diff options
Diffstat (limited to 'actioncable/lib/action_cable/channel')
| -rw-r--r-- | actioncable/lib/action_cable/channel/base.rb | 41 | ||||
| -rw-r--r-- | actioncable/lib/action_cable/channel/periodic_timers.rb | 52 | ||||
| -rw-r--r-- | actioncable/lib/action_cable/channel/streams.rb | 100 |
3 files changed, 150 insertions, 43 deletions
diff --git a/actioncable/lib/action_cable/channel/base.rb b/actioncable/lib/action_cable/channel/base.rb index 86c8f12f6e..845b747fc5 100644 --- a/actioncable/lib/action_cable/channel/base.rb +++ b/actioncable/lib/action_cable/channel/base.rb @@ -32,8 +32,8 @@ module ActionCable # # == Action processing # - # Unlike subclasses of ActionController::Base, channels do not follow a REST - # constraint form for their actions. Instead, ActionCable operates through a + # Unlike subclasses of ActionController::Base, channels do not follow a RESTful + # constraint form for their actions. Instead, Action Cable operates through a # remote-procedure call model. You can declare any public method on the # channel (optionally taking a <tt>data</tt> argument), and this method is # automatically exposed as callable to the client. @@ -63,10 +63,10 @@ module ActionCable # end # end # - # In this example, subscribed/unsubscribed are not callable methods, as they + # In this example, the subscribed and unsubscribed methods are not callable methods, as they # were already declared in ActionCable::Channel::Base, but <tt>#appear</tt> # and <tt>#away</tt> are. <tt>#generate_connection_token</tt> is also not - # callable as it's a private method. You'll see that appear accepts a data + # callable, since it's a private method. You'll see that appear accepts a data # parameter, which it then uses as part of its model call. <tt>#away</tt> # does not, since it's simply a trigger action. # @@ -125,7 +125,7 @@ module ActionCable protected # action_methods are cached and there is sometimes need to refresh # them. ::clear_action_methods! allows you to do that, so next time - # you run action_methods, they will be recalculated + # you run action_methods, they will be recalculated. def clear_action_methods! @action_methods = nil end @@ -160,15 +160,18 @@ module ActionCable action = extract_action(data) if processable_action?(action) - dispatch_action(action, data) + payload = { channel_class: self.class.name, action: action, data: data } + ActiveSupport::Notifications.instrument("perform_action.action_cable", payload) do + dispatch_action(action, data) + end else logger.error "Unable to process #{action_signature(action, data)}" end end - # Called by the cable connection when its cut so the channel has a chance to cleanup with callbacks. + # Called by the cable connection when it's cut, so the channel has a chance to cleanup with callbacks. # This method is not intended to be called directly by the user. Instead, overwrite the #unsubscribed callback. - def unsubscribe_from_channel + def unsubscribe_from_channel # :nodoc: run_callbacks :unsubscribe do unsubscribed end @@ -183,7 +186,7 @@ module ActionCable end # Called once a consumer has cut its cable connection. Can be used for cleaning up connections or marking - # people as offline or the like. + # users as offline or the like. def unsubscribed # Override in subclasses end @@ -192,7 +195,11 @@ module ActionCable # the proper channel identifier marked as the recipient. def transmit(data, via: nil) logger.info "#{self.class.name} transmitting #{data.inspect.truncate(300)}".tap { |m| m << " (via #{via})" if via } - connection.transmit ActiveSupport::JSON.encode(identifier: @identifier, message: data) + + payload = { channel_class: self.class.name, data: data, via: via } + ActiveSupport::Notifications.instrument("transmit.action_cable", payload) do + connection.transmit identifier: @identifier, message: data + end end def defer_subscription_confirmation! @@ -224,7 +231,6 @@ module ActionCable end end - def subscribe_to_channel run_callbacks :subscribe do subscribed @@ -237,7 +243,6 @@ module ActionCable end end - def extract_action(data) (data['action'].presence || :receive).to_sym end @@ -267,8 +272,11 @@ module ActionCable def transmit_subscription_confirmation unless subscription_confirmation_sent? logger.info "#{self.class.name} is transmitting the subscription confirmation" - connection.transmit ActiveSupport::JSON.encode(identifier: @identifier, type: ActionCable::INTERNAL[:message_types][:confirmation]) - @subscription_confirmation_sent = true + + ActiveSupport::Notifications.instrument("transmit_subscription_confirmation.action_cable", channel_class: self.class.name) do + connection.transmit identifier: @identifier, type: ActionCable::INTERNAL[:message_types][:confirmation] + @subscription_confirmation_sent = true + end end end @@ -279,7 +287,10 @@ module ActionCable def transmit_subscription_rejection logger.info "#{self.class.name} is transmitting the subscription rejection" - connection.transmit ActiveSupport::JSON.encode(identifier: @identifier, type: ActionCable::INTERNAL[:message_types][:rejection]) + + ActiveSupport::Notifications.instrument("transmit_subscription_rejection.action_cable", channel_class: