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Action Cable Server Base

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
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Included Modules

Attributes

[R] config
[R] mutex

Class Public methods

logger()

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 21
def self.logger; config.logger; end

new(config: self.class.config)

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 26
def initialize(config: self.class.config)
  @config = config
  @mutex = Monitor.new
  @remote_connections = @event_loop = @worker_pool = @pubsub = nil
end

Instance Public methods

call(env)

Called by Rack to set up the server.

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 33
def call(env)
  return config.health_check_application.call(env) if env["PATH_INFO"] == config.health_check_path
  setup_heartbeat_timer
  config.connection_class.call.new(self, env).process
end

connection_identifiers()

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

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 90
def connection_identifiers
  config.connection_class.call.identifiers
end

disconnect(identifiers)

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

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 40
def disconnect(identifiers)
  remote_connections.where(identifiers).disconnect
end

event_loop()

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 65
def event_loop
  @event_loop || @mutex.synchronize { @event_loop ||= ActionCable::Connection::StreamEventLoop.new }
end

pubsub()

Adapter used for all streams/broadcasting.

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 85
def pubsub
  @pubsub || @mutex.synchronize { @pubsub ||= config.pubsub_adapter.new(self) }
end

remote_connections()

Gateway to RemoteConnections. See that class for details.

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 61
def remote_connections
  @remote_connections || @mutex.synchronize { @remote_connections ||= RemoteConnections.new(self) }
end

restart()

Source: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 44
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

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: show | on GitHub 

# File actioncable/lib/action_cable/server/base.rb, line 80
def worker_pool
  @worker_pool || @mutex.synchronize { @worker_pool ||= ActionCable::Server::Worker.new(max_size: config.worker_pool_size) }
end