Just v -> withExclusiveLock gitAnnexContentIdentifierLock $
ContentIdentifier.updateFromLog db v
Nothing -> noop
liftIO $ atomically $ putTMVar dbtv db
return db
-- loser waits for winner to open the db and
-- can then also use its handle
, liftIO $ atomically (readTMVar dbtv)
)
-- Only open the database once it's needed.
--
-- After opening the database, check if the export log is
-- different than the database, and update the database, to notice
-- when an export has been updated from another repository.
getexportdb (dbv, lcklckv, exportinconflict) =
liftIO (atomically (tryReadTMVar dbv)) >>= \case
Just db -> return db
-- let only one thread take the lock
Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
( do
db <- Export.openDb (uuid r)
updateexportdb db exportinconflict
liftIO $ atomically $ putTMVar dbv db
return db
-- loser waits for winner to open the db and
-- can then also use its handle
, liftIO $ atomically (readTMVar dbv)
)
getexportinconflict (_, _, v) = v
updateexportdb db exportinconflict =
Export.updateExportTreeFromLog db >>= \case
Export.ExportUpdateSuccess -> return ()
Export.ExportUpdateConflict -> do
warnExportImportConflict r
liftIO $ atomically $
writeTVar exportinconflict True
getexportlocs dbv k = do
db <- getexportdb dbv
liftIO $ Export.getExportTree db k
retrieveKeyFileFromExport dbv k _af dest p = unVerified $
if maybe False (isJust . verifyKeyContent) (maybeLookupBackendVariety (fromKey keyVariety k))
then do
locs <- getexportlocs dbv k
case locs of
[] -> do
ifM (liftIO $ atomically $ readTVar $ getexportinconflict dbv)
( warning "unknown export location, likely due to the export conflict"
, warning "unknown export location"
)
return False
(l:_) -> retrieveExport (exportActions r) k l dest p
else do
warning $ "exported content cannot be verified due to using the " ++ decodeBS (formatKeyVariety (fromKey keyVariety k)) ++ " backend"
return False