Fresh start

3 files changed, 1449 insertions, 0 deletions

diff --git a/jni/ruby/lib/rinda/rinda.rb b/jni/ruby/lib/rinda/rinda.rb
new file mode 100644
index 0000000..d9cd378
--- /dev/null
+++ b/jni/ruby/lib/rinda/rinda.rb
@@ -0,0 +1,327 @@
+require 'drb/drb'
+require 'thread'
+
+##
+# A module to implement the Linda distributed computing paradigm in Ruby.
+#
+# Rinda is part of DRb (dRuby).
+#
+# == Example(s)
+#
+# See the sample/drb/ directory in the Ruby distribution, from 1.8.2 onwards.
+#
+#--
+# TODO
+# == Introduction to Linda/rinda?
+#
+# == Why is this library separate from DRb?
+
+module Rinda
+
+  ##
+  # Rinda error base class
+
+  class RindaError < RuntimeError; end
+
+  ##
+  # Raised when a hash-based tuple has an invalid key.
+
+  class InvalidHashTupleKey < RindaError; end
+
+  ##
+  # Raised when trying to use a canceled tuple.
+
+  class RequestCanceledError < ThreadError; end
+
+  ##
+  # Raised when trying to use an expired tuple.
+
+  class RequestExpiredError < ThreadError; end
+
+  ##
+  # A tuple is the elementary object in Rinda programming.
+  # Tuples may be matched against templates if the tuple and
+  # the template are the same size.
+
+  class Tuple
+
+    ##
+    # Creates a new Tuple from +ary_or_hash+ which must be an Array or Hash.
+
+    def initialize(ary_or_hash)
+      if hash?(ary_or_hash)
+        init_with_hash(ary_or_hash)
+      else
+        init_with_ary(ary_or_hash)
+      end
+    end
+
+    ##
+    # The number of elements in the tuple.
+
+    def size
+      @tuple.size
+    end
+
+    ##
+    # Accessor method for elements of the tuple.
+
+    def [](k)
+      @tuple[k]
+    end
+
+    ##
+    # Fetches item +k+ from the tuple.
+
+    def fetch(k)
+      @tuple.fetch(k)
+    end
+
+    ##
+    # Iterate through the tuple, yielding the index or key, and the
+    # value, thus ensuring arrays are iterated similarly to hashes.
+
+    def each # FIXME
+      if Hash === @tuple
+        @tuple.each { |k, v| yield(k, v) }
+      else
+        @tuple.each_with_index { |v, k| yield(k, v) }
+      end
+    end
+
+    ##
+    # Return the tuple itself
+    def value
+      @tuple
+    end
+
+    private
+
+    def hash?(ary_or_hash)
+      ary_or_hash.respond_to?(:keys)
+    end
+
+    ##
+    # Munges +ary+ into a valid Tuple.
+
+    def init_with_ary(ary)
+      @tuple = Array.new(ary.size)
+      @tuple.size.times do |i|
+        @tuple[i] = ary[i]
+      end
+    end
+
+    ##
+    # Ensures +hash+ is a valid Tuple.
+
+    def init_with_hash(hash)
+      @tuple = Hash.new
+      hash.each do |k, v|
+        raise InvalidHashTupleKey unless String === k
+        @tuple[k] = v
+      end
+    end
+
+  end
+
+  ##
+  # Templates are used to match tuples in Rinda.
+
+  class Template < Tuple
+
+    ##
+    # Matches this template against +tuple+.  The +tuple+ must be the same
+    # size as the template.  An element with a +nil+ value in a template acts
+    # as a wildcard, matching any value in the corresponding position in the
+    # tuple.  Elements of the template match the +tuple+ if the are #== or
+    # #===.
+    #
+    #   Template.new([:foo, 5]).match   Tuple.new([:foo, 5]) # => true
+    #   Template.new([:foo, nil]).match Tuple.new([:foo, 5]) # => true
+    #   Template.new([String]).match    Tuple.new(['hello']) # => true
+    #
+    #   Template.new([:foo]).match      Tuple.new([:foo, 5]) # => false
+    #   Template.new([:foo, 6]).match   Tuple.new([:foo, 5]) # => false
+    #   Template.new([:foo, nil]).match Tuple.new([:foo])    # => false
+    #   Template.new([:foo, 6]).match   Tuple.new([:foo])    # => false
+
+    def match(tuple)
+      return false unless tuple.respond_to?(:size)
+      return false unless tuple.respond_to?(:fetch)
+      return false unless self.size == tuple.size
+      each do |k, v|
+        begin
+          it = tuple.fetch(k)
+        rescue
+          return false
+        end
+        next if v.nil?
+        next if v == it
+        next if v === it
+        return false
+      end
+      return true
+    end
+
+    ##
+    # Alias for #match.
