class Concurrent::ProcessingActor
A new implementation of actor which also simulates the process, therefore it can be used in the same way as Erlang's actors but *without* occupying thread. A tens of thousands ProcessingActors can run at the same time sharing a thread pool. @example
# Runs on a pool, does not consume 50_000 threads actors = 50_000.times.map do |i| Concurrent::ProcessingActor.act(i) { |a, i| a.receive.then_on(:fast, i) { |m, i| m + i } } end actors.each { |a| a.tell 1 } values = actors.map(&:termination).map(&:value) values[0,5] # => [1, 2, 3, 4, 5] values[-5, 5] # => [49996, 49997, 49998, 49999, 50000]
@!macro warn.edge
Public Class Methods
Creates an actor. @see act_listening Behaves the same way, but does not take mailbox as a first argument. @return [ProcessingActor] @example
actor = Concurrent::ProcessingActor.act do |actor| actor.receive.then do |message| # the actor ends normally with message message end end actor.tell :a_message # => <#Concurrent::ProcessingActor:0x7fff11280560 termination:pending> actor.termination.value! # => :a_message
# File lib-edge/concurrent/edge/processing_actor.rb, line 50 def self.act(*args, &process) act_listening Promises::Channel.new, *args, &process end
Creates an actor listening to a specified channel (mailbox). @param [Object] args Arguments passed to the process. @param [Promises::Channel] channel which serves as mailing box. The channel can have limited
size to achieve backpressure.
@yield args to the process to get back a future which represents the actors execution. @yieldparam [Object] *args @yieldreturn [Promises::Future(Object)] a future representing next step of execution @return [ProcessingActor] @example
# TODO (pitr-ch 19-Jan-2017): actor with limited mailbox
# File lib-edge/concurrent/edge/processing_actor.rb, line 64 def self.act_listening(channel, *args, &process) actor = ProcessingActor.new channel Promises. future(actor, *args, &process). run. chain_resolvable(actor.instance_variable_get(:@Terminated)) actor end
# File lib-edge/concurrent/edge/processing_actor.rb, line 154 def initialize(channel = Promises::Channel.new) @Mailbox = channel @Terminated = Promises.resolvable_future super() end
Public Instance Methods
Simplifies common pattern when a message sender also requires an answer to the message from the actor. It appends a resolvable_future for the answer after the message. @todo has to be nice also on the receive side, cannot make structure like this [message = […], answer]
all receives should receive something friendly
@param [Object] message @param [Promises::ResolvableFuture] answer @return [Promises::Future] a future which will be fulfilled with the answer to the message @example
add_once_actor = Concurrent::ProcessingActor.act do |actor| actor.receive.then do |(a, b), answer| result = a + b answer.fulfill result # terminate with result value result end end # => <#Concurrent::ProcessingActor:0x7fcd1315f6e8 termination:pending> add_once_actor.ask([1, 2]).value! # => 3 # fails the actor already added once add_once_actor.ask(%w(ab cd)).reason # => #<RuntimeError: actor terminated normally before answering with a value: 3> add_once_actor.termination.value! # => 3
# File lib-edge/concurrent/edge/processing_actor.rb, line 129 def ask(message, answer = Promises.resolvable_future) tell [message, answer] # do not leave answers unanswered when actor terminates. Promises.any( Promises.fulfilled_future(:answer).zip(answer), Promises.fulfilled_future(:termination).zip(@Terminated) ).chain do |fulfilled, (which, value), (_, reason)| # TODO (pitr-ch 20-Jan-2017): we have to know which future was resolved # TODO (pitr-ch 20-Jan-2017): make the combinator programmable, so anyone can create what is needed # FIXME (pitr-ch 19-Jan-2017): ensure no callbacks are accumulated on @Terminated if which == :termination raise reason.nil? ? format('actor terminated normally before answering with a value: %s', value) : reason else fulfilled ? value : raise(reason) end end end
@return [String] string representation.
# File lib-edge/concurrent/edge/processing_actor.rb, line 148 def inspect format '%s termination:%s>', super[0..-2], termination.state end
@return [Promises::Channel] actor's mailbox.
# File lib-edge/concurrent/edge/processing_actor.rb, line 25 def mailbox @Mailbox end
Receives a message when available, used in the actor's process. @return [Promises::Future(Object)] a future which will be fulfilled with a message from
mailbox when it is available.
# File lib-edge/concurrent/edge/processing_actor.rb, line 76 def receive(probe = Promises.resolvable_future) # TODO (pitr-ch 27-Dec-2016): patterns @Mailbox.pop probe end
Tells a message to the actor. @param [Object] message @return [Promises::Future(ProcessingActor)] a future which will be fulfilled with the actor
when the message is pushed to mailbox.
# File lib-edge/concurrent/edge/processing_actor.rb, line 102 def tell(message) @Mailbox.push(message).then(self) { |_, actor| actor } end
Tells a message to the actor. May block current thread if the mailbox is full. {#tell} is a better option since it does not block. It's usually used to integrate with threading code. @example
Thread.new(actor) do |actor| # ... actor.tell! :a_message # blocks until the message is told # (there is a space for it in the channel) # ... end
@param [Object] message @return [self]
# File lib-edge/concurrent/edge/processing_actor.rb, line 93 def tell!(message) @Mailbox.push(message).wait! self end
@return [Promises::Future(Object)] a future which is resolved when the actor ends its processing.
It can either be fulfilled with a value when actor ends normally or rejected with a reason (exception) when actor fails.
# File lib-edge/concurrent/edge/processing_actor.rb, line 32 def termination @Terminated.with_hidden_resolvable end