1 files changed, 53 insertions, 0 deletions
diff --git a/app/models/ci/unlock_pipeline_request.rb b/app/models/ci/unlock_pipeline_request.rb
new file mode 100644
index 00000000000..c8fc82f3e55
--- /dev/null
+++ b/app/models/ci/unlock_pipeline_request.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module Ci
+  class UnlockPipelineRequest
+    QUEUE_REDIS_KEY = 'ci_unlock_pipeline_requests:queue'
+
+    def self.enqueue(pipeline_id)
+      unix_timestamp = Time.current.utc.to_i
+      pipeline_ids = Array(pipeline_id).uniq
+      pipeline_ids_with_scores = pipeline_ids.map do |id|
+        # The order of values per pair is `[score, key]`, so in this case, the unix timestamp is the score.
+        # By default, the sort order of sorted sets is from lowest to highest, though this does not matter much
+        # because we use `ZPOPMIN` to make sure to return the lowest/oldest request in terms of unix timestamp score.
+        [unix_timestamp, id]
+      end
+
+      with_redis do |redis|
+        added = redis.zadd(QUEUE_REDIS_KEY, pipeline_ids_with_scores, nx: true)
+        log_event(:enqueued, pipeline_ids) if added > 0
+        added
+      end
+    end
+
+    def self.next!
+      with_redis do |redis|
+        pipeline_id, enqueue_timestamp = redis.zpopmin(QUEUE_REDIS_KEY)
+        break unless pipeline_id
+
+        pipeline_id = pipeline_id.to_i
+        log_event(:picked_next, pipeline_id)
+
+        [pipeline_id, enqueue_timestamp.to_i]
+      end
+    end
+
+    def self.total_pending
+      with_redis do |redis|
+        redis.zcard(QUEUE_REDIS_KEY)
+      end
+    end
+
+    def self.with_redis(&block)
+      Gitlab::Redis::SharedState.with(&block)
+    end
+
+    def self.log_event(event, pipeline_id)
+      Gitlab::AppLogger.info(
+        message: "Pipeline unlock - #{event}",
+        pipeline_id: pipeline_id
+      )
+    end
+  end
+end