Shopify/identity_cache

IdentityCache is a Ruby gem that provides high-performance caching for ActiveRecord models by storing associated records and attributes in Memcached. It supports complex association patterns, including recursive relationships and polymorphic references, while optimizing database load through batch fetching and lazy loading strategies. The system ensures cache consistency via deferred expiration hooks and handles thundering herd problems with locking mechanisms.

7 changes.

This period focused on the complete architectural rewrite of IdentityCache into version 2.0, introducing a modular design with new caching primitives, association handling, and consistency mechanisms. The work included establishing a robust development environment, expanding test coverage for core components, and adding performance benchmarking tools to validate the new implementation.

7 changes.

The project refactored caching internals into modular classes and added support for recursive associations and batch fetching to improve performance. This period also focused on expanding test coverage for these new components and establishing robust CI and local development environments to ensure compatibility across various dependency versions.

This change introduces the \.spin\ directory to support the Spin local development environment. It includes a bootstrap script that installs system dependencies (libsasl2-dev, libpq-dev), initializes a MySQL database for testing, and runs bundle install, alongside a service configuration file that defines Memcached and MySQL as required backend services.

.spin · high confidence

New scripts have been added to the \performance/\ directory to measure and analyze the library's runtime behavior. \cpu.rb\ provides basic CPU time benchmarking across various cache runner scenarios (find, fetch hit/miss, deleted), while \profile.rb\ leverages \stackprof\ to generate detailed CPU profiles, including the ability to target specific runners via environment variables. Additionally, \externals.rb\ uses \ruby-prof\ to count external calls to Memcache and the database, helping users understand the overhead of different caching strategies.

performance · high confidence

This change introduces the foundational configuration and documentation for the IdentityCache gem, establishing the development workflow and project standards. It sets the development Ruby version to 3.3.4 via \.ruby-version\ and configures code style enforcement using RuboCop with the \rubocop-shopify\ gem. A \dev.yml\ file is added to streamline local environment setup, providing commands for running tests across multiple dependency configurations (default, minimum supported, latest release, and Rails edge), executing style checks, and running CPU benchmarks or profiling. The project also includes a \CAVEATS.md\ document to warn users about potential issues such as large cache blobs, hot keys, and the thundering herd problem, alongside a comprehensive \README.md\ detailing installation, usage, and configuration for Memcached backends.

(repo-wide) · high confidence

The library now supports caching for recursive associations (e.g., a model referencing itself). This is implemented by introducing a new \IdentityCache::Cached::Recursive::Association\ class that handles the reading, writing, and hydration of self-referential cached data, along with specific \HasMany\ and \HasOne\ subclasses to manage these relationships within the caching layer.

_lib/identity\cache/cached/recursive · high confidence

The \IdentityCache::Cached::Reference\ module for \has\_many\ and \has\_one\ associations has been refactored to implement batch fetching. Instead of loading associated records individually, the library now uses \fetch\_multi\ to load multiple records in a single operation, which improves performance when accessing cached associations. This change introduces new internal methods for managing cached IDs and records, and ensures that pre-fetched or embedded associations are handled correctly without redundant cache lookups.

_lib/identity\cache/cached/reference · high confidence

IdentityCache has been completely rewritten from scratch, replacing the previous implementation with a new modular architecture. This version introduces a new \CacheFetcher\ interface that supports both optimistic locking (CAS) and a \FallbackFetcher\ for backends without CAS support, along with a \FillLock\ mechanism to prevent thundering herd problems. The association caching API has been restructured into distinct classes (\Cached::BelongsTo\, \Cached::Reference::HasMany\, etc.) and now supports recursive embedding and ID-based embedding. A new \CacheKeyLoader\ and \LoadStrategy\ system (Eager/Lazy) manages batch loading and memoization, while \CacheInvalidation\ and \ParentModelExpiration\ handle cache consistency with deferred expiry hooks. The gem also adds \MemCacheStoreCAS\ patching for Dalli, \CacheHash\ for optimized key hashing, and an \Encoder\ with ActiveSupport::Notifications for hydration/dehydration events.

