Class: Skyfall::Stream

Inherits:
Object
  • Object
show all
Extended by:
Events
Defined in:
lib/skyfall/stream.rb

Overview

Base class of a websocket client. It provides basic websocket client functionality such as connecting to the service, keeping the connection alive and running lifecycle callbacks.

In most cases, you will not create instances of this class directly, but rather use either Firehose or Jetstream. Use this class as a superclass if you need to implement some custom client for a websocket API that isn’t supported yet.

Direct Known Subclasses

Firehose, Jetstream

Constant Summary collapse

MAX_RECONNECT_INTERVAL = 
300

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(server) ⇒ Stream

Returns a new instance of Stream.

Parameters:

  • server (String) —

    Address of the server to connect to. Expects a string with either just a hostname, or a ws:// or wss:// URL.

Raises:

  • (ArgumentError) —

    if the server parameter is invalid



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# File 'lib/skyfall/stream.rb', line 83

def initialize(server)
  @root_url = build_root_url(server)

  @handlers = {}
  @auto_reconnect = true
  @check_heartbeat = false
  @connection_attempts = 0
  @heartbeat_interval = 10
  @heartbeat_timeout = 300
  @last_update = nil
  @user_agent = default_user_agent

  @handlers[:error] = proc { |e| puts "ERROR: #{e}" }
end

Instance Attribute Details

#auto_reconnect ⇒ Boolean

If enabled, the client will try to reconnect if the connection is closed unexpectedly. (Default: true)

When the reconnect attempt fails, it will wait with an exponential backoff delay before retrying again, up to MAX_RECONNECT_INTERVAL seconds.

Returns:

  • (Boolean) 


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# File 'lib/skyfall/stream.rb', line 32

def auto_reconnect
  @auto_reconnect
end

#check_heartbeat ⇒ Boolean

If enabled, runs a timer which does periodical “heatbeat checks”.

The heartbeat timer is started when the client connects to the service, and checks if the stream hasn’t stalled and is still regularly sending new messages. If no messages are detected for some period of time, the client forces a reconnect.

This is not enabled by default, because depending on the service you’re connecting to, it might be normal to not receive any messages for a while.

Returns:

  • (Boolean)

See Also:



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# File 'lib/skyfall/stream.rb', line 57

def check_heartbeat
  @check_heartbeat
end

#heartbeat_interval ⇒ Numeric

Interval in seconds between heartbeat checks (default: 10). Only used if #check_heartbeat is set.

Returns:

  • (Numeric) 


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# File 'lib/skyfall/stream.rb', line 61

def heartbeat_interval
  @heartbeat_interval
end

#heartbeat_timeout ⇒ Numeric

Number of seconds without messages after which reconnect is triggered (default: 300). Only used if #check_heartbeat is set.

Returns:

  • (Numeric) 


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# File 'lib/skyfall/stream.rb', line 66

def heartbeat_timeout
  @heartbeat_timeout
end

#last_update ⇒ Time? (readonly)

Time when the most recent message was received from the websocket.

Note: this is _local time_ when the message was received; this is different from the timestamp of the message, which is the server time of the original source (PDS) when emitting the message, and different from a potential created_at saved in the record.

Returns:

  • (Time, nil) 


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# File 'lib/skyfall/stream.rb', line 75

def last_update
  @last_update
end

#user_agent ⇒ String

User agent sent in the header when connecting.

Default value is #default_user_agent = #version_string ‘(Skyfall/x.y)`. It’s recommended to set it or extend it with some information that indicates what service this is and who is running it (e.g. a Bluesky handle).

Examples:

client.user_agent = "my.service (@my.handle) #{client.version_string}"

Returns:

  • (String) 


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# File 'lib/skyfall/stream.rb', line 43

def user_agent
  @user_agent
end

Instance Method Details

#connect ⇒ nil

Opens a connection to the configured websocket.

This method starts an EventMachine reactor on the current thread, and will only return once the connection is closed.

Returns:

  • (nil)

Raises:



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# File 'lib/skyfall/stream.rb', line 108

def connect
  return if @ws

  if @handlers[:message].nil? && @handlers[:raw_message].nil?
    raise ConfigError, "Either on_message or on_raw_message handler needs to be set"
  end

  url = build_websocket_url

  @handlers[:connecting]&.call(url)

  @reconnect_timer&.cancel
  @reconnect_timer = nil

  raise ReactorActiveError if existing_reactor?

