make LockPool's LockHandle be able to support multiple different types of file locks

Utility/LockPool/LockHandle.hs

@@ -10,33 +10,38 @@
 module Utility.LockPool.LockHandle where
 
 import qualified Utility.LockPool.STM as P
-#ifndef mingw32_HOST_OS
-import qualified Utility.LockFile.Posix as F
-#else
-import qualified Utility.LockFile.Windows as F
-#endif
 
 import Control.Concurrent.STM
 import Control.Exception
 
-data LockHandle = LockHandle P.LockHandle F.LockHandle
+data LockHandle = LockHandle
+	{ poolHandle :: P.LockHandle
+	, fileLockOps :: FileLockOps
+	}
+
+data FileLockOps = FileLockOps
+	{ fDropLock :: IO ()
+#ifndef mingw32_HOST_OS
+	, fCheckSaneLock :: FilePath -> IO Bool
+#endif
+	}
 
 dropLock :: LockHandle -> IO ()
-dropLock (LockHandle ph fh) = P.releaseLock ph (F.dropLock fh)
+dropLock h = P.releaseLock (poolHandle h) (fDropLock (fileLockOps h))
 
 -- Take a lock, by first updating the lock pool, and then taking the file
 -- lock. If taking the file lock fails for any reason, take care to
 -- release the lock in the lock pool.
-makeLockHandle :: STM P.LockHandle -> IO F.LockHandle -> IO LockHandle
+makeLockHandle :: STM P.LockHandle -> IO FileLockOps -> IO LockHandle
 makeLockHandle pa fa = bracketOnError setup cleanup go
   where
 	setup = atomically pa
 	cleanup ph = P.releaseLock ph (return ())
 	go ph = do
-		fh <- fa
+		fo <- fa
-		return $ LockHandle ph fh
+		return $ LockHandle ph fo
 
-tryMakeLockHandle :: STM (Maybe P.LockHandle) -> IO (Maybe F.LockHandle) -> IO (Maybe LockHandle)
+tryMakeLockHandle :: STM (Maybe P.LockHandle) -> IO (Maybe FileLockOps) -> IO (Maybe LockHandle)
 tryMakeLockHandle pa fa = bracketOnError setup cleanup go
   where
 	setup = atomically pa
@@ -44,9 +49,9 @@ tryMakeLockHandle pa fa = bracketOnError setup cleanup go
 	cleanup (Just ph) = P.releaseLock ph (return ())
 	go Nothing = return Nothing
 	go (Just ph) = do
-		mfh <- fa
+		mfo <- fa
-		case mfh of
+		case mfo of
 			Nothing -> do
 				cleanup (Just ph)
 				return Nothing
-			Just fh -> return $ Just $ LockHandle ph fh
+			Just fo -> return $ Just $ LockHandle ph fo

Utility/LockPool/Posix.hs

@@ -35,25 +35,25 @@ import Prelude
 lockShared :: Maybe FileMode -> LockFile -> IO LockHandle
 lockShared mode file = makeLockHandle
 	(P.waitTakeLock P.lockPool file LockShared)
-	(F.lockShared mode file)
+	(mk <$> F.lockShared mode file)
 
 -- Takes an exclusive lock, blocking until the lock is available.
 lockExclusive :: Maybe FileMode -> LockFile -> IO LockHandle
 lockExclusive mode file = makeLockHandle
 	(P.waitTakeLock P.lockPool file LockExclusive)
-	(F.lockExclusive mode file)
+	(mk <$> F.lockExclusive mode file)
 
 -- Tries to take a shared lock, but does not block.
 tryLockShared :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle)
 tryLockShared mode file = tryMakeLockHandle
 	(P.tryTakeLock P.lockPool file LockShared)
-	(F.tryLockShared mode file)
+	(fmap mk <$> F.tryLockShared mode file)
 
 -- Tries to take an exclusive lock, but does not block.
 tryLockExclusive :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle)
 tryLockExclusive mode file = tryMakeLockHandle
 	(P.tryTakeLock P.lockPool file LockExclusive)
-	(F.tryLockExclusive mode file)
+	(fmap mk <$> F.tryLockExclusive mode file)
 
 -- Returns Nothing when the file doesn't exist, for cases where
 -- that is different from it not being locked.
@@ -68,4 +68,10 @@ getLockStatus file = P.getLockStatus P.lockPool file
 	(F.getLockStatus file)
 
 checkSaneLock :: LockFile -> LockHandle -> IO Bool
-checkSaneLock lockfile (LockHandle _ fh) = F.checkSaneLock lockfile fh
+checkSaneLock lockfile (LockHandle _ flo) = fCheckSaneLock flo lockfile
+
+mk :: F.LockHandle -> FileLockOps
+mk h = FileLockOps
+	{ fDropLock = F.dropLock h
+	, fCheckSaneLock = \f -> F.checkSaneLock f h
+	}

Utility/LockPool/Windows.hs

@@ -24,7 +24,7 @@ import Utility.LockPool.STM (LockFile, LockMode(..))
 lockShared :: LockFile -> IO (Maybe LockHandle)
 lockShared file = tryMakeLockHandle
 	(P.tryTakeLock P.lockPool file LockShared)
-	(F.lockShared file)
+	(fmap mk <$> F.lockShared file)
 
 {- Tries to take an exclusive lock on a file. Fails if another process has
  - a shared or exclusive lock.
@@ -35,9 +35,14 @@ lockShared file = tryMakeLockHandle
 lockExclusive :: LockFile -> IO (Maybe LockHandle)
 lockExclusive file = tryMakeLockHandle
 	(P.tryTakeLock P.lockPool file LockExclusive)
-	(F.lockExclusive file)
+	(fmap mk <$> F.lockExclusive file)
 
 {- If the initial lock fails, this is a BUSY wait, and does not
  - guarentee FIFO order of waiters. In other news, Windows is a POS. -}
 waitToLock :: IO (Maybe lockhandle) -> IO lockhandle
 waitToLock = F.waitToLock
+
+mk :: F.LockHandle -> FileLockOps
+mk h = FileLockOps
+	{ fDropLock = F.dropLock h
+	}