+
+    def ===(tuple)
+      match(tuple)
+    end
+
+  end
+
+  ##
+  # <i>Documentation?</i>
+
+  class DRbObjectTemplate
+
+    ##
+    # Creates a new DRbObjectTemplate that will match against +uri+ and +ref+.
+
+    def initialize(uri=nil, ref=nil)
+      @drb_uri = uri
+      @drb_ref = ref
+    end
+
+    ##
+    # This DRbObjectTemplate matches +ro+ if the remote object's drburi and
+    # drbref are the same.  +nil+ is used as a wildcard.
+
+    def ===(ro)
+      return true if super(ro)
+      unless @drb_uri.nil?
+        return false unless (@drb_uri === ro.__drburi rescue false)
+      end
+      unless @drb_ref.nil?
+        return false unless (@drb_ref === ro.__drbref rescue false)
+      end
+      true
+    end
+
+  end
+
+  ##
+  # TupleSpaceProxy allows a remote Tuplespace to appear as local.
+
+  class TupleSpaceProxy
+    ##
+    # A Port ensures that a moved tuple arrives properly at its destination
+    # and does not get lost.
+    #
+    # See https://bugs.ruby-lang.org/issues/8125
+
+    class Port # :nodoc:
+      attr_reader :value
+
+      def self.deliver
+        port = new
+
+        begin
+          yield(port)
+        ensure
+          port.close
+        end
+
+        port.value
+      end
+
+      def initialize
+        @open = true
+        @value = nil
+      end
+
+      ##
+      # Don't let the DRb thread push to it when remote sends tuple
+
+      def close
+        @open = false
+      end
+
+      ##
+      # Stores +value+ and ensure it does not get marshaled multiple times.
+
+      def push value
+        raise 'port closed' unless @open
+
+        @value = value
+
+        nil # avoid Marshal
+      end
+    end
+
+    ##
+    # Creates a new TupleSpaceProxy to wrap +ts+.
+
+    def initialize(ts)
+      @ts = ts
+    end
+
+    ##
+    # Adds +tuple+ to the proxied TupleSpace.  See TupleSpace#write.
+
+    def write(tuple, sec=nil)
+      @ts.write(tuple, sec)
+    end
+
+    ##
+    # Takes +tuple+ from the proxied TupleSpace.  See TupleSpace#take.
+
+    def take(tuple, sec=nil, &block)
+      Port.deliver do |port|
+        @ts.move(DRbObject.new(port), tuple, sec, &block)
+      end
+    end
+
+    ##
+    # Reads +tuple+ from the proxied TupleSpace.  See TupleSpace#read.
+
+    def read(tuple, sec=nil, &block)
+      @ts.read(tuple, sec, &block)
+    end
+
+    ##
+    # Reads all tuples matching +tuple+ from the proxied TupleSpace.  See
+    # TupleSpace#read_all.
+
+    def read_all(tuple)
+      @ts.read_all(tuple)
+    end
+
+    ##
+    # Registers for notifications of event +ev+ on the proxied TupleSpace.
+    # See TupleSpace#notify
+
+    def notify(ev, tuple, sec=nil)
+      @ts.notify(ev, tuple, sec)
+    end
+
+  end
+
+  ##
+  # An SimpleRenewer allows a TupleSpace to check if a TupleEntry is still
+  # alive.
+
+  class SimpleRenewer
+
+    include DRbUndumped
+
+    ##
+    # Creates a new SimpleRenewer that keeps an object alive for another +sec+
+    # seconds.
+
+    def initialize(sec=180)
+      @sec = sec
+    end
+
+    ##
+    # Called by the TupleSpace to check if the object is still alive.
+
+    def renew
+      @sec
+    end
+  end
+
+end
+
diff --git a/jni/ruby/lib/rinda/ring.rb b/jni/ruby/lib/rinda/ring.rb
new file mode 100644
index 0000000..fe33420
--- /dev/null
+++ b/jni/ruby/lib/rinda/ring.rb
@@ -0,0 +1,480 @@
+#
+# Note: Rinda::Ring API is unstable.
+#
+require 'drb/drb'
+require 'rinda/rinda'
+require 'thread'
+require 'ipaddr'
+
+module Rinda
+
+  ##
+  # The default port Ring discovery will use.
+
+  Ring_PORT = 7647
+
+  ##
+  # A RingServer allows a Rinda::TupleSpace to be located via UDP broadcasts.
+  # Default service location uses the following steps:
+  #
+  # 1. A RingServer begins listening on the network broadcast UDP address.
+  # 2. A RingFinger sends a UDP packet containing the DRb URI where it will
+  #    listen for a reply.
+  # 3. The RingServer receives the UDP packet and connects back to the
+  #    provided DRb URI with the DRb service.
