class Ably::Realtime::Connection
Enables the management of a connection to Ably
.
Constants
- DEFAULTS
Defaults for automatic connection recovery and timeouts
- EVENT
Describes the events emitted by a {Ably::Realtime::Connection} object. An event is either an UPDATE or a {Ably::Realtime::Connection::STATE}.
UPDATE RTN4h An event for changes to connection conditions for which the {Ably::Realtime::Connection::STATE} does not change.
- MAX_PROTOCOL_MESSAGE_BATCH_SIZE
Max number of messages to bundle in a single ProtocolMessage
- RECOVER_REGEX
Expected format for a connection recover key
- STATE
The current {Ably::Realtime::Connection::STATE} of the connection. Describes the realtime [Connection]{@link Connection} object states.
@spec RTN4d
INITIALIZED A connection with this state has been initialized but no connection has yet been attempted. CONNECTING A connection attempt has been initiated. The connecting state is entered as soon as the library
has completed initialization, and is reentered each time connection is re-attempted following disconnection.
CONNECTED A connection exists and is active. DISCONNECTED A temporary failure condition. No current connection exists because there is no network connectivity
or no host is available. The disconnected state is entered if an established connection is dropped, or if a connection attempt was unsuccessful. In the disconnected state the library will periodically attempt to open a new connection (approximately every 15 seconds), anticipating that the connection will be re-established soon and thus connection and channel continuity will be possible. In this state, developers can continue to publish messages as they are automatically placed in a local queue, to be sent as soon as a connection is reestablished. Messages published by other clients while this client is disconnected will be delivered to it upon reconnection, so long as the connection was resumed within 2 minutes. After 2 minutes have elapsed, recovery is no longer possible and the connection will move to the SUSPENDED state.
SUSPENDED A long term failure condition. No current connection exists because there is no network connectivity
or no host is available. The suspended state is entered after a failed connection attempt if there has then been no connection for a period of two minutes. In the suspended state, the library will periodically attempt to open a new connection every 30 seconds. Developers are unable to publish messages in this state. A new connection attempt can also be triggered by an explicit call to {Ably::Realtime::Connection#connect}. Once the connection has been re-established, channels will be automatically re-attached. The client has been disconnected for too long for them to resume from where they left off, so if it wants to catch up on messages published by other clients while it was disconnected, it needs to use the History API.
CLOSING An explicit request by the developer to close the connection has been sent to the
Ably
service.If a reply is not received from Ably within a short period of time, the connection is forcibly terminated and the connection state becomes CLOSED.
CLOSED The connection has been explicitly closed by the client. In the closed state, no reconnection attempts
are made automatically by the library, and clients may not publish messages. No connection state is preserved by the service or by the library. A new connection attempt can be triggered by an explicit call to {Ably::Realtime::Connection#connect}, which results in a new connection.
FAILED This state is entered if the client library encounters a failure condition that it cannot recover from.
This may be a fatal connection error received from the Ably service, for example an attempt to connect with an incorrect API key, or a local terminal error, for example the token in use has expired and the library does not have any way to renew it. In the failed state, no reconnection attempts are made automatically by the library, and clients may not publish messages. A new connection attempt can be triggered by an explicit call to {Ably::Realtime::Connection#connect}.
@return [Ably::Realtime::Connection::STATE]
Attributes
An internal queue used to manage unsent outgoing messages. You should never interface with this array directly @return [Array] @api private
An internal queue used to manage sent messages. You should never interface with this array directly @return [Array] @api private
{Ably::Realtime::Client} associated with this connection @return [Ably::Realtime::Client]
@return [String] The current host that is configured following a call to method {#determine_host} @api private
Configured recovery and timeout defaults for this {Connection}. See the configurable options in {Ably::Realtime::Client#initialize}. The defaults are immutable @return [Hash]
Connection
details of the currently established connection @return [Ably::Models::ConnectionDetails]
An {Ably::Models::ErrorInfo} object describing the last error received if a connection failure occurs.
@spec RTN14a
@return [Ably::Models::ErrorInfo,Ably::Exceptions::BaseAblyException]
A unique public identifier for this connection, used to identify this member.
