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require 'redis'
require 'flipper'
module Flipper
module Adapters
# Public: Adapter that wraps another adapter with the ability to cache
# adapter calls in Redis
class RedisCache
include ::Flipper::Adapter
Version = 'v1'.freeze
Namespace = "flipper/#{Version}".freeze
FeaturesKey = "#{Namespace}/features".freeze
GetAllKey = "#{Namespace}/get_all".freeze
# Private
def self.key_for(key)
"#{Namespace}/feature/#{key}"
end
# Internal
attr_reader :cache
# Public: The name of the adapter.
attr_reader :name
# Public
def initialize(adapter, cache, ttl = 3600)
@adapter = adapter
@name = :redis_cache
@cache = cache
@ttl = ttl
end
# Public
def features
read_feature_keys
end
# Public
def add(feature)
result = @adapter.add(feature)
@cache.del(FeaturesKey)
result
end
# Public
def remove(feature)
result = @adapter.remove(feature)
@cache.del(FeaturesKey)
@cache.del(key_for(feature.key))
result
end
# Public
def clear(feature)
result = @adapter.clear(feature)
@cache.del(key_for(feature.key))
result
end
# Public
def get(feature)
fetch(key_for(feature.key)) do
@adapter.get(feature)
end
end
def get_multi(features)
read_many_features(features)
end
def get_all
if @cache.setnx(GetAllKey, Time.now.to_i)
@cache.expire(GetAllKey, @ttl)
response = @adapter.get_all
response.each do |key, value|
set_with_ttl key_for(key), value
end
set_with_ttl FeaturesKey, response.keys.to_set
response
else
features = read_feature_keys.map { |key| Flipper::Feature.new(key, self) }
read_many_features(features)
end
end
# Public
def enable(feature, gate, thing)
result = @adapter.enable(feature, gate, thing)
@cache.del(key_for(feature.key))
result
end
# Public
def disable(feature, gate, thing)
result = @adapter.disable(feature, gate, thing)
@cache.del(key_for(feature.key))
result
end
private
def key_for(key)
self.class.key_for(key)
end
def read_feature_keys
fetch(FeaturesKey) { @adapter.features }
end
def read_many_features(features)
keys = features.map(&:key)
cache_result = Hash[keys.zip(multi_cache_get(keys))]
uncached_features = features.reject { |feature| cache_result[feature.key] }
if uncached_features.any?
response = @adapter.get_multi(uncached_features)
response.each do |key, value|
set_with_ttl(key_for(key), value)
cache_result[key] = value
end
end
result = {}
features.each do |feature|
result[feature.key] = cache_result[feature.key]
end
result
end
def fetch(cache_key)
cached = @cache.get(cache_key)
if cached
Marshal.load(cached)
else
to_cache = yield
set_with_ttl(cache_key, to_cache)
to_cache
end
end
def set_with_ttl(key, value)
@cache.setex(key, @ttl, Marshal.dump(value))
end
def multi_cache_get(keys)
cache_keys = keys.map { |key| key_for(key) }
@cache.mget(cache_keys).map do |value|
value ? Marshal.load(value) : nil
end
end
end
end
end
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