attempt to backport PR QueueClassic#318 to v3.1.0

lib/queue_classic.rb

@@ -58,12 +58,17 @@ def self.has_connection?
 
   def self.default_conn_adapter
     return @conn_adapter if defined?(@conn_adapter) && @conn_adapter
+
     if rails_connection_sharing_enabled?
-      @conn_adapter = ConnAdapter.new(ActiveRecord::Base.connection.raw_connection)
-    else
-      @conn_adapter = ConnAdapter.new
+      # AR connection should never be memoized, as call to
+      # ActiveRecord::Base.clear_active_connections! in current thread
+      # will cause it to return to AR pool, and it will become shared
+      # between memoized value and pool. And Rails does
+      # clear_active_connections! after each request
+      return ConnAdapter.new(ActiveRecord::Base.connection.raw_connection)
     end
-    @conn_adapter
+
+    @conn_adapter = ConnAdapter.new
   end
 
   def self.default_conn_adapter=(conn)

lib/queue_classic/queue.rb

@@ -17,7 +17,7 @@ def conn_adapter=(a)
     end
 
     def conn_adapter
-      @adapter ||= QC.default_conn_adapter
+      (defined?(@adapter) && @adapter) || QC.default_conn_adapter
     end
 
     # enqueue(m,a) inserts a row into the jobs table and trigger a notification.

queue_classic.gemspec

@@ -19,4 +19,5 @@ Gem::Specification.new do |s|
   s.require_paths = %w[lib]
 
   s.add_dependency "pg", ">= 0.17", "< 0.19"
+  s.add_development_dependency "activerecord", "~> 5.2.3"
 end

test/activerecord_integration_test.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require File.expand_path("../helper.rb", __FILE__)
+require 'active_record'
+
+class QueueClassicActiverecorgdIntegrationTest < QCTest
+  def setup
+    super
+    reset_globals
+    ActiveRecord::Base.establish_connection "#{ENV["DATABASE_URL"]}?pool=1"
+  end
+
+  def teardown
+    super
+  end
+
+  def test_connection_not_returned_to_pool
+    take_connection_until_checked = Mutex.new
+    conn_adapter_ready = Queue.new
+    connection_from_adapter = nil
+    take_connection_until_checked.synchronize do
+      Thread.new do
+        with_env 'QC_RAILS_DATABASE' => 'true' do
+          conn_adapter_ready.push QC.default_conn_adapter.connection
+        end
+        take_connection_until_checked.synchronize {}
+        ActiveRecord::Base.clear_active_connections!
+      end
+
+      connection_from_adapter = conn_adapter_ready.pop
+
+      ActiveRecord::Base.connection_pool.reap
+
+      # Pool now has no free connections available
+      assert_raises(ActiveRecord::ConnectionTimeoutError) do
+        ActiveRecord::Base.connection_pool.checkout 0.1
+      end
+    end
+  end
+end

test/helper.rb

@@ -2,9 +2,13 @@
 $: << File.expand_path("test")
 
 require "bundler"
-Bundler.setup :default, :test
+Bundler.setup :default, :development, :test
 
 ENV["DATABASE_URL"] ||= "postgres:///queue_classic_test"
+# Rails integration is enabled if ActiveRecord module constant is
+# present, and it will be present after tests that use
+# ActiveRecord. So forcifully disable Rails by default.
+ENV["QC_RAILS_DATABASE"] = "false"
 
 require "queue_classic"
 require "stringio"
@@ -18,6 +22,7 @@ def setup
 
   def teardown
     QC.delete_all
+    reset_globals
   end
 
   def init_db
@@ -29,6 +34,11 @@ def init_db
     c.disconnect
   end
 
+  def reset_globals
+    QC.default_conn_adapter = nil
+    QC.default_queue = nil
+  end
+
   def capture_stderr_output
     original_stderr = $stderr
     $stderr = StringIO.new
@@ -51,4 +61,16 @@ def capture_debug_output
     $stdout = original_stdout
   end
 
+  def with_env(temporary_environment)
+    original_environment = {}
+    temporary_environment.each do |name, value|
+      original_environment[name] = ENV[name]
+      ENV[name] = value
+    end
+    yield
+  ensure
+    original_environment.each { |name, value| ENV[name] = value }
+  end
+
+
 end

test/lib/queue_classic_rails_connection_test.rb

@@ -1,23 +1,72 @@
 require File.expand_path("../../helper.rb", __FILE__)
 
 class QueueClassicRailsConnectionTest < QCTest
-  def before_setup
-    Object.send :const_set, :ActiveRecord, Module.new
-    ActiveRecord.const_set :Base, Module.new
+  # Stubs ActiveRecord::Base with empty module. Works if real
+  # ActiveRecord is loaded too, restoring it when unstubbing.
+  class StubActiveRecord
+    def stub
+      stub_module
+      stub_base
+    end
+
+    def unstub
+      unstub_base
+      unstub_module
+    end
+
+    private
+
+    def stub_module
+      unless Object.const_defined? :ActiveRecord
+        Object.send :const_set, :ActiveRecord, Module.new
+        @module_stubbed = true
+      else
+        @module_stubbed = false
+      end
+    end
+
+    def unstub_module
+      if @module_stubbed
+        Object.send :remove_const, :ActiveRecord
+      end
+    end
 
+    def stub_base
+      if Object.const_defined? 'ActiveRecord::Base'
+        @activerecord_orig = ActiveRecord::Base
+        ActiveRecord.send :remove_const, :Base
+      else
+        @activerecord_orig = nil
+      end
+      ActiveRecord.const_set :Base, Module.new
+    end
+
+    def unstub_base
+      ActiveRecord.send :remove_const, :Base
+      if @activerecord_orig
+        ActiveRecord.send :const_set, :Base, @activerecord_orig
+      end
+    end
+  end
+
+  def setup
+    super
+    @active_record_stub = StubActiveRecord.new
+    @active_record_stub.stub
     @original_conn_adapter = QC.default_conn_adapter
     QC.default_conn_adapter = nil
   end
 
-  def after_teardown
-    ActiveRecord.send :remove_const, :Base
-    Object.send :remove_const, :ActiveRecord
-
+  def teardown
+    @active_record_stub.unstub
     QC.default_conn_adapter = @original_conn_adapter
+    super
   end
 
   def test_uses_active_record_connection_if_exists
-    connection = get_connection
+    connection = with_env 'QC_RAILS_DATABASE' => nil do
+      get_connection
+    end
     assert connection.verify
   end
 

test/worker_test.rb

@@ -178,7 +178,7 @@ def test_work_with_more_complex_construct
   end
 
   def test_init_worker_with_arg
-    set_database 'postgres:///invalid'
+    set_database 'postgres:///queue_classic_test'
 
     conn = PG::Connection.connect(dbname: 'queue_classic_test')
     QC::Worker.new connection: conn
@@ -201,9 +201,10 @@ def test_init_worker_with_database_url
   end
 
   def test_init_worker_without_conn
-    set_database nil
-
-    assert_raises(ArgumentError) { QC::Worker.new }
+    assert_raises(ArgumentError) do
+      set_database nil
+      QC::Worker.new
+    end
 
   ensure
     reset_database