class Rinda::TupleSpace

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) click to toggle source

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

# File lib/rinda/tuplespace.rb, line 438
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

Public Instance Methods

move(port, tuple, sec=nil) { |template| ... } click to toggle source

Moves tuple to port.

# File lib/rinda/tuplespace.rb, line 485
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 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 entry.value
        end
        template.wait
      end
    ensure
      @take_waiter.delete(template)
    end
  end
end

notify(event, tuple, sec=nil) click to toggle source

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.

# File lib/rinda/tuplespace.rb, line 568
def notify(event, tuple, sec=nil)
  template = NotifyTemplateEntry.new(self, event, tuple, sec)
  synchronize do
    @notify_waiter.push(template)
  end
  template
end

read(tuple, sec=nil) { |template| ... } click to toggle source

Reads tuple, but does not remove it.

# File lib/rinda/tuplespace.rb, line 522
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

read_all(tuple) click to toggle source

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

# File lib/rinda/tuplespace.rb, line 546
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

take(tuple, sec=nil, &block) click to toggle source

Removes tuple

# File lib/rinda/tuplespace.rb, line 478
def take(tuple, sec=nil, &block)
  move(nil, tuple, sec, &block)
end

write(tuple, sec=nil) click to toggle source

Adds tuple

# File lib/rinda/tuplespace.rb, line 451
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

Private Instance Methods

create_entry(tuple, sec) click to toggle source

# File lib/rinda/tuplespace.rb, line 578
def create_entry(tuple, sec)
  TupleEntry.new(tuple, sec)
end

keep_clean() click to toggle source

Removes dead tuples.

# File lib/rinda/tuplespace.rb, line 585
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

need_keeper?() click to toggle source

Checks the tuplespace to see if it needs cleaning.

# File lib/rinda/tuplespace.rb, line 632
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

notify_event(event, tuple) click to toggle source

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

# File lib/rinda/tuplespace.rb, line 606
def notify_event(event, tuple)
  ev = [event, tuple]
  @notify_waiter.find_all_template(ev).each do |template|
    template.notify(ev)
  end
end

start_keeper() click to toggle source

Creates a thread that scans the tuplespace for expired tuples.

# File lib/rinda/tuplespace.rb, line 616
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