Fresh start

1 files changed, 1864 insertions, 0 deletions

diff --git a/jni/ruby/lib/drb/drb.rb b/jni/ruby/lib/drb/drb.rb
new file mode 100644
index 0000000..ab352af
--- /dev/null
+++ b/jni/ruby/lib/drb/drb.rb
@@ -0,0 +1,1864 @@
+#
+# = drb/drb.rb
+#
+# Distributed Ruby: _dRuby_ version 2.0.4
+#
+# Copyright (c) 1999-2003 Masatoshi SEKI.  You can redistribute it and/or
+# modify it under the same terms as Ruby.
+#
+# Author:: Masatoshi SEKI
+#
+# Documentation:: William Webber (william@williamwebber.com)
+#
+# == Overview
+#
+# dRuby is a distributed object system for Ruby.  It allows an object in one
+# Ruby process to invoke methods on an object in another Ruby process on the
+# same or a different machine.
+#
+# The Ruby standard library contains the core classes of the dRuby package.
+# However, the full package also includes access control lists and the
+# Rinda tuple-space distributed task management system, as well as a
+# large number of samples.  The full dRuby package can be downloaded from
+# the dRuby home page (see *References*).
+#
+# For an introduction and examples of usage see the documentation to the
+# DRb module.
+#
+# == References
+#
+# [http://www2a.biglobe.ne.jp/~seki/ruby/druby.html]
+#    The dRuby home page, in Japanese.  Contains the full dRuby package
+#    and links to other Japanese-language sources.
+#
+# [http://www2a.biglobe.ne.jp/~seki/ruby/druby.en.html]
+#    The English version of the dRuby home page.
+#
+# [http://pragprog.com/book/sidruby/the-druby-book]
+#    The dRuby Book: Distributed and Parallel Computing with Ruby
+#    by Masatoshi Seki and Makoto Inoue
+#
+# [http://www.ruby-doc.org/docs/ProgrammingRuby/html/ospace.html]
+#   The chapter from *Programming* *Ruby* by Dave Thomas and Andy Hunt
+#   which discusses dRuby.
+#
+# [http://www.clio.ne.jp/home/web-i31s/Flotuard/Ruby/PRC2K_seki/dRuby.en.html]
+#   Translation of presentation on Ruby by Masatoshi Seki.
+
+require 'socket'
+require 'thread'
+require 'fcntl'
+require 'drb/eq'
+
+#
+# == Overview
+#
+# dRuby is a distributed object system for Ruby.  It is written in
+# pure Ruby and uses its own protocol.  No add-in services are needed
+# beyond those provided by the Ruby runtime, such as TCP sockets.  It
+# does not rely on or interoperate with other distributed object
+# systems such as CORBA, RMI, or .NET.
+#
+# dRuby allows methods to be called in one Ruby process upon a Ruby
+# object located in another Ruby process, even on another machine.
+# References to objects can be passed between processes.  Method
+# arguments and return values are dumped and loaded in marshalled
+# format.  All of this is done transparently to both the caller of the
+# remote method and the object that it is called upon.
+#
+# An object in a remote process is locally represented by a
+# DRb::DRbObject instance.  This acts as a sort of proxy for the
+# remote object.  Methods called upon this DRbObject instance are
+# forwarded to its remote object.  This is arranged dynamically at run
+# time.  There are no statically declared interfaces for remote
+# objects, such as CORBA's IDL.
+#
+# dRuby calls made into a process are handled by a DRb::DRbServer
+# instance within that process.  This reconstitutes the method call,
+# invokes it upon the specified local object, and returns the value to
+# the remote caller.  Any object can receive calls over dRuby.  There
+# is no need to implement a special interface, or mixin special
+# functionality.  Nor, in the general case, does an object need to
+# explicitly register itself with a DRbServer in order to receive
+# dRuby calls.
+#
+# One process wishing to make dRuby calls upon another process must
+# somehow obtain an initial reference to an object in the remote
+# process by some means other than as the return value of a remote
+# method call, as there is initially no remote object reference it can
+# invoke a method upon.  This is done by attaching to the server by
+# URI.  Each DRbServer binds itself to a URI such as
+# 'druby://example.com:8787'.  A DRbServer can have an object attached
+# to it that acts as the server's *front* *object*.  A DRbObject can
+# be explicitly created from the server's URI.  This DRbObject's
+# remote object will be the server's front object.  This front object
+# can then return references to other Ruby objects in the DRbServer's
+# process.
+#
+# Method calls made over dRuby behave largely the same as normal Ruby
+# method calls made within a process.  Method calls with blocks are
+# supported, as are raising exceptions.  In addition to a method's
+# standard errors, a dRuby call may also raise one of the
+# dRuby-specific errors, all of which are subclasses of DRb::DRbError.
+#
+# Any type of object can be passed as an argument to a dRuby call or
+# returned as its return value.  By default, such objects are dumped
+# or marshalled at the local end, then loaded or unmarshalled at the
+# remote end.  The remote end therefore receives a copy of the local
+# object, not a distributed reference to it; methods invoked upon this
+# copy are executed entirely in the remote process, not passed on to
+# the local original.  This has semantics similar to pass-by-value.
+#
+# However, if an object cannot be marshalled, a dRuby reference to it
+# is passed or returned instead.  This will turn up at the remote end
+# as a DRbObject instance.  All methods invoked upon this remote proxy
+# are forwarded to the local object, as described in the discussion of
+# DRbObjects.  This has semantics similar to the normal Ruby
+# pass-by-reference.
+#
+# The easiest way to signal that we want an otherwise marshallable
+# object to be passed or returned as a DRbObject reference, rather
+# than marshalled and sent as a copy, is to include the
+# DRb::DRbUndumped mixin module.
+#
+# dRuby supports calling remote methods with blocks.  As blocks (or
+# rather the Proc objects that represent them) are not marshallable,
+# the block executes in the local, not the remote, context.  Each
+# value yielded to the block is passed from the remote object to the
+# local block, then the value returned by each block invocation is
+# passed back to the remote execution context to be collected, before
+# the collected values are finally returned to the local context as
+# the return value of the method invocation.
+#
+# == Examples of usage
+#
+# For more dRuby samples, see the +samples+ directory in the full
+# dRuby distribution.
+#
+# === dRuby in client/server mode
+#
+# This illustrates setting up a simple client-server drb
+# system.  Run the server and client code in different terminals,
+# starting the server code first.
+#
+# ==== Server code
+#
+#   require 'drb/drb'
+#
+#   # The URI for the server to connect to
+#   URI="druby://localhost:8787"
+#
+#   class TimeServer
+#
+#     def get_current_time
+#       return Time.now
+#     end
+#
+#   end
+#
+#   # The object that handles requests on the server
+#   FRONT_OBJECT=TimeServer.new
+#
+#   $SAFE = 1   # disable eval() and friends
+#
+#   DRb.start_service(URI, FRONT_OBJECT)
+#   # Wait for the drb server thread to finish before exiting.
+#   DRb.thread.join
+#
+# ==== Client code
+#
+#   require 'drb/drb'
+#
+#   # The URI to connect to
+#   SERVER_URI="druby://localhost:8787"
+#
+#   # Start a local DRbServer to handle callbacks.
+#   #
+#   # Not necessary for this small example, but will be required
+#   # as soon as we pass a non-marshallable object as an argument
+#   # to a dRuby call.
+#   #
+#   # Note: this must be called at least once per process to take any effect.