@spec RTN8
@return [String]
A unique private connection key used to recover or resume a connection, assigned by Ably
. When recovering a connection explicitly, the recoveryKey is used in the recover client options as it contains both the key and the last message serial. This private connection key can also be used by other REST clients to publish on behalf of this client. See the publishing over REST on behalf of a realtime client docs for more info.
@spec RTN9
@return [String]
The Connection
manager responsible for creating, maintaining and closing the connection and underlying transport @return [Ably::Realtime::Connection::ConnectionManager] @api private
The serial number of the last message to be received on this connection, used automatically by the library when recovering or resuming a connection. When recovering a connection explicitly, the recoveryKey is used in the recover client options as it contains both the key and the last message serial.
@spec RTN10
@return [Integer]
Underlying socket transport used for this connection, for internal use by the client library @return [Ably::Realtime::Connection::WebsocketTransport] @api private
Public Class Methods
@api public
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 169 def initialize(client, options) @client = client @__outgoing_message_queue__ = [] @__pending_message_ack_queue__ = [] @defaults = DEFAULTS.dup options.each do |key, val| @defaults[key] = val if DEFAULTS.has_key?(key) end if options.kind_of?(Hash) @defaults.freeze # If a recover client options is provided, then we need to ensure that the msgSerial matches the # recover serial immediately at client library instantiation. This is done immediately so that any queued # publishes use the correct serial number for these queued messages as well. # There is no harm if the msgSerial is higher than expected if the recover fails. recovery_msg_serial = connection_recover_parts && connection_recover_parts[:msg_serial].to_i if recovery_msg_serial @client_msg_serial = recovery_msg_serial else reset_client_msg_serial end Client::IncomingMessageDispatcher.new client, self Client::OutgoingMessageDispatcher.new client, self @state_machine = ConnectionStateMachine.new(self) @state = STATE(state_machine.current_state) @manager = ConnectionManager.new(self) @current_host = client.endpoint.host end
Public Instance Methods
@!attribute [r] incoming_protocol_msgbus @return [Ably::Util::PubSub] Client
library internal incoming protocol message bus @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 397 def __incoming_protocol_msgbus__ @__incoming_protocol_msgbus__ ||= create_pub_sub_message_bus end
@!attribute [r] outgoing_protocol_msgbus @return [Ably::Util::PubSub] Client
library internal outgoing protocol message bus @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 390 def __outgoing_protocol_msgbus__ @__outgoing_protocol_msgbus__ ||= create_pub_sub_message_bus end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 456 def add_message_to_outgoing_queue(protocol_message) __outgoing_message_queue__ << protocol_message end
Returns false if messages cannot be published as a result of message queueing being disabled @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 567 def can_publish_messages? connected? || ( (initialized? || connecting? || disconnected?) && client.queue_messages ) end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 538 def clear_error_reason @error_reason = nil end
Causes the connection to close, entering the {Ably::Realtime::Connection::STATE} CLOSING state. Once closed, the library does not attempt to re-establish the connection without an explicit call to {Ably::Realtime::Connection#connect}.
@spec RTN12
@yield block is called as soon as this connection is in the Closed state
@return [EventMachine::Deferrable]
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 211 def close(&success_block) unless closing? || closed? unless can_transition_to?(:closing) return Ably::Util::SafeDeferrable.new_and_fail_immediately(logger, exception_for_state_change_to(:closing)) end transition_state_machine :closing end deferrable_for_state_change_to(STATE.Closed, &success_block) end
Following a new connection being made, the connection ID, connection key and connection serial need to match the details provided by the server.
@return [void] @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 365 def configure_new(connection_id, connection_key, connection_serial) @id = connection_id @key = connection_key update_connection_serial connection_serial end
Explicitly calling connect() is unnecessary unless the autoConnect attribute of the ClientOptions object is false. Unless already connected or connecting, this method causes the connection to open, entering the {Ably::Realtime::Connection::STATE} CONNECTING state.
