web: optimize offline shard checker (#1708)

* web: add per-guild status endpoint * frontend: use new per-guild status endpoint * frontend: store offline check timer on window
botlabs-gg · Jul 22, 2024 · 61058ff · 61058ff
1 parent b9dabf9
commit 61058ff
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Showing 3 changed files with 31 additions and 16 deletions.
diff --git a/frontend/templates/cp_main.html b/frontend/templates/cp_main.html
@@ -168,20 +168,19 @@ <h2 class="card-title">
     });
 
     {{if .ActiveGuild}}
-        async function runShardOfflineChecker() {
-            let wasOffline = await checkShardOffline();
-            let shardCheckerRunning = sessionStorage.getItem('isShardOfflineCheckerRunning');
-            if (shardCheckerRunning === 'true') {
-              return;
+        async function startShardOfflineChecker() {
+            if (typeof window.offlineShardCheckerInterval !== 'undefined') {
+                clearInterval(window.offlineShardCheckerInterval);
             }
-            sessionStorage.setItem('isShardOfflineCheckerRunning', 'true');
-            setInterval(async () => {
-                const currentlyOffline = await checkShardOffline();
+
+            let wasOnline = await checkGuildShardOnline();
+            window.offlineShardCheckerInterval = setInterval(async () => {
+                const currentlyOnline = await checkGuildShardOnline();
 
                 // To prevent spurious warnings during routine shard reconnections,
                 // only show an alert if a shard appears to be offline for two
                 // checks in a row.
-                if (wasOffline && currentlyOffline) {
+                if (!wasOnline && !currentlyOnline) {
                     upsertAlert(
                         "The shard the bot is on for your server is currently offline; some functionality may not work as expected. \
                         Join the support server for more information if this issue persists."
@@ -190,14 +189,13 @@ <h2 class="card-title">
                     $("#shard-problems-warning").remove();
                 }
 
-                wasOffline = currentlyOffline;
+                wasOnline = currentlyOnline;
             }, 15_000);
         }
 
-        async function checkShardOffline() {
-            const data = await fetch("/status.json").then((resp) => resp.json());
-            const shardId = Number(BigInt("{{.ActiveGuild.ID}}") >> BigInt(22)) % data.total_shards;
-            return data.offline_shards && data.offline_shards.includes(shardId);
+        async function checkGuildShardOnline() {
+            const status = await fetch("/api/{{.ActiveGuild.ID}}/status.json").then((resp) => resp.json());
+            return status.shard_online;
         }
 
         function upsertAlert(msg) {
@@ -208,8 +206,7 @@ <h2 class="card-title">
             }
         }
 
-        // Computing the shard number requires BigInt support.
-        if (typeof BigInt !== "undefined") runShardOfflineChecker();
+        startShardOfflineChecker();
     {{end}}
 })
 </script>

diff --git a/web/handlers_general.go b/web/handlers_general.go
@@ -289,6 +289,23 @@ func HandleStatusJSON(w http.ResponseWriter, r *http.Request) interface{} {
 	return status
 }
 
+type GuildStatus struct {
+	ShardOnline bool `json:"shard_online"`
+}
+
+// HandleGuildStatusJSON handles GET /api/:server/status.json
+func HandleGuildStatusJSON(w http.ResponseWriter, r *http.Request) interface{} {
+	g := r.Context().Value(common.ContextKeyCurrentGuild).(*dstate.GuildSet)
+	status, err := getFullBotStatus()
+	if err != nil {
+		return err
+	}
+
+	shard := int(g.ID>>22) % status.TotalShards
+	isOffline := common.ContainsIntSlice(status.OfflineShards, shard)
+	return GuildStatus{ShardOnline: !isOffline}
+}
+
 type HostStatus struct {
 	Name string
 

diff --git a/web/web.go b/web/web.go
@@ -293,6 +293,7 @@ func setupRoutes() *goji.Mux {
 	RootMux.Handle(pat.Get("/api/:server/*"), ServerPublicAPIMux)
 
 	ServerPublicAPIMux.Handle(pat.Get("/channelperms/:channel"), RequireActiveServer(APIHandler(HandleChannelPermissions)))
+	ServerPublicAPIMux.Handle(pat.Get("/status.json"), RequireActiveServer(APIHandler(HandleGuildStatusJSON)))
 
 	// Server selection has its own handler
 	RootMux.Handle(pat.Get("/manage"), SelectServerHomePageHandler)