- Performs file locking using the flock or LockFileEx function

- Performs a lock on the file, if the lock is already on the file, then the function fails or returns the lock identifier to undefined, depending on the a_quiet argument

- Removes a locks on a file

- Checks if a file is locked.

- Performs a lock on a named mutex

- Locks a named mutex without waiting. If the mutex is already locked, the function fails and the error object contains the unavailable field set to true. If a_quiet is true, then if the mutex is already locked, the function calls the callback with a lock index value of undefined.

- Performs a mutex unlock

- Checks whether the named mutex is locked