Merge pull request #2361 from alexzherdev/2358-sha1

Add config to use SHA1 instead of MD5 for caching

CHANGELOG.md

@@ -6,6 +6,8 @@ Breaking changes:
 
 Features:
 
+- [#2361](https://github.com/rails-api/active_model_serializers/pull/2361) Add `ActiveModelSerializers.config.use_sha1_digests` to allow customization of the hashing algorithm used for serializer caching (@alexzherdev)
+
 Fixes:
 
 - [#2344](https://github.com/rails-api/active_model_serializers/pull/2344) Fixes #2341 introduced since #2223 (@wasifhossain)

docs/general/configuration_options.md

@@ -111,6 +111,18 @@ ActiveModelSerializers.config.serializer_lookup_chain.unshift(
 
 See [lookup_chain.rb](https://github.com/rails-api/active_model_serializers/blob/master/lib/active_model_serializers/lookup_chain.rb) for further explanations and examples.
 
+#### use_sha1_digests
+
+Determines which hashing algorithm to use internally when caching serializers.
+
+Possible values:
+
+- `true`
+- `false` (default)
+
+When `true`, ActiveModelSerializers will use SHA1. Otherwise, it will default to using MD5.
+Be warned that changing this value may result in serializer caches being invalidated.
+
 ## JSON API
 
 ##### jsonapi_resource_type

lib/active_model/serializer/concerns/caching.rb

@@ -56,7 +56,8 @@ def _cache_digest
         def digest_caller_file(caller_line)
           serializer_file_path = caller_line[CALLER_FILE]
           serializer_file_contents = IO.read(serializer_file_path)
-          Digest::MD5.hexdigest(serializer_file_contents)
+          algorithm = ActiveModelSerializers.config.use_sha1_digests ? Digest::SHA1 : Digest::MD5
+          algorithm.hexdigest(serializer_file_contents)
         rescue TypeError, Errno::ENOENT
           warn <<-EOF.strip_heredoc
             Cannot digest non-existent file: '#{caller_line}'.

test/cache_test.rb

@@ -446,17 +446,41 @@ def test_a_serializer_rendered_by_two_adapter_returns_differently_fetch_attribut
     # rubocop:enable Metrics/AbcSize
 
     def test_uses_file_digest_in_cache_key
+      reset_cache_digest(@blog_serializer)
       render_object_with_cache(@blog)
       file_digest = Digest::MD5.hexdigest(File.open(__FILE__).read)
       key = "#{@blog.cache_key}/#{adapter.cache_key}/#{file_digest}"
       assert_equal(@blog_serializer.attributes, cache_store.fetch(key))
     end
 
+    def test_uses_sha1_digest_in_cache_key_when_configured
+      reset_cache_digest(@blog_serializer)
+      previous_use_sha1_digests = ActiveModelSerializers.config.use_sha1_digests
+      ActiveModelSerializers.config.use_sha1_digests = true
+      render_object_with_cache(@blog)
+      file_digest = Digest::SHA1.hexdigest(File.open(__FILE__).read)
+      key = "#{@blog.cache_key}/#{adapter.cache_key}/#{file_digest}"
+      assert_equal(@blog_serializer.attributes, cache_store.fetch(key))
+    ensure
+      ActiveModelSerializers.config.use_sha1_digests = previous_use_sha1_digests
+    end
+
     def test_cache_digest_definition
+      reset_cache_digest(@post_serializer)
       file_digest = Digest::MD5.hexdigest(File.open(__FILE__).read)
       assert_equal(file_digest, @post_serializer.class._cache_digest)
     end
 
+    def test_cache_sha1_digest_definition
+      reset_cache_digest(@post_serializer)
+      previous_use_sha1_digests = ActiveModelSerializers.config.use_sha1_digests
+      ActiveModelSerializers.config.use_sha1_digests = true
+      file_digest = Digest::SHA1.hexdigest(File.open(__FILE__).read)
+      assert_equal(file_digest, @post_serializer.class._cache_digest)
+    ensure
+      ActiveModelSerializers.config.use_sha1_digests = previous_use_sha1_digests
+    end
+
     def test_object_cache_keys
       serializable = ActiveModelSerializers::SerializableResource.new([@comment, @comment])
       include_directive = JSONAPI::IncludeDirective.new('*', allow_wildcard: true)
@@ -715,5 +739,10 @@ def render_object_with_cache(obj, options = {})
     def adapter
       @serializable_resource.adapter
     end
+
+    def reset_cache_digest(serializer)
+      return unless serializer.class.instance_variable_defined?(:@_cache_digest)
+      serializer.class.remove_instance_variable(:@_cache_digest)
+    end
   end
 end