Revert #93, bring back the ping worker.

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2019-03-23 14:16:02 -0400 using RuboCop version 0.58.2.
+# on 2019-05-17 17:30:35 -0400 using RuboCop version 0.58.2.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -16,6 +16,11 @@ Layout/IndentHeredoc:
     - 'sample_apps/sample_app_activerecord/commands/help.rb'
     - 'sample_apps/sample_app_mongoid/commands/help.rb'
 
+# Offense count: 1
+Lint/HandleExceptions:
+  Exclude:
+    - 'lib/slack-ruby-bot-server/ping.rb'
+
 # Offense count: 3
 # Configuration parameters: Blacklist.
 # Blacklist: (?-mix:(^|\s)(EO[A-Z]{1}|END)(\s|$))

README.md

@@ -196,6 +196,22 @@ SlackRubyBotServer::Service.instance # MyService
 SlackRubyBotServer::Service.instance.url # https://www.example.com
 ```
 
+#### Ping Worker
+
+Each `SlackRubyBotServer::Server` instance will start a ping worker that will periodically check the online status of the bot via the Slack web [auth.test](https://api.slack.com/methods/auth.test) and [users.getPresence](https://api.slack.com/methods/users.getPresence) APIs, and will forcefully close the connection if the bot goes offline, causing an automatic reconnect.
+
+You can configure the ping interval, number of retries before restart, and disable the ping worker entirely.
+
+```ruby
+SlackRubyBotServer.configure do |config|
+  config.ping = {
+    enabled: true, # set to false to disable the ping worker
+    ping_interval: 30, # interval in seconds
+    retry_count: 3 # number of unsuccessful retries until a restart
+  }
+end
+```
+
 ### Access Tokens
 
 By default the implementation of [Team](lib/slack-ruby-bot-server/models/team) stores a `bot_access_token` as `token` that grants a certain amount of privileges to the bot user as described in [Slack OAuth Docs](https://api.slack.com/docs/oauth) along with `activated_user_access_token` that represents the token of the installing user. You may not want a bot user at all, or may require different auth scopes, such as `users.profile:read` to access user profile information via `Slack::Web::Client#users_profile_get`. To change required scopes make the following changes.

lib/slack-ruby-bot-server.rb

@@ -4,6 +4,7 @@
 require 'slack-ruby-bot'
 require 'slack-ruby-bot-server/service'
 require 'slack-ruby-bot-server/server'
+require 'slack-ruby-bot-server/ping'
 require 'slack-ruby-bot-server/config'
 
 require 'slack-ruby-bot-server/ext'

lib/slack-ruby-bot-server/config.rb

@@ -4,9 +4,11 @@ module Config
 
     attr_accessor :server_class
     attr_accessor :service_class
+    attr_accessor :ping
     attr_accessor :database_adapter
 
     def reset!
+      self.ping = nil
       self.server_class = SlackRubyBotServer::Server
       self.service_class = SlackRubyBotServer::Service
       self.database_adapter = if defined?(::Mongoid)

lib/slack-ruby-bot-server/ping.rb

@@ -0,0 +1,149 @@
+require 'active_support/core_ext/string/filters'
+
+module SlackRubyBotServer
+  class Ping
+    attr_reader :client
+    attr_reader :options
+    attr_reader :error_count
+
+    def initialize(client, options = {})
+      @options = options
+      @client = client
+      @error_count = 0
+    end
+
+    def start!
+      ::Async::Reactor.run do |task|
+        run(task)
+      end
+    end
+
+    private
+
+    def run(task)
+      logger.debug "PING: #{owner}, every #{ping_interval} second(s)"
+      loop do
+        task.sleep ping_interval
+        break unless check!
+      end
+      logger.debug "PING: #{owner}, done."
+    rescue StandardError => e
+      logger.error e
+      raise e
+    end
+
+    def check!
+      if online?
+        @error_count = 0
+        true
+      else
+        down!
+      end
+    rescue StandardError => e
+      case e.message
+      when 'account_inactive', 'invalid_auth' then
+        logger.warn "Error pinging team #{owner.id}: #{e.message}, terminating."
