1 files changed, 34 insertions, 12 deletions

diff --git a/actioncable/lib/action_cable/server/base.rb b/actioncable/lib/action_cable/server/base.rb
index 3385a4c9f3..778f5ffeed 100644
--- a/actioncable/lib/action_cable/server/base.rb
+++ b/actioncable/lib/action_cable/server/base.rb
@@ -1,9 +1,11 @@
+require 'monitor'
+
 module ActionCable
   module Server
-    # A singleton ActionCable::Server instance is available via ActionCable.server. It's used by the rack process that starts the cable server, but
-    # also by the user to reach the RemoteConnections instead for finding and disconnecting connections across all servers.
+    # 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 details.
+    # Also, this is the server instance used for broadcasting. See Broadcasting for more information.
     class Base
       include ActionCable::Server::Broadcasting
       include ActionCable::Server::Connections
@@ -13,10 +15,14 @@ module ActionCable
       def self.logger; config.logger; end
       delegate :logger, to: :config
 
+      attr_reader :mutex
+
       def initialize
+        @mutex = Monitor.new
+        @remote_connections = @event_loop = @worker_pool = @channel_classes = @pubsub = nil
       end
 
-      # Called by rack to setup the server.
+      # Called by Rack to setup the server.
       def call(env)
         setup_heartbeat_timer
         config.connection_class.new(self, env).process
@@ -27,30 +33,46 @@ module ActionCable
         remote_connections.where(identifiers).disconnect
       end
 
+      def restart
+        connections.each(&:close)
+
+        @mutex.synchronize do
+          worker_pool.halt if @worker_pool
+
+          @worker_pool = nil
+        end
+      end
+
       # Gateway to RemoteConnections. See that class for details.
       def remote_connections
-        @remote_connections ||= RemoteConnections.new(self)
+        @remote_connections || @mutex.synchronize { @remote_connections ||= RemoteConnections.new(self) }
+      end
+
+      def event_loop
+        @event_loop || @mutex.synchronize { @event_loop ||= config.event_loop_class.new }
       end
 
       # The thread worker pool for handling all the connection work on this server. Default size is set by config.worker_pool_size.
       def worker_pool
-        @worker_pool ||= ActionCable::Server::Worker.new(max_size: config.worker_pool_size)
+        @worker_pool || @mutex.synchronize { @worker_pool ||= ActionCable::Server::Worker.new(max_size: config.worker_pool_size) }
       end
 
-      # Requires and returns a hash of all the channel class constants keyed by name.
+      # Requires and returns a hash of all of the channel class constants, which are keyed by name.
       def channel_classes
-        @channel_classes ||= begin
-          config.channel_paths.each { |channel_path| require channel_path }
-          config.channel_class_names.each_with_object({}) { |name, hash| hash[name] = name.constantize }
+        @channel_classes || @mutex.synchronize do
+          @channel_classes ||= begin
+            config.channel_paths.each { |channel_path| require channel_path }
+            config.channel_class_names.each_with_object({}) { |name, hash| hash[name] = name.constantize }
+          end
         end
       end
 
       # Adapter used for all streams/broadcasting.
       def pubsub
-        @pubsub ||= config.pubsub_adapter.new(self)
+        @pubsub || @mutex.synchronize { @pubsub ||= config.pubsub_adapter.new(self) }
       end
 
-      # All the identifiers applied to the connection class associated with this server.
+      # All of the identifiers applied to the connection class associated with this server.
       def connection_identifiers
         config.connection_class.identifiers
       end