@spec RTC1b, RTN3, RTN11
@yield block is called as soon as this connection is in the Connected state
@return [EventMachine::Deferrable]
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 231 def connect(&success_block) unless connecting? || connected? unless can_transition_to?(:connecting) return Ably::Util::SafeDeferrable.new_and_fail_immediately(logger, exception_for_state_change_to(:connecting)) end # If connect called in a suspended block, we want to ensure the other callbacks have finished their work first EventMachine.next_tick { transition_state_machine :connecting if can_transition_to?(:connecting) } end Ably::Util::SafeDeferrable.new(logger).tap do |deferrable| deferrable.callback do yield if block_given? end succeed_callback = deferrable.method(:succeed) fail_callback = deferrable.method(:fail) unsafe_once(:connected) do deferrable.succeed off(&fail_callback) end unsafe_once(:failed, :closed, :closing) do deferrable.fail off(&succeed_callback) end end end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 579 def connection_state_ttl defaults[:max_connection_state_ttl] || # undocumented max TTL configuration (details && details.connection_state_ttl) || defaults.fetch(:connection_state_ttl) end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 585 def connection_state_ttl=(val) @connection_state_ttl = val end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 573 def create_transport(host, port, url, &block) logger.debug { "Connection: EventMachine connecting to #{host}:#{port} with URL: #{url}" } EventMachine.connect(host, port, WebsocketTransport, self, url.to_s, &block) end
@return [EventMachine::Deferrable] @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 467 def create_websocket_transport EventMachine::DefaultDeferrable.new.tap do |websocket_deferrable| # Getting auth params can be blocking so uses a Deferrable client.auth.auth_params.tap do |auth_deferrable| auth_deferrable.callback do |auth_params| url_params = auth_params.merge( 'format' => client.protocol, 'echo' => client.echo_messages, 'v' => Ably::PROTOCOL_VERSION, 'agent' => client.rest_client.agent ) # Use native websocket heartbeats if possible, but allow Ably protocol heartbeats url_params['heartbeats'] = if defaults.fetch(:websocket_heartbeats_disabled) 'true' else 'false' end url_params['clientId'] = client.auth.client_id if client.auth.has_client_id? url_params.merge!(client.transport_params) if connection_resumable? url_params.merge! resume: key, connection_serial: serial logger.debug { "Resuming connection key #{key} with serial #{serial}" } elsif connection_recoverable? url_params.merge! recover: connection_recover_parts[:recover], connectionSerial: connection_recover_parts[:connection_serial] logger.debug { "Recovering connection with key #{client.recover}" } unsafe_once(:connected, :closed, :failed) do client.disable_automatic_connection_recovery end end url = URI(client.endpoint).tap do |endpoint| endpoint.query = URI.encode_www_form(url_params) end determine_host do |host| # Ensure the hostname matches the fallback host name url.hostname = host url.port = port begin logger.debug { "Connection: Opening socket connection to #{host}:#{port}/#{url.path}?#{url.query}" } @transport = create_transport(host, port, url) do |websocket_transport| websocket_deferrable.succeed websocket_transport end rescue EventMachine::ConnectionError => error websocket_deferrable.fail error end end end auth_deferrable.errback do |error| websocket_deferrable.fail error end end end end
Determines the correct host name to use for the next connection attempt and updates current_host
@yield [String] The host name used for this connection, for network connection failures a {Ably::FALLBACK_HOSTS fallback host} is used to route around networking or intermittent problems if an Internet connection is available @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 404 def determine_host raise ArgumentError, 'Block required' unless block_given? if should_use_fallback_hosts? internet_up? do |internet_is_up_result| @current_host = if internet_is_up_result client.fallback_endpoint.host else client.endpoint.host end yield current_host end else @current_host = client.endpoint.host yield current_host end end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 590 def heartbeat_interval # See RTN23a (details && details.max_idle_interval).to_i + defaults.fetch(:realtime_request_timeout) end
@yield [Boolean] True if an internet connection check appears to be up following an HTTP request to a reliable CDN @return [EventMachine::Deferrable] @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 327 def internet_up? url = "http#{'s' if client.use_tls?}:#{Ably::INTERNET_CHECK.fetch(:url)}" EventMachine::DefaultDeferrable.new.tap do |deferrable| EventMachine::AblyHttpRequest::HttpRequest.new(url, tls: { verify_peer: true }).get.tap do |http| http.errback do yield false if block_given? deferrable.fail Ably::Exceptions::ConnectionFailed.new("Unable to connect to #{url}", nil, Ably::Exceptions::Codes::CONNECTION_FAILED) end http.callback do EventMachine.next_tick do result = http.response_header.status == 200 && http.response.strip == Ably::INTERNET_CHECK.fetch(:ok_text) yield result if block_given? if result deferrable.succeed else deferrable.fail Ably::Exceptions::ConnectionFailed.new("Unexpected response from #{url} (#{http.response_header.status})", 400, Ably::Exceptions::Codes::BAD_REQUEST) end end end end end end
@!attribute [r] logger @return [Logger] The {Ably::Logger} for this client.
