Class: LaunchDarkly::RedisFeatureStore

Inherits:
Object
  • Object
show all
Defined in:
lib/ldclient-rb/redis_store.rb

Overview

An implementation of the LaunchDarkly client’s feature store that uses a Redis instance. This object holds feature flags and related data received from the streaming API. Feature data can also be further cached in memory to reduce overhead of calls to Redis.

To use this class, you must first have the ‘redis`, `connection-pool`, and `moneta` gems installed. Then, create an instance and store it in the `feature_store` property of your client configuration.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ RedisFeatureStore

Constructor for a RedisFeatureStore instance.

Parameters:

  • opts (Hash) (defaults to: {}) —

    the configuration options

Options Hash (opts):

  • :redis_url (String) —

    URL of the Redis instance (shortcut for omitting redis_opts)

  • :redis_opts (Hash) —

    options to pass to the Redis constructor (if you want to specify more than just redis_url)

  • :prefix (String) —

    namespace prefix to add to all hash keys used by LaunchDarkly

  • :logger (Logger) —

    a ‘Logger` instance; defaults to `Config.default_logger`

  • :max_connections (Integer) —

    size of the Redis connection pool

  • :expiration (Integer) —

    expiration time for the in-memory cache, in seconds; 0 for no local caching

  • :capacity (Integer) —

    maximum number of feature flags (or related objects) to cache locally

  • :pool (Object) —

    custom connection pool, used for testing only



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# File 'lib/ldclient-rb/redis_store.rb', line 39

def initialize(opts = {})
  if !REDIS_ENABLED
    raise RuntimeError.new("can't use RedisFeatureStore because one of these gems is missing: redis, connection_pool, moneta")
  end
  @redis_opts = opts[:redis_opts] || Hash.new
  if opts[:redis_url]
    @redis_opts[:url] = opts[:redis_url]
  end
  if !@redis_opts.include?(:url)
    @redis_opts[:url] = RedisFeatureStore.default_redis_url
  end
  max_connections = opts[:max_connections] || 16
  @pool = opts[:pool] || ConnectionPool.new(size: max_connections) do
    Redis.new(@redis_opts)
  end
  @prefix = opts[:prefix] || RedisFeatureStore.default_prefix
  @logger = opts[:logger] || Config.default_logger

  @expiration_seconds = opts[:expiration] || 15
  @capacity = opts[:capacity] || 1000
  # We're using Moneta only to provide expiration behavior for the in-memory cache.
  # Moneta can also be used as a wrapper for Redis, but it doesn't support the Redis
  # hash operations that we use.
  if @expiration_seconds > 0
    @cache = Moneta.new(:LRUHash, expires: true, threadsafe: true, max_count: @capacity)
  else
    @cache = Moneta.new(:Null)  # a stub that caches nothing
  end

  @stopped = Concurrent::AtomicBoolean.new(false)
  @inited = MemoizedValue.new {
    query_inited
  }

  with_connection do |redis|
    @logger.info("RedisFeatureStore: using Redis instance at #{redis.connection[:host]}:#{redis.connection[:port]} \
and prefix: #{@prefix}")
  end
end

Class Method Details

.default_prefix ⇒ Object

Default value for the ‘prefix` constructor parameter.



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# File 'lib/ldclient-rb/redis_store.rb', line 90

def self.default_prefix
  'launchdarkly'
end

.default_redis_url ⇒ Object

Default value for the ‘redis_url` constructor parameter; points to an instance of Redis running at `localhost` with its default port.



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# File 'lib/ldclient-rb/redis_store.rb', line 83

def self.default_redis_url
  'redis://localhost:6379/0'
end

Instance Method Details

#all(kind) ⇒ Object 



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# File 'lib/ldclient-rb/redis_store.rb', line 121

def all(kind)
  fs = {}
  with_connection do |redis|
    begin
      hashfs = redis.hgetall(items_key(kind))
    rescue => e
      @logger.error("RedisFeatureStore: could not retrieve all '#{kind[:namespace]}' items from Redis with error: #{e}; returning none")
      hashfs = {}
    end
    hashfs.each do |k, jsonItem|
      f = JSON.parse(jsonItem, symbolize_names: true)
      if !f[:deleted]
        fs[k.to_sym] = f
      end
    end
  end
  fs
end

#clear_local_cache ⇒ Object

exposed for testing



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# File 'lib/ldclient-rb/redis_store.rb', line 199

def clear_local_cache()
  @cache.clear
end

#delete(kind, key, version) ⇒ Object 



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# File 'lib/ldclient-rb/redis_store.rb', line 140

def delete(kind, key, version)
  with_connection do |redis|
    f = get_redis(kind, redis, key)
    if f.nil?
      put_redis_and_cache(kind, redis, key, { deleted: true, version: version })
    else
      if f[:version] < version
        f1 = f.clone
        f1[:deleted] = true
        f1[:version] = version
        put_redis_and_cache(kind, redis, key, f1)
      else
        @logger.warn("RedisFeatureStore: attempted to delete #{key} version: #{f[:version]} \
  in '#{kind[:namespace]}' with a version that is the same or older: #{version}")
      end
    end
  end
end

#get(kind, key) ⇒ Object 



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# File 'lib/ldclient-rb/redis_store.rb', line 94

def get(kind, key)
  f = @cache[cache_key(kind, key)]
  if f.nil?
    @logger.debug("RedisFeatureStore: no cache hit for #{key} in '#{kind[:namespace]}', requesting from Redis")
    f = with_connection do |redis|
      begin
        get_redis(kind, redis, key.to_sym)
      rescue => e
        @logger.error("RedisFeatureStore: could not retrieve #{key} from Redis in '#{kind[:namespace]}', with error: #{e}")
        nil
      end
    end
    if !f.nil?
      put_cache(kind, key, f)
    end
  end
  if f.nil?
    @logger.debug("RedisFeatureStore: #{key} not found in '#{kind[:namespace]}'")
    nil
  elsif f[:deleted]
    @logger.debug("RedisFeatureStore: #{key} was deleted in '#{kind[:namespace]}', returning nil")
    nil
  else
    f
  end
end

#init(all_data) ⇒ Object 



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# File 'lib/ldclient-rb/redis_store.rb', line 159

def init(all_data)
  @cache.clear
  count = 0
  with_connection do |redis|
    all_data.each do |kind, items|
      redis.multi do |multi|
        multi.del(items_key(kind))
        count = count + items.count
        items.each { |k, v| put_redis_and_cache(kind, multi, k, v) }
      end
    end
  end
  @inited.set(true)
  @logger.info("RedisFeatureStore: initialized with #{count} items")
end

#initialized? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ldclient-rb/redis_store.rb', line 187

def initialized?
  @inited.get
end

#stop ⇒ Object 



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# File 'lib/ldclient-rb/redis_store.rb', line 191

def stop
  if @stopped.make_true
    @pool.shutdown { |redis| redis.close }
    @cache.clear
  end
end

#upsert(kind, item) ⇒ Object 



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# File 'lib/ldclient-rb/redis_store.rb', line 175

def upsert(kind, item)
  with_connection do |redis|
    redis.watch(items_key(kind)) do
      old = get_redis(kind, redis, item[:key])
      if old.nil? || (old[:version] < item[:version])
        put_redis_and_cache(kind, redis, item[:key], item)
      end
      redis.unwatch
    end
  end
end