class DRb::DRbServer - Documentation for Ruby 3.3

# class DRb::DRbServer

`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`.

### Constants

INSECURE_METHOD

  List of insecure methods.

  These methods are not callable via dRuby.

### Attributes

config[R]

The configuration of this DRbServer

front[R]

The front object of the DRbServer.

This object receives remote method calls made on the server’s `URI` alone, with an object id.

thread[R]

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.

uri[R]

The `URI` of this DRbServer.

### Public Class Methods

default_acl(acl) click to toggle source

`Set` the default access control list to `acl`. The default `ACL` is `nil`.

See also `DRb::ACL` and new()

    # File lib/drb/drb.rb, line 1375
    def self.default_acl(acl)
      @@acl = acl
    end

default_argc_limit(argc) click to toggle source

`Set` the default value for the :argc_limit option.

See new(). The initial default value is 256.

    # File lib/drb/drb.rb, line 1361
    def self.default_argc_limit(argc)
      @@argc_limit = argc
    end

default_id_conv(idconv) click to toggle source

`Set` the default value for the :id_conv option.

See new(). The initial default value is a `DRbIdConv` instance.

    # File lib/drb/drb.rb, line 1382
    def self.default_id_conv(idconv)
      @@idconv = idconv
    end

default_load_limit(sz) click to toggle source

`Set` the default value for the :load_limit option.

See new(). The initial default value is 25 MB.

    # File lib/drb/drb.rb, line 1368
    def self.default_load_limit(sz)
      @@load_limit = sz
    end

new(uri=nil, front=nil, config_or_acl=nil) click to toggle source

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.

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.

    # File lib/drb/drb.rb, line 1451
    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]

      @grp = ThreadGroup.new
      @thread = run

      DRb.regist_server(self)
    end

verbose() click to toggle source

Get the default value of the :verbose option.

    # File lib/drb/drb.rb, line 1394
    def self.verbose
      @@verbose
    end

verbose=(on) click to toggle source

`Set` the default value of the :verbose option.

See new(). The initial default value is false.

    # File lib/drb/drb.rb, line 1389
    def self.verbose=(on)
      @@verbose = on
    end

### Public Instance Methods

alive?() click to toggle source

Is this server alive?

    # File lib/drb/drb.rb, line 1506
    def alive?
      @thread.alive?
    end

check_insecure_method(obj, msg_id) click to toggle source

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.

    # File lib/drb/drb.rb, line 1594
    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)

      case obj
      when Object
        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
      else
        if Kernel.instance_method(:private_methods).bind(obj).call.include?(msg_id)
          desc = any_to_s(obj)
          raise NoMethodError, "private method `#{msg_id}' called for #{desc}"
        elsif Kernel.instance_method(:protected_methods).bind(obj).call.include?(msg_id)
          desc = any_to_s(obj)
          raise NoMethodError, "protected method `#{msg_id}' called for #{desc}"
        else
          true
        end
      end
    end

here?(uri) click to toggle source

Is `uri` the `URI` for this server?

    # File lib/drb/drb.rb, line 1511
    def here?(uri)
      @exported_uri.include?(uri)
    end

stop_service() click to toggle source

Stop this server.

    # File lib/drb/drb.rb, line 1516
    def stop_service
      DRb.remove_server(self)
      if  Thread.current['DRb'] && Thread.current['DRb']['server'] == self
        Thread.current['DRb']['stop_service'] = true
      else
        shutdown
      end
    end

to_id(obj) click to toggle source

Convert a local object to a dRuby reference.

    # File lib/drb/drb.rb, line 1533
    def to_id(obj)
      return nil if obj.__id__ == front.__id__
      @idconv.to_id(obj)
    end

to_obj(ref) click to toggle source

Convert a dRuby reference to the local object it refers to.

    # File lib/drb/drb.rb, line 1526
    def to_obj(ref)
      return front if ref.nil?
      return front[ref.to_s] if DRbURIOption === ref
      @idconv.to_obj(ref)
    end

verbose() click to toggle source

Get whether the server is in verbose mode.

In verbose mode, failed calls are logged to stdout.

    # File lib/drb/drb.rb, line 1503
    def verbose; @config[:verbose]; end

verbose=(v) click to toggle source

`Set` whether to operate in verbose mode.

In verbose mode, failed calls are logged to stdout.

    # File lib/drb/drb.rb, line 1498
    def verbose=(v); @config[:verbose]=v; end

### Private Instance Methods

any_to_s(obj) click to toggle source

Coerce an object to a string, providing our own representation if to_s is not defined for the object.

    # File lib/drb/drb.rb, line 1580
    def any_to_s(obj)
      "#{obj}:#{obj.class}"
    rescue
      Kernel.instance_method(:to_s).bind_call(obj)
    end

error_print(exception) click to toggle source

    # File lib/drb/drb.rb, line 1696
    def error_print(exception)
      exception.backtrace.inject(true) do |first, x|
        if first
          $stderr.puts "#{x}: #{exception} (#{exception.class})"
        else
          $stderr.puts "\tfrom #{x}"
        end
        false
      end
    end

insecure_method?(msg_id) click to toggle source

Has a method been included in the list of insecure methods?

    # File lib/drb/drb.rb, line 1574
    def insecure_method?(msg_id)
      INSECURE_METHOD.include?(msg_id)
    end

main_loop() click to toggle source

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.

    # File lib/drb/drb.rb, line 1714
    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
        _last_invoke_method = nil
        loop do
          begin
            succ = false
            invoke_method = InvokeMethod.new(self, client)
            succ, result = invoke_method.perform
            error_print(result) if !succ && verbose
            unless DRbConnError === result && result.message == 'connection closed'
              client.send_reply(succ, result)
            end
          rescue Exception => e
            error_print(e) if verbose
          ensure
            _last_invoke_method = invoke_method
            client.close unless succ
            if Thread.current['DRb']['stop_service']
              shutdown
              break
            end
            break unless succ
          end
        end
      end
    end

run() click to toggle source

Starts the `DRb` main loop in a new thread.

    # File lib/drb/drb.rb, line 1555
    def run
      Thread.start do
        begin
          while main_loop
          end
        ensure
          @protocol.close if @protocol
        end
      end
    end

shutdown() click to toggle source

    # File lib/drb/drb.rb, line 1540
    def shutdown
      current = Thread.current
      if @protocol.respond_to? :shutdown
        @protocol.shutdown
      else
        [@thread, *@grp.list].each { |thread|
          thread.kill unless thread == current # xxx: Thread#kill
        }
      end
      @thread.join unless @thread == current
    end