Configure the log_level with the `:log_level` option, refer to {Ably::Realtime::Client#initialize}
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 435 def logger client.logger end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 461 def notify_message_dispatcher_of_new_message(protocol_message) __outgoing_protocol_msgbus__.publish :protocol_message, protocol_message end
Remove a registered connection resume callback @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 561 def off_resume(&callback) resume_callbacks.delete(callback) end
Provides a simple hook to inject a callback when a connection is successfully resumed @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 555 def on_resume(&callback) resume_callbacks << callback end
When connected, sends a heartbeat ping to the Ably
server and executes the callback with any error and the response time in milliseconds when a heartbeat ping request is echoed from the server. This can be useful for measuring true round-trip latency to the connected Ably
server.
@spec RTN13
@yield [Integer] if a block is passed to this method, then this block will be called once the ping heartbeat is received with the time elapsed in seconds.
If the ping is not received within an acceptable timeframe, the block will be called with +nil+ as he first argument
@example
client = Ably::Rest::Client.new(key: 'key.id:secret') client.connection.ping do |elapsed_s| puts "Ping took #{elapsed_s}s" end
@return [Ably::Util::SafeDeferrable]
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 276 def ping(&block) if initialized? || suspended? || closing? || closed? || failed? error = Ably::Models::ErrorInfo.new(message: "Cannot send a ping when the connection is #{state}", code: Ably::Exceptions::Codes::DISCONNECTED) return Ably::Util::SafeDeferrable.new_and_fail_immediately(logger, error) end Ably::Util::SafeDeferrable.new(logger).tap do |deferrable| started = nil finished = false ping_id = SecureRandom.hex(16) heartbeat_action = Ably::Models::ProtocolMessage::ACTION.Heartbeat wait_for_ping = lambda do |protocol_message| next if finished if protocol_message.action == heartbeat_action && protocol_message.id == ping_id finished = true __incoming_protocol_msgbus__.unsubscribe(:protocol_message, &wait_for_ping) time_passed = Time.now.to_f - started.to_f deferrable.succeed time_passed safe_yield block, time_passed if block_given? end end once_or_if(STATE.Connected) do next if finished started = Time.now send_protocol_message action: heartbeat_action.to_i, id: ping_id __incoming_protocol_msgbus__.subscribe :protocol_message, &wait_for_ping end once_or_if([:suspended, :closing, :closed, :failed]) do next if finished finished = true deferrable.fail Ably::Models::ErrorInfo.new(message: "Ping failed as connection has changed state to #{state}", code: Ably::Exceptions::Codes::DISCONNECTED) end EventMachine.add_timer(defaults.fetch(:realtime_request_timeout)) do next if finished finished = true __incoming_protocol_msgbus__.unsubscribe(:protocol_message, &wait_for_ping) error_msg = "Ping timed out after #{defaults.fetch(:realtime_request_timeout)}s" logger.warn { error_msg } deferrable.fail Ably::Models::ErrorInfo.new(message: error_msg, code: Ably::Exceptions::Codes::TIMEOUT_ERROR) safe_yield block, nil if block_given? end end end
@!attribute [r] port @return [Integer] The default port used for this connection
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 428 def port client.use_tls? ? client.custom_tls_port || 443 : client.custom_port || 80 end
The recovery key string can be used by another client to recover this connection’s state in the recover client options property. See connection state recover options for more information.
