Re: Locking files for CLASH_DETECTION now supported on MS-Windows

[Paul Eggert]

On 02/25/2013 06:43 PM, Daniel Colascione wrote:
> File creation is atomic. File deletion is atomic.
> The lock is signaled by the presence of the file, right?

Not in the recently-added MS-Windows implementation, no.
The lock is signaled by a nonempty file (approximately;
the details are a bit more complicated).

There are races where two Emacs instances can both
grab the lock simultaneously.  For example, one Emacs
instance can call create_lock_file with !FORCE and another
with FORCE, and afterwards both Emacs instances
think they own the lock (and the lock file itself
says the !FORCE Emacs owns it).