# File lib/daemon_controller/lock_file.rb, line 113 def try_exclusive_lock File.open(@filename, 'w') do |f| if Fcntl.const_defined? :F_SETFD f.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) end if f.flock(File::LOCK_EX | File::LOCK_NB) yield else raise AlreadyLocked end end end