console: allow Object.prototype fields as labels

This is a backport of 6c3647c from
v0.12 to v0.10.

Console.prototype.timeEnd() returns NaN if the timer label
corresponds to a property on Object.prototype. In v0.12, this was fixed
by using Object.create(null) to construct the _times object

However, the version of V8 in the v0.10 branch makes this fix not work
as expected. In v0.10, this commit changes the _times object into a
array of objects of the form:

{ label: someLabel, time: staringWallClockTime }

someLabel can thus be any string, including any string that represents
any Object.prototype field.

Fixes nodejs#9116.

lib/console.js

@@ -20,6 +20,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 var util = require('util');
+var assert = require('assert');
 
 function Console(stdout, stderr) {
   if (!(this instanceof Console)) {
@@ -40,7 +41,7 @@ function Console(stdout, stderr) {
   Object.defineProperty(this, '_stdout', prop);
   prop.value = stderr;
   Object.defineProperty(this, '_stderr', prop);
-  prop.value = {};
+  prop.value = [];
   Object.defineProperty(this, '_times', prop);
 
   // bind the prototype functions to this Console instance
@@ -70,18 +71,44 @@ Console.prototype.dir = function(object) {
 };
 
 
+function findTimeWithLabel(times, label) {
+  assert(Array.isArray(times), 'times must be an Array');
+  assert(typeof label === 'string', 'label must be a string');
+
+  var found;
+
+  times.some(function findTime(item) {
+    if (item.label === label) {
+      found = item;
+      return true;
+    }
+  });
+
+  return found;
+}
+
 Console.prototype.time = function(label) {
-  this._times[label] = Date.now();
+  var timeEntry = findTimeWithLabel(this._times, label);
+  var wallClockTime = Date.now();
+  if (!timeEntry) {
+    this._times.push({ label: label, time: wallClockTime });
+  } else {
+    timeEntry.time = wallClockTime;
+  }
 };
 
-
 Console.prototype.timeEnd = function(label) {
-  var time = this._times[label];
-  if (!time) {
+  var wallClockTimeEnd = Date.now();
+  var timeEntry = findTimeWithLabel(this._times, label);
+
+  if (!timeEntry) {
     throw new Error('No such label: ' + label);
+  } else {
+    assert(typeof timeEntry.time === 'number',
+           'start time must be a number');
+    var duration = wallClockTimeEnd - timeEntry.time;
+    this.log('%s: %dms', label, duration);
   }
-  var duration = Date.now() - time;
-  this.log('%s: %dms', label, duration);
 };
 
 

test/simple/test-console.js

@@ -46,6 +46,22 @@ console.log({slashes: '\\\\'});
 console._stderr = process.stdout;
 console.trace('This is a %j %d', { formatted: 'trace' }, 10, 'foo');
 
+assert.throws(function () {
+  console.timeEnd('no such label');
+});
+
+assert.doesNotThrow(function () {
+  console.time('label');
+  console.timeEnd('label');
+});
+
+console.time('__proto__');
+console.timeEnd('__proto__');
+console.time('constructor');
+console.timeEnd('constructor');
+console.time('hasOwnProperty');
+console.timeEnd('hasOwnProperty');
+
 global.process.stdout.write = stdout_write;
 
 assert.equal('foo\n', strings.shift());
@@ -55,11 +71,8 @@ assert.equal("{ slashes: '\\\\\\\\' }\n", strings.shift());
 assert.equal('Trace: This is a {"formatted":"trace"} 10 foo',
              strings.shift().split('\n').shift());
 
-assert.throws(function () {
-  console.timeEnd('no such label');
-});
-
-assert.doesNotThrow(function () {
-  console.time('label');
-  console.timeEnd('label');
-});
+assert.ok(/^label: \d+ms$/.test(strings.shift().trim()));
+assert.ok(/^__proto__: \d+ms$/.test(strings.shift().trim()));
+assert.ok(/^constructor: \d+ms$/.test(strings.shift().trim()));
+assert.ok(/^hasOwnProperty: \d+ms$/.test(strings.shift().trim()));
+assert.equal(strings.length, 0);