Single instance check with ruby and windows

global_lock.rb

require 'win32/mutex'
require 'windows/error'

def with_global_lock(lockname, &block)
  mutex = Win32::Mutex.new(true, lockname)

  if mutex.GetLastError == Windows::Error::ERROR_ALREADY_EXISTS
    raise RuntimeError, 'Already running!'
  end

  begin
    block.call
  ensure
    mutex.release
    mutex.close
  end
end

with_global_lock('my_unique_lock_name') do
  10.times do |i|
    puts i
    sleep 1
  end
end