self.class.name) do + connection.transmit identifier: @identifier, type: ActionCable::INTERNAL[:message_types][:rejection] + end end end end diff --git a/actioncable/lib/action_cable/channel/periodic_timers.rb b/actioncable/lib/action_cable/channel/periodic_timers.rb index 0f6e854520..dab604440f 100644 --- a/actioncable/lib/action_cable/channel/periodic_timers.rb +++ b/actioncable/lib/action_cable/channel/periodic_timers.rb @@ -12,11 +12,42 @@ module ActionCable end module ClassMethods - # Allows you to call a private method <tt>every</tt> so often seconds. This periodic timer can be useful - # for sending a steady flow of updates to a client based off an object that was configured on subscription. - # It's an alternative to using streams if the channel is able to do the work internally. - def periodically(callback, every:) - self.periodic_timers += [ [ callback, every: every ] ] + # Periodically performs a task on the channel, like updating an online + # user counter, polling a backend for new status messages, sending + # regular "heartbeat" messages, or doing some internal work and giving + # progress updates. + # + # Pass a method name or lambda argument or provide a block to call. + # Specify the calling period in seconds using the <tt>every:</tt> + # keyword argument. + # + # periodically :transmit_progress, every: 5.seconds + # + # periodically every: 3.minutes do + # transmit action: :update_count, count: current_count + # end + # + def periodically(callback_or_method_name = nil, every:, &block) + callback = + if block_given? + raise ArgumentError, 'Pass a block or provide a callback arg, not both' if callback_or_method_name + block + else + case callback_or_method_name + when Proc + callback_or_method_name + when Symbol + -> { __send__ callback_or_method_name } + else + raise ArgumentError, "Expected a Symbol method name or a Proc, got #{callback_or_method_name.inspect}" + end + end + + unless every.kind_of?(Numeric) && every > 0 + raise ArgumentError, "Expected every: to be a positive number of seconds, got #{every.inspect}" + end + + self.periodic_timers += [[ callback, every: every ]] end end @@ -27,14 +58,21 @@ module ActionCable def start_periodic_timers self.class.periodic_timers.each do |callback, options| - active_periodic_timers << Concurrent::TimerTask.new(execution_interval: options[:every]) do - connection.worker_pool.async_run_periodic_timer(self, callback) + active_periodic_timers << start_periodic_timer(callback, every: options.fetch(:every)) + end + end + + def start_periodic_timer(callback, every:) + connection.server.event_loop.timer every do + connection.worker_pool.async_invoke connection do + instance_exec(&callback) end end end def stop_periodic_timers active_periodic_timers.each { |timer| timer.shutdown } + active_periodic_timers.clear end end end diff --git a/actioncable/lib/action_cable/channel/streams.rb b/actioncable/lib/action_cable/channel/streams.rb index 3158f30814..0a0a95f453 100644 --- a/actioncable/lib/action_cable/channel/streams.rb +++ b/actioncable/lib/action_cable/channel/streams.rb @@ -1,8 +1,8 @@ module ActionCable module Channel - # Streams allow channels to route broadcastings to the subscriber. A broadcasting is, as discussed elsewhere, a pub/sub queue where any data - # put into it is automatically sent to the clients that are connected at that time. It's purely an online queue, though. If you're not - # streaming a broadcasting at the very moment it sends out an update, you'll not get that update when connecting later. + # Streams allow channels to route broadcastings to the subscriber. A broadcasting is, as discussed elsewhere, a pubsub queue where any data + # placed into it is automatically sent to the clients that are connected at that time. It's purely an online queue, though. If you're not + # streaming a broadcasting at the very moment it sends out an update, you will not get that update, even if you connect after it has been sent. # # Most commonly, the streamed broadcast is sent straight to the subscriber on the client-side. The channel just acts as a connector between # the two parties (the broadcaster and the channel subscriber). Here's an example of a channel that allows subscribers to get all new @@ -18,13 +18,15 @@ module ActionCable # end # end # - # So the subscribers of this channel will get whatever data is put into the, let's say, `comments_for_45` broadcasting as soon as it's put there. - # That looks like so from that side of things: + # Based on the above example, the subscribers of this channel will get whatever data is put into the, + # let's say, <tt>comments_for_45</tt> broadcasting as soon as it's put there. + # + # An example broadcasting for this channel looks like so: # # ActionCable.server.broadcast "comments_for_45", author: 'DHH', content: 'Rails is just swell' # # If you have a stream that is related to a model, then the broadcasting used can be generated from the model and channel. - # The following example would subscribe to a broadcasting like `comments:Z2lkOi8vVGVzdEFwcC9Qb3N0LzE` + # The following example would subscribe to a