A singleton ActionCable::Server instance is available via ActionCable.server. It's used by the Rack process that starts the Action Cable server, but is also used by the user to reach the RemoteConnections object, which is used for finding and disconnecting connections across all servers.

Also, this is the server instance used for broadcasting. See Broadcasting for more information.

Methods

Included Modules

Attributes

[R] config
[R] mutex

Class Public methods

logger()

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 19
      def self.logger; config.logger; end
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new(config: self.class.config)

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 24
      def initialize(config: self.class.config)
        @config = config
        @mutex = Monitor.new
        @remote_connections = @event_loop = @worker_pool = @pubsub = nil
      end
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Instance Public methods

call(env)

Called by Rack to set up the server.

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 31
      def call(env)
        setup_heartbeat_timer
        config.connection_class.call.new(self, env).process
      end
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connection_identifiers()

All of the identifiers applied to the connection class associated with this server.

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 87
      def connection_identifiers
        config.connection_class.call.identifiers
      end
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disconnect(identifiers)

Disconnect all the connections identified by identifiers on this server or any others via RemoteConnections.

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 37
      def disconnect(identifiers)
        remote_connections.where(identifiers).disconnect
      end
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event_loop()

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 62
      def event_loop
        @event_loop || @mutex.synchronize { @event_loop ||= ActionCable::Connection::StreamEventLoop.new }
      end
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pubsub()

Adapter used for all streams/broadcasting.

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 82
      def pubsub
        @pubsub || @mutex.synchronize { @pubsub ||= config.pubsub_adapter.new(self) }
      end
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remote_connections()

Gateway to RemoteConnections. See that class for details.

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 58
      def remote_connections
        @remote_connections || @mutex.synchronize { @remote_connections ||= RemoteConnections.new(self) }
      end
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restart()

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 41
      def restart
        connections.each do |connection|
          connection.close(reason: ActionCable::INTERNAL[:disconnect_reasons][:server_restart])
        end

        @mutex.synchronize do
          # Shutdown the worker pool
          @worker_pool.halt if @worker_pool
          @worker_pool = nil

          # Shutdown the pub/sub adapter
          @pubsub.shutdown if @pubsub
          @pubsub = nil
        end
      end
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worker_pool()

The worker pool is where we run connection callbacks and channel actions. We do as little as possible on the server's main thread. The worker pool is an executor service that's backed by a pool of threads working from a task queue. The thread pool size maxes out at 4 worker threads by default. Tune the size yourself with config.action_cable.worker_pool_size.

Using Active Record, Redis, etc within your channel actions means you'll get a separate connection from each thread in the worker pool. Plan your deployment accordingly: 5 servers each running 5 Puma workers each running an 8-thread worker pool means at least 200 database connections.

Also, ensure that your database connection pool size is as least as large as your worker pool size. Otherwise, workers may oversubscribe the database connection pool and block while they wait for other workers to release their connections. Use a smaller worker pool or a larger database connection pool instead.

📝 Source code 
# File actioncable/lib/action_cable/server/base.rb, line 77
      def worker_pool
        @worker_pool || @mutex.synchronize { @worker_pool ||= ActionCable::Server::Worker.new(max_size: config.worker_pool_size) }
      end
🔎 See on GitHub