+#   # This is particularly important if your application forks.
+#   DRb.start_service
+#
+#   timeserver = DRbObject.new_with_uri(SERVER_URI)
+#   puts timeserver.get_current_time
+#
+# === Remote objects under dRuby
+#
+# This example illustrates returning a reference to an object
+# from a dRuby call.  The Logger instances live in the server
+# process.  References to them are returned to the client process,
+# where methods can be invoked upon them.  These methods are
+# executed in the server process.
+#
+# ==== Server code
+#
+#   require 'drb/drb'
+#
+#   URI="druby://localhost:8787"
+#
+#   class Logger
+#
+#       # Make dRuby send Logger instances as dRuby references,
+#       # not copies.
+#       include DRb::DRbUndumped
+#
+#       def initialize(n, fname)
+#           @name = n
+#           @filename = fname
+#       end
+#
+#       def log(message)
+#           File.open(@filename, "a") do |f|
+#               f.puts("#{Time.now}: #{@name}: #{message}")
+#           end
+#       end
+#
+#   end
+#
+#   # We have a central object for creating and retrieving loggers.
+#   # This retains a local reference to all loggers created.  This
+#   # is so an existing logger can be looked up by name, but also
+#   # to prevent loggers from being garbage collected.  A dRuby
+#   # reference to an object is not sufficient to prevent it being
+#   # garbage collected!
+#   class LoggerFactory
+#
+#       def initialize(bdir)
+#           @basedir = bdir
+#           @loggers = {}
+#       end
+#
+#       def get_logger(name)
+#           if !@loggers.has_key? name
+#               # make the filename safe, then declare it to be so
+#               fname = name.gsub(/[.\/\\\:]/, "_").untaint
+#               @loggers[name] = Logger.new(name, @basedir + "/" + fname)
+#           end
+#           return @loggers[name]
+#       end
+#
+#   end
+#
+#   FRONT_OBJECT=LoggerFactory.new("/tmp/dlog")
+#
+#   $SAFE = 1   # disable eval() and friends
+#
+#   DRb.start_service(URI, FRONT_OBJECT)
+#   DRb.thread.join
+#
+# ==== Client code
+#
+#   require 'drb/drb'
+#
+#   SERVER_URI="druby://localhost:8787"
+#
+#   DRb.start_service
+#
+#   log_service=DRbObject.new_with_uri(SERVER_URI)
+#
+#   ["loga", "logb", "logc"].each do |logname|
+#
+#       logger=log_service.get_logger(logname)
+#
+#       logger.log("Hello, world!")
+#       logger.log("Goodbye, world!")
+#       logger.log("=== EOT ===")
+#
+#   end
+#
+# == Security
+#
+# As with all network services, security needs to be considered when
+# using dRuby.  By allowing external access to a Ruby object, you are
+# not only allowing outside clients to call the methods you have
+# defined for that object, but by default to execute arbitrary Ruby
+# code on your server.  Consider the following:
+#
+#    # !!! UNSAFE CODE !!!
+#    ro = DRbObject::new_with_uri("druby://your.server.com:8989")
+#    class << ro
+#      undef :instance_eval  # force call to be passed to remote object
+#    end
+#    ro.instance_eval("`rm -rf *`")
+#
+# The dangers posed by instance_eval and friends are such that a
+# DRbServer should generally be run with $SAFE set to at least
+# level 1.  This will disable eval() and related calls on strings
+# passed across the wire.  The sample usage code given above follows
+# this practice.
+#
+# A DRbServer can be configured with an access control list to
+# selectively allow or deny access from specified IP addresses.  The
+# main druby distribution provides the ACL class for this purpose.  In
+# general, this mechanism should only be used alongside, rather than
+# as a replacement for, a good firewall.
+#
+# == dRuby internals
+#
+# dRuby is implemented using three main components: a remote method
+# call marshaller/unmarshaller; a transport protocol; and an
+# ID-to-object mapper.  The latter two can be directly, and the first
+# indirectly, replaced, in order to provide different behaviour and
+# capabilities.
+#
+# Marshalling and unmarshalling of remote method calls is performed by
+# a DRb::DRbMessage instance.  This uses the Marshal module to dump
+# the method call before sending it over the transport layer, then
+# reconstitute it at the other end.  There is normally no need to
+# replace this component, and no direct way is provided to do so.
+# However, it is possible to implement an alternative marshalling
+# scheme as part of an implementation of the transport layer.
+#
+# The transport layer is responsible for opening client and server
+# network connections and forwarding dRuby request across them.
+# Normally, it uses DRb::DRbMessage internally to manage marshalling
+# and unmarshalling.  The transport layer is managed by
+# DRb::DRbProtocol.  Multiple protocols can be installed in
+# DRbProtocol at the one time; selection between them is determined by
+# the scheme of a dRuby URI.  The default transport protocol is
+# selected by the scheme 'druby:', and implemented by
+# DRb::DRbTCPSocket.  This uses plain TCP/IP sockets for
+# communication.  An alternative protocol, using UNIX domain sockets,
+# is implemented by DRb::DRbUNIXSocket in the file drb/unix.rb, and
+# selected by the scheme 'drbunix:'.  A sample implementation over
+# HTTP can be found in the samples accompanying the main dRuby
+# distribution.
+#
+# The ID-to-object mapping component maps dRuby object ids to the
+# objects they refer to, and vice versa.  The implementation to use
+# can be specified as part of a DRb::DRbServer's configuration.  The
+# default implementation is provided by DRb::DRbIdConv.  It uses an
+# object's ObjectSpace id as its dRuby id.  This means that the dRuby
+# reference to that object only remains meaningful for the lifetime of
+# the object's process and the lifetime of the object within that
+# process.  A modified implementation is provided by DRb::TimerIdConv
+# in the file drb/timeridconv.rb.  This implementation retains a local
+# reference to all objects exported over dRuby for a configurable
+# period of time (defaulting to ten minutes), to prevent them being
+# garbage-collected within this time.  Another sample implementation
+# is provided in sample/name.rb in the main dRuby distribution.  This
+# allows objects to specify their own id or "name".  A dRuby reference
+# can be made persistent across processes by having each process
+# register an object using the same dRuby name.
+#
+module DRb
+
+  # Superclass of all errors raised in the DRb module.
+  class DRbError < RuntimeError; end
+
+  # Error raised when an error occurs on the underlying communication
+  # protocol.
+  class DRbConnError < DRbError; end
+
+  # Class responsible for converting between an object and its id.
+  #
+  # This, the default implementation, uses an object's local ObjectSpace
+  # __id__ as its id.  This means that an object's identification over
+  # drb remains valid only while that object instance remains alive
+  # within the server runtime.
+  #
+  # For alternative mechanisms, see DRb::TimerIdConv in rdb/timeridconv.rb
+  # and DRbNameIdConv in sample/name.rb in the full drb distribution.
+  class DRbIdConv
+
+    # Convert an object reference id to an object.
+    #
+    # This implementation looks up the reference id in the local object
+    # space and returns the object it refers to.
+    def to_obj(ref)
+      ObjectSpace._id2ref(ref)
+    end
+
+    # Convert an object into a reference id.
+    #
+    # This implementation returns the object's __id__ in the local
+    # object space.
+    def to_id(obj)
+      obj.nil? ? nil : obj.__id__
+    end
+  end
+
+  # Mixin module making an object undumpable or unmarshallable.
