module for PidLocks in LockPool

Utility/LockPool/PidLock.hs

@@ -0,0 +1,63 @@
+{- Pid locks, using lock pools.
+ -
+ - Copyright 2015 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+module Utility.LockPool.PidLock (
+	P.LockFile,
+	LockHandle,
+	waitLock,
+	tryLock,
+	checkLocked,
+	getLockStatus,
+	LockStatus(..),
+	dropLock,
+	checkSaneLock,
+) where
+
+import qualified Utility.LockFile.PidLock as F
+import Utility.LockFile.LockStatus
+import qualified Utility.LockPool.STM as P
+import Utility.LockPool.STM (LockFile, LockMode(..))
+import Utility.LockPool.LockHandle
+
+import System.IO
+import System.Posix
+import Data.Maybe
+import Control.Applicative
+import Prelude
+
+-- Takes a pid lock, blocking until the lock is available.
+--
+-- May block forever on stale locks, see PidLock documentation for details.
+waitLock :: LockFile -> IO LockHandle
+waitLock file = makeLockHandle
+	(P.waitTakeLock P.lockPool file LockExclusive)
+	(mk <$> F.waitLock file)
+
+-- Tries to take a pid lock, but does not block.
+tryLock :: LockFile -> IO (Maybe LockHandle)
+tryLock file = tryMakeLockHandle
+	(P.tryTakeLock P.lockPool file LockShared)
+	(fmap mk <$> F.tryLock file)
+
+checkLocked :: LockFile -> IO (Maybe Bool)
+checkLocked file = P.getLockStatus P.lockPool file
+	(pure (Just True))
+	(F.checkLocked file)
+
+getLockStatus :: LockFile -> IO LockStatus
+getLockStatus file = P.getLockStatus P.lockPool file
+	(StatusLockedBy <$> getProcessID)
+	(F.getLockStatus file)
+
+checkSaneLock :: LockFile -> LockHandle -> IO Bool
+checkSaneLock lockfile (LockHandle _ flo) = fCheckSaneLock flo lockfile
+
+mk :: F.LockHandle -> FileLockOps
+mk h = FileLockOps
+	{ fDropLock = F.dropLock h
+	, fCheckSaneLock = \f -> F.checkSaneLock f h
+	}