Experimental: parallel batch compilation of grammars

On my laptop these changes speed up the full build of the RGL and example
grammars with 'cabal build' from ~95s to ~43s and the zero build from ~18s
to ~5s.

The main change is the introduction of the module GF.CompileInParallel that
replaces GF.Compile and the function GF.Compile.ReadFiles.getAllFiles. At
present, it is activated with the new -j flag, and it is only used when
combined with --make or --batch. In addition, to get parallel computations,
you need to add GHC run-time flags, e.g., +RTS -N -A20M -RTS, to the command
line.

The Setup.hs script has been modified to pass the appropriate flags to GF
for parallel compilation when compiling the RGL and example grammars, but you
need a recent version of Cabal for this to work (probably >=1.20).

Some additonal refactoring were made during this work. A new monad is used to
avoid warnings/error messages from different modules to be intertwined when
compiling in parallel, so some functios that were hardiwred to the IO or IOE
monads have been lifted to work in arbitrary monads that are instances in
the appropriate classes.

2 files changed, 45 insertions, 42 deletions

diff --git a/src/compiler/GF/Infra/Option.hs b/src/compiler/GF/Infra/Option.hs
index 88767c72e..15feda1d0 100644
--- a/src/compiler/GF/Infra/Option.hs
+++ b/src/compiler/GF/Infra/Option.hs
@@ -172,8 +172,8 @@ data Flags = Flags {
       optTagsOnly        :: Bool,
       optHeuristicFactor :: Maybe Double,
       optMetaProb        :: Maybe Double,
-      optMetaToknProb    :: Maybe Double{-,
-      optNewComp         :: Bool-}
+      optMetaToknProb    :: Maybe Double,
+      optJobs            :: Maybe (Maybe String)
     }
   deriving (Show)
 
@@ -284,7 +284,8 @@ defaultFlags = Flags {
       optTagsOnly        = False,
       optHeuristicFactor = Nothing,
       optMetaProb        = Nothing,
-      optMetaToknProb    = Nothing
+      optMetaToknProb    = Nothing,
+      optJobs            = Nothing
     }
 
 -- | Option descriptions
@@ -297,6 +298,7 @@ optDescr =
      Option ['v'] ["verbose"] (OptArg verbosity "N") "Set verbosity (default 1). -v alone is the same as -v 2.",
      Option ['q','s'] ["quiet"] (NoArg (verbosity (Just "0"))) "Quiet, same as -v 0.",
      Option [] ["batch"] (NoArg (mode ModeCompiler)) "Run in batch compiler mode.",
+     Option ['j'] ["jobs"] (OptArg jobs "N") "Compile N modules in parallel with -batch (default 1).",
      Option [] ["interactive"] (NoArg (mode ModeInteractive)) "Run in interactive mode (default).",
      Option [] ["run"] (NoArg (mode ModeRun)) "Run in interactive mode, showing output only (no other messages).",
      Option [] ["server"] (OptArg modeServer "port") $
@@ -387,6 +389,7 @@ optDescr =
            ms = mode . ModeServer
            readPort p = maybe err ms (readMaybe p)
                  where err = fail $ "Bad server port: "++p
+       jobs mv       = set $ \ o -> o { optJobs = Just mv }
        verbosity mv  = case mv of
                            Nothing -> set $ \o -> o { optVerbosity = Verbose }
                            Just v  -> case readMaybe v >>= toEnumBounded of
diff --git a/src/compiler/GF/Infra/UseIO.hs b/src/compiler/GF/Infra/UseIO.hs
index a0a36ad52..6de68bc44 100644
--- a/src/compiler/GF/Infra/UseIO.hs
+++ b/src/compiler/GF/Infra/UseIO.hs
@@ -1,4 +1,3 @@
-{-# OPTIONS -cpp #-}
 ----------------------------------------------------------------------
 -- |
 -- Module      : UseIO
@@ -22,7 +21,7 @@ import GF.Infra.Option
 import GF.System.Catch
 import Paths_gf(getDataDir)
 
-import System.Directory
+import GF.System.Directory
 import System.FilePath
 import System.IO
 import System.IO.Error(isUserError,ioeGetErrorString)
@@ -36,24 +35,9 @@ import Control.Monad
 import Control.Monad.Trans(MonadIO(..))
 import Control.Exception(evaluate)
 
---putShow' :: Show a => (c -> a) -> c -> IO ()
---putShow' f = putStrLn . show . length . show . f
-
-putIfVerb :: MonadIO io => Options -> String -> io ()
-putIfVerb opts msg =
-      when (verbAtLeast opts Verbose) $ liftIO $ putStrLn msg
-
-putIfVerbW :: MonadIO io => Options -> String -> io ()
-putIfVerbW opts msg =
-      when (verbAtLeast opts Verbose) $ liftIO $ putStr (' ' : msg)
-{-
-errOptIO :: Options -> a -> Err a -> IO a
-errOptIO os e m = case m of
-  Ok x  -> return x
-  Bad k -> do  
-    putIfVerb os k
-    return e
--}
+--putIfVerb :: MonadIO io => Options -> String -> io ()
+putIfVerb opts msg = when (verbAtLeast opts Verbose) $ putStrLnE msg
+
 type FileName = String
 type InitPath = String -- ^ the directory portion of a pathname
 type FullPath = String
@@ -68,8 +52,8 @@ getLibraryDirectory opts =
     Nothing   -> liftIO $ catch (getEnv gfLibraryPath)
                                 (\ex -> fmap (</> "lib") getDataDir)
 
