X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/73cf2bb90245787fbbd7c18da51329524c40f6af..c4b2d43234205a0d9b1310e55b1f00dee9c20625:/services/api/app/middlewares/rack_socket.rb

diff --git a/services/api/app/middlewares/rack_socket.rb b/services/api/app/middlewares/rack_socket.rb
index e2ca570af6..1b301e27ab 100644
--- a/services/api/app/middlewares/rack_socket.rb
+++ b/services/api/app/middlewares/rack_socket.rb
@@ -1,16 +1,40 @@
+# Copyright (C) The Arvados Authors. All rights reserved.
+#
+# SPDX-License-Identifier: AGPL-3.0
+
 require 'rack'
 require 'faye/websocket'
 require 'eventmachine'
 
+# A Rack middleware to handle inbound websocket connection requests and hand
+# them over to the faye websocket library.
 class RackSocket
 
   DEFAULT_ENDPOINT  = '/websocket'
 
+  # Stop EventMachine on signal, this should give it a chance to to unwind any
+  # open connections.
   def die_gracefully_on_signal
     Signal.trap("INT") { EM.stop }
     Signal.trap("TERM") { EM.stop }
   end
 
+  # Create a new RackSocket handler
+  # +app+  The next layer of the Rack stack.
+  #
+  # Accepts options:
+  # +:handler+ (Required) A class to handle new connections.  #initialize will
+  # call handler.new to create the actual handler instance object.  When a new
+  # websocket connection is established, #on_connect on the handler instance
+  # object will be called with the new connection.
+  #
+  # +:mount+ The HTTP request path that will be recognized for websocket
+  # connect requests, defaults to '/websocket'.
+  #
+  # +:websocket_only+  If true, the server will only handle websocket requests,
+  # and all other requests will result in an error.  If false, unhandled
+  # non-websocket requests will be passed along on to 'app' in the usual Rack
+  # way.
   def initialize(app = nil, options = nil)
     @app = app if app.respond_to?(:call)
     @options = [app, options].grep(Hash).first || {}
@@ -24,28 +48,46 @@ class RackSocket
         if forked && EM.reactor_running?
           EM.stop
         end
-        Thread.new {
-          EM.run
-        }
+        Thread.new do
+          begin
+            EM.run
+          ensure
+            ActiveRecord::Base.connection.close
+          end
+        end
         die_gracefully_on_signal
       end
     else
       # faciliates debugging
       Thread.abort_on_exception = true
       # just spawn a thread and start it up
-      Thread.new {
-        EM.run
-      }
+      Thread.new do
+        begin
+          EM.run
+        ensure
+          ActiveRecord::Base.connection.close
+        end
+      end
     end
 
+    # Create actual handler instance object from handler class.
     @handler = @options[:handler].new
   end
 
+  # Handle websocket connection request, or pass on to the next middleware
+  # supplied in +app+ initialize (unless +:websocket_only+ option is true, in
+  # which case return an error response.)
+  # +env+ the Rack environment with information about the request.
   def call env
     request = Rack::Request.new(env)
     if request.path_info == @endpoint and Faye::WebSocket.websocket?(env)
-      ws = Faye::WebSocket.new(env)
+      if @handler.overloaded?
+        return [503, {"Content-Type" => "text/plain"}, ["Too many connections, try again later."]]
+      end
+
+      ws = Faye::WebSocket.new(env, nil, :ping => 30)
 
+      # Notify handler about new connection
       @handler.on_connect ws
 
       # Return async Rack response