+  #
+  # If an object which includes this module is returned by method
+  # called over drb, then the object remains in the server space
+  # and a reference to the object is returned, rather than the
+  # object being marshalled and moved into the client space.
+  module DRbUndumped
+    def _dump(dummy)  # :nodoc:
+      raise TypeError, 'can\'t dump'
+    end
+  end
+
+  # Error raised by the DRb module when an attempt is made to refer to
+  # the context's current drb server but the context does not have one.
+  # See #current_server.
+  class DRbServerNotFound < DRbError; end
+
+  # Error raised by the DRbProtocol module when it cannot find any
+  # protocol implementation support the scheme specified in a URI.
+  class DRbBadURI < DRbError; end
+
+  # Error raised by a dRuby protocol when it doesn't support the
+  # scheme specified in a URI.  See DRb::DRbProtocol.
+  class DRbBadScheme < DRbError; end
+
+  # An exception wrapping a DRb::DRbUnknown object
+  class DRbUnknownError < DRbError
+
+    # Create a new DRbUnknownError for the DRb::DRbUnknown object +unknown+
+    def initialize(unknown)
+      @unknown = unknown
+      super(unknown.name)
+    end
+
+    # Get the wrapped DRb::DRbUnknown object.
+    attr_reader :unknown
+
+    def self._load(s)  # :nodoc:
+      Marshal::load(s)
+    end
+
+    def _dump(lv) # :nodoc:
+      Marshal::dump(@unknown)
+    end
+  end
+
+  # An exception wrapping an error object
+  class DRbRemoteError < DRbError
+
+    # Creates a new remote error that wraps the Exception +error+
+    def initialize(error)
+      @reason = error.class.to_s
+      super("#{error.message} (#{error.class})")
+      set_backtrace(error.backtrace)
+    end
+
+    # the class of the error, as a string.
+    attr_reader :reason
+  end
+
+  # Class wrapping a marshalled object whose type is unknown locally.
+  #
+  # If an object is returned by a method invoked over drb, but the
+  # class of the object is unknown in the client namespace, or
+  # the object is a constant unknown in the client namespace, then
+  # the still-marshalled object is returned wrapped in a DRbUnknown instance.
+  #
+  # If this object is passed as an argument to a method invoked over
+  # drb, then the wrapped object is passed instead.
+  #
+  # The class or constant name of the object can be read from the
+  # +name+ attribute.  The marshalled object is held in the +buf+
+  # attribute.
+  class DRbUnknown
+
+    # Create a new DRbUnknown object.
+    #
+    # +buf+ is a string containing a marshalled object that could not
+    # be unmarshalled.  +err+ is the error message that was raised
+    # when the unmarshalling failed.  It is used to determine the
+    # name of the unmarshalled object.
+    def initialize(err, buf)
+      case err.to_s
+      when /uninitialized constant (\S+)/
+        @name = $1
+      when /undefined class\/module (\S+)/
+        @name = $1
+      else
+        @name = nil
+      end
+      @buf = buf
+    end
+
+    # The name of the unknown thing.
+    #
+    # Class name for unknown objects; variable name for unknown
+    # constants.
+    attr_reader :name
+
+    # Buffer contained the marshalled, unknown object.
+    attr_reader :buf
+
+    def self._load(s) # :nodoc:
+      begin
+        Marshal::load(s)
+      rescue NameError, ArgumentError
+        DRbUnknown.new($!, s)
+      end
+    end
+
+    def _dump(lv) # :nodoc:
+      @buf
+    end
+
+    # Attempt to load the wrapped marshalled object again.
+    #
+    # If the class of the object is now known locally, the object
+    # will be unmarshalled and returned.  Otherwise, a new
+    # but identical DRbUnknown object will be returned.
+    def reload
+      self.class._load(@buf)
+    end
+
+    # Create a DRbUnknownError exception containing this object.
+    def exception
+      DRbUnknownError.new(self)
+    end
+  end
+
+  # An Array wrapper that can be sent to another server via DRb.
+  #
+  # All entries in the array will be dumped or be references that point to
+  # the local server.
+
+  class DRbArray
+
+    # Creates a new DRbArray that either dumps or wraps all the items in the
+    # Array +ary+ so they can be loaded by a remote DRb server.
+
+    def initialize(ary)
+      @ary = ary.collect { |obj|
+        if obj.kind_of? DRbUndumped
+          DRbObject.new(obj)
+        else
+          begin
+            Marshal.dump(obj)
+            obj
+          rescue
+            DRbObject.new(obj)
+          end
+        end
+      }
+    end
+
+    def self._load(s) # :nodoc:
+      Marshal::load(s)
+    end
+
+    def _dump(lv) # :nodoc:
+      Marshal.dump(@ary)
+    end
+  end
+
+  # Handler for sending and receiving drb messages.
+  #
+  # This takes care of the low-level marshalling and unmarshalling
+  # of drb requests and responses sent over the wire between server
+  # and client.  This relieves the implementor of a new drb
+  # protocol layer with having to deal with these details.
+  #
+  # The user does not have to directly deal with this object in
+  # normal use.
+  class DRbMessage
+    def initialize(config) # :nodoc:
+      @load_limit = config[:load_limit]
+      @argc_limit = config[:argc_limit]
+    end
+
+    def dump(obj, error=false)  # :nodoc:
+      obj = make_proxy(obj, error) if obj.kind_of? DRbUndumped
+      begin
+        str = Marshal::dump(obj)
+      rescue
+        str = Marshal::dump(make_proxy(obj, error))
+      end
+      [str.size].pack('N') + str
+    end
+
+    def load(soc)  # :nodoc:
+      begin
+        sz = soc.read(4)        # sizeof (N)
+      rescue
+        raise(DRbConnError, $!.message, $!.backtrace)
+      end
+      raise(DRbConnError, 'connection closed') if sz.nil?
+      raise(DRbConnError, 'premature header') if sz.size < 4
+      sz = sz.unpack('N')[0]
+      raise(DRbConnError, "too large packet #{sz}") if @load_limit < sz
+      begin
+        str = soc.read(sz)
+      rescue
+        raise(DRbConnError, $!.message, $!.backtrace)
+      end
+      raise(DRbConnError, 'connection closed') if str.nil?
+      raise(DRbConnError, 'premature marshal format(can\'t read)') if str.size < sz
+      DRb.mutex.synchronize do
+        begin
+          save = Thread.current[:drb_untaint]
+          Thread.current[:drb_untaint] = []
+          Marshal::load(str)
+        rescue NameError, ArgumentError
+          DRbUnknown.new($!, str)
+        ensure
+          Thread.current[:drb_untaint].each do |x|
+            x.untaint
+          end
+          Thread.current[:drb_untaint] = save
+        end
+      end
+    end
+
+    def send_request(stream, ref, msg_id, arg, b) # :nodoc:
+      ary = []
+      ary.push(dump(ref.__drbref))
+      ary.push(dump(msg_id.id2name))
+      ary.push(dump(arg.length))
+      arg.each do |e|
+        ary.push(dump(e))
+      end
+      ary.push(dump(b))
+      stream.write(ary.join(''))
+    rescue
+      raise(DRbConnError, $!.message, $!.backtrace)
+    end
+
+    def recv_request(stream) # :nodoc:
+      ref = load(stream)
+      ro = DRb.to_obj(ref)
+      msg = load(stream)
+      argc = load(stream)
+      raise(DRbConnError, "too many arguments") if @argc_limit < argc
+      argv = Array.new(argc, nil)
+      argc.times do |n|
+        argv[n] = load(stream)
+      end
+      block = load(stream)
+      return ro, msg, argv, block
+    end
+
+    def send_reply(stream, succ, result)  # :nodoc:
+      stream.write(dump(succ) + dump(result, !succ))
+    rescue
+      raise(DRbConnError, $!.message, $!.backtrace)
+    end
+
+    def recv_reply(stream)  # :nodoc:
+      succ = load(stream)
+      result = load(stream)
+      [succ, result]
+    end
+
+    private
+    def make_proxy(obj, error=false) # :nodoc:
+      if error
+        DRbRemoteError.new(obj)
+      else
+        DRbObject.new(obj)
+      end
+    end
+  end
+
+  # Module managing the underlying network protocol(s) used by drb.
