Class: MessageBus::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/message_bus/client.rb

Overview

Represents a connected subscriber and delivers published messages over its connected socket.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts) ⇒ Client

Returns a new instance of Client.

Parameters:

  • opts (Hash)

Options Hash (opts):

  • :client_id (String) —

    the unique ID provided by the client

  • :user_id (String, Integer) — default: `nil` —

    the user ID the client was authenticated for

  • :group_ids (Array<String,Integer>) — default: `[]` —

    the group IDs the authenticated client is a member of

  • :site_id (String) — default: `nil` —

    the site ID the client was authenticated for; used for hosting multiple applications or instances of an application against a single message_bus

  • :seq (#to_i) — default: `0` —

    the connection sequence number the client provided when connecting

  • :message_bus (MessageBus::Instance) — default: `MessageBus` —

    a specific instance of message_bus



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# File 'lib/message_bus/client.rb', line 38

def initialize(opts)
  self.client_id = opts[:client_id]
  self.user_id = opts[:user_id]
  self.group_ids = opts[:group_ids] || []
  self.site_id = opts[:site_id]
  self.seq = opts[:seq].to_i
  self.connect_time = Time.now
  @lock = Mutex.new
  @bus = opts[:message_bus] || MessageBus
  @subscriptions = {}
  @chunks_sent = 0
  @async_response = nil
  @io = nil
  @wrote_headers = false
end

Instance Attribute Details

#async_response ⇒ Thin::AsyncResponse?

Returns:



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# File 'lib/message_bus/client.rb', line 20

def async_response
  @async_response
end

#cleanup_timer ⇒ MessageBus::TimerThread::Cancelable

Returns a timer job that is used to auto-disconnect the client at the configured long-polling interval.

Returns:



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# File 'lib/message_bus/client.rb', line 18

def cleanup_timer
  @cleanup_timer
end

#client_id ⇒ String

Returns the unique ID provided by the client.

Returns:

  • (String) —

    the unique ID provided by the client



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# File 'lib/message_bus/client.rb', line 7

def client_id
  @client_id
end

#connect_time ⇒ Time

Returns the time at which the client connected.

Returns:

  • (Time) —

    the time at which the client connected



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# File 'lib/message_bus/client.rb', line 13

def connect_time
  @connect_time
end

#group_ids ⇒ Array<String,Integer>

Returns the group IDs the authenticated client is a member of.

Returns:

  • (Array<String,Integer>) —

    the group IDs the authenticated client is a member of



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# File 'lib/message_bus/client.rb', line 11

def group_ids
  @group_ids
end

#headers ⇒ Hash<String => String>

Returns custom headers to include in HTTP responses.

Returns:

  • (Hash<String => String>) —

    custom headers to include in HTTP responses



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# File 'lib/message_bus/client.rb', line 24

def headers
  @headers
end

#io ⇒ IO

Returns the HTTP socket the client is connected on.

Returns:

  • (IO) —

    the HTTP socket the client is connected on



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# File 'lib/message_bus/client.rb', line 22

def io
  @io
end

#seq ⇒ Integer

Returns the connection sequence number the client provided when connecting.

Returns:

  • (Integer) —

    the connection sequence number the client provided when connecting



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# File 'lib/message_bus/client.rb', line 26

def seq
  @seq
end

#site_id ⇒ String

Returns the site ID the client was authenticated for; used for hosting multiple.

Returns:

  • (String) —

    the site ID the client was authenticated for; used for hosting multiple



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# File 'lib/message_bus/client.rb', line 15

def site_id
  @site_id
end

#use_chunked ⇒ Boolean

Returns whether or not the client should use chunked encoding.

Returns:

  • (Boolean) —

    whether or not the client should use chunked encoding



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# File 'lib/message_bus/client.rb', line 28

def use_chunked
  @use_chunked
end

#user_id ⇒ String, Integer

Returns the user ID the client was authenticated for.

Returns:

  • (String, Integer) —

    the user ID the client was authenticated for



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# File 'lib/message_bus/client.rb', line 9

def user_id
  @user_id
end

Instance Method Details

#<<(msg) ⇒ void

This method returns an undefined value.

Delivers a message to the client, even if it’s empty

Parameters:



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# File 'lib/message_bus/client.rb', line 121

def <<(msg)
  json = messages_to_json([msg])
  if use_chunked
    write_chunk json
  else
    write_and_close json
  end
end

#allowed?(msg) ⇒ Boolean

Returns whether or not the client has permission to receive the passed message.