+  #
+  # A RingServer requires a TupleSpace:
+  #
+  #   ts = Rinda::TupleSpace.new
+  #   rs = Rinda::RingServer.new
+  #
+  # RingServer can also listen on multicast addresses for announcements.  This
+  # allows multiple RingServers to run on the same host.  To use network
+  # broadcast and multicast:
+  #
+  #   ts = Rinda::TupleSpace.new
+  #   rs = Rinda::RingServer.new ts, %w[Socket::INADDR_ANY, 239.0.0.1 ff02::1]
+
+  class RingServer
+
+    include DRbUndumped
+
+    ##
+    # Special renewer for the RingServer to allow shutdown
+
+    class Renewer # :nodoc:
+      include DRbUndumped
+
+      ##
+      # Set to false to shutdown future requests using this Renewer
+
+      attr_writer :renew
+
+      def initialize # :nodoc:
+        @renew = true
+      end
+
+      def renew # :nodoc:
+        @renew ? 1 : true
+      end
+    end
+
+    ##
+    # Advertises +ts+ on the given +addresses+ at +port+.
+    #
+    # If +addresses+ is omitted only the UDP broadcast address is used.
+    #
+    # +addresses+ can contain multiple addresses.  If a multicast address is
+    # given in +addresses+ then the RingServer will listen for multicast
+    # queries.
+    #
+    # If you use IPv4 multicast you may need to set an address of the inbound
+    # interface which joins a multicast group.
+    #
+    #   ts = Rinda::TupleSpace.new
+    #   rs = Rinda::RingServer.new(ts, [['239.0.0.1', '9.5.1.1']])
+    #
+    # You can set addresses as an Array Object.  The first element of the
+    # Array is a multicast address and the second is an inbound interface
+    # address.  If the second is omitted then '0.0.0.0' is used.
+    #
+    # If you use IPv6 multicast you may need to set both the local interface
+    # address and the inbound interface index:
+    #
+    #   rs = Rinda::RingServer.new(ts, [['ff02::1', '::1', 1]])
+    #
+    # The first element is a multicast address and the second is an inbound
+    # interface address.  The third is an inbound interface index.
+    #
+    # At this time there is no easy way to get an interface index by name.
+    #
+    # If the second is omitted then '::1' is used.
+    # If the third is omitted then 0 (default interface) is used.
+
+    def initialize(ts, addresses=[Socket::INADDR_ANY], port=Ring_PORT)
+      @port = port
+
+      if Integer === addresses then
+        addresses, @port = [Socket::INADDR_ANY], addresses
+      end
+
+      @renewer = Renewer.new
+
+      @ts = ts
+      @sockets = []
+      addresses.each do |address|
+        if Array === address
+          make_socket(*address)
+        else
+          make_socket(address)
+        end
+      end
+
+      @w_services = write_services
+      @r_service  = reply_service
+    end
+
+    ##
+    # Creates a socket at +address+
+    #
+    # If +address+ is multicast address then +interface_address+ and
+    # +multicast_interface+ can be set as optional.
+    #
+    # A created socket is bound to +interface_address+.  If you use IPv4
+    # multicast then the interface of +interface_address+ is used as the
+    # inbound interface.  If +interface_address+ is omitted or nil then
+    # '0.0.0.0' or '::1' is used.
+    #
+    # If you use IPv6 multicast then +multicast_interface+ is used as the
+    # inbound interface.  +multicast_interface+ is a network interface index.
+    # If +multicast_interface+ is omitted then 0 (default interface) is used.
+
+    def make_socket(address, interface_address=nil, multicast_interface=0)
+      addrinfo = Addrinfo.udp(address, @port)
+
+      socket = Socket.new(addrinfo.pfamily, addrinfo.socktype,
+                          addrinfo.protocol)
+      @sockets << socket
+
+      if addrinfo.ipv4_multicast? or addrinfo.ipv6_multicast? then
+        if Socket.const_defined?(:SO_REUSEPORT) then
+          socket.setsockopt(:SOCKET, :SO_REUSEPORT, true)
+        else
+          socket.setsockopt(:SOCKET, :SO_REUSEADDR, true)
+        end
+
+        if addrinfo.ipv4_multicast? then
+          interface_address = '0.0.0.0' if interface_address.nil?
+          socket.bind(Addrinfo.udp(interface_address, @port))
+
+          mreq = IPAddr.new(addrinfo.ip_address).hton +
+            IPAddr.new(interface_address).hton
+
+          socket.setsockopt(:IPPROTO_IP, :IP_ADD_MEMBERSHIP, mreq)
+        else
+          interface_address = '::1' if interface_address.nil?
+          socket.bind(Addrinfo.udp(interface_address, @port))
+
+          mreq = IPAddr.new(addrinfo.ip_address).hton +
+            [multicast_interface].pack('I')
+
+          socket.setsockopt(:IPPROTO_IPV6, :IPV6_JOIN_GROUP, mreq)
+        end
+      else
+        socket.bind(addrinfo)
+      end
+
+      socket
+    end
+
+    ##
+    # Creates threads that pick up UDP packets and passes them to do_write for
+    # decoding.
