net: require 'dns' only once

Avoid unnecessary calls to require('dns') by caching the result of the first one. PR-URL: #12342 Reviewed-By: Benjamin Gruenbaum <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Evan Lucas <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Luigi Pinca <[email protected]>
nodejs · Apr 25, 2017 · 2957449 · 2957449
1 parent ae51ddd
commit 2957449
Showing 1 changed file with 11 additions and 3 deletions.
diff --git a/lib/net.js b/lib/net.js
@@ -19,8 +19,9 @@ const PipeConnectWrap = process.binding('pipe_wrap').PipeConnectWrap;
 const ShutdownWrap = process.binding('stream_wrap').ShutdownWrap;
 const WriteWrap = process.binding('stream_wrap').WriteWrap;
 
-
 var cluster;
+var dns;
+
 const errnoException = util._errnoException;
 const exceptionWithHostPort = util._exceptionWithHostPort;
 const isLegalPort = internalNet.isLegalPort;
@@ -948,7 +949,7 @@ function realConnect(options, cb) {
 
 
 function lookupAndConnect(self, options) {
-  const dns = require('dns');
+  const dns = lazyDns();
   var host = options.host || 'localhost';
   var port = options.port;
   var localAddress = options.localAddress;
@@ -1286,6 +1287,13 @@ function emitListeningNT(self) {
 }
 
 
+function lazyDns() {
+  if (dns === undefined)
+    dns = require('dns');
+  return dns;
+}
+
+
 function listenInCluster(server, address, port, addressType,
                          backlog, fd, exclusive) {
   exclusive = !!exclusive;
@@ -1414,7 +1422,7 @@ Server.prototype.listen = function() {
 };
 
 function lookupAndListen(self, port, address, backlog, exclusive) {
-  const dns = require('dns');
+  const dns = lazyDns();
   dns.lookup(address, function doListen(err, ip, addressType) {
     if (err) {
       self.emit('error', err);