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{- Sqlite database of information about Keys
-
- Copyright 2015-2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE ScopedTypeVariables #-}
module Database.Keys (
DbHandle,
closeDb,
addAssociatedFile,
getAssociatedFiles,
getAssociatedKey,
removeAssociatedFile,
storeInodeCaches,
addInodeCaches,
getInodeCaches,
removeInodeCaches,
runWriter,
) where
import qualified Database.Keys.SQL as SQL
import Database.Types
import Database.Keys.Handle
import qualified Database.Queue as H
import Database.Init
import Annex.Locations
import Annex.Common hiding (delete)
import Annex.Version (versionUsesKeysDatabase)
import qualified Annex
import Annex.LockFile
import Utility.InodeCache
import Annex.InodeSentinal
import Git.FilePath
{- Runs an action that reads from the database.
-
- If the database doesn't already exist, it's not created; mempty is
- returned instead. This way, when the keys database is not in use,
- there's minimal overhead in checking it.
-
- If the database is already open, any writes are flushed to it, to ensure
- consistency.
-
- Any queued writes will be flushed before the read.
-}
runReader :: Monoid v => (SQL.ReadHandle -> Annex v) -> Annex v
runReader a = do
h <- getDbHandle
withDbState h go
where
go DbUnavailable = return (mempty, DbUnavailable)
go st@(DbOpen qh) = do
liftIO $ H.flushDbQueue qh
v <- a (SQL.ReadHandle qh)
return (v, st)
go DbClosed = do
st' <- openDb False DbClosed
v <- case st' of
(DbOpen qh) -> a (SQL.ReadHandle qh)
_ -> return mempty
return (v, st')
runReaderIO :: Monoid v => (SQL.ReadHandle -> IO v) -> Annex v
runReaderIO a = runReader (liftIO . a)
{- Runs an action that writes to the database. Typically this is used to
- queue changes, which will be flushed at a later point.
-
- The database is created if it doesn't exist yet. -}
runWriter :: (SQL.WriteHandle -> Annex ()) -> Annex ()
runWriter a = do
h <- getDbHandle
withDbState h go
where
go st@(DbOpen qh) = do
v <- a (SQL.WriteHandle qh)
return (v, st)
go st = do
st' <- openDb True st
v <- case st' of
DbOpen qh -> a (SQL.WriteHandle qh)
_ -> error "internal"
return (v, st')
runWriterIO :: (SQL.WriteHandle -> IO ()) -> Annex ()
runWriterIO a = runWriter (liftIO . a)
{- Gets the handle cached in Annex state; creates a new one if it's not yet
- available, but doesn't open the database. -}
getDbHandle :: Annex DbHandle
getDbHandle = go =<< Annex.getState Annex.keysdbhandle
where
go (Just h) = pure h
go Nothing = do
h <- ifM versionUsesKeysDatabase
( liftIO newDbHandle
, liftIO unavailableDbHandle
)
Annex.changeState $ \s -> s { Annex.keysdbhandle = Just h }
return h
{- Opens the database, perhaps creating it if it doesn't exist yet.
-
- Multiple readers and writers can have the database open at the same
- time. Database.Handle deals with the concurrency issues.
- The lock is held while opening the database, so that when
- the database doesn't exist yet, one caller wins the lock and
- can create it undisturbed.
-}
openDb :: Bool -> DbState -> Annex DbState
openDb _ st@(DbOpen _) = return st
openDb False DbUnavailable = return DbUnavailable
openDb createdb _ = catchPermissionDenied permerr $ withExclusiveLock gitAnnexKeysDbLock $ do
dbdir <- fromRepo gitAnnexKeysDb
let db = dbdir </> "db"
dbexists <- liftIO $ doesFileExist db
case (dbexists, createdb) of
(True, _) -> open db
(False, True) -> do
initDb db SQL.createTables
open db
(False, False) -> return DbUnavailable
where
open db = liftIO $ DbOpen <$> H.openDbQueue H.MultiWriter db SQL.containedTable
-- If permissions don't allow opening the database, treat it as if
-- it does not exist.
permerr e = case createdb of
False -> return DbUnavailable
True -> throwM e
{- Closes the database if it was open. Any writes will be flushed to it.
-
- This does not normally need to be called; the database will auto-close
- when the handle is garbage collected. However, this can be used to
- force a re-read of the database, in case another process has written
- data to it.
-}
closeDb :: Annex ()
closeDb = liftIO . closeDbHandle =<< getDbHandle
addAssociatedFile :: Key -> TopFilePath -> Annex ()
addAssociatedFile k f = runWriterIO $ SQL.addAssociatedFile (toIKey k) f
{- Note that the files returned were once associated with the key, but
- some of them may not be any longer. -}
getAssociatedFiles :: Key -> Annex [TopFilePath]
getAssociatedFiles = runReaderIO . SQL.getAssociatedFiles . toIKey
{- Gets any keys that are on record as having a particular associated file.
- (Should be one or none but the database doesn't enforce that.) -}
getAssociatedKey :: TopFilePath -> Annex [Key]
getAssociatedKey = map fromIKey <$$> runReaderIO . SQL.getAssociatedKey
removeAssociatedFile :: Key -> TopFilePath -> Annex ()
removeAssociatedFile k = runWriterIO . SQL.removeAssociatedFile (toIKey k)
{- Stats the files, and stores their InodeCaches. -}
storeInodeCaches :: Key -> [FilePath] -> Annex ()
storeInodeCaches k fs = withTSDelta $ \d ->
addInodeCaches k . catMaybes =<< liftIO (mapM (`genInodeCache` d) fs)
addInodeCaches :: Key -> [InodeCache] -> Annex ()
addInodeCaches k is = runWriterIO $ SQL.addInodeCaches (toIKey k) is
{- A key may have multiple InodeCaches; one for the annex object, and one
- for each pointer file that is a copy of it. -}
getInodeCaches :: Key -> Annex [InodeCache]
getInodeCaches = runReaderIO . SQL.getInodeCaches . toIKey
removeInodeCaches :: Key -> Annex ()
removeInodeCaches = runWriterIO . SQL.removeInodeCaches . toIKey
|
