This package provides access to platform dependent file locking APIs:

• Open file descriptor locking on Linux (Lukko.OFD)

• BSD-style flock(2) locks on UNIX platforms (Lukko.FLock)

• Windows locking via LockFileEx (Lukko.Windows)

• No-op locking, which throws exceptions (Lukko.NoOp)

• Lukko module exports the best option for the target platform with uniform API.

There are alternative file locking packages:

• GHC.IO.Handle.Lock in base >= 4.10 is good enough for most use cases. However, uses only Handles so these locks cannot be used for intra-process locking. (You should use e.g. MVar in addition).

• filelock doesn't support OFD locking.

Lukko means lock in Finnish.

Submodules Lukko.OFD, Lukko.Windows etc are available based on following conditions.

if os(windows)
  cpp-options: -DHAS_WINDOWS_LOCK

elif (os(linux) && flag(ofd-locking))
  cpp-options: -DHAS_OFD_LOCKING
  cpp-options: -DHAS_FLOCK

elif !(os(solaris) || os(aix))
  cpp-options: -DHAS_FLOCK

Lukko.FLock is available on not (Windows or Solaris or AIX). Lukko.NoOp is always available.