split out Annex/BranchState.hs

Annex/BranchState.hs

@@ -0,0 +1,56 @@
+{- git-annex branch state management
+ -
+ - Runtime state about the git-annex branch, including a small read cache.
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Annex.BranchState where
+
+import Common.Annex
+import Types.BranchState
+import qualified Annex
+
+getState :: Annex BranchState
+getState = Annex.getState Annex.branchstate
+
+setState :: BranchState -> Annex ()
+setState state = Annex.changeState $ \s -> s { Annex.branchstate = state }
+
+setCache :: FilePath -> String -> Annex ()
+setCache file content = do
+	state <- getState
+	setState state { cachedFile = Just file, cachedContent = content }
+
+getCache :: FilePath -> Annex (Maybe String)
+getCache file = getState >>= go
+	where
+		go state
+			| cachedFile state == Just file =
+				return $ Just $ cachedContent state
+			| otherwise = return Nothing
+
+invalidateCache :: Annex ()
+invalidateCache = do
+	state <- getState
+	setState state { cachedFile = Nothing, cachedContent = "" }
+
+{- Runs an action to update the branch, if it's not been updated before
+ - in this run of git-annex. -}
+runUpdateOnce :: Annex () -> Annex ()
+runUpdateOnce a = unlessM (branchUpdated <$> getState) $ do
+	a
+	disableUpdate
+
+{- Avoids updating the branch. A useful optimisation when the branch
+ - is known to have not changed, or git-annex won't be relying on info
+ - from it. -}
+disableUpdate :: Annex ()
+disableUpdate = Annex.changeState setupdated
+	where
+		setupdated s = s { Annex.branchstate = new }
+			where
+				new = old { branchUpdated = True }
+				old = Annex.branchstate s