git-annex/Messages/Concurrent.hs

110 lines
3.4 KiB
Haskell

{-# OPTIONS_GHC -fno-warn-orphans #-}
{- git-annex output messages, including concurrent output to display regions
-
- Copyright 2010-2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Messages.Concurrent where
import Common
import Annex
import Types.Messages
#ifdef WITH_CONCURRENTOUTPUT
import qualified System.Console.Concurrent as Console
import qualified System.Console.Regions as Regions
import Control.Concurrent.STM
import qualified Data.Text as T
#endif
{- Outputs a message in a concurrency safe way.
-
- The message may be an error message, in which case it goes to stderr.
-
- When built without concurrent-output support, the fallback action is run
- instead.
-}
concurrentMessage :: Bool -> String -> Annex () -> Annex ()
#ifdef WITH_CONCURRENTOUTPUT
concurrentMessage iserror msg _ = go =<< consoleRegion <$> Annex.getState Annex.output
where
go Nothing
| iserror = liftIO $ Console.errorConcurrent msg
| otherwise = liftIO $ Console.outputConcurrent msg
go (Just r) = do
-- Can't display the error to stdout while
-- console regions are in use, so set the errflag
-- to get it to display to stderr later.
when iserror $ do
Annex.changeState $ \s ->
s { Annex.output = (Annex.output s) { consoleRegionErrFlag = True } }
liftIO $ atomically $ do
Regions.appendConsoleRegion r msg
rl <- takeTMVar Regions.regionList
putTMVar Regions.regionList
(if r `elem` rl then rl else r:rl)
#else
concurrentMessage _ _ fallback = fallback
#endif
{- Runs an action in its own dedicated region of the console.
-
- The region is closed at the end or on exception, and at that point
- the value of the region is displayed in the scrolling area above
- any other active regions.
-
- When not at a console, a region is not displayed until the action is
- complete.
-}
inOwnConsoleRegion :: Annex a -> Annex a
#ifdef WITH_CONCURRENTOUTPUT
inOwnConsoleRegion a = do
r <- mkregion
setregion (Just r)
eret <- tryNonAsync a `onException` rmregion r
case eret of
Left e -> do
-- Add error message to region before it closes.
concurrentMessage True (show e) noop
rmregion r
throwM e
Right ret -> do
rmregion r
return ret
where
-- The region is allocated here, but not displayed until
-- a message is added to it. This avoids unnecessary screen
-- updates when a region does not turn out to need to be used.
mkregion = Regions.newConsoleRegion Regions.Linear ""
setregion r = Annex.changeState $ \s -> s { Annex.output = (Annex.output s) { consoleRegion = r } }
rmregion r = do
errflag <- consoleRegionErrFlag <$> Annex.getState Annex.output
let h = if errflag then Console.StdErr else Console.StdOut
Annex.changeState $ \s ->
s { Annex.output = (Annex.output s) { consoleRegionErrFlag = False } }
setregion Nothing
liftIO $ atomically $ do
t <- Regions.getConsoleRegion r
unless (T.null t) $
Console.bufferOutputSTM h t
Regions.closeConsoleRegion r
#else
inOwnConsoleRegion = id
#endif
{- The progress region is displayed inline with the current console region. -}
#ifdef WITH_CONCURRENTOUTPUT
withProgressRegion :: (Regions.ConsoleRegion -> Annex a) -> Annex a
withProgressRegion a = do
parent <- consoleRegion <$> Annex.getState Annex.output
Regions.withConsoleRegion (maybe Regions.Linear Regions.InLine parent) a
instance Regions.LiftRegion Annex where
liftRegion = liftIO . atomically
#endif