Optimize Idle CPU/Dash

server/handlers/system.js

@@ -20,20 +20,89 @@ import logger from '../utils/logger.js'
 /** @type {Map<string, { username: string, serveraddress?: string }>} */
 const registryAuth = new Map()
 
-export function registerSystemHandlers(session) {
-  session.respond('ping', async () => {
-    let dockerOk = false
-    let apiVersion = null
-    let osType = null
-    let error = null
-    try {
+/**
+ * Cached Docker probe for high-frequency ping RPCs.
+ * Clients poll health every ~10s; version() is heavier than needed every tick.
+ * TTL keeps degraded detection responsive without hammering the socket.
+ */
+const PING_DOCKER_CACHE_TTL_MS = 10_000
+/** @type {{ at: number, ok: boolean, apiVersion: string|null, os: string|null, error: string|null }|null} */
+let pingDockerCache = null
+
+/**
+ * Lightweight Docker health for ping. Uses docker.ping() for liveness; refreshes
+ * apiVersion/os via version() only when cache is cold or after a failure.
+ * @returns {Promise<{ ok: boolean, apiVersion: string|null, os: string|null, error: string|null }>}
+ */
+export async function probeDockerForPing() {
+  const now = Date.now()
+  if (
+    pingDockerCache &&
+    now - pingDockerCache.at < PING_DOCKER_CACHE_TTL_MS &&
+    pingDockerCache.ok
+  ) {
+    return {
+      ok: true,
+      apiVersion: pingDockerCache.apiVersion,
+      os: pingDockerCache.os,
+      error: null,
+    }
+  }
+
+  let dockerOk = false
+  let apiVersion = pingDockerCache?.apiVersion ?? null
+  let osType = pingDockerCache?.os ?? null
+  let error = null
+
+  try {
+    // Prefer cheap ping; fall back to version if ping is unavailable
+    if (typeof docker.ping === 'function') {
+      await docker.ping()
+      dockerOk = true
+      // Refresh version metadata when cache empty or expired
+      if (!apiVersion || !pingDockerCache || now - pingDockerCache.at >= PING_DOCKER_CACHE_TTL_MS) {
+        try {
+          const version = await docker.version()
+          apiVersion = version.ApiVersion || version.apiVersion || apiVersion
+          osType = version.Os || version.os || osType
+        } catch {
+          // ok remains true from ping; version is optional decoration
+        }
+      }
+    } else {
       const version = await docker.version()
       dockerOk = true
       apiVersion = version.ApiVersion || version.apiVersion || null
       osType = version.Os || version.os || null
-    } catch (err) {
-      error = err.message
     }
+  } catch (err) {
+    error = err.message || String(err)
+    dockerOk = false
+  }
+
+  pingDockerCache = {
+    at: Date.now(),
+    ok: dockerOk,
+    apiVersion,
+    os: osType,
+    error,
+  }
+  return {
+    ok: dockerOk,
+    apiVersion,
+    os: osType,
+    error,
+  }
+}
+
+/** Test helper: clear ping Docker probe cache */
+export function clearPingDockerCache() {
+  pingDockerCache = null
+}
+
+export function registerSystemHandlers(session) {
+  session.respond('ping', async () => {
+    const dockerProbe = await probeDockerForPing()
     return {
       success: true,
       pong: Date.now(),
@@ -41,10 +110,10 @@ export function registerSystemHandlers(session) {
       protocolVersion: PROTOCOL_VERSION,
       role: session.role,
       docker: {
-        ok: dockerOk,
-        apiVersion,
-        os: osType,
-        error,
+        ok: dockerProbe.ok,
+        apiVersion: dockerProbe.apiVersion,
+        os: dockerProbe.os,
+        error: dockerProbe.error,
       },
       features: {
         swarm: isSwarmEnabled(),