Class: Rinda::TupleSpace

Inherits:
Object
  • Object
show all
Includes:
DRbUndumped, MonitorMixin
Defined in:
lib/rinda/tuplespace.rb

Overview

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.

Instance Method Summary collapse

Constructor Details

#initialize(period = 60) ⇒ TupleSpace

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.



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# 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

Instance Method Details

#move(port, tuple, sec = nil) {|template| ... } ⇒ Object

Moves tuple to port.

Yields:

  • (template)


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# 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 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

#notify(event, tuple, sec = nil) ⇒ Object

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.



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# 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| ... } ⇒ Object

Reads tuple, but does not remove it.

Yields:

  • (template)


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# 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) ⇒ Object

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



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# 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) ⇒ Object

Removes tuple



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# File 'lib/rinda/tuplespace.rb', line 478

def take(tuple, sec=nil, &block)
  move(nil, tuple, sec, &block)
end

#write(tuple, sec = nil) ⇒ Object

Adds tuple



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# 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