+
+    def write_services
+      @sockets.map do |s|
+        Thread.new(s) do |socket|
+          loop do
+            msg = socket.recv(1024)
+            do_write(msg)
+          end
+        end
+      end
+    end
+
+    ##
+    # Extracts the response URI from +msg+ and adds it to TupleSpace where it
+    # will be picked up by +reply_service+ for notification.
+
+    def do_write(msg)
+      Thread.new do
+        begin
+          tuple, sec = Marshal.load(msg)
+          @ts.write(tuple, sec)
+        rescue
+        end
+      end
+    end
+
+    ##
+    # Creates a thread that notifies waiting clients from the TupleSpace.
+
+    def reply_service
+      Thread.new do
+        loop do
+          do_reply
+        end
+      end
+    end
+
+    ##
+    # Pulls lookup tuples out of the TupleSpace and sends their DRb object the
+    # address of the local TupleSpace.
+
+    def do_reply
+      tuple = @ts.take([:lookup_ring, nil], @renewer)
+      Thread.new { tuple[1].call(@ts) rescue nil}
+    rescue
+    end
+
+    ##
+    # Shuts down the RingServer
+
+    def shutdown
+      @renewer.renew = false
+
+      @w_services.each do |thread|
+        thread.kill
+        thread.join
+      end
+
+      @sockets.each do |socket|
+        socket.close
+      end
+
+      @r_service.kill
+      @r_service.join
+    end
+
+  end
+
+  ##
+  # RingFinger is used by RingServer clients to discover the RingServer's
+  # TupleSpace.  Typically, all a client needs to do is call
+  # RingFinger.primary to retrieve the remote TupleSpace, which it can then
+  # begin using.
+  #
+  # To find the first available remote TupleSpace:
+  #
+  #   Rinda::RingFinger.primary
+  #
+  # To create a RingFinger that broadcasts to a custom list:
+  #
+  #   rf = Rinda::RingFinger.new  ['localhost', '192.0.2.1']
+  #   rf.primary
+  #
+  # Rinda::RingFinger also understands multicast addresses and sets them up
+  # properly.  This allows you to run multiple RingServers on the same host:
+  #
+  #   rf = Rinda::RingFinger.new ['239.0.0.1']
+  #   rf.primary
+  #
+  # You can set the hop count (or TTL) for multicast searches using
+  # #multicast_hops.
+  #
+  # If you use IPv6 multicast you may need to set both an address and the
+  # outbound interface index:
+  #
+  #   rf = Rinda::RingFinger.new ['ff02::1']
+  #   rf.multicast_interface = 1
+  #   rf.primary
+  #
+  # At this time there is no easy way to get an interface index by name.
+
+  class RingFinger
+
+    @@broadcast_list = ['<broadcast>', 'localhost']
+
+    @@finger = nil
+
+    ##
+    # Creates a singleton RingFinger and looks for a RingServer.  Returns the
+    # created RingFinger.
+
+    def self.finger
+      unless @@finger
+        @@finger = self.new
+        @@finger.lookup_ring_any
+      end
+      @@finger
+    end
+
+    ##
+    # Returns the first advertised TupleSpace.
+
+    def self.primary
+      finger.primary
+    end
+
+    ##
+    # Contains all discovered TupleSpaces except for the primary.
+
+    def self.to_a
+      finger.to_a
+    end
+
+    ##
+    # The list of addresses where RingFinger will send query packets.
+
+    attr_accessor :broadcast_list
+
+    ##
+    # Maximum number of hops for sent multicast packets (if using a multicast
+    # address in the broadcast list).  The default is 1 (same as UDP
+    # broadcast).
+
+    attr_accessor :multicast_hops
+
+    ##
+    # The interface index to send IPv6 multicast packets from.
+
+    attr_accessor :multicast_interface
+
+    ##
+    # The port that RingFinger will send query packets to.
+
+    attr_accessor :port
+
+    ##
+    # Contain the first advertised TupleSpace after lookup_ring_any is called.
+
+    attr_accessor :primary
+
+    ##
+    # Creates a new RingFinger that will look for RingServers at +port+ on
+    # the addresses in +broadcast_list+.
+    #
+    # If +broadcast_list+ contains a multicast address then multicast queries
+    # will be made using the given multicast_hops and multicast_interface.
+
+    def initialize(broadcast_list=@@broadcast_list, port=Ring_PORT)
+      @broadcast_list = broadcast_list || ['localhost']
+      @port = port
+      @primary = nil
+      @rings = []
+
+      @multicast_hops = 1
+      @multicast_interface = 0
+    end
+
+    ##
+    # Contains all discovered TupleSpaces except for the primary.
+
+    def to_a
+      @rings
+    end
+
+    ##
+    # Iterates over all discovered TupleSpaces starting with the primary.
