Merge pull request rails#44983 from shiro16/dalli-store-optimised-cac…

…he-read_multi

Fixed: MemCacheStore#read_multi_entries NoMethodError: undefined method `expired?` for nil:NilClass

activesupport/lib/active_support/cache/mem_cache_store.rb

@@ -255,7 +255,7 @@ def read_multi_entries(names, **options)
           raw_values.each do |key, value|
             entry = deserialize_entry(value, raw: options[:raw])
 
-            unless entry.expired? || entry.mismatched?(normalize_version(keys_to_names[key], options))
+            unless entry.nil? || entry.expired? || entry.mismatched?(normalize_version(keys_to_names[key], options))
               values[keys_to_names[key]] = entry.value
             end
           end

activesupport/test/cache/stores/mem_cache_store_test.rb

@@ -287,6 +287,13 @@ def test_can_load_raw_falsey_values_from_dalli_store_with_local_cache
     end
   end
 
+  def test_can_read_multi_entries_raw_values_from_dalli_store
+    key = "test-with-nil-value-the-way-the-dalli-store-did"
+
+    @cache.instance_variable_get(:@data).with { |c| c.set(@cache.send(:normalize_key, key, nil), nil, 0, compress: false) }
+    assert_equal({}, @cache.send(:read_multi_entries, [key]))
+  end
+
   private
     def random_string(length)
       (0...length).map { (65 + rand(26)).chr }.join