GridPane Redis Object Cache

Tags: redis, predis, phpredis, hhvm, pecl, caching, cache, object cache, performance, replication, clustering
Requires at least: 3.3
Tested up to: 5.2
Requires PHP: 7.3
Stable tag: 1.0
License: GPLv3
License URI: http://www.gnu.org/licenses/gpl-3.0.html

A persistent object cache backend powered by Redis. Supports Predis, PhpRedis, HHVM, replication, clustering and WP-CLI.

Description

A persistent object cache backend powered by Redis.

Supports:
Predis
PhpRedis (PECL)
HHVM
replication
clustering
WP-CLI

To adjust the connection parameters, prefix cache keys or configure replication/clustering.

Forked from Till Kruss work, so send any donations his way:
https://www.paypal.me/tillkruss
(He forked from Eric Mann's and Erick Hitter's Redis Object Cache.)

Installation

For detailed installation instructions, please read the standard installation procedure for WordPress plugins.

Make sure Redis is installed and running.
Install and activate plugin.
Enable the object cache under Settings -> Redis, or in Multisite setups under Network Admin -> Settings -> Redis.
If necessary, adjust connection parameters.

If your server doesn't support the WordPress Filesystem API, you have to manually copy the object-cache.php file from the /plugins/redis-cache/includes/ directory to the /wp-content/ directory.

Connection Parameters

By default the object cache drop-in will connect to Redis over TCP at 127.0.0.1:6379 and select database 0.

To adjust the connection parameters, define any of the following constants in your wp-config.php file.

WP_REDIS_CLIENT (default: not set)

Specifies the client used to communicate with Redis. Supports hhvm, pecl and predis.
WP_REDIS_SCHEME (default: tcp)

Specifies the protocol used to communicate with an instance of Redis. Internally the client uses the connection class associated to the specified connection scheme. Supports tcp (TCP/IP), unix (UNIX domain sockets), tls (transport layer security) or http (HTTP protocol through Webdis).
WP_REDIS_HOST (default: 127.0.0.1)

IP or hostname of the target server. This is ignored when connecting to Redis using UNIX domain sockets.
WP_REDIS_PORT (default: 6379)

TCP/IP port of the target server. This is ignored when connecting to Redis using UNIX domain sockets.
WP_REDIS_PATH (default: not set)

Path of the UNIX domain socket file used when connecting to Redis using UNIX domain sockets.
WP_REDIS_DATABASE (default: 0)

Accepts a numeric value that is used to automatically select a logical database with the SELECT command.
WP_REDIS_PASSWORD (default: not set)

Accepts a value used to authenticate with a Redis server protected by password with the AUTH command.

Configuration Parameters

To adjust the configuration, define any of the following constants in your wp-config.php file.

WP_CACHE_KEY_SALT (default: not set)

Set the prefix for all cache keys. Useful in setups where multiple installs share a common wp-config.php or $table_prefix to guarantee uniqueness of cache keys.
WP_REDIS_SELECTIVE_FLUSH (default: not set)

If set to true, flushing the cache will only delete keys that are prefixed with WP_CACHE_KEY_SALT (instead of emptying the entire Redis database). The selective flush is an atomic O(n) operation.
WP_REDIS_MAXTTL (default: not set)

Set maximum time-to-live (in seconds) for cache keys with an expiration time of 0.
WP_REDIS_GLOBAL_GROUPS (default: ['blog-details', 'blog-id-cache', 'blog-lookup', 'global-posts', 'networks', 'rss', 'sites', 'site-details', 'site-lookup', 'site-options', 'site-transient', 'users', 'useremail', 'userlogins', 'usermeta', 'user_meta', 'userslugs'])

Set the list of network-wide cache groups that should not be prefixed with the blog-id (Multisite only).
WP_REDIS_IGNORED_GROUPS (default: ['counts', 'plugins'])

Set the cache groups that should not be cached in Redis.
WP_REDIS_DISABLED (default: not set)

Set to true to disable the object cache at runtime.
WP_REDIS_GRACEFUL (default: not set)

Set to false to disable graceful failures and throw exceptions.
WP_REDIS_IGBINARY (default: not set)

Set to true to enable the igbinary serializer.