+
+    def each
+      lookup_ring_any unless @primary
+      return unless @primary
+      yield(@primary)
+      @rings.each { |x| yield(x) }
+    end
+
+    ##
+    # Looks up RingServers waiting +timeout+ seconds.  RingServers will be
+    # given +block+ as a callback, which will be called with the remote
+    # TupleSpace.
+
+    def lookup_ring(timeout=5, &block)
+      return lookup_ring_any(timeout) unless block_given?
+
+      msg = Marshal.dump([[:lookup_ring, DRbObject.new(block)], timeout])
+      @broadcast_list.each do |it|
+        send_message(it, msg)
+      end
+      sleep(timeout)
+    end
+
+    ##
+    # Returns the first found remote TupleSpace.  Any further recovered
+    # TupleSpaces can be found by calling +to_a+.
+
+    def lookup_ring_any(timeout=5)
+      queue = Queue.new
+
+      Thread.new do
+        self.lookup_ring(timeout) do |ts|
+          queue.push(ts)
+        end
+        queue.push(nil)
+      end
+
+      @primary = queue.pop
+      raise('RingNotFound') if @primary.nil?
+
+      Thread.new do
+        while it = queue.pop
+          @rings.push(it)
+        end
+      end
+
+      @primary
+    end
+
+    ##
+    # Creates a socket for +address+ with the appropriate multicast options
+    # for multicast addresses.
+
+    def make_socket(address) # :nodoc:
+      addrinfo = Addrinfo.udp(address, @port)
+
+      soc = Socket.new(addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol)
+      begin
+        if addrinfo.ipv4_multicast? then
+          soc.setsockopt(Socket::Option.ipv4_multicast_loop(1))
+          soc.setsockopt(Socket::Option.ipv4_multicast_ttl(@multicast_hops))
+        elsif addrinfo.ipv6_multicast? then
+          soc.setsockopt(:IPPROTO_IPV6, :IPV6_MULTICAST_LOOP, true)
+          soc.setsockopt(:IPPROTO_IPV6, :IPV6_MULTICAST_HOPS,
+                         [@multicast_hops].pack('I'))
+          soc.setsockopt(:IPPROTO_IPV6, :IPV6_MULTICAST_IF,
+                         [@multicast_interface].pack('I'))
+        else
+          soc.setsockopt(:SOL_SOCKET, :SO_BROADCAST, true)
+        end
+
+        soc.connect(addrinfo)
+      rescue Exception
+        soc.close
+        raise
+      end
+
+      soc
+    end
+
+    def send_message(address, message) # :nodoc:
+      soc = make_socket(address)
+
+      soc.send(message, 0)
+    rescue
+      nil
+    ensure
+      soc.close if soc
+    end
+
+  end
+
+  ##
+  # RingProvider uses a RingServer advertised TupleSpace as a name service.
+  # TupleSpace clients can register themselves with the remote TupleSpace and
+  # look up other provided services via the remote TupleSpace.
+  #
+  # Services are registered with a tuple of the format [:name, klass,
+  # DRbObject, description].
+
+  class RingProvider
+
+    ##
+    # Creates a RingProvider that will provide a +klass+ service running on
+    # +front+, with a +description+.  +renewer+ is optional.
+
+    def initialize(klass, front, desc, renewer = nil)
+      @tuple = [:name, klass, front, desc]
+      @renewer = renewer || Rinda::SimpleRenewer.new
+    end
+
+    ##
+    # Advertises this service on the primary remote TupleSpace.
+
+    def provide
+      ts = Rinda::RingFinger.primary
+      ts.write(@tuple, @renewer)
+    end
+
+  end
+
+end
diff --git a/jni/ruby/lib/rinda/tuplespace.rb b/jni/ruby/lib/rinda/tuplespace.rb
new file mode 100644
index 0000000..11532fd
--- /dev/null
+++ b/jni/ruby/lib/rinda/tuplespace.rb
@@ -0,0 +1,642 @@
+require 'monitor'
+require 'thread'
+require 'drb/drb'
+require 'rinda/rinda'
+require 'enumerator'
+require 'forwardable'
+
+module Rinda
+
+  ##
+  # A TupleEntry is a Tuple (i.e. a possible entry in some Tuplespace)
+  # together with expiry and cancellation data.
+
+  class TupleEntry
+
+    include DRbUndumped
+
+    attr_accessor :expires
+
+    ##
+    # Creates a TupleEntry based on +ary+ with an optional renewer or expiry
+    # time +sec+.
+    #
+    # A renewer must implement the +renew+ method which returns a Numeric,
+    # nil, or true to indicate when the tuple has expired.
+
+    def initialize(ary, sec=nil)
+      @cancel = false
+      @expires = nil
+      @tuple = make_tuple(ary)
+      @renewer = nil
+      renew(sec)
+    end
+
+    ##
+    # Marks this TupleEntry as canceled.
+
+    def cancel
+      @cancel = true
+    end
+
+    ##
+    # A TupleEntry is dead when it is canceled or expired.
+
+    def alive?
