source: extensions/gsdl-video/trunk/installed/cmdline/lib/ruby/1.8/drb/extservm.rb@ 18425

=begin
 external service manager
    Copyright (c) 2000 Masatoshi SEKI 
=end

require 'drb/drb'
require 'thread'

module DRb
  class ExtServManager
    include DRbUndumped

    @@command = {}

    def self.command
      @@command
    end

    def self.command=(cmd)
      @@command = cmd
    end
      
    def initialize
      @servers = {}
      @waiting = []
      @queue = Queue.new
      @thread = invoke_thread
      @uri = nil
    end
    attr_accessor :uri

    def service(name)
      while true
    server = nil
    Thread.exclusive do
      server = @servers[name] if @servers[name]
    end
    return server if server && server.alive?
    invoke_service(name)
      end
    end

    def regist(name, ro)
      ary = nil
      Thread.exclusive do
    @servers[name] = ro
    ary = @waiting
    @waiting = []
      end
      ary.each do |th|
    begin
      th.run
    rescue ThreadError
    end
      end
      self
    end
    
    def unregist(name)
      Thread.exclusive do
    @servers.delete(name)
      end
    end

    private
    def invoke_thread
      Thread.new do
    while true
      name = @queue.pop
      invoke_service_command(name, @@command[name])
    end
      end
    end

    def invoke_service(name)
      Thread.critical = true
      @waiting.push Thread.current
      @queue.push name
      Thread.stop
    end

    def invoke_service_command(name, command)
      raise "invalid command. name: #{name}" unless command
      Thread.exclusive do
    return if @servers.include?(name)
    @servers[name] = false
      end
      uri = @uri || DRb.uri
      if RUBY_PLATFORM =~ /mswin32/ && /NT/ =~ ENV["OS"]
        system(%Q'cmd /c start "ruby" /b #{command} #{uri} #{name}')
      else
    system("#{command} #{uri} #{name} &")
      end
    end
  end
end