Fresh start

1 files changed, 642 insertions, 0 deletions

diff --git a/jni/ruby/lib/rinda/tuplespace.rb b/jni/ruby/lib/rinda/tuplespace.rb
new file mode 100644
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+++ 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
+