+      !canceled? && !expired?
+    end
+
+    ##
+    # Return the object which makes up the tuple itself: the Array
+    # or Hash.
+
+    def value; @tuple.value; end
+
+    ##
+    # Returns the canceled status.
+
+    def canceled?; @cancel; end
+
+    ##
+    # Has this tuple expired? (true/false).
+    #
+    # A tuple has expired when its expiry timer based on the +sec+ argument to
+    # #initialize runs out.
+
+    def expired?
+      return true unless @expires
+      return false if @expires > Time.now
+      return true if @renewer.nil?
+      renew(@renewer)
+      return true unless @expires
+      return @expires < Time.now
+    end
+
+    ##
+    # Reset the expiry time according to +sec_or_renewer+.
+    #
+    # +nil+::    it is set to expire in the far future.
+    # +true+::   it has expired.
+    # Numeric::  it will expire in that many seconds.
+    #
+    # Otherwise the argument refers to some kind of renewer object
+    # which will reset its expiry time.
+
+    def renew(sec_or_renewer)
+      sec, @renewer = get_renewer(sec_or_renewer)
+      @expires = make_expires(sec)
+    end
+
+    ##
+    # Returns an expiry Time based on +sec+ which can be one of:
+    # Numeric:: +sec+ seconds into the future
+    # +true+::  the expiry time is the start of 1970 (i.e. expired)
+    # +nil+::   it is  Tue Jan 19 03:14:07 GMT Standard Time 2038 (i.e. when
+    #           UNIX clocks will die)
+
+    def make_expires(sec=nil)
+      case sec
+      when Numeric
+        Time.now + sec
+      when true
+        Time.at(1)
+      when nil
+        Time.at(2**31-1)
+      end
+    end
+
+    ##
+    # Retrieves +key+ from the tuple.
+
+    def [](key)
+      @tuple[key]
+    end
+
+    ##
+    # Fetches +key+ from the tuple.
+
+    def fetch(key)
+      @tuple.fetch(key)
+    end
+
+    ##
+    # The size of the tuple.
+
+    def size
+      @tuple.size
+    end
+
+    ##
+    # Creates a Rinda::Tuple for +ary+.
+
+    def make_tuple(ary)
+      Rinda::Tuple.new(ary)
+    end
+
+    private
+
+    ##
+    # Returns a valid argument to make_expires and the renewer or nil.
+    #
+    # Given +true+, +nil+, or Numeric, returns that value and +nil+ (no actual
+    # renewer).  Otherwise it returns an expiry value from calling +it.renew+
+    # and the renewer.
+
+    def get_renewer(it)
+      case it
+      when Numeric, true, nil
+        return it, nil
+      else
+        begin
+          return it.renew, it
+        rescue Exception
+          return it, nil
+        end
+      end
+    end
+
+  end
+
+  ##
+  # A TemplateEntry is a Template together with expiry and cancellation data.
+
+  class TemplateEntry < TupleEntry
+    ##
+    # Matches this TemplateEntry against +tuple+.  See Template#match for
+    # details on how a Template matches a Tuple.
+
+    def match(tuple)
+      @tuple.match(tuple)
+    end
+
+    alias === match
+
+    def make_tuple(ary) # :nodoc:
+      Rinda::Template.new(ary)
+    end
+
+  end
+
+  ##
+  # <i>Documentation?</i>
+
+  class WaitTemplateEntry < TemplateEntry
+
+    attr_reader :found
+
+    def initialize(place, ary, expires=nil)
+      super(ary, expires)
+      @place = place
+      @cond = place.new_cond
+      @found = nil
+    end
+
+    def cancel
+      super
+      signal
+    end
+
+    def wait
+      @cond.wait
+    end
+
+    def read(tuple)
+      @found = tuple
+      signal
+    end
+
+    def signal
+      @place.synchronize do
+        @cond.signal
+      end
+    end
+
+  end
+
+  ##
+  # A NotifyTemplateEntry is returned by TupleSpace#notify and is notified of
+  # TupleSpace changes.  You may receive either your subscribed event or the
+  # 'close' event when iterating over notifications.
+  #
+  # See TupleSpace#notify_event for valid notification types.
+  #
+  # == Example
+  #
+  #   ts = Rinda::TupleSpace.new
+  #   observer = ts.notify 'write', [nil]
+  #
+  #   Thread.start do
+  #     observer.each { |t| p t }
+  #   end
+  #
+  #   3.times { |i| ts.write [i] }
+  #
+  # Outputs:
+  #
+  #   ['write', [0]]
+  #   ['write', [1]]
+  #   ['write', [2]]
+
+  class NotifyTemplateEntry < TemplateEntry
+
+    ##
+    # Creates a new NotifyTemplateEntry that watches +place+ for +event+s that
+    # match +tuple+.
