A WordPress object cache backend that implements all available methods using Redis and either the Redis PECL library or the Predis library for PHP.

• Eric Mann
• Erick Hitter

1. Install and configure Redis. There is a good tutorial here.
2. Install the Redis PECL module or the Predis library (included in this repository as a submodule) in the /wp-content/predis directory (since that's where the object cache expects it to reside if it's to be used).
3. Add object-cache.php to the wp-content directory. It is a drop-in file, not a plugin, so it belongs in the wp-content directory, not the plugins directory.
4. By default, the script will connect to Redis at 127.0.0.1:6379. See the Connecting to Redis section for further options.

By default, the plugin uses 127.0.0.1 and 6379 as the default host and port when creating a new client instance; the default database of 0 is also used. Three constants are provided to override these default values.

Specify WP_REDIS_BACKEND_HOST, WP_REDIS_BACKEND_PORT, and WP_REDIS_BACKEND_DB to set the necessary, non-default connection values for your Redis instance.

The constant WP_CACHE_KEY_SALT is provided to add a prefix to all cache keys used by the plugin. If running two single instances of WordPress from the same Redis instance, this constant could be used to avoid overlap in cache keys. Note that special handling is not needed for WordPress Multisite.