feat: Optimize server availability checks with parallelized TCP connections and in-memory caching, and update Dashboard to handle paginated API responses for improved performance and user experience

backend/server.js

@@ -1397,36 +1397,59 @@ app.get('/api/auto-urls', async (req, res) => {
 });
 
 // --- Servers availability check ---
-// Simple TCP connect check to 80 then 443 with short timeouts
+// Optimized TCP check: parallelize ports and hosts, cap per-host time, add in-memory TTL cache
 function tcpCheck(host, port, timeoutMs) {
   return new Promise((resolve) => {
     const socket = new net.Socket();
     let settled = false;
-    const onOk = () => { if (!settled) { settled = true; try{ socket.destroy(); }catch{} resolve(true); } };
-    const onFail = () => { if (!settled) { settled = true; try{ socket.destroy(); }catch{} resolve(false); } };
-    socket.setTimeout(timeoutMs);
-    socket.once('error', onFail);
-    socket.once('timeout', onFail);
-    socket.connect(port, host, onOk);
+    const settle = (ok) => { if (!settled) { settled = true; try { socket.destroy(); } catch {} resolve(ok); } };
+    socket.setTimeout(timeoutMs, () => settle(false));
+    socket.once('error', () => settle(false));
+    socket.connect(port, host, () => settle(true));
   });
 }
 
-async function checkOneServer(srv, timeoutMs = 1500) {
-  const hostCandidates = [];
-  if (srv.ip) hostCandidates.push(srv.ip);
-  if (srv.dns) hostCandidates.push(srv.dns);
-  for (const host of hostCandidates) {
-    // try 80 then 443
-    const ok80 = await tcpCheck(host, 80, timeoutMs);
-    if (ok80) return true;
-    const ok443 = await tcpCheck(host, 443, timeoutMs);
-    if (ok443) return true;
-  }
-  return false;
+function anyTrue(promises) {
+  return new Promise((resolve) => {
+    if (!Array.isArray(promises) || promises.length === 0) return resolve(false);
+    let remaining = promises.length;
+    let resolved = false;
+    for (const p of promises) {
+      Promise.resolve(p).then((v) => {
+        if (v && !resolved) { resolved = true; resolve(true); }
+      }).finally(() => {
+        remaining -= 1;
+        if (remaining === 0 && !resolved) resolve(false);
+      });
+    }
+  });
 }
 
+async function checkOneServerFast(srv, perSocketTimeoutMs = 800, perServerBudgetMs = 1000) {
+  const hosts = [];
+  if (srv.ip) hosts.push(String(srv.ip));
+  if (srv.dns) hosts.push(String(srv.dns));
+  const tryOneHost = (host) => anyTrue([
+    // try common ports simultaneously
+    tcpCheck(host, 443, perSocketTimeoutMs),
+    tcpCheck(host, 80, perSocketTimeoutMs),
+  ]);
+  const run = anyTrue(hosts.map((h) => tryOneHost(h)));
+  // Per-server overall budget
+  const timeout = new Promise((resolve) => setTimeout(() => resolve(false), perServerBudgetMs));
+  return Promise.race([run, timeout]);
+}
+
+const availabilityCache = { at: 0, data: null };
+
 app.get('/api/servers/availability', async (req, res) => {
   try {
+    const ttlSeconds = Math.max(0, Math.min(300, Number(req.query.ttlSeconds) || 30));
+    const now = Date.now();
+    if (availabilityCache.data && (now - availabilityCache.at) < ttlSeconds * 1000) {
+      return res.json({ ...availabilityCache.data, cached: true });
+    }
+
     const data = await s3.getObject({ Bucket: BUCKET_NAME, Key: 'servers.json' }).promise();
     let servers = [];
     try {
@@ -1435,10 +1458,14 @@ app.get('/api/servers/availability', async (req, res) => {
     } catch {
       servers = [];
     }
-    const checks = await Promise.allSettled(servers.map(s => checkOneServer(s)));
+
+    const checks = await Promise.allSettled(servers.map((s) => checkOneServerFast(s)));
     const statuses = servers.map((s, i) => ({ ip: s.ip, dns: s.dns, online: checks[i].status === 'fulfilled' ? Boolean(checks[i].value) : false }));
-    const online = statuses.filter(x => x.online).length;
-    res.json({ online, total: servers.length, statuses });
+    const online = statuses.filter((x) => x.online).length;
+    const payload = { online, total: servers.length, statuses };
+    availabilityCache.at = Date.now();
+    availabilityCache.data = payload;
+    res.json(payload);
   } catch (e) {
     console.error('availability error', e);
     res.status(500).json({ online: 0, total: 0, statuses: [] });