class DRb::ExtServManager

# File lib/drb/extservm.rb, line 18
def self.command
  @@command
end

# File lib/drb/extservm.rb, line 22
def self.command=(cmd)
  @@command = cmd
end

# File lib/drb/extservm.rb, line 26
def initialize
  super()
  @cond = new_cond
  @servers = {}
  @waiting = []
  @queue = Queue.new
  @thread = invoke_thread
  @uri = nil
end

# File lib/drb/extservm.rb, line 48
def regist(name, ro)
  synchronize do
    @servers[name] = ro
    @cond.signal
  end
  self
end

# File lib/drb/extservm.rb, line 37
def service(name)
  synchronize do
    while true
      server = @servers[name]
      return server if server&.alive?
      invoke_service(name)
      @cond.wait
    end
  end
end

# File lib/drb/extservm.rb, line 56
def unregist(name)
  synchronize do
    @servers.delete(name)
  end
end

# File lib/drb/extservm.rb, line 72
def invoke_service(name)
  @queue.push(name)
end

# File lib/drb/extservm.rb, line 76
def invoke_service_command(name, command)
  raise "invalid command. name: #{name}" unless command
  synchronize do
    return if @servers.include?(name)
    @servers[name] = false
  end
  uri = @uri || DRb.uri
  if command.respond_to? :to_ary
    command = command.to_ary + [uri, name]
    pid = spawn(*command)
  else
    pid = spawn("#{command} #{uri} #{name}")
  end
  th = Process.detach(pid)
  th[:drb_service] = name
  th
end

# File lib/drb/extservm.rb, line 63
def invoke_thread
  Thread.new do
    while true
      name = @queue.pop
      invoke_service_command(name, @@command[name])
    end
  end
end