1 files changed, 75 insertions, 0 deletions
diff --git a/actioncable/lib/action_cable/server/worker.rb b/actioncable/lib/action_cable/server/worker.rb
new file mode 100644
index 0000000000..187c8f7939
--- /dev/null
+++ b/actioncable/lib/action_cable/server/worker.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+require "active_support/callbacks"
+require "active_support/core_ext/module/attribute_accessors_per_thread"
+require "concurrent"
+
+module ActionCable
+  module Server
+    # Worker used by Server.send_async to do connection work in threads.
+    class Worker # :nodoc:
+      include ActiveSupport::Callbacks
+
+      thread_mattr_accessor :connection
+      define_callbacks :work
+      include ActiveRecordConnectionManagement
+
+      attr_reader :executor
+
+      def initialize(max_size: 5)
+        @executor = Concurrent::ThreadPoolExecutor.new(
+          min_threads: 1,
+          max_threads: max_size,
+          max_queue: 0,
+        )
+      end
+
+      # Stop processing work: any work that has not already started
+      # running will be discarded from the queue
+      def halt
+        @executor.shutdown
+      end
+
+      def stopping?
+        @executor.shuttingdown?
+      end
+
+      def work(connection)
+        self.connection = connection
+
+        run_callbacks :work do
+          yield
+        end
+      ensure
+        self.connection = nil
+      end
+
+      def async_exec(receiver, *args, connection:, &block)
+        async_invoke receiver, :instance_exec, *args, connection: connection, &block
+      end
+
+      def async_invoke(receiver, method, *args, connection: receiver, &block)
+        @executor.post do
+          invoke(receiver, method, *args, connection: connection, &block)
+        end
+      end
+
+      def invoke(receiver, method, *args, connection:, &block)
+        work(connection) do
+          receiver.send method, *args, &block
+        rescue Exception => e
+          logger.error "There was an exception - #{e.class}(#{e.message})"
+          logger.error e.backtrace.join("\n")
+
+          receiver.handle_exception if receiver.respond_to?(:handle_exception)
+        end
+      end
+
+      private
+
+        def logger
+          ActionCable.server.logger
+        end
+    end
+  end
+end