timers: use uv_now instead of Date.now

This saves a few calls to gettimeofday which can be expensive, and
potentially subject to clock drift. Instead use the loop time which
uses hrtime internally.

fixes nodejs#5497

Author: tjfontaine

lib/timers.js

@@ -45,7 +45,7 @@ var lists = {};
 // the main function - creates lists on demand and the watchers associated
 // with them.
 function insert(item, msecs) {
-  item._idleStart = Date.now();
+  item._idleStart = Timer.now();
   item._idleTimeout = msecs;
 
   if (msecs < 0) return;
@@ -75,7 +75,7 @@ function listOnTimeout() {
 
   debug('timeout callback %d', msecs);
 
-  var now = Date.now();
+  var now = Timer.now();
   debug('now: %s', now);
 
   var first;
@@ -165,7 +165,7 @@ exports.active = function(item) {
     if (!list || L.isEmpty(list)) {
       insert(item, msecs);
     } else {
-      item._idleStart = Date.now();
+      item._idleStart = Timer.now();
       L.append(list, item);
     }
   }
@@ -277,7 +277,7 @@ var Timeout = function(after) {
 
 Timeout.prototype.unref = function() {
   if (!this._handle) {
-    var now = Date.now();
+    var now = Timer.now();
     if (!this._idleStart) this._idleStart = now;
     var delay = this._idleStart + this._idleTimeout - now;
     if (delay < 0) delay = 0;

lib/tls.js

@@ -28,6 +28,8 @@ var stream = require('stream');
 var assert = require('assert').ok;
 var constants = require('constants');
 
+var Timer = process.binding('timer_wrap').Timer;
+
 var DEFAULT_CIPHERS = 'ECDHE-RSA-AES128-SHA256:AES128-GCM-SHA256:' + // TLS 1.2
                       'RC4:HIGH:!MD5:!aNULL:!EDH';                   // TLS 1.0
 
@@ -720,7 +722,7 @@ function onhandshakestart() {
 
   var self = this;
   var ssl = self.ssl;
-  var now = Date.now();
+  var now = Timer.now();
 
   assert(now >= ssl.lastHandshakeTime);
 

src/timer_wrap.cc

@@ -51,6 +51,8 @@ class TimerWrap : public HandleWrap {
     constructor->InstanceTemplate()->SetInternalFieldCount(1);
     constructor->SetClassName(String::NewSymbol("Timer"));
 
+    NODE_SET_METHOD(constructor, "now", Now);
+
     NODE_SET_PROTOTYPE_METHOD(constructor, "close", HandleWrap::Close);
     NODE_SET_PROTOTYPE_METHOD(constructor, "ref", HandleWrap::Ref);
     NODE_SET_PROTOTYPE_METHOD(constructor, "unref", HandleWrap::Unref);
@@ -163,6 +165,13 @@ class TimerWrap : public HandleWrap {
     MakeCallback(wrap->object_, ontimeout_sym, ARRAY_SIZE(argv), argv);
   }
 
+  static Handle<Value> Now(const Arguments& args) {
+    HandleScope scope(node_isolate);
+
+    double now = static_cast<double>(uv_now(uv_default_loop()));
+    return scope.Close(v8::Number::New(now));
+  }
+
   uv_timer_t handle_;
 };