Lukko · lukko-0.1.2 · horizon-platform

datadata FileLockingNotSupported

#

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

FileLockingNotSupported

Instances2Show, Exception

Show FileLockingNotSupportedDefined in lukko-0.1.2 · Lukko.Internal.Types
Exception FileLockingNotSupportedDefined in lukko-0.1.2 · Lukko.Internal.Types

valuefileLockingSupported :: Bool

#

A constants specifying whether file locking is supported.

typetype FileLockingSupported = 'True

#

A type level fileLockingSupported.

datadata FileLockingMethod

#

Potentially availble lock methods.

Constructors

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

Instances5Bounded, Enum, Eq, Ord, Show

Bounded FileLockingMethodDefined in lukko-0.1.2 · Lukko.Internal.Types
Enum FileLockingMethodDefined in lukko-0.1.2 · Lukko.Internal.Types
Eq FileLockingMethodDefined in lukko-0.1.2 · Lukko.Internal.Types
Ord FileLockingMethodDefined in lukko-0.1.2 · Lukko.Internal.Types
Show FileLockingMethodDefined in lukko-0.1.2 · Lukko.Internal.Types

valuefileLockingMethod :: FileLockingMethod

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A constant specifying this method

datadata LockMode

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Indicates a mode in which a file should be locked.

SharedLock ExclusiveLock

File descriptors

6 declarations

typetype FD = FD

#

Opaque file descriptor

An int / CInt on unix systems, and HANDLE on windows.

valuefdOpen :: FilePath -> IO FD

#

Open file to be used for locking.

valuefdClose :: FD -> IO ()

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Close lock file.

valuefdLock :: FD -> LockMode -> IO ()

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Like hLock, but work on "raw" file descriptor, as handled by fdOpen and fdClose.

valuefdTryLock :: FD -> LockMode -> IO Bool

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Non-blocking version of fdLock.

valuefdUnlock :: FD -> IO ()

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Release a lock taken with fdLock or fdTryLock.

Handles

4 declarations

valuehandleToFd :: Handle -> IO FD

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Convert GHC Handle to lukko FD.

valuehLock :: Handle -> LockMode -> IO ()

#

If a Handle references a file descriptor, attempt to lock contents of the underlying file in appropriate mode. If the file is already locked in incompatible mode, this function blocks until the lock is established. The lock is automatically released upon closing a Handle.

Things to be aware of:

1) This function may block inside a C call. If it does, in order to be able to interrupt it with asynchronous exceptions and/or for other threads to continue working, you MUST use threaded version of the runtime system.

2) The implementation uses LockFileEx on Windows, open file descriptor locks on Linux, and flock otherwise, hence all of their caveats also apply here.

3) On non-Windows plaftorms that don't support flock (e.g. Solaris) this function throws FileLockingNotImplemented. We deliberately choose to not provide fcntl based locking instead because of its broken semantics.

valuehTryLock :: Handle -> LockMode -> IO Bool

#

Non-blocking version of hLock.

valuehUnlock :: Handle -> IO ()

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Release a lock taken with hLock or hTryLock.