+  #
+  # By default, drb uses the DRbTCPSocket protocol.  Other protocols
+  # can be defined.  A protocol must define the following class methods:
+  #
+  #   [open(uri, config)] Open a client connection to the server at +uri+,
+  #                       using configuration +config+.  Return a protocol
+  #                       instance for this connection.
+  #   [open_server(uri, config)] Open a server listening at +uri+,
+  #                              using configuration +config+.  Return a
+  #                              protocol instance for this listener.
+  #   [uri_option(uri, config)] Take a URI, possibly containing an option
+  #                             component (e.g. a trailing '?param=val'),
+  #                             and return a [uri, option] tuple.
+  #
+  # All of these methods should raise a DRbBadScheme error if the URI
+  # does not identify the protocol they support (e.g. "druby:" for
+  # the standard Ruby protocol).  This is how the DRbProtocol module,
+  # given a URI, determines which protocol implementation serves that
+  # protocol.
+  #
+  # The protocol instance returned by #open_server must have the
+  # following methods:
+  #
+  # [accept] Accept a new connection to the server.  Returns a protocol
+  #          instance capable of communicating with the client.
+  # [close] Close the server connection.
+  # [uri] Get the URI for this server.
+  #
+  # The protocol instance returned by #open must have the following methods:
+  #
+  # [send_request (ref, msg_id, arg, b)]
+  #      Send a request to +ref+ with the given message id and arguments.
+  #      This is most easily implemented by calling DRbMessage.send_request,
+  #      providing a stream that sits on top of the current protocol.
+  # [recv_reply]
+  #      Receive a reply from the server and return it as a [success-boolean,
+  #      reply-value] pair.  This is most easily implemented by calling
+  #      DRb.recv_reply, providing a stream that sits on top of the
+  #      current protocol.
+  # [alive?]
+  #      Is this connection still alive?
+  # [close]
+  #      Close this connection.
+  #
+  # The protocol instance returned by #open_server().accept() must have
+  # the following methods:
+  #
+  # [recv_request]
+  #     Receive a request from the client and return a [object, message,
+  #     args, block] tuple.  This is most easily implemented by calling
+  #     DRbMessage.recv_request, providing a stream that sits on top of
+  #     the current protocol.
+  # [send_reply(succ, result)]
+  #     Send a reply to the client.  This is most easily implemented
+  #     by calling DRbMessage.send_reply, providing a stream that sits
+  #     on top of the current protocol.
+  # [close]
+  #     Close this connection.
+  #
+  # A new protocol is registered with the DRbProtocol module using
+  # the add_protocol method.
+  #
+  # For examples of other protocols, see DRbUNIXSocket in drb/unix.rb,
+  # and HTTP0 in sample/http0.rb and sample/http0serv.rb in the full
+  # drb distribution.
+  module DRbProtocol
+
+    # Add a new protocol to the DRbProtocol module.
+    def add_protocol(prot)
+      @protocol.push(prot)
+    end
+    module_function :add_protocol
+
+    # Open a client connection to +uri+ with the configuration +config+.
+    #
+    # The DRbProtocol module asks each registered protocol in turn to
+    # try to open the URI.  Each protocol signals that it does not handle that
+    # URI by raising a DRbBadScheme error.  If no protocol recognises the
+    # URI, then a DRbBadURI error is raised.  If a protocol accepts the
+    # URI, but an error occurs in opening it, a DRbConnError is raised.
+    def open(uri, config, first=true)
+      @protocol.each do |prot|
+        begin
+          return prot.open(uri, config)
+        rescue DRbBadScheme
+        rescue DRbConnError
+          raise($!)
+        rescue
+          raise(DRbConnError, "#{uri} - #{$!.inspect}")
+        end
+      end
+      if first && (config[:auto_load] != false)
+        auto_load(uri, config)
+        return open(uri, config, false)
+      end
+      raise DRbBadURI, 'can\'t parse uri:' + uri
+    end
+    module_function :open
+
+    # Open a server listening for connections at +uri+ with
+    # configuration +config+.
+    #
+    # The DRbProtocol module asks each registered protocol in turn to
+    # try to open a server at the URI.  Each protocol signals that it does
+    # not handle that URI by raising a DRbBadScheme error.  If no protocol
+    # recognises the URI, then a DRbBadURI error is raised.  If a protocol
+    # accepts the URI, but an error occurs in opening it, the underlying
+    # error is passed on to the caller.
+    def open_server(uri, config, first=true)
+      @protocol.each do |prot|
+        begin
+          return prot.open_server(uri, config)
+        rescue DRbBadScheme
+        end
+      end
+      if first && (config[:auto_load] != false)
+        auto_load(uri, config)
+        return open_server(uri, config, false)
+      end
+      raise DRbBadURI, 'can\'t parse uri:' + uri
+    end
+    module_function :open_server
+
+    # Parse +uri+ into a [uri, option] pair.
+    #
+    # The DRbProtocol module asks each registered protocol in turn to
+    # try to parse the URI.  Each protocol signals that it does not handle that
+    # URI by raising a DRbBadScheme error.  If no protocol recognises the
+    # URI, then a DRbBadURI error is raised.
+    def uri_option(uri, config, first=true)
+      @protocol.each do |prot|
+        begin
+          uri, opt = prot.uri_option(uri, config)
+          # opt = nil if opt == ''
+          return uri, opt
+        rescue DRbBadScheme
+        end
+      end
+      if first && (config[:auto_load] != false)
+        auto_load(uri, config)
+        return uri_option(uri, config, false)
+      end
+      raise DRbBadURI, 'can\'t parse uri:' + uri
+    end
+    module_function :uri_option
+
+    def auto_load(uri, config)  # :nodoc:
+      if uri =~ /^drb([a-z0-9]+):/
+        require("drb/#{$1}") rescue nil
+      end
+    end
+    module_function :auto_load
+  end
+
+  # The default drb protocol which communicates over a TCP socket.
+  #
+  # The DRb TCP protocol URI looks like:
+  # <code>druby://<host>:<port>?<option></code>.  The option is optional.
+
+  class DRbTCPSocket
+    # :stopdoc:
+    private
+    def self.parse_uri(uri)
+      if uri =~ /^druby:\/\/(.*?):(\d+)(\?(.*))?$/
+        host = $1
+        port = $2.to_i
+        option = $4
+        [host, port, option]
+      else
+        raise(DRbBadScheme, uri) unless uri =~ /^druby:/
+        raise(DRbBadURI, 'can\'t parse uri:' + uri)
+      end
+    end
+
+    public
+
+    # Open a client connection to +uri+ (DRb URI string) using configuration
+    # +config+.
