From 476e3f552f59d208cb284f509760b44ad780c17a Mon Sep 17 00:00:00 2001 From: "Alberto F. Capel" Date: Tue, 14 Jul 2015 23:47:16 +0100 Subject: Add #cache_key to ActiveRecord::Relation. --- activerecord/CHANGELOG.md | 10 ++++ activerecord/lib/active_record.rb | 1 + activerecord/lib/active_record/base.rb | 1 + .../lib/active_record/collection_cache_key.rb | 29 +++++++++ activerecord/lib/active_record/relation.rb | 26 ++++++++ .../test/cases/collection_cache_key_test.rb | 70 ++++++++++++++++++++++ 6 files changed, 137 insertions(+) create mode 100644 activerecord/lib/active_record/collection_cache_key.rb create mode 100644 activerecord/test/cases/collection_cache_key_test.rb (limited to 'activerecord') diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index 3fa24f3837..ba32de497c 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,3 +1,13 @@ +* Add `cache_key` to ActiveRecord::Relation. + + Example: + + @users = User.where("name like ?", "%Alberto%") + @users.cache_key + => "/users/query-5942b155a43b139f2471b872ac54251f-3-20150714212107656125000" + + *Alberto Fernández-Capel* + * Fix a bug where counter_cache doesn't always work with polymorphic relations. diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb index f5cf92db64..264f869c68 100644 --- a/activerecord/lib/active_record.rb +++ b/activerecord/lib/active_record.rb @@ -53,6 +53,7 @@ module ActiveRecord autoload :Persistence autoload :QueryCache autoload :Querying + autoload :CollectionCacheKey autoload :ReadonlyAttributes autoload :RecordInvalid, 'active_record/validations' autoload :Reflection diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb index c918e88590..55a7e053bc 100644 --- a/activerecord/lib/active_record/base.rb +++ b/activerecord/lib/active_record/base.rb @@ -280,6 +280,7 @@ module ActiveRecord #:nodoc: extend Explain extend Enum extend Delegation::DelegateCache + extend CollectionCacheKey include Core include Persistence diff --git a/activerecord/lib/active_record/collection_cache_key.rb b/activerecord/lib/active_record/collection_cache_key.rb new file mode 100644 index 0000000000..72b50c1d28 --- /dev/null +++ b/activerecord/lib/active_record/collection_cache_key.rb @@ -0,0 +1,29 @@ +module ActiveRecord + module CollectionCacheKey + + def collection_cache_key(collection = all, timestamp_column = :updated_at) # :nodoc: + query_signature = Digest::MD5.hexdigest(collection.to_sql) + key = "#{collection.model_name.cache_key}/query-#{query_signature}" + + if collection.loaded? + size = collection.size + timestamp = collection.max_by(×tamp_column).public_send(timestamp_column) + else + column_type = type_for_attribute(timestamp_column.to_s) + column = "#{connection.quote_table_name(collection.table_name)}.#{connection.quote_column_name(timestamp_column)}" + + query = collection.select("COUNT(*) AS size", "MAX(#{column}) AS timestamp") + result = connection.select_one(query) + + size = result["size"] + timestamp = column_type.deserialize(result["timestamp"]) + end + + if timestamp + "#{key}-#{size}-#{timestamp.utc.to_s(cache_timestamp_format)}" + else + "#{key}-#{size}" + end + end + end +end diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb index e4df122af6..3ed04dee3b 100644 --- a/activerecord/lib/active_record/relation.rb +++ b/activerecord/lib/active_record/relation.rb @@ -298,6 +298,32 @@ module ActiveRecord limit_value ? to_a.many? : size > 1 end + # Returns a cache key that can be used to identify the records fetched by + # this query. The cache key is built with a fingerprint of the sql query, + # the number of records matched by the query and a timestamp of the last + # updated record. When a new record comes to match the query, or any of + # the existing records is updated or deleted, the cache key changes. + # + # Product.where("name like ?", "%Cosmic Encounter%").cache_key + # => "products/query-1850ab3d302391b85b8693e941286659-1-20150714212553907087000" + # + # If the collection is loaded, the method will iterate through the records + # to generate the timestamp, otherwise it will trigger one SQL query like: + # + # SELECT COUNT(*), MAX("products"."updated_at") FROM "products" WHERE (name like '%Cosmic Encounter%') + # + # You can also pass a custom timestamp column to fetch the timestamp of the + # last updated record. + # + # Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at) + # + # You can customize the strategy to generate the key on a per model basis + # overriding ActiveRecord::Base#collection_cache_key. + def cache_key(timestamp_column = :updated_at) + @cache_keys ||= {} + @cache_keys[timestamp_column] ||= @klass.collection_cache_key(self, timestamp_column) + end + # Scope all queries to the current scope. # # Comment.where(post_id: 1).scoping do diff --git a/activerecord/test/cases/collection_cache_key_test.rb b/activerecord/test/cases/collection_cache_key_test.rb new file mode 100644 index 0000000000..a794347889 --- /dev/null +++ b/activerecord/test/cases/collection_cache_key_test.rb @@ -0,0 +1,70 @@ +require "cases/helper" +require "models/computer" +require "models/developer" +require "models/project" +require "models/topic" +require "models/post" +require "models/comment" + +module ActiveRecord + class CollectionCacheKeyTest < ActiveRecord::TestCase + fixtures :developers, :projects, :developers_projects, :topics, :comments, :posts + + test "collection_cache_key on model" do + assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, Developer.collection_cache_key) + end + + test "cache_key for relation" do + developers = Developer.where(name: "David") + last_developer_timestamp = developers.order(updated_at: :desc).first.updated_at + + assert_match /\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, developers.cache_key + + /\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/ =~ developers.cache_key + + assert_equal Digest::MD5.hexdigest(developers.to_sql), $1 + assert_equal developers.count.to_s, $2 + assert_equal last_developer_timestamp.to_s(ActiveRecord::Base.cache_timestamp_format), $3 + end + + test "it triggers at most one query" do + developers = Developer.where(name: "David") + + assert_queries(1) { developers.cache_key } + assert_queries(0) { developers.cache_key } + end + + test "it doesn't trigger any query if the relation is already loaded" do + developers = Developer.where(name: "David").load + assert_queries(0) { developers.cache_key } + end + + test "relation cache_key changes when the sql query changes" do + developers = Developer.where(name: "David") + other_relation = Developer.where(name: "David").where("1 = 1") + + assert_not_equal developers.cache_key, other_relation.cache_key + end + + test "cache_key for empty relation" do + developers = Developer.where(name: "Non Existent Developer") + assert_match(/\Adevelopers\/query-(\h+)-0\Z/, developers.cache_key) + end + + test "cache_key with custom timestamp column" do + topics = Topic.where("title like ?", "%Topic%") + last_topic_timestamp = topics(:fifth).written_on.utc.to_s(:nsec) + assert_match(last_topic_timestamp, topics.cache_key(:written_on)) + end + + test "cache_key with unknown timestamp column" do + topics = Topic.where("title like ?", "%Topic%") + assert_raises(ActiveRecord::StatementInvalid) { topics.cache_key(:published_at) } + end + + test "collection proxy provides a cache_key" do + developers = projects(:active_record).developers + assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\Z/, developers.cache_key) + end + end +end -- cgit v1.2.3