-getGrammarPath :: FilePath -> IO [FilePath]
-getGrammarPath lib_dir = do
+getGrammarPath :: MonadIO io => FilePath -> io [FilePath]
+getGrammarPath lib_dir = liftIO $ do
   catch (fmap splitSearchPath $ getEnv gfGrammarPathVar) 
         (\_ -> return [lib_dir </> "alltenses",lib_dir </> "prelude"])     -- e.g. GF_GRAMMAR_PATH
 
@@ -110,15 +94,14 @@ getSubdirs dir = do
 justModuleName :: FilePath -> String
 justModuleName = dropExtension . takeFileName
 
-isGFO :: FilePath -> Bool
+isGF,isGFO :: FilePath -> Bool
+isGF  = (== ".gf")  . takeExtensions
 isGFO = (== ".gfo") . takeExtensions
 
-gfoFile :: FilePath -> FilePath
+gfFile,gfoFile :: FilePath -> FilePath
+gfFile  f = addExtension f "gf"
 gfoFile f = addExtension f "gfo"
 
-gfFile :: FilePath -> FilePath
-gfFile f = addExtension f "gf"
-
 gf2gfo :: Options -> FilePath -> FilePath
 gf2gfo = gf2gfo' . flag optGFODir
 
@@ -143,6 +126,8 @@ newtype IOE a = IOE { appIOE :: IO (Err a) }
 ioe :: IO (Err a) -> IOE a
 ioe = IOE
 
+runIOE m = err fail return =<< appIOE m
+
 instance MonadIO IOE where liftIO io = ioe (io >>= return . return)
 
 instance ErrorMonad IOE where
@@ -162,11 +147,11 @@ instance  Monad IOE where
                   appIOE $ err raise f x         -- f :: a -> IOE a
   fail = raise
 
-maybeIO io = either (const Nothing) Just `fmap` liftIO (try io)
-
 useIOE :: a -> IOE a -> IO a
 useIOE a ioe = appIOE ioe >>= err (\s -> putStrLn s >> return a) return 
 
+maybeIO io = either (const Nothing) Just `fmap` liftIO (try io)
+
 --foldIOE :: (a -> b -> IOE a) -> a -> [b] -> IOE (a, Maybe String)
 foldIOE f s xs = case xs of
   [] -> return (s,Nothing)
@@ -180,27 +165,42 @@ die :: String -> IO a
 die s = do hPutStrLn stderr s
            exitFailure
 
-ePutStr, ePutStrLn, putStrE, putStrLnE :: MonadIO m => String -> m ()
-ePutStr s = liftIO $ hPutStr stderr s
-ePutStrLn s = liftIO $ hPutStrLn stderr s
-putStrLnE s = liftIO $ putStrLn s >> hFlush stdout
-putStrE s = liftIO $ putStr s >> hFlush stdout
+class Monad m => Output m where
+  ePutStr, ePutStrLn, putStrE, putStrLnE :: String -> m ()
+
+instance Output IO where
+  ePutStr   s = hPutStr stderr s `catch` oops
+    where oops _ = return () -- prevent crash on character encoding problem
+  ePutStrLn s = hPutStrLn stderr s `catch` oops
+    where oops _ = ePutStrLn "" -- prevent crash on character encoding problem
+  putStrLnE s = putStrLn s >> hFlush stdout
+  putStrE   s = putStr s >> hFlush stdout
 
-putPointE :: MonadIO m => Verbosity -> Options -> String -> m a -> m a
+instance Output IOE where
+  ePutStr   = liftIO . ePutStr
+  ePutStrLn = liftIO . ePutStrLn
+  putStrLnE = liftIO . putStrLnE
+  putStrE   = liftIO . putStrE
+
+--putPointE :: Verbosity -> Options -> String -> IO a -> IO a
 putPointE v opts msg act = do
   when (verbAtLeast opts v) $ putStrE msg
 
-  t1 <- liftIO $ getCPUTime
-  a <- act >>= liftIO . evaluate
-  t2 <- liftIO $ getCPUTime
+  (t,a) <- timeIt act
 
   if flag optShowCPUTime opts
-      then do let msec = (t2 - t1) `div` 1000000000
+      then do let msec = t `div` 1000000000
               putStrLnE (printf " %5d msec" msec)
       else when (verbAtLeast opts v) $ putStrLnE ""
 
   return a
 
+timeIt act =
+  do t1 <- liftIO $ getCPUTime
+     a <- liftIO . evaluate =<< act
+     t2 <- liftIO $ getCPUTime
+     return (t2-t1,a)
+
 -- * File IO
 
 writeUTF8File :: FilePath -> String -> IO ()