  @engines_on = true

  EM.run do
    EventMachine.error_handler do |e|
      @handlers[:error]&.call(e)
    end

    @ws = build_websocket_client(url)

    @ws.on(:open) do |e|
      @handlers[:connect]&.call
      @last_update = Time.now
      start_heartbeat_timer
    end

    @ws.on(:message) do |msg|
      @reconnecting = false
      @connection_attempts = 0
      @last_update = Time.now
      handle_message(msg)
    end

    @ws.on(:error) do |e|
      @handlers[:error]&.call(e)
    end

    @ws.on(:close) do |e|
      @ws = nil

      if @reconnecting || @auto_reconnect && @engines_on
        @handlers[:reconnect]&.call

        @reconnect_timer&.cancel
        @reconnect_timer = EM::Timer.new(reconnect_delay) do
          @connection_attempts += 1
          connect
        end
      else
        stop_heartbeat_timer
        @engines_on = false
        @handlers[:disconnect]&.call
        EM.stop_event_loop unless @ws
      end
    end
  end
end

#default_user_agent ⇒ String

Default user agent sent when connecting to the service. (Currently ‘“##version_string”`)

Returns:

  • (String) 


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# File 'lib/skyfall/stream.rb', line 200

def default_user_agent
  version_string
end

#disconnect ⇒ nil Also known as: close

Closes the connection and stops the EventMachine reactor thread.

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 186

def disconnect
  return unless EM.reactor_running?

  @reconnecting = false
  @engines_on = false
  EM.stop_event_loop
end

#inspect ⇒ String

Returns a string with a representation of the object for debugging purposes.

Returns:

  • (String) 


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# File 'lib/skyfall/stream.rb', line 303

def inspect
  vars = inspectable_variables.map { |v| "#{v}=#{instance_variable_get(v).inspect}" }.join(", ")
  "#<#{self.class}:0x#{object_id} #{vars}>"
end

#on_connect(block) ⇒ nil

Defines a callback to be run after a connection to the websocket is opened. Can be also run as a setter on_connect=.

Parameters:

  • block (Proc)

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 238

event_handler :connect

#on_connecting(block) {|url| ... } ⇒ nil

Defines a callback to be run when the client tries to open a connection to the websocket. Can be also run as a setter on_connecting=.

Parameters:

  • block (Proc)

Yield Parameters:

  • url (String) —

    URL to which the client is connecting

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 230

event_handler :connecting

#on_disconnect(block) ⇒ nil

Defines a callback to be run after a connection to the websocket is closed (and the client does not reconnect). Can be also run as a setter on_disconnect=.

This callback is not run when on_reconnect fires.

Parameters:

  • block (Proc)

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 266

event_handler :disconnect

#on_error(block) {|error| ... } ⇒ nil

Defines a callback to be run when the websocket connection returns an error. Can be also run as a setter on_error=.

Default handler prints the error to stdout.

Parameters:

  • block (Proc)

Yield Parameters:

  • error (Exception) —

    the received error

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 298

event_handler :error

#on_message(block) {|message| ... } ⇒ nil

Defines a callback to be run when a message is received, passing the message as a parsed object of an appropriate message class. Can be also run as a setter on_message=.

Parameters:

  • block (Proc)

Yield Parameters:

  • message (Object) —

    parsed message of an appropriate class

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 256

event_handler :message

#on_raw_message(block) {|data| ... } ⇒ nil

Defines a callback to be run when a message is received, passing a raw data packet as received from the websocket (plain text or binary). Can be also run as a setter on_raw_message=.

Parameters:

  • block (Proc)

Yield Parameters:

  • data (String) —

    payload of the received message

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 247

event_handler :raw_message

#on_reconnect(block) ⇒ nil

Defines a callback to be run when a connection to the websocket is broken, but the client initiates or schedules a reconnect (which may happen after a delay). Can be also run as a setter on_reconnect=.

Parameters:

  • block (Proc)

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 275

event_handler :reconnect

#on_timeout(block) ⇒ nil

Defines a callback to be run when the heartbeat timer forces a reconnect. A reconnect is triggered after not receiving any messages for a period of time specified in #heartbeat_timeout (if #check_heartbeat is enabled). Can be also run as a setter on_timeout=.

This callback is also followed by on_reconnect.

Parameters:

  • block (Proc)

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 286

event_handler :timeout

#reconnect ⇒ nil

Forces a reconnect, closing the connection and calling #connect again.

Returns:

  • (nil) 


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# File 'lib/skyfall/stream.rb', line 175

def reconnect
  @reconnecting = true
  @connection_attempts = 0

  @ws ? @ws.close : connect
end

#version_string ⇒ String

Skyfall version string for use in user agent strings (‘“Skyfall/x.y”`).

Returns:

  • (String) 


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# File 'lib/skyfall/stream.rb', line 208

def version_string
  "Skyfall/#{Skyfall::VERSION}"
end