Fix Thread leakage when scoring or testing submissions

It is discouraged to do anything directly within the
Tubesock hijack block. We might only use the callbacks
(onopen, onmessage, onclose, onerror). Otherwise,
Tubesock might not close all Threads correctly and
will keep them awake every five seconds.

Gemfile

@@ -42,7 +42,7 @@ gem 'sass-rails'
 gem 'slim-rails'
 gem 'sorcery' # Causes a deprecation warning in Rails 6.0+, see: https://github.com/Sorcery/sorcery/pull/255
 gem 'telegraf'
-gem 'tubesock', github: 'gosukiwi/tubesock', branch: 'patch-1' # Switch to a fork which is compatible with Rails 5
+gem 'tubesock'
 gem 'turbolinks'
 gem 'webpacker'
 gem 'whenever', require: false

Gemfile.lock

@@ -6,15 +6,6 @@ GIT
       json (~> 2.6.1)
       structured_warnings (~> 0.4.0)
 
-GIT
-  remote: https://github.com/gosukiwi/tubesock.git
-  revision: 86a5ca4f7d3c3a7b9a727ad91df3b9b4912eda39
-  branch: patch-1
-  specs:
-    tubesock (0.2.7)
-      rack (>= 1.5.0)
-      websocket (>= 1.1.0)
-
 GIT
   remote: https://github.com/openHPI/proforma.git
   revision: dc68000325388e1d75f31be9e136a82edad8a56d
@@ -162,7 +153,7 @@ GEM
       regexp_parser (~> 2.2)
     erubi (1.10.0)
     eventmachine (1.2.7)
-    excon (0.92.1)
+    excon (0.92.2)
     factory_bot (6.2.1)
       activesupport (>= 5.0.0)
     factory_bot_rails (6.2.0)
@@ -238,7 +229,7 @@ GEM
     listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    loofah (2.15.0)
+    loofah (2.16.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
     mail (2.7.1)
@@ -264,7 +255,7 @@ GEM
     mnemosyne-ruby (1.12.1)
       activesupport (>= 4)
       bunny
-    msgpack (1.4.5)
+    msgpack (1.5.1)
     multi_json (1.15.0)
     multi_xml (0.6.0)
     nested_form (0.3.2)
@@ -287,7 +278,7 @@ GEM
       rack (>= 1.2, < 3)
     pagedown-bootstrap-rails (2.1.4)
       railties (> 3.1)
-    parallel (1.22.0)
+    parallel (1.22.1)
     parser (3.1.1.0)
       ast (~> 2.4.1)
     path_expander (1.1.0)
@@ -397,7 +388,7 @@ GEM
     rspec-expectations (3.11.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
-    rspec-mocks (3.11.0)
+    rspec-mocks (3.11.1)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-rails (5.1.1)
@@ -495,6 +486,9 @@ GEM
     temple (0.8.2)
     thor (1.2.1)
     tilt (2.0.10)
+    tubesock (0.2.9)
+      rack (>= 1.5.0)
+      websocket (>= 1.1.0)
     turbolinks (5.2.1)
       turbolinks-source (~> 5.2)
     turbolinks-source (5.2.0)
@@ -603,7 +597,7 @@ DEPENDENCIES
   sorcery
   spring
   telegraf
-  tubesock!
+  tubesock
   turbolinks
   web-console
   webmock

app/controllers/submissions_controller.rb

@@ -85,7 +85,10 @@ class SubmissionsController < ApplicationController
 
     hijack do |tubesock|
       client_socket = tubesock
-      return kill_client_socket(client_socket) if @embed_options[:disable_run]
+
+      client_socket.onopen do |_event|
+        kill_client_socket(client_socket) if @embed_options[:disable_run]
+      end
 
       client_socket.onclose do |_event|
         runner_socket&.close(:terminated_by_client)
@@ -177,16 +180,18 @@ class SubmissionsController < ApplicationController
 
   def score
     hijack do |tubesock|
-      return if @embed_options[:disable_score]
+      tubesock.onopen do |_event|
+        kill_client_socket(tubesock) if @embed_options[:disable_score]
 
-      tubesock.send_data(JSON.dump(@submission.calculate_score))
+        tubesock.send_data(JSON.dump(@submission.calculate_score))
-      # To enable hints when scoring a submission, uncomment the next line:
+        # To enable hints when scoring a submission, uncomment the next line:
-      # send_hints(tubesock, StructuredError.where(submission: @submission))
+        # send_hints(tubesock, StructuredError.where(submission: @submission))
+        kill_client_socket(tubesock)
+      end
     rescue Runner::Error => e
       tubesock.send_data JSON.dump({cmd: :status, status: :container_depleted})
-      Rails.logger.debug { "Runner error while scoring submission #{@submission.id}: #{e.message}" }
-    ensure
       kill_client_socket(tubesock)
+      Rails.logger.debug { "Runner error while scoring submission #{@submission.id}: #{e.message}" }
     end
   end
 
@@ -196,14 +201,16 @@ class SubmissionsController < ApplicationController
 
   def test
     hijack do |tubesock|
-      return kill_client_socket(tubesock) if @embed_options[:disable_run]
+      tubesock.onopen do |_event|
+        kill_client_socket(tubesock) if @embed_options[:disable_run]
 
-      tubesock.send_data(JSON.dump(@submission.test(@file)))
+        tubesock.send_data(JSON.dump(@submission.test(@file)))
+        kill_client_socket(tubesock)
+      end
     rescue Runner::Error => e
       tubesock.send_data JSON.dump({cmd: :status, status: :container_depleted})
-      Rails.logger.debug { "Runner error while testing submission #{@submission.id}: #{e.message}" }
-    ensure
       kill_client_socket(tubesock)
+      Rails.logger.debug { "Runner error while testing submission #{@submission.id}: #{e.message}" }
     end
   end