tillkruss/redis-object-cache

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

Thursday, August 11, 2016
by tillkruss
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The README.md

Redis Object Cache for WordPress

A persistent object cache backend powered by Redis®¹. Supports Predis, PhpRedis (PECL), Relay, replication, sentinels, clustering and WP-CLI., _(*1)

, _(*2)

Object Cache Pro

A business class Redis®¹ object cache backend. Truly reliable, highly optimized, fully customizable and with a dedicated engineer when you most need it., _(*3)

Rewritten for raw performance
100% WordPress API compliant
Faster serialization and compression
Easy debugging & logging
Cache prefetching and advanced analytics
Fully unit tested (100% code coverage)
Optimized for WooCommerce, Jetpack & Yoast SEO
And much more...

Installation

To get started, please see the installation instructions., _(*4)

FAQ & Troubleshooting

Answers to common questions and troubleshooting of common errors can be found in the FAQ., _(*5)

Configuration

The Redis Object Cache plugin comes with vast set of configuration options. If you're unsure how to use them read the installation instructions., _(*6)

Configuration constant	Default	Description
`WP_REDIS_HOST`	`127.0.0.1`	The hostname of the Redis server
`WP_REDIS_PORT`	`6379`	The port of the Redis server
`WP_REDIS_PATH`		The path to the unix socket of the Redis server
`WP_REDIS_SCHEME`	`tcp`	The scheme used to connect: `tcp` or `unix`
`WP_REDIS_DATABASE`	`0`	The database used by the cache: `0-15`
`WP_REDIS_PREFIX`		The prefix used for all cache keys to avoid data collisions (replaces `WP_CACHE_KEY_SALT`), should be human readable and not a "salt"
`WP_REDIS_PASSWORD`		The password of the Redis server, supports Redis ACLs arrays: `['user', 'password']`
`WP_REDIS_MAXTTL`	`0`	The maximum time-to-live of cache keys
`WP_REDIS_CLIENT`		The client used to communicate with Redis (defaults to `phpredis` when installed, otherwise `predis`), supports `phpredis`, `predis`, `relay`
`WP_REDIS_TIMEOUT`	`1`	The connection timeout in seconds
`WP_REDIS_READ_TIMEOUT`	`1`	The timeout in seconds when reading/writing
`WP_REDIS_IGNORED_GROUPS`	`[]`	Groups that should not be cached between requests in Redis

Advanced configuration options

, _(*7)

Configuration constant	Default	Description
`WP_CACHE_KEY_SALT`		Deprecated. Replaced by `WP_REDIS_PREFIX`
`WP_REDIS_FLUSH_TIMEOUT`	`5`	Experimental. The timeout in seconds when flushing
`WP_REDIS_RETRY_INTERVAL`		The number of milliseconds between retries (PhpRedis only)
`WP_REDIS_GLOBAL_GROUPS`	`[]`	Additional groups that are considered global on multisite networks
`WP_REDIS_METRICS_MAX_TIME`	`3600`	The maximum number of seconds metrics should be stored
`WP_REDIS_IGBINARY`	`false`	Whether to use the igbinary PHP extension for serialization
`WP_REDIS_DISABLED`	`false`	Emergency switch to bypass the object cache without deleting the drop-in
`WP_REDIS_DISABLE_ADMINBAR`	`false`	Disables admin bar display
`WP_REDIS_DISABLE_METRICS`	`false`	Disables metrics collection and display
`WP_REDIS_DISABLE_DROPIN_CHECK`	`false`	Disables the extended drop-in write test
`WP_REDIS_DISABLE_DROPIN_AUTOUPDATE`	`false`	Disables the drop-in auto-update
`WP_REDIS_DISABLE_GROUP_FLUSH`	`false`	Disables group flushing with Lua script and uses `flushdb` call instead
`WP_REDIS_DISABLE_BANNERS`	`false`	Disables promotional banners and notices
`WP_REDIS_DISABLE_COMMENT`	`false`	Disables HTML source comment
`WP_REDIS_SSL_CONTEXT`	`[]`	TLS connection options for `tls` or `rediss` scheme
`WP_REDIS_MANAGER_CAPABILITY`		The capability a user must have to manage the plugin

, _(*8)

Unsupported configuration options

, _(*9)

Options that exist, but should not, may break without notice in future releases and won't receive any support whatsoever from our team:, _(*10)

