git-annex/Messages/Concurrent.hs

138 lines
4.5 KiB
Haskell

{- git-annex output messages, including concurrent output to display regions
-
- Copyright 2010-2017 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Messages.Concurrent where
import Types
import Types.Messages
import qualified Annex
import Common
import qualified System.Console.Concurrent as Console
import qualified System.Console.Regions as Regions
import Control.Concurrent.STM
import Control.Monad.IO.Class
import qualified Data.Text as T
#ifndef mingw32_HOST_OS
import GHC.IO.Encoding
#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 :: MessageState -> Bool -> String -> Annex () -> Annex ()
concurrentMessage s iserror msg fallback
| concurrentOutputEnabled s =
go =<< consoleRegion <$> Annex.getState Annex.output
| otherwise = fallback
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 $ \st ->
st { Annex.output = (Annex.output st) { 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)
{- 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 :: MessageState -> Annex a -> Annex a
inOwnConsoleRegion s a
| concurrentOutputEnabled s = 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 s True (show e) noop
rmregion r
throwM e
Right ret -> do
rmregion r
return ret
| otherwise = a
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 $ \st -> st
{ Annex.output = (Annex.output st) { consoleRegion = r } }
rmregion r = do
errflag <- consoleRegionErrFlag <$> Annex.getState Annex.output
let h = if errflag then Console.StdErr else Console.StdOut
Annex.changeState $ \st -> st
{ Annex.output = (Annex.output st) { consoleRegionErrFlag = False } }
setregion Nothing
liftIO $ atomically $ do
t <- Regions.getConsoleRegion r
unless (T.null t) $
Console.bufferOutputSTM h t
Regions.closeConsoleRegion r
{- The progress region is displayed inline with the current console region. -}
withProgressRegion
:: (MonadIO m, MonadMask m)
=> MessageState
-> (Regions.ConsoleRegion -> m a) -> m a
withProgressRegion st a =
Regions.withConsoleRegion (maybe Regions.Linear Regions.InLine parent) a
where
parent = consoleRegion st
instance Regions.LiftRegion Annex where
liftRegion = liftIO . atomically
{- The concurrent-output library uses Text, which bypasses the normal use
- of the fileSystemEncoding to roundtrip invalid characters, when in a
- non-unicode locale. Work around that problem by avoiding using
- concurrent output when not in a unicode locale. -}
concurrentOutputSupported :: IO Bool
#ifndef mingw32_HOST_OS
concurrentOutputSupported = do
enc <- getLocaleEncoding
return ("UTF" `isInfixOf` textEncodingName enc)
#else
concurrentOutputSupported = return True -- Windows is always unicode
#endif
{- Hide any currently displayed console regions while running the action,
- so that the action can use the console itself. -}
hideRegionsWhile :: (MonadIO m, Monad m, MonadMask m) => MessageState -> m a -> m a
hideRegionsWhile s a
| concurrentOutputEnabled s = bracket setup cleanup go
| otherwise = a
where
setup = liftIO $
Regions.waitDisplayChange $ swapTMVar Regions.regionList []
cleanup = liftIO . void . atomically . swapTMVar Regions.regionList
go _ = do
liftIO $ hFlush stdout
a