on admin index page, show number of messages in queue next to link to the queue list

http/admin.go

@@ -1447,6 +1447,13 @@ func (Admin) QueueList(ctx context.Context) []queue.Msg {
 	return l
 }
 
+// QueueSize returns the number of messages currently in the outgoing queue.
+func (Admin) QueueSize(ctx context.Context) int {
+	n, err := queue.Count()
+	xcheckf(ctx, err, "listing messages in queue")
+	return n
+}
+
 // QueueKick initiates delivery of a message from the queue.
 func (Admin) QueueKick(ctx context.Context, id int64) {
 	n, err := queue.Kick(id, "", "")

http/admin.html

@@ -188,7 +188,10 @@ const formatSize = n => {
 }
 
 const index = async () => {
-	const domains = await api.Domains()
+	const [domains, queueSize] = await Promise.all([
+		await api.Domains(),
+		await api.QueueSize(),
+	])
 
 	let fieldset, domain, account, localpart
 
@@ -197,7 +200,7 @@ const index = async () => {
 		crumbs('Mox Admin'),
 		dom.p(
 			dom.a('Accounts', attr({href: '#accounts'})), dom.br(),
-			dom.a('Queue', attr({href: '#queue'})), dom.br(),
+			dom.a('Queue', attr({href: '#queue'})), ' ('+queueSize+')', dom.br(),
 		),
 		dom.h2('Domains'),
 		domains.length === 0 ? box(red, 'No domains') :

http/adminapi.json

@@ -552,6 +552,19 @@
 				}
 			]
 		},
+		{
+			"Name": "QueueSize",
+			"Docs": "QueueSize returns the number of messages currently in the outgoing queue.",
+			"Params": [],
+			"Returns": [
+				{
+					"Name": "r0",
+					"Typewords": [
+						"int32"
+					]
+				}
+			]
+		},
 		{
 			"Name": "QueueKick",
 			"Docs": "QueueKick initiates delivery of a message from the queue.",

queue/queue.go

@@ -162,6 +162,11 @@ func List() ([]Msg, error) {
 	return qmsgs, nil
 }
 
+// Count returns the number of messages in the delivery queue.
+func Count() (int, error) {
+	return bstore.QueryDB[Msg](queueDB).Count()
+}
+
 // Add a new message to the queue. The queue is kicked immediately to start a
 // first delivery attempt.
 //