Configuration constant	Default	Description
`WP_REDIS_GRACEFUL`	`false`	Prevents exceptions from being thrown, but will cause data corruption
`WP_REDIS_SELECTIVE_FLUSH`	`false`	Uses terribly slow Lua script for flushing
`WP_REDIS_UNFLUSHABLE_GROUPS`	`[]`	Uses terribly slow Lua script to prevent groups from being flushed

, _(*11)

Connections

Connecting over Unix socket

, _(*12)

define( 'WP_REDIS_SCHEME', 'unix' );
define( 'WP_REDIS_PATH', '/var/run/redis.sock' );

, _(*13)

Connecting over TCP+TLS

, _(*14)

define( 'WP_REDIS_SCHEME', 'tls' );
define( 'WP_REDIS_HOST', 'master.ncit.ameaqx.use1.cache.amazonaws.com' );
define( 'WP_REDIS_PORT', 6379 );

Additional TLS/SSL stream connection options for connections can be defined using WP_REDIS_SSL_CONTEXT:, _(*15)

define( 'WP_REDIS_SSL_CONTEXT', [
    'verify_peer' => false,
    'verify_peer_name' => false,
]);

, _(*16)

Connecting using ACL authentication

, _(*17)

define( 'WP_REDIS_PASSWORD', [ 'username', 'password' ] );

, _(*18)

Scaling

Redis Object Cache offers various replication, sharding, cluster and sentinel setups to users with advanced technical knowledge of Redis and PHP, that have consulted the Predis, PhpRedis or Relay documentation., _(*19)

Relay

, _(*20)

Relay is a next-generation cache that keeps a partial replica of Redis' dataset in PHP's memory for ridiculously fast lookups, especially when Redis Server is not on the same machine as WordPress., _(*21)

define( 'WP_REDIS_CLIENT', 'relay' );

define( 'WP_REDIS_HOST', '127.0.0.1' );
define( 'WP_REDIS_PORT', 6379 );

// when using Relay, each WordPress installation
// MUST a dedicated Redis database and unique prefix
define( 'WP_REDIS_DATABASE', 0 );
define( 'WP_REDIS_PREFIX', 'db3:' );

// consume less memory
define( 'WP_REDIS_IGBINARY', true );

, _(*22)

Replication

, _(*23)

https://redis.io/docs/management/replication/, _(*24)

define( 'WP_REDIS_CLIENT', 'predis' );

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

, _(*25)

Sharding

, _(*26)

This is a PhpRedis specific feature using RedisArray., _(*27)

define( 'WP_REDIS_CLIENT', 'phpredis' );

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',
] );

, _(*28)

Redis Sentinel

, _(*29)

https://redis.io/docs/management/sentinel/, _(*30)

define( 'WP_REDIS_CLIENT', 'predis' );

define( 'WP_REDIS_SENTINEL', 'my-sentinel' );
define( 'WP_REDIS_SERVERS', [
    'tcp://127.0.0.1:5380',
    'tcp://127.0.0.2:5381',
    'tcp://127.0.0.3:5382',
] );

, _(*31)

Redis Cluster

, _(*32)

https://redis.io/docs/management/scaling/, _(*33)

define( 'WP_REDIS_CLIENT', 'phpredis' );

define( 'WP_REDIS_CLUSTER', [
    'tcp://127.0.0.1:6379?alias=node-01',
    'tcp://127.0.0.2:6379?alias=node-02',
    'tcp://127.0.0.3:6379?alias=node-03',
] );

, _(*34)

WP CLI commands

Redis Object Cache has various WP CLI commands, for more information run wp help redis., _(*35)

Command	Description
`wp redis status`	Shows the object cache status and diagnostics
`wp redis enable`	Enables the object cache
`wp redis disable`	Disables the object cache
`wp redis update-dropin`	Updates the object cache drop-in

Actions & Filters

Redis Object Cache has various hooks and the commonly used ones are listed below., _(*36)

Filter / Action	Description
`redis_cache_expiration`	Filters the cache expiration for individual keys
`redis_cache_validate_dropin`	Filters whether the drop-in is valid
`redis_cache_add_non_persistent_groups`	Filters the groups to be marked as non persistent
`redis_cache_manager_capability`	Filters the capability a user needs to manage the plugin

Footnotes

¹ Redis is a registered trademark of Redis Ltd. Any rights therein are reserved to Redis Ltd. Any use by Redis Object Cache is for referential purposes only and does not indicate any sponsorship, endorsement or affiliation between Redis and Redis Object Cache., _(*37)