+
+    def initialize(place, event, tuple, expires=nil)
+      ary = [event, Rinda::Template.new(tuple)]
+      super(ary, expires)
+      @queue = Queue.new
+      @done = false
+    end
+
+    ##
+    # Called by TupleSpace to notify this NotifyTemplateEntry of a new event.
+
+    def notify(ev)
+      @queue.push(ev)
+    end
+
+    ##
+    # Retrieves a notification.  Raises RequestExpiredError when this
+    # NotifyTemplateEntry expires.
+
+    def pop
+      raise RequestExpiredError if @done
+      it = @queue.pop
+      @done = true if it[0] == 'close'
+      return it
+    end
+
+    ##
+    # Yields event/tuple pairs until this NotifyTemplateEntry expires.
+
+    def each # :yields: event, tuple
+      while !@done
+        it = pop
+        yield(it)
+      end
+    rescue
+    ensure
+      cancel
+    end
+
+  end
+
+  ##
+  # TupleBag is an unordered collection of tuples. It is the basis
+  # of Tuplespace.
+
+  class TupleBag
+    class TupleBin
+      extend Forwardable
+      def_delegators '@bin', :find_all, :delete_if, :each, :empty?
+
+      def initialize
+        @bin = []
+      end
+
+      def add(tuple)
+        @bin.push(tuple)
+      end
+
+      def delete(tuple)
+        idx = @bin.rindex(tuple)
+        @bin.delete_at(idx) if idx
+      end
+
+      def find
+        @bin.reverse_each do |x|
+          return x if yield(x)
+        end
+        nil
+      end
+    end
+
+    def initialize # :nodoc:
+      @hash = {}
+      @enum = enum_for(:each_entry)
+    end
+
+    ##
+    # +true+ if the TupleBag to see if it has any expired entries.
+
+    def has_expires?
+      @enum.find do |tuple|
+        tuple.expires
+      end
+    end
+
+    ##
+    # Add +tuple+ to the TupleBag.
+
+    def push(tuple)
+      key = bin_key(tuple)
+      @hash[key] ||= TupleBin.new
+      @hash[key].add(tuple)
+    end
+
+    ##
+    # Removes +tuple+ from the TupleBag.
+
+    def delete(tuple)
+      key = bin_key(tuple)
+      bin = @hash[key]
+      return nil unless bin
+      bin.delete(tuple)
+      @hash.delete(key) if bin.empty?
+      tuple
+    end
+
+    ##
+    # Finds all live tuples that match +template+.
+    def find_all(template)
+      bin_for_find(template).find_all do |tuple|
+        tuple.alive? && template.match(tuple)
+      end
+    end
+
+    ##
+    # Finds a live tuple that matches +template+.
+
+    def find(template)
+      bin_for_find(template).find do |tuple|
+        tuple.alive? && template.match(tuple)
+      end
+    end
+
+    ##
+    # Finds all tuples in the TupleBag which when treated as templates, match
+    # +tuple+ and are alive.
+
+    def find_all_template(tuple)
+      @enum.find_all do |template|
+        template.alive? && template.match(tuple)
+      end
+    end
+
+    ##
+    # Delete tuples which dead tuples from the TupleBag, returning the deleted
+    # tuples.
+
+    def delete_unless_alive
+      deleted = []
+      @hash.each do |key, bin|
+        bin.delete_if do |tuple|
+          if tuple.alive?
+            false
+          else
+            deleted.push(tuple)
+            true
+          end
+        end
+      end
+      deleted
+    end
+
+    private
+    def each_entry(&blk)
+      @hash.each do |k, v|
+        v.each(&blk)
+      end
+    end
+
+    def bin_key(tuple)
+      head = tuple[0]
+      if head.class == Symbol
+        return head
+      else
+        false
+      end
+    end
+
+    def bin_for_find(template)
+      key = bin_key(template)
+      key ? @hash.fetch(key, []) : @enum
+    end
+  end
+
+  ##
+  # The Tuplespace manages access to the tuples it contains,
+  # ensuring mutual exclusion requirements are met.
+  #
+  # The +sec+ option for the write, take, move, read and notify methods may
+  # either be a number of seconds or a Renewer object.
+
+  class TupleSpace
+
+    include DRbUndumped
+    include MonitorMixin
+
+    ##
+    # Creates a new TupleSpace.  +period+ is used to control how often to look
+    # for dead tuples after modifications to the TupleSpace.
+    #
+    # If no dead tuples are found +period+ seconds after the last
+    # modification, the TupleSpace will stop looking for dead tuples.
+
+    def initialize(period=60)
+      super()
+      @bag = TupleBag.new
+      @read_waiter = TupleBag.new
+      @take_waiter = TupleBag.new
+      @notify_waiter = TupleBag.new
+      @period = period
+      @keeper = nil
+    end
+
+    ##
+    # Adds +tuple+
+
+    def write(tuple, sec=nil)
+      entry = create_entry(tuple, sec)
+      synchronize do
+        if entry.expired?
