Merge pull request #1162 from ripienaar/pre_fetch_watch

Perform a single pre-fretch for some watches
nats-io · Sep 26, 2024 · db5dbae · db5dbae
2 parents 9aeb804 + f42e729
commit db5dbae
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Showing 2 changed files with 31 additions and 1 deletion.
diff --git 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
@@ -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 {