1 files changed, 68 insertions, 0 deletions
diff --git a/app/services/protected_branches/cache_service.rb b/app/services/protected_branches/cache_service.rb
new file mode 100644
index 00000000000..8c521f4ebcb
--- /dev/null
+++ b/app/services/protected_branches/cache_service.rb
@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+module ProtectedBranches
+  class CacheService < ProtectedBranches::BaseService
+    CACHE_ROOT_KEY = 'cache:gitlab:protected_branch'
+    TTL_UNSET = -1
+    CACHE_EXPIRE_IN = 1.day
+    CACHE_LIMIT = 1000
+
+    def fetch(ref_name, dry_run: false)
+      record = OpenSSL::Digest::SHA256.hexdigest(ref_name)
+
+      Gitlab::Redis::Cache.with do |redis|
+        cached_result = redis.hget(redis_key, record)
+
+        decoded_result = Gitlab::Redis::Boolean.decode(cached_result) unless cached_result.nil?
+
+        # If we're dry-running, don't break because we need to check against
+        # the real value to ensure the cache is working properly.
+        # If the result is nil we'll need to run the block, so don't break yet.
+        break decoded_result unless dry_run || decoded_result.nil?
+
+        calculated_value = yield
+
+        check_and_log_discrepancy(decoded_result, calculated_value, ref_name) if dry_run
+
+        redis.hset(redis_key, record, Gitlab::Redis::Boolean.encode(calculated_value))
+
+        # We don't want to extend cache expiration time
+        if redis.ttl(redis_key) == TTL_UNSET
+          redis.expire(redis_key, CACHE_EXPIRE_IN)
+        end
+
+        # If the cache record has too many elements, then something went wrong and
+        # it's better to drop the cache key.
+        if redis.hlen(redis_key) > CACHE_LIMIT
+          redis.unlink(redis_key)
+        end
+
+        calculated_value
+      end
+    end
+
+    def refresh
+      Gitlab::Redis::Cache.with { |redis| redis.unlink(redis_key) }
+    end
+
+    private
+
+    def check_and_log_discrepancy(cached_value, real_value, ref_name)
+      return if cached_value.nil?
+      return if cached_value == real_value
+
+      encoded_ref_name = Gitlab::EncodingHelper.encode_utf8_with_replacement_character(ref_name)
+
+      log_error(
+        'class' => self.class.name,
+        'message' => "Cache mismatch '#{encoded_ref_name}': cached value: #{cached_value}, real value: #{real_value}",
+        'project_id' => @project.id,
+        'project_path' => @project.full_path
+      )
+    end
+
+    def redis_key
+      @redis_key ||= [CACHE_ROOT_KEY, @project.id].join(':')
+    end
+  end
+end