Replication & Clustering

To use Replication, Sharding or Clustering, make sure your server is running PHP7 or higher (HHVM is not supported) and you consulted the Predis or PhpRedis documentation.

For replication use the WP_REDIS_SERVERS constant, for sharding the WP_REDIS_SHARDS constant and for clustering the WP_REDIS_CLUSTER constant.

For authentication use the WP_REDIS_PASSWORD constant.

Replication (Master-Slave):

define( 'WP_REDIS_SERVERS', [
    'tcp://127.0.0.1:6379?database=5&alias=master',
    'tcp://127.0.0.2:6379?database=5&alias=slave-01',
] );

Replication (Redis Sentinel):

define( 'WP_REDIS_CLIENT', 'predis' );
define( 'WP_REDIS_SENTINEL', 'mymaster' );
define( 'WP_REDIS_SERVERS', [
    'tcp://127.0.0.1:5380',
    'tcp://127.0.0.2:5381',
    'tcp://127.0.0.3:5382',
] );

Sharding:

define( 'WP_REDIS_SHARDS', [
    'tcp://127.0.0.1:6379?database=10&alias=shard-01',
    'tcp://127.0.0.2:6379?database=10&alias=shard-02',
    'tcp://127.0.0.3:6379?database=10&alias=shard-03',
] );

Clustering (Redis 3.0+):

define( 'WP_REDIS_CLUSTER', [
    'tcp://127.0.0.1:6379?database=15&alias=node-01',
    'tcp://127.0.0.2:6379?database=15&alias=node-02',
] );

WP-CLI Commands

To use the WP-CLI commands, make sure the plugin is activated:

wp plugin activate redis-cache

The following commands are supported:

wp redis status

Show the Redis object cache status and (when possible) client.
wp redis enable

Enables the Redis object cache. Default behavior is to create the object cache drop-in, unless an unknown object cache drop-in is present.
wp redis disable

Disables the Redis object cache. Default behavior is to delete the object cache drop-in, unless an unknown object cache drop-in is present.
wp redis update-dropin

Updates the Redis object cache drop-in. Default behavior is to overwrite any existing object cache drop-in.

Changelog

= 1.0 =

Added optional flush button in admin bar
Added option to display cached objects in footer

FORKED

= 1.4.3 =

Require PHP 5.4 or newer
Use pretty print in diagnostics
Throw exception if Redis library is missing
Fixed cache not flushing for some users
Fixed admin issues when WP_REDIS_DISABLED is false

= 1.4.2 =

Added graceful Redis failures and WP_REDIS_GRACEFUL constant
Improved cluster support
Added redis_cache_expiration filter
Renamed redis_object_cache_get filter to redis_object_cache_get_value

= 1.4.1 =

Fixed potential fatal error related to wp_suspend_cache_addition()

= 1.4.0 =

Added support for igbinary
Added support for wp_suspend_cache_addition()

= 1.3.9 =

Fixed WP_REDIS_SHARDS not showing up in server list
Fixed WP_REDIS_SHARDS not working when using PECL extension
Removed WP_REDIS_SCHEME and WP_REDIS_PATH leftovers

= 1.3.8 =

Switched from single file Predis version to full library

= 1.3.7 =

Revert back to single file Predis version

= 1.3.6 =

Added support for Redis Sentinel
Added support for sharing
Switched to PHAR version of Predis
Improved diagnostics
Added WP_REDIS_SELECTIVE_FLUSH
Added $fail_gracefully parameter to WP_Object_Cache::__construct()
Always enforce WP_REDIS_MAXTTL
Pass $selective and $salt to redis_object_cache_flush action
Don’t set WP_CACHE_KEY_SALT constant

