Safe Haskell	Trustworthy
Language	Haskell2010

Lukko.OFD

Contents

Types
File descriptors
Handles

Description

Linux open file descriptor locking.

https://www.gnu.org/software/libc/manual/html_node/Open-File-Description-Locks.html

We prefer this over BSD locking (e.g. flock) since the latter appears to break in some NFS configurations. Note that we intentionally do not try to use ordinary POSIX file locking due to its peculiar semantics under multi-threaded environments.

Synopsis

data FileLockingNotSupported = FileLockingNotSupported
fileLockingSupported :: Bool
type FileLockingSupported = True
data FileLockingMethod
- = MethodOFD
- | MethodFLock
- | MethodWindows
- | MethodNoOp
fileLockingMethod :: FileLockingMethod
data LockMode
- = SharedLock
- | ExclusiveLock
data FD
fdOpen :: FilePath -> IO FD
fdClose :: FD -> IO ()
fdLock :: FD -> LockMode -> IO ()
fdTryLock :: FD -> LockMode -> IO Bool
fdUnlock :: FD -> IO ()
hLock :: Handle -> LockMode -> IO ()
hTryLock :: Handle -> LockMode -> IO Bool
hUnlock :: Handle -> IO ()

Types

data FileLockingNotSupported Source #

Exception thrown by hLock on non-Windows platforms that don't support flock.

Constructors

FileLockingNotSupported

Instances

Instances details

Exception FileLockingNotSupported Source #
Instance details Defined in Lukko.Internal.Types Methods toException :: FileLockingNotSupported -> SomeException # fromException :: SomeException -> Maybe FileLockingNotSupported # displayException :: FileLockingNotSupported -> String #
Show FileLockingNotSupported Source #
Instance details Defined in Lukko.Internal.Types Methods showsPrec :: Int -> FileLockingNotSupported -> ShowS # show :: FileLockingNotSupported -> String # showList :: [FileLockingNotSupported] -> ShowS #

fileLockingSupported :: Bool Source #

A constants specifying whether file locking is supported.

type FileLockingSupported = True Source #

A type level fileLockingSupported.

data FileLockingMethod Source #

Potentially availble lock methods.

Constructors

MethodOFD	open file descriptor locking
MethodFLock	BSD `flock`
MethodWindows	Windows locking
MethodNoOp	No-Op (throws `FileLockingNotSupported`)

Instances

Instances details

Bounded FileLockingMethod Source #
Instance details Defined in Lukko.Internal.Types Methods minBound :: FileLockingMethod # maxBound :: FileLockingMethod #
Enum FileLockingMethod Source #
Instance details Defined in Lukko.Internal.Types Methods succ :: FileLockingMethod -> FileLockingMethod # pred :: FileLockingMethod -> FileLockingMethod # toEnum :: Int -> FileLockingMethod # fromEnum :: FileLockingMethod -> Int # enumFrom :: FileLockingMethod -> [FileLockingMethod] # enumFromThen :: FileLockingMethod -> FileLockingMethod -> [FileLockingMethod] # enumFromTo :: FileLockingMethod -> FileLockingMethod -> [FileLockingMethod] # enumFromThenTo :: FileLockingMethod -> FileLockingMethod -> FileLockingMethod -> [FileLockingMethod] #
Show FileLockingMethod Source #
Instance details Defined in Lukko.Internal.Types Methods showsPrec :: Int -> FileLockingMethod -> ShowS # show :: FileLockingMethod -> String # showList :: [FileLockingMethod] -> ShowS #
Eq FileLockingMethod Source #
Instance details Defined in Lukko.Internal.Types Methods (==) :: FileLockingMethod -> FileLockingMethod -> Bool # (/=) :: FileLockingMethod -> FileLockingMethod -> Bool #
Ord FileLockingMethod Source #
Instance details Defined in Lukko.Internal.Types Methods compare :: FileLockingMethod -> FileLockingMethod -> Ordering # (<) :: FileLockingMethod -> FileLockingMethod -> Bool # (<=) :: FileLockingMethod -> FileLockingMethod -> Bool # (>) :: FileLockingMethod -> FileLockingMethod -> Bool # (>=) :: FileLockingMethod -> FileLockingMethod -> Bool # max :: FileLockingMethod -> FileLockingMethod -> FileLockingMethod # min :: FileLockingMethod -> FileLockingMethod -> FileLockingMethod #