Twee Object Cache

Twee Object Cache is a suite of high-performance, lightweight object caches built for large-scale WordPress and WooCommerce projects. It provides highly optimized drop-in replacements for the native WordPress in-memory runtime cache, minimizing database load and maximizing execution speed through persistent backend storage.

This repository contains caching plugins for three different backends: APCu, Memcached, and Redis.

Features

1. High-Performance Integration

• Natively leverages the respective PHP extensions (apcu, memcached, or redis) for ultra-fast, persistent object caching.
• Reduces heavy database queries by reliably maintaining options, transients, and object metadata in memory.
• Safely handles bulk operations (utilizing native methods like getMulti and setMulti for Memcached and Redis) to minimize network latency.
• For APCu, safely handles memory exhaustion by gracefully deleting keys when storage fails, forcing fresh database reads instead of serving stale data.
• The Memcached implementation automatically splits huge cache payloads into smaller chunks to bypass the server's hard item size limits, completely preventing "Payload too large" errors on massive datasets.

2. Dual-Layer Caching Engine

• Implements an internal runtime cache array to prevent redundant backend round-trips during a single page load.
• Automatically trims the runtime cache limit using an efficient, key-preserving slice mechanism to prevent memory exhaustion and array key corruption on massive bulk operations.
• Strictly adheres to functional and procedural paradigms native to WordPress core.

3. Advanced Group Management

• Fully supports global cache groups for shared data across networks.
• Natively handles non-persistent groups (such as counts and plugins) by enforcing that they remain exclusively in the runtime cache and never hit the persistent backend.
• The Redis implementation natively utilizes Redis Hashes (hSet, hGet, hDel) to cleanly group cache data, dramatically organizing the global keyspace.
• The Memcached implementation manages group isolation using an efficient versioning (namespace) architecture to securely separate keys by their respective cache group.

4. Multisite & Context Compatibility

• Provides full WordPress Multisite support.
• Automatically isolates cache keys using the blog ID prefix to prevent data bleeding across the network.
• Context-aware key prefixing ensures CLI, Cron, and web requests all target the identical caching environment.

5. Safe Cache Flushing & Iteration

• Utilizes O(1) group versioning (namespaces) for instant, non-blocking cache invalidation in Memcached.
• The Redis implementation achieves true instant cache group invalidation by dropping entire Redis Hashes directly (via non-blocking UNLINK), completely bypassing the need for fallback key versioning.
• Actively prevents memory leaks and stale bloat ("ghost keys") by automatically cleaning up orphaned chunk payloads and harvested keys during individual deletions and group flushes.
• Flushes only the keys belonging to the specific WordPress installation using dynamic key salts, preventing conflicts with other applications or sites running on the same server.

Installation

Twee Object Cache can be installed as a standard WordPress plugin or as a manual drop-in.

1. WordPress Plugin Installation (Recommended)

• Switch to PHP 8.0 or a newer version.
• Ensure your preferred caching service (APCu, Memcached, or Redis) is running on your web server and install the corresponding PHP extension.
• Upload the twee-object-cache folder to your wp-content/plugins/ directory and activate the plugin via the WordPress dashboard.
• Hover over the "Object Cache" menu in the WordPress Admin Bar.
• Select "Enable Redis", "Enable Memcached", or "Enable APCu" based on your environment. The plugin will automatically deploy the correct drop-in, verify connectivity, and start caching.

2. Manual Drop-in Installation

• Ensure your preferred caching service and PHP extension are installed.
• Manually copy the object-cache.php file from the respective folder (apcu/, memcached/, or redis/) directly into your wp-content/ directory.
• WordPress will automatically detect the drop-in and initialize the persistent cache.

Configuration

All configuration is automatic, but you can explicitly define your cache salt in wp-config.php to guarantee prefix consistency across different execution environments (like WP-CLI).

About

Author: Andrii Toniievych

Contact: toniyevych@gmail.com

Feel free to contact me if you have any questions.

Contribution

• Fork this repository
• Commit your changes
• Push it to the branch
• Create the new pull request

License

Twee is released under the MIT Public License.

Note: The "About" section in README.md and the author (@author) notice in the file-headers shall not be edited or deleted without permission. Thank you!