+    #
+    # This can raise DRb::DRbBadScheme or DRb::DRbBadURI if +uri+ is not for a
+    # recognized protocol.  See DRb::DRbServer.new for information on built-in
+    # URI protocols.
+    def self.open(uri, config)
+      host, port, = parse_uri(uri)
+      host.untaint
+      port.untaint
+      soc = TCPSocket.open(host, port)
+      self.new(uri, soc, config)
+    end
+
+    # Returns the hostname of this server
+    def self.getservername
+      host = Socket::gethostname
+      begin
+        Socket::gethostbyname(host)[0]
+      rescue
+        'localhost'
+      end
+    end
+
+    # For the families available for +host+, returns a TCPServer on +port+.
+    # If +port+ is 0 the first available port is used.  IPv4 servers are
+    # preferred over IPv6 servers.
+    def self.open_server_inaddr_any(host, port)
+      infos = Socket::getaddrinfo(host, nil,
+                                  Socket::AF_UNSPEC,
+                                  Socket::SOCK_STREAM,
+                                  0,
+                                  Socket::AI_PASSIVE)
+      families = Hash[*infos.collect { |af, *_| af }.uniq.zip([]).flatten]
+      return TCPServer.open('0.0.0.0', port) if families.has_key?('AF_INET')
+      return TCPServer.open('::', port) if families.has_key?('AF_INET6')
+      return TCPServer.open(port)
+      # :stopdoc:
+    end
+
+    # Open a server listening for connections at +uri+ using
+    # configuration +config+.
+    def self.open_server(uri, config)
+      uri = 'druby://:0' unless uri
+      host, port, _ = parse_uri(uri)
+      config = {:tcp_original_host => host}.update(config)
+      if host.size == 0
+        host = getservername
+        soc = open_server_inaddr_any(host, port)
+      else
+        soc = TCPServer.open(host, port)
+      end
+      port = soc.addr[1] if port == 0
+      config[:tcp_port] = port
+      uri = "druby://#{host}:#{port}"
+      self.new(uri, soc, config)
+    end
+
+    # Parse +uri+ into a [uri, option] pair.
+    def self.uri_option(uri, config)
+      host, port, option = parse_uri(uri)
+      return "druby://#{host}:#{port}", option
+    end
+
+    # Create a new DRbTCPSocket instance.
+    #
+    # +uri+ is the URI we are connected to.
+    # +soc+ is the tcp socket we are bound to.  +config+ is our
+    # configuration.
+    def initialize(uri, soc, config={})
+      @uri = uri
+      @socket = soc
+      @config = config
+      @acl = config[:tcp_acl]
+      @msg = DRbMessage.new(config)
+      set_sockopt(@socket)
+      @shutdown_pipe_r, @shutdown_pipe_w = IO.pipe
+    end
+
+    # Get the URI that we are connected to.
+    attr_reader :uri
+
+    # Get the address of our TCP peer (the other end of the socket
+    # we are bound to.
+    def peeraddr
+      @socket.peeraddr
+    end
+
+    # Get the socket.
+    def stream; @socket; end
+
+    # On the client side, send a request to the server.
+    def send_request(ref, msg_id, arg, b)
+      @msg.send_request(stream, ref, msg_id, arg, b)
+    end
+
+    # On the server side, receive a request from the client.
+    def recv_request
+      @msg.recv_request(stream)
+    end
+
+    # On the server side, send a reply to the client.
+    def send_reply(succ, result)
+      @msg.send_reply(stream, succ, result)
+    end
+
+    # On the client side, receive a reply from the server.
+    def recv_reply
+      @msg.recv_reply(stream)
+    end
+
+    public
+
+    # Close the connection.
+    #
+    # If this is an instance returned by #open_server, then this stops
+    # listening for new connections altogether.  If this is an instance
+    # returned by #open or by #accept, then it closes this particular
+    # client-server session.
+    def close
+      if @socket
+        @socket.close
+        @socket = nil
+      end
+      close_shutdown_pipe
+    end
+
+    def close_shutdown_pipe
+      if @shutdown_pipe_r && !@shutdown_pipe_r.closed?
+        @shutdown_pipe_r.close
+        @shutdown_pipe_r = nil
+      end
+      if @shutdown_pipe_w && !@shutdown_pipe_w.closed?
+        @shutdown_pipe_w.close
+        @shutdown_pipe_w = nil
+      end
+    end
+    private :close_shutdown_pipe
+
+    # On the server side, for an instance returned by #open_server,
+    # accept a client connection and return a new instance to handle
+    # the server's side of this client-server session.
+    def accept
+      while true
+        s = accept_or_shutdown
+        return nil unless s
+        break if (@acl ? @acl.allow_socket?(s) : true)
+        s.close
+      end
+      if @config[:tcp_original_host].to_s.size == 0
+        uri = "druby://#{s.addr[3]}:#{@config[:tcp_port]}"
+      else
+        uri = @uri
+      end
+      self.class.new(uri, s, @config)
+    end
+
+    def accept_or_shutdown
+      readables, = IO.select([@socket, @shutdown_pipe_r])
+      if readables.include? @shutdown_pipe_r
+        return nil
+      end
+      @socket.accept
+    end
+    private :accept_or_shutdown
+
+    # Graceful shutdown
+    def shutdown
+      @shutdown_pipe_w.close if @shutdown_pipe_w && !@shutdown_pipe_w.closed?
+    end
+
+    # Check to see if this connection is alive.
+    def alive?
+      return false unless @socket
+      if IO.select([@socket], nil, nil, 0)
+        close
+        return false
+      end
+      true
+    end
+
+    def set_sockopt(soc) # :nodoc:
+      soc.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
+      soc.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::FD_CLOEXEC
+    end
+  end
+
+  module DRbProtocol
+    @protocol = [DRbTCPSocket] # default
+  end
+
+  class DRbURIOption  # :nodoc:  I don't understand the purpose of this class...
+    def initialize(option)
+      @option = option.to_s
+    end
+    attr_reader :option
+    def to_s; @option; end
+
+    def ==(other)
+      return false unless DRbURIOption === other
+      @option == other.option
+    end
+
+    def hash
+      @option.hash
+    end
+
+    alias eql? ==
+  end
+
+  # Object wrapping a reference to a remote drb object.
+  #
+  # Method calls on this object are relayed to the remote
+  # object that this object is a stub for.
+  class DRbObject
+
+    # Unmarshall a marshalled DRbObject.
+    #
+    # If the referenced object is located within the local server, then
+    # the object itself is returned.  Otherwise, a new DRbObject is
+    # created to act as a stub for the remote referenced object.
+    def self._load(s)
+      uri, ref = Marshal.load(s)
+
+      if DRb.here?(uri)
+        obj = DRb.to_obj(ref)
+        if ((! obj.tainted?) && Thread.current[:drb_untaint])
+          Thread.current[:drb_untaint].push(obj)
+        end
+        return obj
+      end
+
+      self.new_with(uri, ref)
+    end
+
+    # Creates a DRb::DRbObject given the reference information to the remote
+    # host +uri+ and object +ref+.
+
+    def self.new_with(uri, ref)
+      it = self.allocate
+      it.instance_variable_set(:@uri, uri)
+      it.instance_variable_set(:@ref, ref)
+      it
+    end
+
+    # Create a new DRbObject from a URI alone.
+    def self.new_with_uri(uri)
+      self.new(nil, uri)
+    end
+
+    # Marshall this object.
+    #
+    # The URI and ref of the object are marshalled.
