refactor database handle code
Use same, simpler method to make only one thread open the export db as is used for the ContentIdentifier db. And, always update the export db once before using.
This commit is contained in:
Joey Hess
parent
fd2a1aaa17
commit
354aafce1a
1 changed files with 64 additions and 61 deletions
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@ -105,7 +105,7 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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Just c -> case yesNo c of
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Just True -> ifM (isExportSupported r)
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( do
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exportdbv <- liftIO $ newTVarIO Nothing
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exportdbv <- prepexportdb
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r' <- isexport exportdbv
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if importTree (config r)
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then isimport r' exportdbv
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@ -132,24 +132,7 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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}
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isimport r' exportdbv = do
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lcklckv <- liftIO newEmptyTMVarIO
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dbtv <- liftIO newEmptyTMVarIO
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-- Only open the database once it's needed, and take an
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-- exclusive write lock. The write lock will then remain
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-- held while the process is running.
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let getdb = liftIO (atomically (tryReadTMVar dbtv)) >>= \case
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Just (db, _lck) -> return db
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-- let only one thread take the lock
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Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
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( do
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lck <- takeExclusiveLock gitAnnexContentIdentifierLock
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db <- ContentIdentifier.openDb
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liftIO $ atomically (putTMVar dbtv (db, lck))
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return db
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-- loser waits for winner to open the db and
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-- can then also use its handle
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, liftIO $ fst <$> atomically (readTMVar dbtv)
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)
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ciddbv <- prepciddb
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let getknowncids db loc = do
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exportdb <- getexportdb exportdbv
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@ -160,7 +143,7 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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return $ r'
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{ exportActions = (exportActions r')
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{ storeExport = \f k loc p -> do
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db <- getdb
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db <- getciddb ciddbv
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knowncids <- getknowncids db loc
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storeExportWithContentIdentifier (importActions r') f k loc knowncids p >>= \case
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Nothing -> return False
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@ -169,7 +152,7 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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recordContentIdentifier (uuid r') newcid k
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return True
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, removeExport = \k loc -> do
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db <- getdb
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db <- getciddb ciddbv
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removeExportWithContentIdentifier (importActions r') k loc
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=<< getknowncids db loc
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, removeExportDirectory = removeExportDirectoryWhenEmpty (importActions r')
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@ -182,48 +165,10 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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}
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}
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getexportdb dbv = liftIO (atomically (readTVar dbv)) >>= \case
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Just db -> return db
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Nothing -> do
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db <- Export.openDb (uuid r)
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liftIO $ atomically $ writeTVar dbv $ Just db
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return db
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isexport dbv = do
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updateflag <- liftIO $ newTVarIO Nothing
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-- When multiple threads run this, all except the first
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-- will block until the first runs doneupdateonce.
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-- Returns True when an update should be done and False
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-- when the update has already been done.
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let startupdateonce = liftIO $ atomically $
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readTVar updateflag >>= \case
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Nothing -> do
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writeTVar updateflag (Just True)
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return True
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Just True -> retry
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Just False -> return False
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let doneupdateonce = \updated ->
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when updated $
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liftIO $ atomically $
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writeTVar updateflag (Just False)
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exportinconflict <- liftIO $ newTVarIO False
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-- Get export locations for a key. Checks once
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-- if the export log is different than the database and
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-- updates the database, to notice when an export has been
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-- updated from another repository.
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-- Get export locations for a key.
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let getexportlocs = \k -> do
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db <- getexportdb dbv
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bracket startupdateonce doneupdateonce $ \updatenow ->
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when updatenow $
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Export.updateExportTreeFromLog db >>= \case
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Export.ExportUpdateSuccess -> return ()
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Export.ExportUpdateConflict -> do
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warnExportConflict r
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liftIO $ atomically $
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writeTVar exportinconflict True
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liftIO $ Export.getExportTree db k
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return $ r
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@ -245,7 +190,7 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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-- so don't need to use retrieveExport. However,
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-- fall back to it if retrieveKeyFile fails.
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, retrieveKeyFile = \k af dest p ->
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let retrieveexport = retrieveKeyFileFromExport getexportlocs exportinconflict k af dest p
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let retrieveexport = retrieveKeyFileFromExport getexportlocs (getexportinconflict dbv) k af dest p
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in if appendonly r
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then do
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ret@(ok, _v) <- retrieveKeyFile r k af dest p
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@ -298,6 +243,64 @@ adjustExportImport r = case M.lookup "exporttree" (config r) of
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is <- getInfo r
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return (is++[("export", "yes"), ("exportedtree", unwords ts)])
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}
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prepciddb = do
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lcklckv <- liftIO newEmptyTMVarIO
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dbtv <- liftIO newEmptyTMVarIO
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return (dbtv, lcklckv)
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prepexportdb = do
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lcklckv <- liftIO newEmptyTMVarIO
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dbv <- liftIO newEmptyTMVarIO
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exportinconflict <- liftIO $ newTVarIO False
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return (dbv, lcklckv, exportinconflict)
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-- Only open the database once it's needed, and take an
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-- exclusive write lock. The write lock will then remain
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-- held while the process is running.
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getciddb (dbtv, lcklckv) =
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liftIO (atomically (tryReadTMVar dbtv)) >>= \case
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Just (db, _lck) -> return db
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-- let only one thread take the lock
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Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
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( do
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lck <- takeExclusiveLock gitAnnexContentIdentifierLock
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db <- ContentIdentifier.openDb
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liftIO $ atomically $ putTMVar dbtv (db, lck)
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return db
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-- loser waits for winner to open the db and
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-- can then also use its handle
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, liftIO $ fst <$> atomically (readTMVar dbtv)
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)
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getexportdb (dbv, lcklckv, exportinconflict) =
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liftIO (atomically (tryReadTMVar dbv)) >>= \case
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Just db -> return db
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-- let only one thread take the lock
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Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
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( do
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db <- Export.openDb (uuid r)
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updateexportdb db exportinconflict
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liftIO $ atomically $ putTMVar dbv db
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return db
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-- loser waits for winner to open the db and
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-- can then also use its handle
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, liftIO $ atomically (readTMVar dbv)
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)
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getexportinconflict (_, _, v) = v
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-- Check if the export log is different than the database and
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-- updates the database, to notice when an export has been
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-- updated from another repository.
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updateexportdb db exportinconflict =
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Export.updateExportTreeFromLog db >>= \case
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Export.ExportUpdateSuccess -> return ()
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Export.ExportUpdateConflict -> do
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warnExportConflict r
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liftIO $ atomically $
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writeTVar exportinconflict True
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retrieveKeyFileFromExport getexportlocs exportinconflict k _af dest p = unVerified $
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if maybe False (isJust . verifyKeyContent) (maybeLookupBackendVariety (keyVariety k))
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then do
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