Class: ActionCable::SubscriptionAdapter::PostgreSQL::Listener

Inherits:
SubscriberMap show all
Defined in:
actioncable/lib/action_cable/subscription_adapter/postgresql.rb

Instance Method Summary collapse

Methods inherited from SubscriberMap

#add_subscriber, #broadcast, #remove_subscriber

Constructor Details

#initialize(adapter, event_loop) ⇒ Listener

Returns a new instance of Listener.


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# File 'actioncable/lib/action_cable/subscription_adapter/postgresql.rb', line 74

def initialize(adapter, event_loop)
  super()

  @adapter = adapter
  @event_loop = event_loop
  @queue = Queue.new

  @thread = Thread.new do
    Thread.current.abort_on_exception = true
    listen
  end
end

Instance Method Details

#add_channel(channel, on_success) ⇒ Object


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# File 'actioncable/lib/action_cable/subscription_adapter/postgresql.rb', line 118

def add_channel(channel, on_success)
  @queue.push([:listen, channel, on_success])
end

#invoke_callbackObject


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# File 'actioncable/lib/action_cable/subscription_adapter/postgresql.rb', line 126

def invoke_callback(*)
  @event_loop.post { super }
end

#listenObject


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# File 'actioncable/lib/action_cable/subscription_adapter/postgresql.rb', line 87

def listen
  @adapter.with_subscriptions_connection do |pg_conn|
    catch :shutdown do
      loop do
        until @queue.empty?
          action, channel, callback = @queue.pop(true)

          case action
          when :listen
            pg_conn.exec("LISTEN #{pg_conn.escape_identifier channel}")
            @event_loop.post(&callback) if callback
          when :unlisten
            pg_conn.exec("UNLISTEN #{pg_conn.escape_identifier channel}")
          when :shutdown
            throw :shutdown
          end
        end

        pg_conn.wait_for_notify(1) do |chan, pid, message|
          broadcast(chan, message)
        end
      end
    end
  end
end

#remove_channel(channel) ⇒ Object


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# File 'actioncable/lib/action_cable/subscription_adapter/postgresql.rb', line 122

def remove_channel(channel)
  @queue.push([:unlisten, channel])
end

#shutdownObject


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# File 'actioncable/lib/action_cable/subscription_adapter/postgresql.rb', line 113

def shutdown
  @queue.push([:shutdown])
  Thread.pass while @thread.alive?
end