ghc-lukko

File locking

This package provides access to platform dependent file locking APIs: * <<a href="https://www.gnu.org/software/libc/manual/html_node/Open-File-Description-Locks.html">https://www.gnu.org/software/libc/manual/html_node/Open-File-Description-Locks.html</a> Open file descriptor locking> on Linux ("Lukko.OFD") * BSD-style 'flock(2)' locks on UNIX platforms ("Lukko.FLock") * Windows locking via <<a href="https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-lockfilee">https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-lockfilee</a> 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 'Handle's so these locks cannot be used for intra-process locking. (You should use e.g. 'MVar' in addition). * <<a href="https://hackage.haskell.org/package/filelock">https://hackage.haskell.org/package/filelock</a> 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.