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
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.
# 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
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 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
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
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
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
Removes tuple
# File lib/rinda/tuplespace.rb, line 478 def take(tuple, sec=nil, &block) move(nil, tuple, sec, &block) end
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
# File lib/rinda/tuplespace.rb, line 578 def create_entry(tuple, sec) TupleEntry.new(tuple, sec) end
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
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
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
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