Introduce .with_deferred_parent_expiration

lib/identity_cache.rb

@@ -191,6 +191,16 @@ def fetch_multi(*keys)
  result
  end
 
+ def with_deferred_parent_expiration
+ # Bonus: Do this in one external call (if possible)
+ Thread.current[:deferred_parent_expiration] = true
+ Thread.current[:parent_records_for_cache_expiry] = Set.new
+
+ yield
+
+ Thread.current[:parent_records_for_cache_expiry].each(&:expire_primary_index)
+ end
+
  def with_fetch_read_only_records(value = true)
  old_value = Thread.current[:identity_cache_fetch_read_only_records]
  Thread.current[:identity_cache_fetch_read_only_records] = value

lib/identity_cache/parent_model_expiration.rb

@@ -47,6 +47,10 @@ def expire_parent_caches
  add_parents_to_cache_expiry_set(parents_to_expire)
  parents_to_expire.select! { |parent| parent.class.primary_cache_index_enabled }
  parents_to_expire.reduce(true) do |all_expired, parent|
+ if Thread.current[:deferred_parent_expiration]
+ Thread.current[:parent_records_for_cache_expiry] << parent
+ next parent
+ end
  parent.expire_primary_index && all_expired
  end
  end

test/index_cache_test.rb

@@ -166,6 +166,84 @@ def test_unique_cache_index_with_non_id_primary_key
  assert_equal(123, KeyedRecord.fetch_by_value("a").id)
  end
 
+ def test_with_deferred_parent_expiration
+ # TODO: Delete these notes
+ # Done: Create a record (`Item`) with associated records (`AssociatedRecord`) outside of "recorded space"
+ # Done: Start recording externals
+ # Done: Open defer block
+ # Done: Open tx
+ # Done: Delete all of the associated records
+ # Done: Inside defer block (outside tx) assert that no external calls have been made yet
+ # Done: Outside defer block (outside tx) assert that:
+ # - External calls have now been made
+ # - `Item` was expired only once
+ # - `AssociatedRecord` was expired once each
+
+ Item.send(:cache_has_many, :associated_records, embed: true)
+
+ @parent = Item.create!(title: "bob")
+ @records = @parent.associated_records.create!([{ name: "foo" }, { name: "bar" }, { name: "baz" }])
+
+ @memcached_spy = Spy.on(backend, :write).and_call_through
+
+ expected_item_expiration_count = Array(@parent).count
+ expected_associated_record_expiration_count = @records.count
+
+ IdentityCache.with_deferred_parent_expiration do
+ @parent.transaction do
+ @parent.associated_records.destroy_all
+ end
+ assert_equal(expected_associated_record_expiration_count, @memcached_spy.calls.count)
+ end
+
+ expired_cache_keys = @memcached_spy.calls.map(&:args).map(&:first)
+ item_expiration_count = expired_cache_keys.count { _1.include?("Item") }
+ associated_record_expiration_count = expired_cache_keys.count { _1.include?("AssociatedRecord") }
+
+ assert_operator(@memcached_spy.calls.count, :>, 0)
+ assert_equal(expected_item_expiration_count, item_expiration_count)
+ assert_equal(expected_associated_record_expiration_count, associated_record_expiration_count)
+ end
+
+ def test_deep_association_with_deferred_parent_expiration
+ # OPTIONAL / EXTRA CREDIT: What happens when nested association does the same thing? Prod/PV/IIV case?
+
+ AssociatedRecord.send(:has_many, :deeply_associated_records, dependent: :destroy)
+ Item.send(:cache_has_many, :associated_records, embed: true)
+
+ @parent = Item.create!(title: "bob")
+ @records = @parent.associated_records.create!([{ name: "foo" }, { name: "bar" }, { name: "baz" }])
+ @records.each do
+ _1.deeply_associated_records.create!([
+ { name: "a", item: @parent },
+ { name: "b", item: @parent },
+ { name: "c", item: @parent },
+ ])
+ end
+
+ @memcached_spy = Spy.on(backend, :write).and_call_through
+
+ expected_item_expiration_count = Array(@parent).count
+ expected_associated_record_expiration_count = @records.count
+ expected_deeply_associated_record_expiration_count = @records.flat_map(&:deeply_associated_records).count
+
+ IdentityCache.with_deferred_parent_expiration do
+ @parent.transaction do
+ @parent.associated_records.destroy_all
+ end
+ end
+
+ expired_cache_keys = @memcached_spy.calls.map(&:args).map(&:first)
+ item_expiration_count = expired_cache_keys.count { _1.include?("Item") }
+ associated_record_expiration_count = expired_cache_keys.count { _1.include?(":AssociatedRecord:") }
+ deeply_associated_record_expiration_count = expired_cache_keys.count { _1.include?("DeeplyAssociatedRecord") }
+
+ assert_operator(@memcached_spy.calls.count, :>, 0)
+ assert_equal(expected_item_expiration_count, item_expiration_count)
+ assert_equal(expected_associated_record_expiration_count, associated_record_expiration_count)
+ assert_equal(expected_deeply_associated_record_expiration_count, deeply_associated_record_expiration_count)
+ end
+
  private
 
  def cache_key(unique: false)