Merge pull request #23 from no92/queue-empty

Author: no92

include/async/queue.hpp

@@ -140,6 +140,10 @@ struct queue {
 		return {this, ct};
 	}
 
+	bool empty() {
+		return buffer_.empty();
+	}
+
 	frg::optional<T> maybe_get() {
 		frg::unique_lock lock{mutex_};