dns: improve performance

benchmark/dns/lookup.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const common = require('../common.js');
+const lookup = require('dns').lookup;
+
+const bench = common.createBenchmark(main, {
+  name: ['', '127.0.0.1', '::1'],
+  all: [true, false],
+  n: [5e6]
+});
+
+function main(conf) {
+  const name = conf.name;
+  const n = +conf.n;
+  const all = !!conf.all;
+  var i = 0;
+
+  if (all) {
+    const opts = { all: true };
+    bench.start();
+    (function cb(err, results) {
+      if (i++ === n) {
+        bench.end(n);
+        return;
+      }
+      lookup(name, opts, cb);
+    })();
+  } else {
+    bench.start();
+    (function cb(err, result) {
+      if (i++ === n) {
+        bench.end(n);
+        return;
+      }
+      lookup(name, cb);
+    })();
+  }
+}

lib/dns.js

@@ -60,33 +60,29 @@ function errnoException(err, syscall, hostname) {
   return ex;
 }
 
-
-// c-ares invokes a callback either synchronously or asynchronously,
-// but the dns API should always invoke a callback asynchronously.
-//
-// This function makes sure that the callback is invoked asynchronously.
-// It returns a function that invokes the callback within nextTick().
-//
-// To avoid invoking unnecessary nextTick(), `immediately` property of
-// returned function should be set to true after c-ares returned.
-//
-// Usage:
-//
-// function someAPI(callback) {
-//   callback = makeAsync(callback);
-//   channel.someAPI(..., callback);
-//   callback.immediately = true;
-// }
-function makeAsync(callback) {
-  return function asyncCallback(...args) {
-    if (asyncCallback.immediately) {
-      // The API already returned, we can invoke the callback immediately.
-      callback.apply(null, args);
-    } else {
-      args.unshift(callback);
-      process.nextTick.apply(null, args);
-    }
-  };
+const digits = [
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0-15
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16-31
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 32-47
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, // 48-63
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 64-79
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 80-95
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 96-111
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0  // 112-127
+];
+function isIPv4(str) {
+  if (!digits[str.charCodeAt(0)]) return false;
+  if (str.length === 1) return false;
+  if (str.charCodeAt(1) === 46/*'.'*/)
+    return true;
+  else if (!digits[str.charCodeAt(1)])
+    return false;
+  if (str.length === 2) return false;
+  if (str.charCodeAt(2) === 46/*'.'*/)
+    return true;
+  else if (!digits[str.charCodeAt(2)])
+    return false;
+  return (str.length > 3 && str.charCodeAt(3) === 46/*'.'*/);
 }
 
 
@@ -97,25 +93,26 @@ function onlookup(err, addresses) {
   if (this.family) {
     this.callback(null, addresses[0], this.family);
   } else {
-    this.callback(null, addresses[0], addresses[0].indexOf(':') >= 0 ? 6 : 4);
+    this.callback(null, addresses[0], isIPv4(addresses[0]) ? 4 : 6);
   }
 }
 
 
 function onlookupall(err, addresses) {
-  var results = [];
   if (err) {
     return this.callback(errnoException(err, 'getaddrinfo', this.hostname));
   }
 
+  var family = this.family;
   for (var i = 0; i < addresses.length; i++) {
-    results.push({
-      address: addresses[i],
-      family: this.family || (addresses[i].indexOf(':') >= 0 ? 6 : 4)
-    });
+    const addr = addresses[i];
+    addresses[i] = {
+      address: addr,
+      family: family || (isIPv4(addr) ? 4 : 6)
+    };
   }
 
-  this.callback(null, results);
+  this.callback(null, addresses);
 }
 
 
@@ -153,23 +150,22 @@ function lookup(hostname, options, callback) {
   if (family !== 0 && family !== 4 && family !== 6)
     throw new TypeError('Invalid argument: family must be 4 or 6');
 
-  callback = makeAsync(callback);
-
   if (!hostname) {
     if (all) {
-      callback(null, []);
+      process.nextTick(callback, null, []);
     } else {
-      callback(null, null, family === 6 ? 6 : 4);
+      process.nextTick(callback, null, null, family === 6 ? 6 : 4);
     }
     return {};
   }
 
   var matchedFamily = isIP(hostname);
   if (matchedFamily) {
     if (all) {
-      callback(null, [{address: hostname, family: matchedFamily}]);
+      process.nextTick(
+        callback, null, [{address: hostname, family: matchedFamily}]);
     } else {
-      callback(null, hostname, matchedFamily);
+      process.nextTick(callback, null, hostname, matchedFamily);
     }
     return {};
   }
@@ -182,11 +178,9 @@ function lookup(hostname, options, callback) {
 
   var err = cares.getaddrinfo(req, hostname, family, hints);
   if (err) {
-    callback(errnoException(err, 'getaddrinfo', hostname));
+    process.nextTick(callback, errnoException(err, 'getaddrinfo', hostname));
     return {};
   }
-
-  callback.immediately = true;
   return req;
 }
 
@@ -217,7 +211,6 @@ function lookupService(host, port, callback) {
     throw new TypeError('"callback" argument must be a function');
 
   port = +port;
-  callback = makeAsync(callback);
 
   var req = new GetNameInfoReqWrap();
   req.callback = callback;
@@ -227,8 +220,6 @@ function lookupService(host, port, callback) {
 
   var err = cares.getnameinfo(req, host, port);
   if (err) throw errnoException(err, 'getnameinfo', host);
-
-  callback.immediately = true;
   return req;
 }
 
@@ -263,7 +254,6 @@ function resolver(bindingName) {
       throw new Error('"callback" argument must be a function');
     }
 
-    callback = makeAsync(callback);
     var req = new QueryReqWrap();
     req.bindingName = bindingName;
     req.callback = callback;
@@ -272,7 +262,6 @@ function resolver(bindingName) {
     req.ttl = !!(options && options.ttl);
     var err = binding(req, name);
     if (err) throw errnoException(err, bindingName);
-    callback.immediately = true;
     return req;
   };
 }

test/internet/test-dns.js

@@ -492,11 +492,12 @@ TEST(function test_lookupservice_invalid(done) {
 
 
 TEST(function test_reverse_failure(done) {
-  const req = dns.reverse('0.0.0.0', function(err) {
+  // 203.0.113.0/24 are addresses reserved for (RFC) documentation use only
+  const req = dns.reverse('203.0.113.0', function(err) {
     assert(err instanceof Error);
     assert.strictEqual(err.code, 'ENOTFOUND');  // Silly error code...
-    assert.strictEqual(err.hostname, '0.0.0.0');
-    assert.ok(/0\.0\.0\.0/.test(err.message));
+    assert.strictEqual(err.hostname, '203.0.113.0');
+    assert.ok(/203\.0\.113\.0/.test(err.message));
 
     done();
   });