= 1.3.5 =

Added basic diagnostics to admin interface
Added WP_REDIS_DISABLED constant to disable cache at runtime
Prevent "Invalid plugin header" error
Return integer from increment() and decrement() methods
Prevent object cache from being instantiated more than once
Always separate cache key prefix and group by semicolon
Improved performance of build_key()
Only apply redis_object_cache_get filter if callbacks have been registered
Fixed add_or_replace() to only set cache key if it doesn't exist
Added redis_object_cache_flush action
Added redis_object_cache_enable action
Added redis_object_cache_disable action
Added redis_object_cache_update_dropin action

= 1.3.4 =

Added WP-CLI support
Show host and port unless scheme is unix
Updated default global and ignored groups
Do a cache flush when activating, deactivating and uninstalling

= 1.3.3 =

Updated Predis to v1.1.1
Added redis_instance() method
Added incr() method alias for Batcache compatibility
Added WP_REDIS_GLOBAL_GROUPS and WP_REDIS_IGNORED_GROUPS constant
Added redis_object_cache_delete action
Use WP_PLUGIN_DIR with WP_CONTENT_DIR as fallback
Set password when using a cluster or replication
Show Redis client in stats()
Change visibility of $cache to public
Use old array syntax, just in case

= 1.3.2 =

Make sure $result is not false in WP_Object_Cache::get()

= 1.3.1 =

Fixed connection issue

= 1.3 =

New admin interface
Added support for wp_cache_get()'s $force and $found parameter
Added support for clustering and replication with Predis

= 1.2.3 =

UI improvements

= 1.2.2 =

Added redis_object_cache_set action
Added redis_object_cache_get action and filter
Prevented duplicated admin status messages
Load bundled Predis library only if necessary
Load bundled Predis library using WP_CONTENT_DIR constant
Updated stats() method output to be uniform with WordPress

= 1.2.1 =

Added composer.json
Added deactivation and uninstall hooks to delete object-cache.php
Added local serialization functions for better advanced-cache.php support
Updated bundled Predis version to 1.0.3
Updated heading structure to be semantic

= 1.2 =

Added Multisite support
Moved admin menu under Settings menu
Fixed PHP notice in get_redis_client_name()

= 1.1.1 =

Call select() and optionally auth() if HHVM extension is used

= 1.1 =

Added support for HHVM's Redis extension
Added support for PECL Redis extension
Added WP_REDIS_CLIENT constant, to set preferred Redis client
Added WP_REDIS_MAXTTL constant, to force expiration of cache keys
Improved add_or_replace(), get(), set() and delete() methods
Improved admin screen styles
Removed all internationalization/localization from drop-in

= 1.0.2 =

Added "Flush Cache" button
Added support for UNIX domain sockets
Improved cache object retrieval performance significantly
Updated bundled Predis library to version 1.0.1

= 1.0.1 =

Load plugin translations
Hide global admin notices from non-admin users
Prevent direct file access to redis-cache.php and admin-page.php
Colorize "Disable Object Cache" button
Call Predis\Client->connect() to avoid potential uncaught Predis\Connection\ConnectionException

= 1.0 =

Initial release

== Upgrade Notice ==

= 1.4.2 =

This update renames the redis_object_cache_get filter to avoid conflicts. Update your code if necessary.

= 1.4.0 =

This update adds support for igbinary and wp_suspend_cache_addition().

= 1.3.9 =

This update contains fixes for sharding.

= 1.3.8 =

This update contains a critical fix for Predis.

= 1.3.7 =

This update fixes an issue with Predis in some environments.

= 1.3.6 =

This update contains various improvements.

= 1.3.5 =

This update contains various changes, including performance improvements and better Batcache compatibility.

= 1.3.4 =

This update contains several improvements, including WP CLI and WordPress 4.6 support.

= 1.3.3 =

This update contains several improvements.

= 1.3.2 =

This update includes a critical fix for PhpRedis.

= 1.3.1 =

This update includes a critical connection issue fix.

= 1.3 =

This update includes a new admin interface and support for clustering and replication with Predis.

= 1.2.3 =

This updated includes several UI improvements.

= 1.2.2 =

This updated includes several bug fixes and improvements.

= 1.2.1 =

This update includes several improvements and compatibility fixes.