_lib/identity\cache · high confidence

The library has been restructured to replace the monolithic \lib/identity\_cache.rb\ with a modular design featuring separate files for caching strategies, associations, and key generation. The \MemoizedCacheProxy\ and \BelongsToCaching\ modules have been moved into the new namespace structure. Additionally, the \AlreadyIncludedError\ class has been changed from inheriting from \Exception\ to \StandardError\, which improves safety by preventing accidental interruption of system-level exceptions.

lib · high confidence

The caching logic in \lib/identity\_cache/cached\ has been reorganized into specific classes (\Cached::Association\, \Cached::Attribute\, \Cached::PrimaryIndex\, etc.) to improve modularity. This change introduces a new \Cached::Prefetcher\ module that handles association loading, including support for the Rails 7.0 preloader API and batch fetching for polymorphic \belongs\_to\ associations. It also adds deferred expiration for records and attributes to reduce blocking during writes, and optimizes database queries for cached attributes by grouping common conditions.

_lib/identity\cache/cached · high confidence

8 commits adding/updating tests in test/fixtures; Added test coverage for IdentityCache core components; Added unit tests for cached association classes; Expanded test infrastructure with multi-database support and new fixtures.

The project now includes three dedicated Gemfiles to streamline testing across different dependency configurations: \Gemfile.latest-release\ pins development tools like Rubocop and uses the latest released versions of ActiveRecord and database drivers; \Gemfile.min-supported\ enforces the minimum supported versions for ActiveRecord (7.0.0) and other dependencies like memcached\_store and dalli; and \Gemfile.rails-edge\ tests against the main branch of the Rails repository. These files allow the CI pipeline to explicitly validate compatibility with the newest releases, the oldest supported versions, and upcoming Rails changes.

gemfiles · high confidence

The gem now requires Ruby 3.0+ and Active Record 7.0+, removing support for older versions. Development dependencies have been updated, including RuboCop to 1.61 and rubocop-shopify to 2.9, while runtime dependencies like ar\_transaction\_changes are bumped to 1.1. The gemspec has been modernized with improved metadata and author information.

(dependencies) · high confidence

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

• First survey — no prior run to compare against. CAI 62.

• Code Health 99
• Architecture 100
• Maturity 50
• Readiness 67
• Security 65

• 300 commits — 243 feature/other, 57 fixes

• (root) — 96 commits
• (repo) — 78 commits
• lib/identity_cache — 53 commits
• .github/workflows — 16 commits
• test/fetch_multi_by_test.rb — 7 commits
• test/helpers — 7 commits
• test/test_helper.rb — 7 commits
• lib/identity_cache.rb — 6 commits
• test/fetch_test.rb — 6 commits
• test/cache_invalidation_test.rb — 5 commits
• test/cache_fetcher_test.rb — 2 commits
• test/identity_cache_test.rb — 2 commits
• test/index_cache_test.rb — 2 commits
• test/prefetch_associations_test.rb — 2 commits
• .github/dependabot.yml — 1 commit
• .github/probots.yml — 1 commit
• gemfiles/Gemfile.min-supported — 1 commit
• gemfiles/Gemfile.rails-edge — 1 commit
• performance/cache_runner.rb — 1 commit
• test/attribute_cache_test.rb — 1 commit

• fix: Avoid rubocop errors by skipping the version of rubocop with a bug (#496)
• fix: Bump bugfix version of ruby in dev.yml
• fix: CI: Use ruby/setup-ruby to fix testing of ruby 3.0 (#487)
• fix: Fix Active Record 7.2 deprecation warnings
• fix: Fix Active Record's connection_pool_list deprecation warning
• fix: Fix ActiveRecord::Associations::Preloader#preload call on rails edge (#478)
• fix: Fix Naming/InclusiveLanguage rubocop offenses
• fix: Fix Style/ParallelAssignment
• fix: Fix Style/PreferredHashMethods
• fix: Fix Style/RedundantReturn
• fix: Fix Style/SafeNavigation
• fix: Fix Style/SpecialGlobalVars
• fix: Fix Style/SymbolProc
• fix: Fix Style/TrailingCommaInArrayLiteral
• fix: Fix Style/TrailingCommaInHashLiteral
• fix: Fix Style/ZeroLengthPredicate
• fix: Fix IdentityCache.fetch_read_only_records default value
• fix: Fix another Active Record deprecation
• fix: Fix broken prefetch_associations of a polymorphic cache_belongs_to (#461)
• fix: Fix class name in AssociationError message (#557)
• …and 280 more

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

Shopify/identity_cache was measured the same way every project in this corpus was: the same rubric, at a pinned commit, with the result published in full. Point a surveyor at a repository you know and see whether you agree with it.