1 files changed, 45 insertions, 0 deletions
diff --git a/lib/gitlab/redis/hll.rb b/lib/gitlab/redis/hll.rb
new file mode 100644
index 00000000000..ff5754675e2
--- /dev/null
+++ b/lib/gitlab/redis/hll.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Redis
+    class HLL
+      KEY_REGEX = %r{\A(\w|-|:)*\{\w*\}(\w|-|:)*\z}.freeze
+      KeyFormatError = Class.new(StandardError)
+
+      def self.count(params)
+        self.new.count(params)
+      end
+
+      def self.add(params)
+        self.new.add(params)
+      end
+
+      def count(keys:)
+        Gitlab::Redis::SharedState.with do |redis|
+          redis.pfcount(*keys)
+        end
+      end
+
+      # Check a basic format for the Redis key in order to ensure the keys are in the same hash slot
+      #
+      # Examples of keys
+      #   project:{1}:set_a
+      #   project:{1}:set_b
+      #   project:{2}:set_c
+      #   2020-216-{project_action}
+      #   i_{analytics}_dev_ops_score-2020-32
+      def add(key:, value:, expiry:)
+        unless KEY_REGEX.match?(key)
+          raise KeyFormatError.new("Invalid key format. #{key} key should have changeable parts in curly braces. See https://docs.gitlab.com/ee/development/redis.html#multi-key-commands")
+        end
+
+        Gitlab::Redis::SharedState.with do |redis|
+          redis.multi do |multi|
+            multi.pfadd(key, value)
+            multi.expire(key, expiry)
+          end
+        end
+      end
+    end
+  end
+end