From 3dc70af0678f9a92cf02e80140cc2becc83f9b58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Piotr=20W=C3=B3jcik?=
 <3044353+pwojcikdev@users.noreply.github.com>
Date: Fri, 3 May 2024 12:20:52 +0200
Subject: [PATCH] Wait until fair queue source drains before removal (#4597)

---
 nano/core_test/fair_queue.cpp | 19 +++++++++++--------
 nano/node/fair_queue.hpp      |  2 +-
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/nano/core_test/fair_queue.cpp b/nano/core_test/fair_queue.cpp
index d60dda7855..eda3d7fc8b 100644
--- a/nano/core_test/fair_queue.cpp
+++ b/nano/core_test/fair_queue.cpp
@@ -260,17 +260,20 @@ TEST (fair_queue, cleanup)
 	ASSERT_EQ (queue.size ({ source_enum::live, channel2 }), 1);
 	ASSERT_EQ (queue.size ({ source_enum::live, channel3 }), 1);
 
-	// Either closing or resetting the channel should remove it from the queue
+	// Either closing or resetting the channel should make it eligible for cleanup
 	channel1->close ();
 	channel2.reset ();
 
-	ASSERT_TRUE (queue.periodic_update ());
+	ASSERT_TRUE (queue.periodic_update (0s));
 
-	// Only channel 3 should remain
-	ASSERT_EQ (queue.size (), 1);
-	ASSERT_EQ (queue.queues_size (), 1);
+	// Until the queue is drained, the entries are still present
+	ASSERT_EQ (queue.size (), 3);
+	ASSERT_EQ (queue.queues_size (), 3);
 
-	ASSERT_EQ (queue.size ({ source_enum::live, channel1 }), 0);
-	ASSERT_EQ (queue.size ({ source_enum::live, channel2 }), 0);
-	ASSERT_EQ (queue.size ({ source_enum::live, channel3 }), 1);
+	queue.next_batch (999);
+
+	ASSERT_TRUE (queue.periodic_update (0s));
+
+	ASSERT_TRUE (queue.empty ());
+	ASSERT_EQ (queue.queues_size (), 1);
 }
diff --git a/nano/node/fair_queue.hpp b/nano/node/fair_queue.hpp
index 738bd43ec7..52bdcc34d0 100644
--- a/nano/node/fair_queue.hpp
+++ b/nano/node/fair_queue.hpp
@@ -330,7 +330,7 @@ class fair_queue final
 		iterator = queues.end ();
 
 		erase_if (queues, [] (auto const & entry) {
-			return !entry.first.alive ();
+			return entry.second.empty () && !entry.first.alive ();
 		});
 	}