Refactor: DNS cache cleanup scheduling

nodejs · Sep 16, 2023 · 83586ef · 83586ef
1 parent 80c60eb
commit 83586ef
Showing 1 changed file with 41 additions and 25 deletions.
diff --git a/lib/dns.js b/lib/dns.js
@@ -31,7 +31,7 @@ const cares = internalBinding('cares_wrap');
 const { isIP } = require('internal/net');
 const { customPromisifyArgs } = require('internal/util');
 const errors = require('internal/errors');
-const { setInterval } = require('timers');
+const { setTimeout, unref } = require('timers');
 const {
   bindDefaultResolver,
   setDefaultResolver,
@@ -134,19 +134,47 @@ function onlookupall(err, addresses) {
   }
 }
 
+function cleanDnsCache() {
+  for (const key in dnsCache) {
+    delete dnsCache[key];
+  }
+}
+
+function scheduleCleanup() {
+  if (cleanupTimeout) {
+    return;
+  }
+
+  cleanupTimeout = setTimeout(() => {
+    cleanDnsCache();
+    cleanupTimeout = null;
+  }, 1000).ref();
+}
+
+function addDnsEntry(cacheKey, address, family) {
+  dnsCache[cacheKey] = {
+    address,
+    family,
+    timestamp: DateNow(),
+  };
+
+  scheduleCleanup();
+
+  return dnsCache[cacheKey];
+}
 
 // Easy DNS A/AAAA look up
 // lookup(hostname, [options,] callback)
 const validFamilies = [0, 4, 6];
 const dnsCache = { __proto__: null };
+const { DateNow } = primordials;
+let cleanupTimeout = null;
 function lookup(hostname, options, callback) {
   let hints = 0;
   let family = 0;
   let all = false;
   let verbatim = getDefaultVerbatim();
 
-  const cacheKey = `${hostname}_${family || 'default'}`;
-  const cachedResult = dnsCache[cacheKey];
 
   // Parse arguments
   if (hostname) {
@@ -196,12 +224,6 @@ function lookup(hostname, options, callback) {
     }
   }
 
-  const { DateNow } = primordials;
-  if (cachedResult && DateNow() - cachedResult.timestamp < 1000) {
-    callback(null, cachedResult.address, cachedResult.family);
-    return {};
-  }
-
   if (!hostname) {
     emitInvalidHostnameWarning(hostname);
     if (all) {
@@ -223,14 +245,19 @@ function lookup(hostname, options, callback) {
     return {};
   }
 
+  const cacheKey = `${hostname}_${family || 'default'}`;
+  const cachedResult = dnsCache[cacheKey];
+
+  if (cachedResult && DateNow() - cachedResult.timestamp < 1000) {
+    callback(null, cachedResult.address, cachedResult.family);
+    return {};
+  }
+
+
   const req = new GetAddrInfoReqWrap();
   req.callback = (error, address, family) => {
     if (!error) {
-      dnsCache[cacheKey] = {
-        address,
-        family,
-        timestamp: DateNow(),
-      };
+      addDnsEntry(cacheKey, address, family);
     }
     callback(error, address, family);
   };
@@ -257,17 +284,6 @@ function lookup(hostname, options, callback) {
   return req;
 }
 
-// DNS cache checks every 1 second
-setInterval(() => {
-  const { DateNow } = primordials;
-  const currentTime = DateNow();
-  for (const key in dnsCache) {
-    if (currentTime - dnsCache[key].timestamp >= 1000) {
-      delete dnsCache[key];
-    }
-  }
-}, 1000).unref();
-
 ObjectDefineProperty(lookup, customPromisifyArgs,
                      { __proto__: null, value: ['address', 'family'], enumerable: false });