From dffbba1e2aed01748cfc79327946175ad51f6b4f Mon Sep 17 00:00:00 2001
From: Keenan Brock <keenan@thebrocks.net>
Date: Wed, 20 Apr 2016 11:23:56 -0400
Subject: schema_load triggers 2nd schema_load (via locking)

Currently, loading the schema (schema_load)
accesses the locking column (locking_column)
which defaults the value (reset_locking_column)
which invalidates the schema (reload_schema_from_cache)
which forces another schema load.

Good news:
The second schema_load does accesses locking_column,
but locking_column is set, so it does not reset_locking_column
and it does not trigger an infinite loop.

The solution is not invalidate the cache while default locking_column
---
 activerecord/lib/active_record/locking/optimistic.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'activerecord')

diff --git a/activerecord/lib/active_record/locking/optimistic.rb b/activerecord/lib/active_record/locking/optimistic.rb
index 1040327a5d..1e37ffefc6 100644
--- a/activerecord/lib/active_record/locking/optimistic.rb
+++ b/activerecord/lib/active_record/locking/optimistic.rb
@@ -150,7 +150,7 @@ module ActiveRecord
 
         # The version column used for optimistic locking. Defaults to +lock_version+.
         def locking_column
-          reset_locking_column unless defined?(@locking_column)
+          @locking_column = DEFAULT_LOCKING_COLUMN unless defined?(@locking_column)
           @locking_column
         end
 
-- 
cgit v1.2.3


From ba05b3c218568467277ea309dcfd10d34bf8e756 Mon Sep 17 00:00:00 2001
From: Keenan Brock <keenan@thebrocks.net>
Date: Wed, 20 Apr 2016 23:36:05 -0400
Subject: test the number of times the schema is loading

---
 activerecord/test/cases/schema_loading_test.rb | 53 ++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 activerecord/test/cases/schema_loading_test.rb

(limited to 'activerecord')

diff --git a/activerecord/test/cases/schema_loading_test.rb b/activerecord/test/cases/schema_loading_test.rb
new file mode 100644
index 0000000000..2815ccd842
--- /dev/null
+++ b/activerecord/test/cases/schema_loading_test.rb
@@ -0,0 +1,53 @@
+require 'thread'
+require "cases/helper"
+
+module SchemaLoadCounter
+  extend ActiveSupport::Concern
+
+  module ClassMethods
+    attr_accessor :load_schema_calls
+
+    def load_schema!
+      self.load_schema_calls ||= 0
+      self.load_schema_calls +=1
+      super
+    end
+  end
+end
+
+class SchemaLoadingTest < ActiveRecord::TestCase
+  def test_basic_model_is_loaded_once
+    klass = define_model
+    klass.new
+    assert_equal 1, klass.load_schema_calls
+  end
+
+  def test_model_with_custom_lock_is_loaded_once
+    klass = define_model do |c|
+      c.table_name = :lock_without_defaults_cust
+      c.locking_column = :custom_lock_version
+    end
+    klass.new
+    assert_equal 1, klass.load_schema_calls
+  end
+
+  def test_model_with_changed_custom_lock_is_loaded_twice
+    klass = define_model do |c|
+      c.table_name = :lock_without_defaults_cust
+    end
+    klass.new
+    klass.locking_column = :custom_lock_version
+    klass.new
+    assert_equal 2, klass.load_schema_calls
+  end
+
+  private
+
+    def define_model
+      Class.new(ActiveRecord::Base) do
+        include SchemaLoadCounter
+        self.table_name = :lock_without_defaults
+        yield self if block_given?
+      end
+    end
+end
-- 
cgit v1.2.3