Fix SystemStackError when paranoid models have a circular `dependen…

…t: :destroy`

- Previously, paranoid models with a circular `dependent: :destroy` would recursively try to delete eachother
- Add a variable to check if the destroy callback has already been
called for that model
- Similar fix to rails/rails#18548

lib/paranoia.rb

@@ -1,8 +1,6 @@
 require 'active_record' unless defined? ActiveRecord
 
-if [ActiveRecord::VERSION::MAJOR, ActiveRecord::VERSION::MINOR] == [5, 2]
-  require 'paranoia/active_record_5_2'
-end
+require 'paranoia/active_record_5_2'
 
 module Paranoia
   @@default_sentinel_value = nil
@@ -305,7 +303,7 @@ def build_relation(klass, *args)
     class UniquenessValidator < ActiveModel::EachValidator
       prepend UniquenessParanoiaValidator
     end
-    
+
     class AssociationNotSoftDestroyedValidator < ActiveModel::EachValidator
       def validate_each(record, attribute, value)
         # if association is soft destroyed, add an error

lib/paranoia/active_record_5_2.rb

@@ -4,6 +4,9 @@ def handle_dependency
 
     case options[:dependent]
     when :destroy
+      @_destroy_callback_already_called ||= false
+      return if @_destroy_callback_already_called
+      @_destroy_callback_already_called = true
       target.destroy
       if target.respond_to?(:paranoia_destroyed?)
         raise ActiveRecord::Rollback unless target.paranoia_destroyed?
@@ -23,7 +26,10 @@ def delete(method = options[:dependent])
       when :delete
         target.delete
       when :destroy
+        @_destroy_callback_already_called ||= false
+        return if @_destroy_callback_already_called
         target.destroyed_by_association = reflection
+        @_destroy_callback_already_called = true
         target.destroy
         if target.respond_to?(:paranoia_destroyed?)
           throw(:abort) unless target.paranoia_destroyed?

test/paranoia_test.rb

@@ -46,8 +46,10 @@ def setup!
     'active_column_models' => 'deleted_at DATETIME, active BOOLEAN',
     'active_column_model_with_uniqueness_validations' => 'name VARCHAR(32), deleted_at DATETIME, active BOOLEAN',
     'paranoid_model_with_belongs_to_active_column_model_with_has_many_relationships' => 'name VARCHAR(32), deleted_at DATETIME, active BOOLEAN, active_column_model_with_has_many_relationship_id INTEGER',
-    'active_column_model_with_has_many_relationships' => 'name VARCHAR(32), deleted_at DATETIME, active BOOLEAN', 
-    'without_default_scope_models' => 'deleted_at DATETIME'
+    'active_column_model_with_has_many_relationships' => 'name VARCHAR(32), deleted_at DATETIME, active BOOLEAN',
+    'without_default_scope_models' => 'deleted_at DATETIME',
+    'paranoid_has_one_dependent_destroys' => 'deleted_at DATETIME',
+    'paranoid_belongs_to_dependent_destroys' => 'deleted_at DATETIME, paranoid_has_one_dependent_destroy_id INTEGER'
   }.each do |table_name, columns_as_sql_string|
     ActiveRecord::Base.connection.execute "CREATE TABLE #{table_name} (id INTEGER NOT NULL PRIMARY KEY, #{columns_as_sql_string})"
   end
@@ -189,11 +191,11 @@ def test_scoping_behavior_for_paranoid_models
     p2 = ParanoidModel.create(:parent_model => parent2)
     p1.destroy
     p2.destroy
-    
+
     assert_equal 0, parent1.paranoid_models.count
     assert_equal 1, parent1.paranoid_models.only_deleted.count
 
-    assert_equal 2, ParanoidModel.only_deleted.joins(:parent_model).count    
+    assert_equal 2, ParanoidModel.only_deleted.joins(:parent_model).count
     assert_equal 1, parent1.paranoid_models.deleted.count
     assert_equal 0, parent1.paranoid_models.without_deleted.count
     p3 = ParanoidModel.create(:parent_model => parent1)
@@ -206,7 +208,7 @@ def test_only_deleted_with_joins
     c1 = ActiveColumnModelWithHasManyRelationship.create(name: 'Jacky')
     c2 = ActiveColumnModelWithHasManyRelationship.create(name: 'Thomas')
     p1 = ParanoidModelWithBelongsToActiveColumnModelWithHasManyRelationship.create(name: 'Hello', active_column_model_with_has_many_relationship: c1)
-    
+
     c1.destroy
     assert_equal 1, ActiveColumnModelWithHasManyRelationship.count
     assert_equal 1, ActiveColumnModelWithHasManyRelationship.only_deleted.count
@@ -1053,6 +1055,18 @@ def test_counter_cache_column_on_restore
       related_model.restore
       assert_equal 1, parent_model_with_counter_cache_column.reload.related_models_count
     end
+
+    def test_circular_dependent_destroy_has_one_belongs_to
+      has_one_dependent_destroy = ParanoidHasOneDependentDestroy.create
+      belongs_to_dependent_destroy = ParanoidBelongsToDependentDestroy.create
+      belongs_to_dependent_destroy.paranoid_has_one_dependent_destroy = has_one_dependent_destroy
+      belongs_to_dependent_destroy.save!
+
+      belongs_to_dependent_destroy.destroy
+
+      refute has_one_dependent_destroy.reload.deleted_at.nil?
+      refute belongs_to_dependent_destroy.reload.deleted_at.nil?
+    end
   end
 
   private
@@ -1356,6 +1370,16 @@ class PolymorphicModel < ActiveRecord::Base
   belongs_to :parent, polymorphic: true
 end
 
+class ParanoidHasOneDependentDestroy < ActiveRecord::Base
+  acts_as_paranoid
+  has_one :paranoid_belongs_to_dependent_destroy, dependent: :destroy
+end
+
+class ParanoidBelongsToDependentDestroy < ActiveRecord::Base
+  acts_as_paranoid
+  belongs_to :paranoid_has_one_dependent_destroy, dependent: :destroy
+end
+
 module Namespaced
   def self.table_name_prefix
     "namespaced_"