broadcasting like <tt>comments:Z2lkOi8vVGVzdEFwcC9Qb3N0LzE</tt>. # # class CommentsChannel < ApplicationCable::Channel # def subscribed @@ -37,16 +39,14 @@ module ActionCable # # CommentsChannel.broadcast_to(@post, @comment) # - # If you don't just want to parlay the broadcast unfiltered to the subscriber, you can supply a callback that lets you alter what goes out. - # Example below shows how you can use this to provide performance introspection in the process: + # If you don't just want to parlay the broadcast unfiltered to the subscriber, you can also supply a callback that lets you alter what is sent out. + # The below example shows how you can use this to provide performance introspection in the process: # # class ChatChannel < ApplicationCable::Channel # def subscribed # @room = Chat::Room[params[:room_number]] # - # stream_for @room, -> (encoded_message) do - # message = ActiveSupport::JSON.decode(encoded_message) - # + # stream_for @room, coder: ActiveSupport::JSON do |message| # if message['originated_at'].present? # elapsed_time = (Time.now.to_f - message['originated_at']).round(2) # @@ -69,15 +69,21 @@ module ActionCable # Start streaming from the named <tt>broadcasting</tt> pubsub queue. Optionally, you can pass a <tt>callback</tt> that'll be used # instead of the default of just transmitting the updates straight to the subscriber. - def stream_from(broadcasting, callback = nil) - # Hold off the confirmation until pubsub#subscribe is successful + # Pass `coder: ActiveSupport::JSON` to decode messages as JSON before passing to the callback. + # Defaults to `coder: nil` which does no decoding, passes raw messages. + def stream_from(broadcasting, callback = nil, coder: nil, &block) + broadcasting = String(broadcasting) + + # Don't send the confirmation until pubsub#subscribe is successful defer_subscription_confirmation! - callback ||= default_stream_callback(broadcasting) - streams << [ broadcasting, callback ] + # Build a stream handler by wrapping the user-provided callback with + # a decoder or defaulting to a JSON-decoding retransmitter. + handler = worker_pool_stream_handler(broadcasting, callback || block, coder: coder) + streams << [ broadcasting, handler ] - Concurrent.global_io_executor.post do - pubsub.subscribe(broadcasting, callback, lambda do + connection.server.event_loop.post do + pubsub.subscribe(broadcasting, handler, lambda do transmit_subscription_confirmation logger.info "#{self.class.name} is streaming from #{broadcasting}" end) @@ -87,8 +93,11 @@ module ActionCable # Start streaming the pubsub queue for the <tt>model</tt> in this channel. Optionally, you can pass a # <tt>callback</tt> that'll be used instead of the default of just transmitting the updates straight # to the subscriber. - def stream_for(model, callback = nil) - stream_from(broadcasting_for([ channel_name, model ]), callback) + # + # Pass `coder: ActiveSupport::JSON` to decode messages as JSON before passing to the callback. + # Defaults to `coder: nil` which does no decoding, passes raw messages. + def stream_for(model, callback = nil, coder: nil, &block) + stream_from(broadcasting_for([ channel_name, model ]), callback || block, coder: coder) end # Unsubscribes all streams associated with this channel from the pubsub queue. @@ -106,11 +115,60 @@ module ActionCable @_streams ||= [] end - def default_stream_callback(broadcasting) + # Always wrap the outermost handler to invoke the user handler on the + # worker pool rather than blocking the event loop. + def worker_pool_stream_handler(broadcasting, user_handler, coder: nil) + handler = stream_handler(broadcasting, user_handler, coder: coder) + + -> message do + connection.worker_pool.async_invoke handler, :call, message, connection: connection + end + end + + # May be overridden to add instrumentation, logging, specialized error + # handling, or other forms of handler decoration. + # + # TODO: Tests demonstrating this. + def stream_handler(broadcasting, user_handler, coder: nil) + if user_handler + stream_decoder user_handler, coder: coder + else + default_stream_handler broadcasting, coder: coder + end + end + + # May be overridden to change the default stream handling behavior + # which decodes JSON and transmits to client. + # + # TODO: Tests demonstrating this. + # + # TODO: Room for optimization. Update transmit API to be coder-aware + # so we can no-op when pubsub and connection are both JSON-encoded. + # Then we can skip decode+encode if we're just proxying messages. + def default_stream_handler(broadcasting, coder:) + coder ||= ActiveSupport::JSON + stream_transmitter stream_decoder(coder: coder), broadcasting: broadcasting + end + + def stream_decoder(handler = identity_handler, coder:) + if coder + -> message { handler.(coder.decode(message)) } + else + handler + end + end + + def stream_transmitter(handler = identity_handler, broadcasting:) + via = "streamed from #{broadcasting}" + -> (message) do - transmit ActiveSupport::JSON.decode(message), via: "streamed from #{broadcasting}" + transmit handler.(message), via: via end end + + def identity_handler + -> message { message } + end end end end |