lib/gitlab/shard_health_cache.rb


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# frozen_string_literal: true

module Gitlab
  class ShardHealthCache
    HEALTHY_SHARDS_KEY = 'gitlab-healthy-shards'
    HEALTHY_SHARDS_TIMEOUT = 300

    # Clears the Redis set storing the list of healthy shards
    def self.clear
      with_redis { |redis| redis.del(HEALTHY_SHARDS_KEY) }
    end

    # Updates the list of healthy shards using a Redis set
    #
    # shards - An array of shard names to store
    def self.update(shards)
      with_redis do |redis|
        redis.multi do |m|
          m.del(HEALTHY_SHARDS_KEY)
          m.sadd(HEALTHY_SHARDS_KEY, shards) unless shards.blank?
          m.expire(HEALTHY_SHARDS_KEY, HEALTHY_SHARDS_TIMEOUT)
        end
      end
    end

    # Returns an array of strings of healthy shards
    def self.cached_healthy_shards
      with_redis { |redis| redis.smembers(HEALTHY_SHARDS_KEY) }
    end

    # Checks whether the given shard name is in the list of healthy shards.
    #
    # shard_name - The string to check
    def self.healthy_shard?(shard_name)
      with_redis { |redis| redis.sismember(HEALTHY_SHARDS_KEY, shard_name) }
    end

    # Returns the number of healthy shards in the Redis set
    def self.healthy_shard_count
      with_redis { |redis| redis.scard(HEALTHY_SHARDS_KEY) }
    end

    def self.with_redis(&block)
      Gitlab::Redis::Cache.with(&block) # rubocop:disable CodeReuse/ActiveRecord
    end
  end
end