+    def _dump(lv)
+      Marshal.dump([@uri, @ref])
+    end
+
+    # Create a new remote object stub.
+    #
+    # +obj+ is the (local) object we want to create a stub for.  Normally
+    # this is +nil+.  +uri+ is the URI of the remote object that this
+    # will be a stub for.
+    def initialize(obj, uri=nil)
+      @uri = nil
+      @ref = nil
+      if obj.nil?
+        return if uri.nil?
+        @uri, option = DRbProtocol.uri_option(uri, DRb.config)
+        @ref = DRbURIOption.new(option) unless option.nil?
+      else
+        @uri = uri ? uri : (DRb.uri rescue nil)
+        @ref = obj ? DRb.to_id(obj) : nil
+      end
+    end
+
+    # Get the URI of the remote object.
+    def __drburi
+      @uri
+    end
+
+    # Get the reference of the object, if local.
+    def __drbref
+      @ref
+    end
+
+    undef :to_s
+    undef :to_a if respond_to?(:to_a)
+
+    # Routes respond_to? to the referenced remote object.
+    def respond_to?(msg_id, priv=false)
+      case msg_id
+      when :_dump
+        true
+      when :marshal_dump
+        false
+      else
+        method_missing(:respond_to?, msg_id, priv)
+      end
+    end
+
+    # Routes method calls to the referenced remote object.
+    def method_missing(msg_id, *a, &b)
+      if DRb.here?(@uri)
+        obj = DRb.to_obj(@ref)
+        DRb.current_server.check_insecure_method(obj, msg_id)
+        return obj.__send__(msg_id, *a, &b)
+      end
+
+      succ, result = self.class.with_friend(@uri) do
+        DRbConn.open(@uri) do |conn|
+          conn.send_message(self, msg_id, a, b)
+        end
+      end
+
+      if succ
+        return result
+      elsif DRbUnknown === result
+        raise result
+      else
+        bt = self.class.prepare_backtrace(@uri, result)
+        result.set_backtrace(bt + caller)
+        raise result
+      end
+    end
+
+    # Given the +uri+ of another host executes the block provided.
+    def self.with_friend(uri) # :nodoc:
+      friend = DRb.fetch_server(uri)
+      return yield() unless friend
+
+      save = Thread.current['DRb']
+      Thread.current['DRb'] = { 'server' => friend }
+      return yield
+    ensure
+      Thread.current['DRb'] = save if friend
+    end
+
+    # Returns a modified backtrace from +result+ with the +uri+ where each call
+    # in the backtrace came from.
+    def self.prepare_backtrace(uri, result) # :nodoc:
+      prefix = "(#{uri}) "
+      bt = []
+      result.backtrace.each do |x|
+        break if /`__send__'$/ =~ x
+        if /^\(druby:\/\// =~ x
+          bt.push(x)
+        else
+          bt.push(prefix + x)
+        end
+      end
+      bt
+    end
+
+    def pretty_print(q)   # :nodoc:
+      q.pp_object(self)
+    end
+
+    def pretty_print_cycle(q)   # :nodoc:
+      q.object_address_group(self) {
+        q.breakable
+        q.text '...'
+      }
+    end
+  end
+
+  # Class handling the connection between a DRbObject and the
+  # server the real object lives on.
+  #
+  # This class maintains a pool of connections, to reduce the
+  # overhead of starting and closing down connections for each
+  # method call.
+  #
+  # This class is used internally by DRbObject.  The user does
+  # not normally need to deal with it directly.
+  class DRbConn
+    POOL_SIZE = 16  # :nodoc:
+    @mutex = Mutex.new
+    @pool = []
+
+    def self.open(remote_uri)  # :nodoc:
+      begin
+        conn = nil
+
+        @mutex.synchronize do
+          #FIXME
+          new_pool = []
+          @pool.each do |c|
+            if conn.nil? and c.uri == remote_uri
+              conn = c if c.alive?
+            else
+              new_pool.push c
+            end
+          end
+          @pool = new_pool
+        end
+
+        conn = self.new(remote_uri) unless conn
+        succ, result = yield(conn)
+        return succ, result
+
+      ensure
+        if conn
+          if succ
+            @mutex.synchronize do
+              @pool.unshift(conn)
+              @pool.pop.close while @pool.size > POOL_SIZE
+            end
+          else
+            conn.close
+          end
+        end
+      end
+    end
+
+    def initialize(remote_uri)  # :nodoc:
+      @uri = remote_uri
+      @protocol = DRbProtocol.open(remote_uri, DRb.config)
+    end
+    attr_reader :uri  # :nodoc:
+
+    def send_message(ref, msg_id, arg, block)  # :nodoc:
+      @protocol.send_request(ref, msg_id, arg, block)
+      @protocol.recv_reply
+    end
+
+    def close  # :nodoc:
+      @protocol.close
+      @protocol = nil
+    end
+
+    def alive?  # :nodoc:
+      return false unless @protocol
+      @protocol.alive?
+    end
+  end
+
+  # Class representing a drb server instance.
+  #
+  # A DRbServer must be running in the local process before any incoming
+  # dRuby calls can be accepted, or any local objects can be passed as
+  # dRuby references to remote processes, even if those local objects are
+  # never actually called remotely. You do not need to start a DRbServer
+  # in the local process if you are only making outgoing dRuby calls
+  # passing marshalled parameters.
+  #
+  # Unless multiple servers are being used, the local DRbServer is normally
+  # started by calling DRb.start_service.
+  class DRbServer
+    @@acl = nil
+    @@idconv = DRbIdConv.new
+    @@secondary_server = nil
+    @@argc_limit = 256
+    @@load_limit = 256 * 102400
+    @@verbose = false
+    @@safe_level = 0
+
+    # Set the default value for the :argc_limit option.
+    #
+    # See #new().  The initial default value is 256.
+    def self.default_argc_limit(argc)
+      @@argc_limit = argc
+    end
+
+    # Set the default value for the :load_limit option.
+    #
+    # See #new().  The initial default value is 25 MB.
+    def self.default_load_limit(sz)
+      @@load_limit = sz
+    end
+
+    # Set the default access control list to +acl+.  The default ACL is +nil+.
+    #
+    # See also DRb::ACL and #new()
+    def self.default_acl(acl)
+      @@acl = acl
+    end
+
+    # Set the default value for the :id_conv option.
+    #
+    # See #new().  The initial default value is a DRbIdConv instance.
+    def self.default_id_conv(idconv)
+      @@idconv = idconv
+    end
+
+    # Set the default safe level to +level+.  The default safe level is 0
+    #
+    # See #new for more information.
+    def self.default_safe_level(level)
+      @@safe_level = level
+    end
+
+    # Set the default value of the :verbose option.
+    #
+    # See #new().  The initial default value is false.
+    def self.verbose=(on)
+      @@verbose = on
+    end
+
+    # Get the default value of the :verbose option.
+    def self.verbose
+      @@verbose
+    end
+
+    def self.make_config(hash={})  # :nodoc:
+      default_config = {
+        :idconv => @@idconv,
+        :verbose => @@verbose,
+        :tcp_acl => @@acl,
+        :load_limit => @@load_limit,
+        :argc_limit => @@argc_limit,
+        :safe_level => @@safe_level
+      }
+      default_config.update(hash)
+    end
+
+    # Create a new DRbServer instance.