@spec RTN16b, RTN16c
@return [String]
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 356 def recovery_key "#{key}:#{serial}:#{client_msg_serial}" if connection_resumable? end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 528 def release_websocket_transport @transport = nil end
Resets the client message serial (msgSerial) sent to Ably
for each new {Ably::Models::ProtocolMessage} (see client_msg_serial
) @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 599 def reset_client_msg_serial @client_msg_serial = -1 end
Disable automatic resume of a connection @return [void] @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 382 def reset_resume_info @key = nil @serial = nil end
Add protocol message to the outgoing message queue and notify the dispatcher that a message is ready to be sent
@param [Ably::Models::ProtocolMessage] protocol_message @return [void] @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 445 def send_protocol_message(protocol_message) add_message_serial_if_ack_required_to(protocol_message) do Ably::Models::ProtocolMessage.new(protocol_message, logger: logger).tap do |message| add_message_to_outgoing_queue message notify_message_dispatcher_of_new_message message logger.debug { "Connection: Prot msg queued =>: #{message.action} #{message}" } end end end
When a hearbeat or any other message from Ably
is received we know it’s alive, see RTN23 @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 606 def set_connection_confirmed_alive @last_liveness_event = Time.now manager.reset_liveness_timer end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 543 def set_connection_details(connection_details) @details = connection_details end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 533 def set_failed_connection_error_reason(error) @error_reason = error end
@api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 612 def time_since_connection_confirmed_alive? Time.now.to_i - @last_liveness_event.to_i end
Executes registered callbacks for a successful connection resume event @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 549 def trigger_resumed resume_callbacks.each(&:call) end
Store last received connection serial so that the connection can be resumed from the last known point-in-time @return [void] @api private
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 375 def update_connection_serial(connection_serial) @serial = connection_serial end
Private Instance Methods
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 646 def add_message_serial_if_ack_required_to(protocol_message) if Ably::Models::ProtocolMessage.ack_required?(protocol_message[:action]) add_message_serial_to(protocol_message) { yield } else yield end end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 654 def add_message_serial_to(protocol_message) @client_msg_serial += 1 protocol_message[:msgSerial] = client_msg_serial yield rescue StandardError => e @client_msg_serial -= 1 raise e end
The client message serial (msgSerial) is incremented for every message that is published that requires an ACK. Note that this is different to the connection serial that contains the last known serial number received from the server.
A message serial number does not guarantee a message has been received, only sent. A connection serial guarantees the server has received the message and is thus used for connection recovery and resumes. @return [Integer] starting at -1 indicating no messages sent, 0 when the first message is sent
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 629 def client_msg_serial @client_msg_serial end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 689 def connection_recover_parts client.recover.to_s.match(RECOVER_REGEX) end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 685 def connection_recoverable? connection_recover_parts end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 668 def connection_resumable? !key.nil? && !serial.nil? && connection_state_available? end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 672 def connection_state_available? return true if connected? return false if time_since_connection_confirmed_alive? > connection_state_ttl + details.max_idle_interval connected_last = state_history.reverse.find { |connected| connected.fetch(:state) == :connected } if connected_last.nil? false else true end end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 637 def create_pub_sub_message_bus Ably::Util::PubSub.new( coerce_into: lambda do |event| raise KeyError, "Expected :protocol_message, :#{event} is disallowed" unless event == :protocol_message :protocol_message end ) end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 705 def custom_host? !!client.custom_realtime_host end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 697 def custom_port? if client.use_tls? !!client.custom_tls_port else !!client.custom_port end end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 717 def disconnected_from_connected_state? most_recent_state_changes = state_history.last(3).first(2) # Ignore current state # A valid connection was disconnected most_recent_state_changes.last.fetch(:state) == Connection::STATE.Disconnected && most_recent_state_changes.first.fetch(:state) == Connection::STATE.Connected end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 693 def production? client.environment.nil? || client.environment == :production end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 633 def resume_callbacks @resume_callbacks ||= [] end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 733 def second_reconnect_attempt_for(state, first_attempt_count) previous_state == state && manager.retry_count_for_state(state) >= first_attempt_count end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 709 def should_use_fallback_hosts? if client.fallback_hosts && !client.fallback_hosts.empty? if connecting? && previous_state && !disconnected_from_connected_state? use_fallback_if_disconnected? || use_fallback_if_suspended? end end end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 725 def use_fallback_if_disconnected? second_reconnect_attempt_for(:disconnected, 1) end
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 729 def use_fallback_if_suspended? second_reconnect_attempt_for(:suspended, 2) # on first suspended state use default Ably host again end
Simply wait until the next EventMachine tick to ensure Connection
initialization is complete
# File lib/submodules/ably-ruby/lib/ably/realtime/connection.rb, line 664 def when_initialized EventMachine.next_tick { yield } end