class Rinda::TupleSpace

Parent:: Object
Included modules:: DRb::DRbUndumped, MonitorMixin

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.

Public Class Methods

new(period=60) Show source

# File lib/rinda/tuplespace.rb, line 437
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

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.

Calls superclass method MonitorMixin::new

Public Instance Methods

move(port, tuple, sec=nil) { |template| ... } Show source

# File lib/rinda/tuplespace.rb, line 484
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

Moves tuple to port.

notify(event, tuple, sec=nil) Show source

# File lib/rinda/tuplespace.rb, line 567
def notify(event, tuple, sec=nil)
  template = NotifyTemplateEntry.new(self, event, tuple, sec)
  synchronize do
    @notify_waiter.push(template)
  end
  template
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.

read(tuple, sec=nil) { |template| ... } Show source

# File lib/rinda/tuplespace.rb, line 521
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

Reads tuple, but does not remove it.

read_all(tuple) Show source

# File lib/rinda/tuplespace.rb, line 545
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

Returns all tuples matching tuple. Does not remove the found tuples.

take(tuple, sec=nil, &block) Show source

# File lib/rinda/tuplespace.rb, line 477
def take(tuple, sec=nil, &block)
  move(nil, tuple, sec, &block)
end

Removes tuple

write(tuple, sec=nil) Show source

# File lib/rinda/tuplespace.rb, line 450
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

Adds tuple

Private Instance Methods

create_entry(tuple, sec) Show source

# File lib/rinda/tuplespace.rb, line 577
def create_entry(tuple, sec)
  TupleEntry.new(tuple, sec)
end

keep_clean() Show source

# File lib/rinda/tuplespace.rb, line 584
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

Removes dead tuples.

need_keeper?() Show source

# File lib/rinda/tuplespace.rb, line 631
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

Checks the tuplespace to see if it needs cleaning.

notify_event(event, tuple) Show source

# File lib/rinda/tuplespace.rb, line 605
def notify_event(event, tuple)
  ev = [event, tuple]
  @notify_waiter.find_all_template(ev).each do |template|
    template.notify(ev)
  end
end

Notifies all registered listeners for event of a status change of tuple.

start_keeper() Show source

# File lib/rinda/tuplespace.rb, line 615
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

Creates a thread that scans the tuplespace for expired tuples.

Ruby Core © 1993–2020 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.