src: fix negative values in process.hrtime()

bnoordhuis · evanlucas · commit a2c257a3ef34 · 2016-01-20T16:06:10.000-06:00
Fix a regression introduced in commit 89f056b ("node: improve performance of hrtime()") where the nanosecond field sometimes had a negative value when calculating the difference between two timestamps. Fixes: #4751 PR-URL: #4757 Reviewed-By: Evan Lucas <evanlucas@me.com> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
diff --git a/src/node.js b/src/node.js
@@ -193,10 +193,9 @@
 
 if (typeof ar !== 'undefined'){
 if (Array.isArray(ar)){
- return [
- (hrValues[0] * 0x100000000 + hrValues[1]) - ar[0],
- hrValues[2] - ar[1]
- ];
+ const sec = (hrValues[0] * 0x100000000 + hrValues[1]) - ar[0];
+ const nsec = hrValues[2] - ar[1];
+ return [nsec < 0 ? sec - 1 : sec, nsec < 0 ? nsec + 1e9 : nsec];
 }
 
 throw new TypeError('process.hrtime() only accepts an Array tuple');
diff --git a/test/parallel/test-process-hrtime.js b/test/parallel/test-process-hrtime.js
@@ -24,3 +24,6 @@ function validateTuple(tuple){
 assert(isFinite(v));
 });
 }
+
+const diff = process.hrtime([0, 1e9 - 1]);
+assert(diff[1] >= 0); // https://github.com/nodejs/node/issues/4751

-Original file line number
+Diff line change
 if(typeofar!=='undefined'){
 if(Array.isArray(ar)){
 -return[
 -(hrValues[0]*0x100000000+hrValues[1])-ar[0],
 -hrValues[2]-ar[1]
 -];
 +constsec=(hrValues[0]*0x100000000+hrValues[1])-ar[0];
 +constnsec=hrValues[2]-ar[1];
 +return[nsec<0 ? sec-1 : sec,nsec<0 ? nsec+1e9 : nsec];
+}
 thrownewTypeError('process.hrtime() only accepts an Array tuple');
Original file line number	Diff line number	Diff line change
`@@ -24,3 +24,6 @@ function validateTuple(tuple){`
`24`	`24`	`assert(isFinite(v));`
`25`	`25`	`});`
`26`	`26`	`}`
	`27`	`+`
	`28`	`+constdiff=process.hrtime([0,1e9-1]);`
	`29`	`+assert(diff[1]>=0);// https://github.com/nodejs/node/issues/4751`