Parameters:

Returns:

  • (Boolean) —

    whether or not the client has permission to receive the passed message



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# File 'lib/message_bus/client.rb', line 133

def allowed?(msg)
  client_allowed = !msg.client_ids || msg.client_ids.length == 0 || msg.client_ids.include?(self.client_id)

  user_allowed = false
  group_allowed = false

  has_users = msg.user_ids && msg.user_ids.length > 0
  has_groups = msg.group_ids && msg.group_ids.length > 0

  if has_users
    user_allowed = msg.user_ids.include?(self.user_id)
  end

  if has_groups
    group_allowed = (
      msg.group_ids - (self.group_ids || [])
    ).length < msg.group_ids.length
  end

  has_permission = client_allowed && (user_allowed || group_allowed || (!has_users && !has_groups))

  return has_permission if !has_permission

  filters_allowed = true

  len = @bus.client_message_filters.length
  while len > 0
    len -= 1
    channel_prefix, blk = @bus.client_message_filters[len]

    if msg.channel.start_with?(channel_prefix)
      filters_allowed = blk.call(msg)
      break if !filters_allowed
    end
  end

  filters_allowed
end

#backlog ⇒ Array<MessageBus::Message>

Returns the set of messages the client is due to receive, based on its subscriptions and permissions. Includes status message if any channels have no messages available and the client requested a message newer than the newest on the channel, or when there are messages available that the client doesn’t have permission for.

Returns:

  • (Array<MessageBus::Message>) —

    the set of messages the client is due to receive, based on its subscriptions and permissions. Includes status message if any channels have no messages available and the client requested a message newer than the newest on the channel, or when there are messages available that the client doesn’t have permission for.



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# File 'lib/message_bus/client.rb', line 177

def backlog
  r = []
  new_message_ids = nil

  last_bus_ids = @bus.last_ids(*@subscriptions.keys, site_id: site_id)

  @subscriptions.each do |k, v|
    last_client_id = v.to_i
    last_bus_id = last_bus_ids[k]

    if last_client_id < -1 # Client requesting backlog relative to bus position
      last_client_id = last_bus_id + last_client_id + 1
      last_client_id = 0 if last_client_id < 0
    elsif last_client_id == -1 # Client not requesting backlog
      next
    elsif last_client_id == last_bus_id # Client already up-to-date
      next
    elsif last_client_id > last_bus_id # Client ahead of the bus
      @subscriptions[k] = -1
      next
    end

    messages = @bus.backlog(k, last_client_id, site_id)

    messages.each do |msg|
      if allowed?(msg)
        r << msg
      else
        new_message_ids ||= {}
        new_message_ids[k] = msg.message_id
      end
    end
  end

  # stats message for all newly subscribed
  status_message = nil
  @subscriptions.each do |k, v|
    if v.to_i == -1 || (new_message_ids && new_message_ids[k])
      status_message ||= {}
      @subscriptions[k] = status_message[k] = last_bus_ids[k]
    end
  end

  r << MessageBus::Message.new(-1, -1, '/__status', status_message) if status_message

  r || []
end

#close ⇒ Object

Closes the client connection



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# File 'lib/message_bus/client.rb', line 61

def close
  if cleanup_timer
    # concurrency may nil cleanup timer
    cleanup_timer.cancel rescue nil
    self.cleanup_timer = nil
  end
  ensure_closed!
end

#closed? ⇒ Boolean

Returns whether the connection is closed or not.

Returns:

  • (Boolean) —

    whether the connection is closed or not



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# File 'lib/message_bus/client.rb', line 95

def closed?
  !@async_response && !@io
end

#deliver_backlog(backlog) ⇒ void

This method returns an undefined value.

Delivers a backlog of messages to the client, if there is anything in it. If chunked encoding/streaming is in use, will keep the connection open; if not, will close it.

Parameters:



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# File 'lib/message_bus/client.rb', line 76

def deliver_backlog(backlog)
  if backlog.length > 0
    if use_chunked
      write_chunk(messages_to_json(backlog))
    else
      write_and_close messages_to_json(backlog)
    end
  end
end

#ensure_first_chunk_sent ⇒ Object

If no data has yet been sent to the client, sends an empty chunk; prevents clients from entering a timeout state if nothing is delivered initially.



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# File 'lib/message_bus/client.rb', line 88

def ensure_first_chunk_sent
  if use_chunked && @chunks_sent == 0
    write_chunk("[]")
  end
end

#subscribe(channel, last_seen_id) ⇒ void

This method returns an undefined value.

Subscribes the client to messages on a channel, optionally from a defined starting point.

Parameters:

  • channel (String) —

    the channel to subscribe to

  • last_seen_id (Integer, nil) —

    the ID of the last message the client received. If nil, will be subscribed from the head of the backlog.



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# File 'lib/message_bus/client.rb', line 106

def subscribe(channel, last_seen_id)
  last_seen_id = nil if last_seen_id == ""
  last_seen_id ||= @bus.last_id(channel)
  @subscriptions[channel] = last_seen_id.to_i
end

#subscriptions ⇒ Hash<String => Integer>

Returns the active subscriptions, mapping channel names to last seen message IDs.

Returns:

  • (Hash<String => Integer>) —

    the active subscriptions, mapping channel names to last seen message IDs



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# File 'lib/message_bus/client.rb', line 114

def subscriptions
  @subscriptions
end

#synchronize { ... } ⇒ void

This method returns an undefined value.

Yields:

  • executed with a lock on the Client instance



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# File 'lib/message_bus/client.rb', line 56

def synchronize
  @lock.synchronize { yield }
end