+    #
+    # +uri+ is the URI to bind to.  This is normally of the form
+    # 'druby://<hostname>:<port>' where <hostname> is a hostname of
+    # the local machine.  If nil, then the system's default hostname
+    # will be bound to, on a port selected by the system; these value
+    # can be retrieved from the +uri+ attribute.  'druby:' specifies
+    # the default dRuby transport protocol: another protocol, such
+    # as 'drbunix:', can be specified instead.
+    #
+    # +front+ is the front object for the server, that is, the object
+    # to which remote method calls on the server will be passed.  If
+    # nil, then the server will not accept remote method calls.
+    #
+    # If +config_or_acl+ is a hash, it is the configuration to
+    # use for this server.  The following options are recognised:
+    #
+    # :idconv :: an id-to-object conversion object.  This defaults
+    #            to an instance of the class DRb::DRbIdConv.
+    # :verbose :: if true, all unsuccessful remote calls on objects
+    #             in the server will be logged to $stdout. false
+    #             by default.
+    # :tcp_acl :: the access control list for this server.  See
+    #             the ACL class from the main dRuby distribution.
+    # :load_limit :: the maximum message size in bytes accepted by
+    #                the server.  Defaults to 25 MB (26214400).
+    # :argc_limit :: the maximum number of arguments to a remote
+    #                method accepted by the server.  Defaults to
+    #                256.
+    # :safe_level :: The safe level of the DRbServer.  The attribute
+    #                sets $SAFE for methods performed in the main_loop.
+    #                Defaults to 0.
+    #
+    # The default values of these options can be modified on
+    # a class-wide basis by the class methods #default_argc_limit,
+    # #default_load_limit, #default_acl, #default_id_conv,
+    # and #verbose=
+    #
+    # If +config_or_acl+ is not a hash, but is not nil, it is
+    # assumed to be the access control list for this server.
+    # See the :tcp_acl option for more details.
+    #
+    # If no other server is currently set as the primary server,
+    # this will become the primary server.
+    #
+    # The server will immediately start running in its own thread.
+    def initialize(uri=nil, front=nil, config_or_acl=nil)
+      if Hash === config_or_acl
+        config = config_or_acl.dup
+      else
+        acl = config_or_acl || @@acl
+        config = {
+          :tcp_acl => acl
+        }
+      end
+
+      @config = self.class.make_config(config)
+
+      @protocol = DRbProtocol.open_server(uri, @config)
+      @uri = @protocol.uri
+      @exported_uri = [@uri]
+
+      @front = front
+      @idconv = @config[:idconv]
+      @safe_level = @config[:safe_level]
+
+      @grp = ThreadGroup.new
+      @thread = run
+
+      DRb.regist_server(self)
+    end
+
+    # The URI of this DRbServer.
+    attr_reader :uri
+
+    # The main thread of this DRbServer.
+    #
+    # This is the thread that listens for and accepts connections
+    # from clients, not that handles each client's request-response
+    # session.
+    attr_reader :thread
+
+    # The front object of the DRbServer.
+    #
+    # This object receives remote method calls made on the server's
+    # URI alone, with an object id.
+    attr_reader :front
+
+    # The configuration of this DRbServer
+    attr_reader :config
+
+    # The safe level for this server.  This is a number corresponding to
+    # $SAFE.
+    #
+    # The default safe_level is 0
+    attr_reader :safe_level
+
+    # Set whether to operate in verbose mode.
+    #
+    # In verbose mode, failed calls are logged to stdout.
+    def verbose=(v); @config[:verbose]=v; end
+
+    # Get whether the server is in verbose mode.
+    #
+    # In verbose mode, failed calls are logged to stdout.
+    def verbose; @config[:verbose]; end
+
+    # Is this server alive?
+    def alive?
+      @thread.alive?
+    end
+
+    # Is +uri+ the URI for this server?
+    def here?(uri)
+      @exported_uri.include?(uri)
+    end
+
+    # Stop this server.
+    def stop_service
+      DRb.remove_server(self)
+      if  Thread.current['DRb'] && Thread.current['DRb']['server'] == self
+        Thread.current['DRb']['stop_service'] = true
+      else
+        if @protocol.respond_to? :shutdown
+          @protocol.shutdown
+        else
+          @thread.kill # xxx: Thread#kill
+        end
+        @thread.join
+      end
+    end
+
+    # Convert a dRuby reference to the local object it refers to.
+    def to_obj(ref)
+      return front if ref.nil?
+      return front[ref.to_s] if DRbURIOption === ref
+      @idconv.to_obj(ref)
+    end
+
+    # Convert a local object to a dRuby reference.
+    def to_id(obj)
+      return nil if obj.__id__ == front.__id__
+      @idconv.to_id(obj)
+    end
+
+    private
+
+    ##
+    # Starts the DRb main loop in a new thread.
+
+    def run
+      Thread.start do
+        begin
+          while main_loop
+          end
+        ensure
+          @protocol.close if @protocol
+        end
+      end
+    end
+
+    # List of insecure methods.
+    #
+    # These methods are not callable via dRuby.
+    INSECURE_METHOD = [
+      :__send__
+    ]
+
+    # Has a method been included in the list of insecure methods?
+    def insecure_method?(msg_id)
+      INSECURE_METHOD.include?(msg_id)
+    end
+
+    # Coerce an object to a string, providing our own representation if
+    # to_s is not defined for the object.
+    def any_to_s(obj)
+      obj.to_s + ":#{obj.class}"
+    rescue
+      sprintf("#<%s:0x%lx>", obj.class, obj.__id__)
+    end
+
+    # Check that a method is callable via dRuby.
+    #
+    # +obj+ is the object we want to invoke the method on. +msg_id+ is the
+    # method name, as a Symbol.
+    #
+    # If the method is an insecure method (see #insecure_method?) a
+    # SecurityError is thrown.  If the method is private or undefined,
+    # a NameError is thrown.
+    def check_insecure_method(obj, msg_id)
+      return true if Proc === obj && msg_id == :__drb_yield
+      raise(ArgumentError, "#{any_to_s(msg_id)} is not a symbol") unless Symbol == msg_id.class
+      raise(SecurityError, "insecure method `#{msg_id}'") if insecure_method?(msg_id)
+
+      if obj.private_methods.include?(msg_id)
+        desc = any_to_s(obj)
+        raise NoMethodError, "private method `#{msg_id}' called for #{desc}"
+      elsif obj.protected_methods.include?(msg_id)
+        desc = any_to_s(obj)
+        raise NoMethodError, "protected method `#{msg_id}' called for #{desc}"
+      else
+        true
+      end
+    end
+    public :check_insecure_method
+
+    class InvokeMethod  # :nodoc:
+      def initialize(drb_server, client)
+        @drb_server = drb_server
+        @safe_level = drb_server.safe_level
+        @client = client
+      end
+
+      def perform
+        @result = nil
+        @succ = false
+        setup_message
+
+        if $SAFE < @safe_level
+          info = Thread.current['DRb']
+          if @block
+            @result = Thread.new {
+              Thread.current['DRb'] = info
+              $SAFE = @safe_level
+              perform_with_block
+            }.value
+          else
+            @result = Thread.new {
+              Thread.current['DRb'] = info
+              $SAFE = @safe_level
+              perform_without_block
+            }.value
+          end
+        else
+          if @block
+            @result = perform_with_block
+          else
+            @result = perform_without_block
+          end
+        end
+        @succ = true
+        if @msg_id == :to_ary && @result.class == Array
+          @result = DRbArray.new(@result)
+        end
+        return @succ, @result
+      rescue StandardError, ScriptError, Interrupt
+        @result = $!