+        false
+      else
+        message = e.message.truncate(24, separator: "\n", omission: '...')
+        logger.warn "Error pinging team #{owner.id}: #{message}."
+        true
+      end
+    end
+
+    def offline?
+      !online?
+    end
+
+    def online?
+      presence.online
+    end
+
+    def presence
+      owner.ping![:presence]
+    end
+
+    def down!
+      logger.warn "DOWN: #{owner}, #{retries_left} #{retries_left == 1 ? 'retry' : 'retries'} left"
+      @error_count += 1
+      return true if retries_left?
+      restart!
+    end
+
+    def restart!
+      logger.warn "RESTART: #{owner}"
+      close_driver
+      emit_close
+      close_connection
+      false
+    rescue StandardError => e
+      logger.warn "Error restarting team #{owner.id}: #{e.message}."
+      true
+    end
+
+    def close_connection
+      return unless connection
+      connection.close
+    rescue Async::Wrapper::Cancelled
+      # ignore, from connection.close
+    rescue StandardError => e
+      logger.warn "Error closing connection for #{owner.id}: #{e.message}."
+      raise e
+    end
+
+    def close_driver
+      return unless driver
+      driver.close
+    rescue StandardError => e
+      logger.warn "Error closing driver for #{owner.id}: #{e.message}."
+      raise e
+    end
+
+    def emit_close
+      return unless driver
+      driver.emit(:close, WebSocket::Driver::CloseEvent.new(1001, 'bot offline'))
+    rescue StandardError => e
+      logger.warn "Error sending :close event to driver for #{owner.id}: #{e.message}."
+      raise e
+    end
+
+    def ping_interval
+      options[:ping_interval] || 60
+    end
+
+    def retries_left?
+      retry_count - error_count >= 0
+    end
+
+    def retries_left
+      [0, retry_count - error_count].max
+    end
+
+    def retry_count
+      options[:retry_count] || 2
+    end
+
+    def socket
+      client.instance_variable_get(:@socket) if client
+    end
+
+    def driver
+      socket.instance_variable_get(:@driver) if socket
+    end
+
+    def connection
+      driver.instance_variable_get(:@socket) if driver
+    end
+
+    def logger
+      @logger ||= begin
+        STDOUT.sync = true
+        Logger.new(STDOUT)
+      end
+    end
+
+    def owner
+      client.owner
+    end
+  end
+end

lib/slack-ruby-bot-server/server.rb

@@ -7,6 +7,7 @@ class Server < SlackRubyBot::Server
     def initialize(attrs = {})
       attrs = attrs.dup
       @team = attrs.delete(:team)
+      @ping_options = attrs.delete(:ping) || {}
       raise 'Missing team' unless @team
       attrs[:token] = @team.token
       super(attrs)
@@ -23,8 +24,19 @@ def restart!(wait = 1)
 
     private
 
+    attr_reader :ping_options
+
+    def create_ping
+      return unless !ping_options.key?(:enabled) || ping_options[:enabled]
+      SlackRubyBotServer::Ping.new(client, ping_options)
+    end
+
     def open!
       client.owner = team
+      client.on :open do |_event|
+        worker = create_ping
+        worker.start! if worker
+      end
     end
   end
 end

lib/slack-ruby-bot-server/service.rb

@@ -31,6 +31,7 @@ def start!(team)
       run_callbacks :starting, team
       logger.info "Starting team #{team}."
       options = { team: team }
+      options[:ping] = SlackRubyBotServer::Config.ping if SlackRubyBotServer::Config.ping
       server = SlackRubyBotServer::Config.server_class.new(options)
       start_server! team, server
       run_callbacks :started, team

slack-ruby-bot-server.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |spec|
   spec.files         = `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(spec)/}) }
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'async-websocket'
+  spec.add_dependency 'async-websocket', '~> 0.8.0'
   spec.add_dependency 'foreman'
   spec.add_dependency 'grape'
   spec.add_dependency 'grape-roar', '>= 0.4.0'