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# frozen_string_literal: true
module Gitlab
class Daemon
def self.initialize_instance(*args)
raise "#{name} singleton instance already initialized" if @instance
@instance = new(*args)
Kernel.at_exit(&@instance.method(:stop))
@instance
end
def self.instance(*args)
@instance ||= initialize_instance(*args)
end
attr_reader :thread
def thread?
!thread.nil?
end
def initialize
@mutex = Mutex.new
end
def enabled?
true
end
def thread_name
self.class.name.demodulize.underscore
end
def start
return unless enabled?
@mutex.synchronize do
break thread if thread?
if start_working
@thread = Thread.new do
Thread.current.name = thread_name
run_thread
end
end
end
end
def stop
@mutex.synchronize do
break unless thread?
stop_working
if thread
thread.wakeup if thread.alive?
begin
thread.join unless Thread.current == thread
rescue Exception # rubocop:disable Lint/RescueException
end
@thread = nil
end
end
end
private
# Executed in lock context before starting thread
# Needs to return success
def start_working
true
end
# Executed in separate thread
def run_thread
raise NotImplementedError
end
# Executed in lock context
def stop_working
# no-ops
end
end
end
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