+          @read_waiter.find_all_template(entry).each do |template|
+            template.read(tuple)
+          end
+          notify_event('write', entry.value)
+          notify_event('delete', entry.value)
+        else
+          @bag.push(entry)
+          start_keeper if entry.expires
+          @read_waiter.find_all_template(entry).each do |template|
+            template.read(tuple)
+          end
+          @take_waiter.find_all_template(entry).each do |template|
+            template.signal
+          end
+          notify_event('write', entry.value)
+        end
+      end
+      entry
+    end
+
+    ##
+    # Removes +tuple+
+
+    def take(tuple, sec=nil, &block)
+      move(nil, tuple, sec, &block)
+    end
+
+    ##
+    # Moves +tuple+ to +port+.
+
+    def move(port, tuple, sec=nil)
+      template = WaitTemplateEntry.new(self, tuple, sec)
+      yield(template) if block_given?
+      synchronize do
+        entry = @bag.find(template)
+        if entry
+          port.push(entry.value) if port
+          @bag.delete(entry)
+          notify_event('take', entry.value)
+          return port ? nil : entry.value
+        end
+        raise RequestExpiredError if template.expired?
+
+        begin
+          @take_waiter.push(template)
+          start_keeper if template.expires
+          while true
+            raise RequestCanceledError if template.canceled?
+            raise RequestExpiredError if template.expired?
+            entry = @bag.find(template)
+            if entry
+              port.push(entry.value) if port
+              @bag.delete(entry)
+              notify_event('take', entry.value)
+              return port ? nil : entry.value
+            end
+            template.wait
+          end
+        ensure
+          @take_waiter.delete(template)
+        end
+      end
+    end
+
+    ##
+    # Reads +tuple+, but does not remove it.
+
+    def read(tuple, sec=nil)
+      template = WaitTemplateEntry.new(self, tuple, sec)
+      yield(template) if block_given?
+      synchronize do
+        entry = @bag.find(template)
+        return entry.value if entry
+        raise RequestExpiredError if template.expired?
+
+        begin
+          @read_waiter.push(template)
+          start_keeper if template.expires
+          template.wait
+          raise RequestCanceledError if template.canceled?
+          raise RequestExpiredError if template.expired?
+          return template.found
+        ensure
+          @read_waiter.delete(template)
+        end
+      end
+    end
+
+    ##
+    # Returns all tuples matching +tuple+.  Does not remove the found tuples.
+
+    def read_all(tuple)
+      template = WaitTemplateEntry.new(self, tuple, nil)
+      synchronize do
+        entry = @bag.find_all(template)
+        entry.collect do |e|
+          e.value
+        end
+      end
+    end
+
+    ##
+    # Registers for notifications of +event+.  Returns a NotifyTemplateEntry.
+    # See NotifyTemplateEntry for examples of how to listen for notifications.
+    #
+    # +event+ can be:
+    # 'write'::  A tuple was added
+    # 'take'::   A tuple was taken or moved
+    # 'delete':: A tuple was lost after being overwritten or expiring
+    #
+    # The TupleSpace will also notify you of the 'close' event when the
+    # NotifyTemplateEntry has expired.
+
+    def notify(event, tuple, sec=nil)
+      template = NotifyTemplateEntry.new(self, event, tuple, sec)
+      synchronize do
+        @notify_waiter.push(template)
+      end
+      template
+    end
+
+    private
+
+    def create_entry(tuple, sec)
+      TupleEntry.new(tuple, sec)
+    end
+
+    ##
+    # Removes dead tuples.
+
+    def keep_clean
+      synchronize do
+        @read_waiter.delete_unless_alive.each do |e|
+          e.signal
+        end
+        @take_waiter.delete_unless_alive.each do |e|
+          e.signal
+        end
+        @notify_waiter.delete_unless_alive.each do |e|
+          e.notify(['close'])
+        end
+        @bag.delete_unless_alive.each do |e|
+          notify_event('delete', e.value)
+        end
+      end
+    end
+
+    ##
+    # Notifies all registered listeners for +event+ of a status change of
+    # +tuple+.
+
+    def notify_event(event, tuple)
+      ev = [event, tuple]
+      @notify_waiter.find_all_template(ev).each do |template|
+        template.notify(ev)
+      end
+    end
+
+    ##
+    # Creates a thread that scans the tuplespace for expired tuples.
+
+    def start_keeper
+      return if @keeper && @keeper.alive?
+      @keeper = Thread.new do
+        while true
+          sleep(@period)
+          synchronize do
+            break unless need_keeper?
+            keep_clean
+          end
+        end
+      end
+    end
+
+    ##
+    # Checks the tuplespace to see if it needs cleaning.
+
+    def need_keeper?
+      return true if @bag.has_expires?
+      return true if @read_waiter.has_expires?
+      return true if @take_waiter.has_expires?
+      return true if @notify_waiter.has_expires?
+    end
+
+  end
+
+end
+