Class: RedisSetStore::Bootstrap

Inherits:
Object
  • Object
show all
Defined in:
lib/redis_set_store/bootstrap.rb

Overview

Bootstrap data into your cache to start using the RedisSetStore.

RedisSetStore depends on looking up cache keys in redis sets to limit the search scope when matching keys or deleting matched keys. If you have an existing cache, then those set entries won’t exist for the existing cache entries and the RedisSetStore#matched and RedisSetStore#delete_matched methods won’t find any keys.

To address that you can bootstrap your existing cache using this utility.

require "redis_set_store/bootstrap"
bootstrap = RedisSetStore::Bootstrap.new
bootstrap.bootstrap_set("user:1")
bootstrap.bootstrap_set("user:2")

Running this will use the redis KEYS method which is very slow (the reason for this gem), so ideally set up a copy or slave of your cache redis instance to use as a read source so you don’t affect your running cache. You can the configure the source for migration.

require "redis_set_store/bootstrap"
slave     = Redis.new(host: "10.0.1.1")
bootstrap = RedisSetStore::Bootstrap.new(source: slave)
bootstrap.bootstrap_set("user:1")
bootstrap.bootstrap_set("user:2")

Instance Method Summary collapse

Constructor Details

#initialize(source: nil, destination: nil) ⇒ Bootstrap

Creates a new Bootstrap utility.

source: The source Redis instance. If not provided uses

the destination redis or RedisSetStore.cache.redis, which
under Rails is the configure Rails.cache store.

destination: The destination Redis instance. If not provided uses

RedisSetStore.cache.redis as a default, which under Rails
is the configure Rails.cache store.



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# File 'lib/redis_set_store/bootstrap.rb', line 39

def initialize(source: nil, destination: nil)
  @source      = source || destination || RedisSetStore.cache.redis
  @destination = destination || RedisSetStore.cache.redis
end

Instance Method Details

#bootstrap_set(prefix) ⇒ Object

Bootstrap a redis set for the matching keys in the cache.

prefix: The prefix to match for keys and to use as the set key.

Reads all keys from the ‘source` redis instance that match the prefix (followed by “:”) and records them in the set used by RedisSetStore. The prefix is expected to the be the same as the `set_owner_regexp` parameters for ActiveSupport::Cache::RedisSetStore.

Note that because this uses the KEYS method in Redis it scans _every key_ in the database each time it is called which can be slow and will lock your database. You should configure a separate redis instance to read from as described in RedisSetStore::Bootstrap or run this with the cache offline.



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# File 'lib/redis_set_store/bootstrap.rb', line 58

def bootstrap_set(prefix)
  keys = @source.keys "#{prefix}:*"
  return if keys.empty?

  set_manager.sadd(prefix, keys)
end