diff options
| author |  Joey Hess <joeyh@joeyh.name> | 2015-10-08 13:40:23 -0400 |
|---|---|---|
| committer | Joey Hess <joeyh@joeyh.name> | 2015-10-08 13:40:23 -0400 |
| commit | dc7576766528bf5b9951b3f355f49a9f8fc1f183 (patch) | |
| tree | d7c3f68d402a4586c469f6177b47e42bfc0aa8ff /Utility | |
| parent | e2693da16db892d002b2993443bcbe38b6c6efa0 (diff) | |
add tryLockShared
Diffstat (limited to 'Utility')
| -rw-r--r-- | Utility/LockFile/Posix.hs | 25 | ||||
| -rw-r--r-- | Utility/LockPool/Posix.hs | 9 |
2 files changed, 26 insertions, 8 deletions
diff --git a/Utility/LockFile/Posix.hs b/Utility/LockFile/Posix.hs index 8f06ae69e..cf88fa87d 100644 --- a/Utility/LockFile/Posix.hs +++ b/Utility/LockFile/Posix.hs @@ -9,6 +9,7 @@ module Utility.LockFile.Posix ( LockHandle, lockShared, lockExclusive, + tryLockShared, tryLockExclusive, checkLocked, getLockStatus, @@ -36,16 +37,13 @@ lockShared = lock ReadLock lockExclusive :: Maybe FileMode -> LockFile -> IO LockHandle lockExclusive = lock WriteLock +-- Tries to take a shared lock, but does not block. +tryLockShared :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle) +tryLockShared = tryLock ReadLock + -- Tries to take an exclusive lock, but does not block. tryLockExclusive :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle) -tryLockExclusive mode lockfile = do - l <- openLockFile WriteLock mode lockfile - v <- tryIO $ setLock l (WriteLock, AbsoluteSeek, 0, 0) - case v of - Left _ -> do - closeFd l - return Nothing - Right _ -> return $ Just $ LockHandle l +tryLockExclusive = tryLock WriteLock -- Setting the FileMode allows creation of a new lock file. -- If it's Nothing then this only succeeds when the lock file already exists. @@ -55,6 +53,17 @@ lock lockreq mode lockfile = do waitToSetLock l (lockreq, AbsoluteSeek, 0, 0) return (LockHandle l) +-- Tries to take an lock, but does not block. +tryLock :: LockRequest -> Maybe FileMode -> LockFile -> IO (Maybe LockHandle) +tryLock lockreq mode lockfile = do + l <- openLockFile lockreq mode lockfile + v <- tryIO $ setLock l (lockreq, AbsoluteSeek, 0, 0) + case v of + Left _ -> do + closeFd l + return Nothing + Right _ -> return $ Just $ LockHandle l + -- Close on exec flag is set so child processes do not inherit the lock. openLockFile :: LockRequest -> Maybe FileMode -> LockFile -> IO Fd openLockFile lockreq filemode lockfile = do diff --git a/Utility/LockPool/Posix.hs b/Utility/LockPool/Posix.hs index 506d7b560..82e0c8e5e 100644 --- a/Utility/LockPool/Posix.hs +++ b/Utility/LockPool/Posix.hs @@ -9,6 +9,7 @@ module Utility.LockPool.Posix ( LockHandle, lockShared, lockExclusive, + tryLockShared, tryLockExclusive, checkLocked, getLockStatus, @@ -35,11 +36,19 @@ lockShared mode file = makeLockHandle (P.waitTakeLock P.lockPool file LockShared) (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) +-- 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) + +-- 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) |