#!ruby
# -*- mode: ruby; coding: utf-8 -*-
# Last updated: <2022/08/17 02:20:57 +0900>
#
# DL, fiddle sample. use mutex.
# Support Ruby 1.9.3 only
#
# Windows10 x64 21H2 + Ruby 1.9.3 p551 i386-mingw32

require "dl"
require "fiddle"

include Fiddle

libc = DL.dlopen("kernel32.dll")
create_mutex = Fiddle::Function.new(libc["CreateMutex"], [TYPE_LONG, TYPE_LONG, TYPE_VOIDP], TYPE_LONG)
release_mutex = Fiddle::Function.new(libc["ReleaseMutex"], [TYPE_LONG], TYPE_LONG)
close_handle = Fiddle::Function.new(libc["CloseHandle"], [TYPE_LONG], TYPE_LONG)
get_last_error = Fiddle::Function.new(libc["GetLastError"], [], TYPE_LONG)

mutex_name = "rubydlfiddlemutexsample"
ERROR_ALREADY_EXISTS = 183

mutex = create_mutex.call(0, 1, mutex_name)

# err = Fiddle::win32_last_error
err = get_last_error.call()

puts "Mutex : #{mutex}"
puts "GetLastError : #{err}"

if mutex == 0 or err == ERROR_ALREADY_EXISTS
  puts "already exists"
  exit
else
  10.times do |i|
    puts i
    sleep 1
  end
end

if mutex != 0
  release_mutex.call(mutex)
  close_handle.call(mutex)
end