From 4cc2dbe316be9d8ac63ee00a6aff5455ecb4cd86 Mon Sep 17 00:00:00 2001
From: "Adam C. Emerson" <aemerson@redhat.com>
Date: Wed, 26 Nov 2025 00:54:21 -0500
Subject: [PATCH] neorados: Actually enforce notification queue limit

We were adding an overflow marker on every message above capacity, not
just the first, vitiating the purpose of the bound. The shame, the
shame.

Signed-off-by: Adam C. Emerson <aemerson@redhat.com>
---
 src/neorados/RADOS.cc             |  4 +++-
 src/test/neorados/watch_notify.cc | 30 ++++++++++++++++++++++++++----
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/neorados/RADOS.cc b/src/neorados/RADOS.cc
index 3cd8fcc50b09..f4f2686b2c68 100644
--- a/src/neorados/RADOS.cc
+++ b/src/neorados/RADOS.cc
@@ -1486,7 +1486,9 @@ public:
     } else if (capacity && notifications.size() >= capacity) {
       // We are allowed one over, so the client knows where in the
       // sequence of notifications we started losing data.
-      notifications.push({errc::notification_overflow, {}});
+      if (notifications.size() == capacity) {
+        notifications.push({errc::notification_overflow, {}});
+      }
     } else {
       notifications.push({{},
 			  Notification{
diff --git a/src/test/neorados/watch_notify.cc b/src/test/neorados/watch_notify.cc
index c567a5b3e226..f7305c37ef1a 100644
--- a/src/test/neorados/watch_notify.cc
+++ b/src/test/neorados/watch_notify.cc
@@ -10,8 +10,8 @@
  *
  */
 
+#include <boost/asio/detached.hpp>
 #include <boost/system/detail/errc.hpp>
-#include <coroutine>
 #include <cstdint>
 #include <iostream>
 #include <utility>
@@ -36,8 +36,6 @@
 
 #include "gtest/gtest.h"
 
-using std::uint64_t;
-
 namespace asio = boost::asio;
 namespace buffer = ceph::buffer;
 namespace container = boost::container;
@@ -46,7 +44,6 @@ namespace sys = boost::system;
 using namespace std::literals;
 
 using neorados::ReadOp;
-using neorados::WriteOp;
 
 using std::uint64_t;
 
@@ -234,6 +231,31 @@ CORO_TEST_F(NeoRadosWatchNotifyPoll, WatchNotify, NeoRadosTest) {
   co_return;
 }
 
+CORO_TEST_F(NeoRadosWatchNotifyPoll, WatchNotifyOverflow, NeoRadosTest) {
+  static constexpr auto oid = "obj"sv;
+  co_await create_obj(oid);
+  auto handle = co_await rados().watch(oid, pool(), asio::use_awaitable,
+                                       std::nullopt, 1);
+  EXPECT_TRUE(rados().check_watch(handle));
+  // TODO: Write an awaitable future. This should work for testing for now.
+  rados().notify(oid, pool(), {}, 1s, asio::detached);
+  rados().notify(oid, pool(), {}, 1s, asio::detached);
+  rados().notify(oid, pool(), {}, 1s, asio::detached);
+  rados().notify(oid, pool(), {}, 1s, asio::detached);
+  co_await wait_for(1s);
+  co_await rados().next_notification(handle, asio::use_awaitable);
+  rados().notify(oid, pool(), {}, 1s, asio::detached);
+  co_await expect_error_code(rados().next_notification(handle, asio::use_awaitable),
+                             neorados::errc::notification_overflow);
+  rados().notify(oid, pool(), {}, 1s, asio::detached);
+  co_await rados().next_notification(handle, asio::use_awaitable);
+  co_await rados().unwatch(handle, pool(), asio::use_awaitable);
+  std::cout << "Flushing..." << std::endl;
+  co_await rados().flush_watch(asio::use_awaitable);
+  std::cout << "Flushed..." << std::endl;
+  co_return;
+}
+
 CORO_TEST_F(NeoRadosWatchNotifyPoll, WatchNotifyTimeout, NeoRadosTest) {
   static constexpr auto oid = "obj"sv;
   static constexpr auto timeout = 1s;
-- 
2.47.3