From 8f6be7ddac7abdb61b669e89621a2942a13022c0 Mon Sep 17 00:00:00 2001
From: Kefu Chai <kchai@redhat.com>
Date: Sun, 7 Mar 2021 21:23:54 +0800
Subject: [PATCH] crimson/osd: differentiate Notify with and without watchers

we don't need to arm the timer, if there is no watchers.

Signed-off-by: Kefu Chai <kchai@redhat.com>
---
 src/crimson/osd/watch.cc | 10 ++++++++++
 src/crimson/osd/watch.h  | 17 ++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/crimson/osd/watch.cc b/src/crimson/osd/watch.cc
index 590e9922777..261bd18040c 100644
--- a/src/crimson/osd/watch.cc
+++ b/src/crimson/osd/watch.cc
@@ -128,6 +128,16 @@ std::ostream &operator<<(std::ostream &out, const notify_reply_t &rhs)
   return out;
 }
 
+Notify::Notify(crimson::net::ConnectionRef conn,
+               const notify_info_t& ninfo,
+               const uint64_t client_gid,
+               const uint64_t user_version)
+  : ninfo(ninfo),
+    conn(std::move(conn)),
+    client_gid(client_gid),
+    user_version(user_version)
+{}
+
 seastar::future<> Notify::remove_watcher(WatchRef watch)
 {
   if (discarded || complete) {
diff --git a/src/crimson/osd/watch.h b/src/crimson/osd/watch.h
index b654efa41c4..d9f7325d3ac 100644
--- a/src/crimson/osd/watch.h
+++ b/src/crimson/osd/watch.h
@@ -130,6 +130,10 @@ class Notify {
   /// Called on Notify timeout
   void do_timeout();
 
+  Notify(crimson::net::ConnectionRef conn,
+         const notify_info_t& ninfo,
+         const uint64_t client_gid,
+         const uint64_t user_version);
   template <class WatchIteratorT>
   Notify(WatchIteratorT begin,
          WatchIteratorT end,
@@ -188,6 +192,7 @@ Notify::Notify(WatchIteratorT begin,
     conn(std::move(conn)),
     client_gid(client_gid),
     user_version(user_version) {
+  assert(!std::empty(watchers));
   if (ninfo.timeout) {
     timeout_timer.arm(std::chrono::seconds{ninfo.timeout});
   }
@@ -202,14 +207,16 @@ seastar::future<> Notify::create_n_propagate(
   static_assert(
     std::is_same_v<typename std::iterator_traits<WatchIteratorT>::value_type,
                    crimson::osd::WatchRef>);
-  auto notify = seastar::make_shared<Notify>(
-    private_ctag_t{},
-    begin,
-    end,
-    std::forward<Args>(args)...);
   if (begin == end) {
+    auto notify = seastar::make_shared<Notify>(
+      private_ctag_t{},
+      std::forward<Args>(args)...);
     return notify->send_completion();
   } else {
+    auto notify = seastar::make_shared<Notify>(
+      private_ctag_t{},
+      begin, end,
+      std::forward<Args>(args)...);
     return seastar::do_for_each(begin, end, [=] (auto& watchref) {
       return watchref->start_notify(notify);
     });
-- 
2.39.5