From f42e72927a86fc90cd1f09b66df550a515b94887 Mon Sep 17 00:00:00 2001
From: "R.I.Pienaar" <rip@devco.net>
Date: Thu, 26 Sep 2024 10:57:58 +0200
Subject: [PATCH] Perform a single pre-fretch for some watches

Signed-off-by: R.I.Pienaar <rip@devco.net>
---
 cli/server_watch_js_command.go  | 16 +++++++++++++++-
 cli/server_watch_srv_command.go | 16 ++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/cli/server_watch_js_command.go b/cli/server_watch_js_command.go
index 84fbd351..d0b7d6db 100644
--- a/cli/server_watch_js_command.go
+++ b/cli/server_watch_js_command.go
@@ -90,14 +90,28 @@ func (c *SrvWatchJSCmd) updateSizes() error {
 	return nil
 }
 
+func (c *SrvWatchJSCmd) prePing(nc *nats.Conn, h nats.MsgHandler) {
+	sub, err := nc.Subscribe(nc.NewRespInbox(), h)
+	if err != nil {
+		return
+	}
+
+	time.AfterFunc(2*time.Second, func() { sub.Unsubscribe() })
+
+	msg := nats.NewMsg("$SYS.REQ.SERVER.PING")
+	msg.Reply = sub.Subject
+	nc.PublishMsg(msg)
+}
+
 func (c *SrvWatchJSCmd) jetstreamAction(_ *fisk.ParseContext) error {
 	nc, _, err := prepareHelper("", natsOpts()...)
 	if err != nil {
 		return err
 	}
 
-	_, err = nc.Subscribe("$SYS.SERVER.*.STATSZ", c.handle)
+	c.prePing(nc, c.handle)
 
+	_, err = nc.Subscribe("$SYS.SERVER.*.STATSZ", c.handle)
 	if err != nil {
 		return err
 	}
diff --git a/cli/server_watch_srv_command.go b/cli/server_watch_srv_command.go
index add91721..357a61ee 100644
--- a/cli/server_watch_srv_command.go
+++ b/cli/server_watch_srv_command.go
@@ -95,12 +95,28 @@ func (c *SrvWatchServerCmd) updateSizes() error {
 
 	return nil
 }
+
+func (c *SrvWatchServerCmd) prePing(nc *nats.Conn, h nats.MsgHandler) {
+	sub, err := nc.Subscribe(nc.NewRespInbox(), h)
+	if err != nil {
+		return
+	}
+
+	time.AfterFunc(2*time.Second, func() { sub.Unsubscribe() })
+
+	msg := nats.NewMsg("$SYS.REQ.SERVER.PING")
+	msg.Reply = sub.Subject
+	nc.PublishMsg(msg)
+}
+
 func (c *SrvWatchServerCmd) serversAction(_ *fisk.ParseContext) error {
 	nc, _, err := prepareHelper("", natsOpts()...)
 	if err != nil {
 		return err
 	}
 
+	c.prePing(nc, c.handle)
+
 	_, err = nc.Subscribe("$SYS.SERVER.*.STATSZ", c.handle)
 
 	if err != nil {