From cae1780b9045db7f2f8b6b5c766e86d89ffd3af4 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>
(cherry picked from commit 4cc2dbe316be9d8ac63ee00a6aff5455ecb4cd86)
Fixes: https://tracker.ceph.com/issues/76434
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 ef27c0779c6..8716ca10747 100644
--- a/src/neorados/RADOS.cc
+++ b/src/neorados/RADOS.cc
@@ -1496,7 +1496,9 @@ 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 2e86af8d717..574720375fe 100644
--- a/src/test/neorados/watch_notify.cc
+++ b/src/test/neorados/watch_notify.cc
@@ -9,8 +9,8 @@
  *
  */
 
+#include <boost/asio/detached.hpp>
 #include <boost/system/detail/errc.hpp>
-#include <coroutine>
 #include <cstdint>
 #include <iostream>
 #include <utility>
@@ -35,8 +35,6 @@
 
 #include "gtest/gtest.h"
 
-using std::uint64_t;
-
 namespace asio = boost::asio;
 namespace buffer = ceph::buffer;
 namespace container = boost::container;
@@ -45,7 +43,6 @@ namespace sys = boost::system;
 using namespace std::literals;
 
 using neorados::ReadOp;
-using neorados::WriteOp;
 
 using std::uint64_t;
 
@@ -233,6 +230,31 @@ 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