+        return @succ, @result
+      end
+
+      private
+      def init_with_client
+        obj, msg, argv, block = @client.recv_request
+        @obj = obj
+        @msg_id = msg.intern
+        @argv = argv
+        @block = block
+      end
+
+      def check_insecure_method
+        @drb_server.check_insecure_method(@obj, @msg_id)
+      end
+
+      def setup_message
+        init_with_client
+        check_insecure_method
+      end
+
+      def perform_without_block
+        if Proc === @obj && @msg_id == :__drb_yield
+          if @argv.size == 1
+            ary = @argv
+          else
+            ary = [@argv]
+          end
+          ary.collect(&@obj)[0]
+        else
+          @obj.__send__(@msg_id, *@argv)
+        end
+      end
+
+    end
+
+    require 'drb/invokemethod'
+    class InvokeMethod
+      include InvokeMethod18Mixin
+    end
+
+    # The main loop performed by a DRbServer's internal thread.
+    #
+    # Accepts a connection from a client, and starts up its own
+    # thread to handle it.  This thread loops, receiving requests
+    # from the client, invoking them on a local object, and
+    # returning responses, until the client closes the connection
+    # or a local method call fails.
+    def main_loop
+      client0 = @protocol.accept
+      return nil if !client0
+      Thread.start(client0) do |client|
+        @grp.add Thread.current
+        Thread.current['DRb'] = { 'client' => client ,
+                                  'server' => self }
+        DRb.mutex.synchronize do
+          client_uri = client.uri
+          @exported_uri << client_uri unless @exported_uri.include?(client_uri)
+        end
+        loop do
+          begin
+            succ = false
+            invoke_method = InvokeMethod.new(self, client)
+            succ, result = invoke_method.perform
+            if !succ && verbose
+              p result
+              result.backtrace.each do |x|
+                puts x
+              end
+            end
+            client.send_reply(succ, result) rescue nil
+          ensure
+            client.close unless succ
+            if Thread.current['DRb']['stop_service']
+              Thread.new { stop_service }
+            end
+            break unless succ
+          end
+        end
+      end
+    end
+  end
+
+  @primary_server = nil
+
+  # Start a dRuby server locally.
+  #
+  # The new dRuby server will become the primary server, even
+  # if another server is currently the primary server.
+  #
+  # +uri+ is the URI for the server to bind to.  If nil,
+  # the server will bind to random port on the default local host
+  # name and use the default dRuby protocol.
+  #
+  # +front+ is the server's front object.  This may be nil.
+  #
+  # +config+ is the configuration for the new server.  This may
+  # be nil.
+  #
+  # See DRbServer::new.
+  def start_service(uri=nil, front=nil, config=nil)
+    @primary_server = DRbServer.new(uri, front, config)
+  end
+  module_function :start_service
+
+  # The primary local dRuby server.
+  #
+  # This is the server created by the #start_service call.
+  attr_accessor :primary_server
+  module_function :primary_server=, :primary_server
+
+  # Get the 'current' server.
+  #
+  # In the context of execution taking place within the main
+  # thread of a dRuby server (typically, as a result of a remote
+  # call on the server or one of its objects), the current
+  # server is that server.  Otherwise, the current server is
+  # the primary server.
+  #
+  # If the above rule fails to find a server, a DRbServerNotFound
+  # error is raised.
+  def current_server
+    drb = Thread.current['DRb']
+    server = (drb && drb['server']) ? drb['server'] : @primary_server
+    raise DRbServerNotFound unless server
+    return server
+  end
+  module_function :current_server
+
+  # Stop the local dRuby server.
+  #
+  # This operates on the primary server.  If there is no primary
+  # server currently running, it is a noop.
+  def stop_service
+    @primary_server.stop_service if @primary_server
+    @primary_server = nil
+  end
+  module_function :stop_service
+
+  # Get the URI defining the local dRuby space.
+  #
+  # This is the URI of the current server.  See #current_server.
+  def uri
+    drb = Thread.current['DRb']
+    client = (drb && drb['client'])
+    if client
+      uri = client.uri
+      return uri if uri
+    end
+    current_server.uri
+  end
+  module_function :uri
+
+  # Is +uri+ the URI for the current local server?
+  def here?(uri)
+    current_server.here?(uri) rescue false
+    # (current_server.uri rescue nil) == uri
+  end
+  module_function :here?
+
+  # Get the configuration of the current server.
+  #
+  # If there is no current server, this returns the default configuration.
+  # See #current_server and DRbServer::make_config.
+  def config
+    current_server.config
+  rescue
+    DRbServer.make_config
+  end
+  module_function :config
+
+  # Get the front object of the current server.
+  #
+  # This raises a DRbServerNotFound error if there is no current server.
+  # See #current_server.
+  def front
+    current_server.front
+  end
+  module_function :front
+
+  # Convert a reference into an object using the current server.
+  #
+  # This raises a DRbServerNotFound error if there is no current server.
+  # See #current_server.
+  def to_obj(ref)
+    current_server.to_obj(ref)
+  end
+
+  # Get a reference id for an object using the current server.
+  #
+  # This raises a DRbServerNotFound error if there is no current server.
+  # See #current_server.
+  def to_id(obj)
+    current_server.to_id(obj)
+  end
+  module_function :to_id
+  module_function :to_obj
+
+  # Get the thread of the primary server.
+  #
+  # This returns nil if there is no primary server.  See #primary_server.
+  def thread
+    @primary_server ? @primary_server.thread : nil
+  end
+  module_function :thread
+
+  # Set the default id conversion object.
+  #
+  # This is expected to be an instance such as DRb::DRbIdConv that responds to
+  # #to_id and #to_obj that can convert objects to and from DRb references.
+  #
+  # See DRbServer#default_id_conv.
+  def install_id_conv(idconv)
+    DRbServer.default_id_conv(idconv)
+  end
+  module_function :install_id_conv
+
+  # Set the default ACL to +acl+.
+  #
+  # See DRb::DRbServer.default_acl.
+  def install_acl(acl)
+    DRbServer.default_acl(acl)
+  end
+  module_function :install_acl
+
+  @mutex = Mutex.new
+  def mutex # :nodoc:
+    @mutex
+  end
+  module_function :mutex
+
+  @server = {}
+  # Registers +server+ with DRb.
+  #
+  # This is called when a new DRb::DRbServer is created.
+  #
+  # If there is no primary server then +server+ becomes the primary server.
+  #
+  # Example:
+  #
+  #  require 'drb'
+  #
+  #  s = DRb::DRbServer.new # automatically calls regist_server
+  #  DRb.fetch_server s.uri #=> #<DRb::DRbServer:0x...>
+  def regist_server(server)
+    @server[server.uri] = server
+    mutex.synchronize do
+      @primary_server = server unless @primary_server
+    end
+  end
+  module_function :regist_server
+
+  # Removes +server+ from the list of registered servers.
+  def remove_server(server)
+    @server.delete(server.uri)
+  end
+  module_function :remove_server
+
+  # Retrieves the server with the given +uri+.
+  #
+  # See also regist_server and remove_server.
+  def fetch_server(uri)
+    @server[uri]
+  end
+  module_function :fetch_server
+end
+
+# :stopdoc:
+DRbObject = DRb::DRbObject
+DRbUndumped = DRb::DRbUndumped
+DRbIdConv = DRb::DRbIdConv