timer: fix off-by-one ms error

Fix #5103

Author: AlexeyKupershtokh

lib/timers.js

@@ -86,7 +86,7 @@ function listOnTimeout() {
   var first;
   while (first = L.peek(list)) {
     var diff = now - first._idleStart;
-    if (diff + 1 < msecs) {
+    if (diff < msecs) {
       list.start(msecs - diff, 0);
       debug(msecs + ' list wait because diff is ' + diff);
       return;

test/simple/test-timers-ordering.js

@@ -0,0 +1,48 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var i;
+
+var N = 30;
+
+var last_i = 0;
+var last_ts = 0;
+var start = Date.now();
+
+var f = function(i) {
+  if (i <= N) {
+    // check order
+    assert.equal(i, last_i + 1, 'order is broken: ' + i + ' != ' + last_i + ' + 1');
+    last_i = i;
+
+    // check that this iteration is fired at least 1ms later than the previous
+    var now = Date.now();
+    console.log(i, now);
+    assert(now >= last_ts + 1, 'current ts ' + now + ' < prev ts ' + last_ts + ' + 1');
+    last_ts = now;
+
+    // schedule next iteration
+    setTimeout(f, 1, i + 1);
+  }
+};
+f(1);