benchmark: use process.hrtime.bigint()

PR-URL: nodejs#38369
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: James M Snell <[email protected]>

benchmark/common.js

@@ -12,7 +12,7 @@ class Benchmark {
     this._ended = false;
 
     // Holds process.hrtime value
-    this._time = [0, 0];
+    this._time = 0n;
 
     // Use the file name as the name of the benchmark
     this.name = require.main.filename.slice(__dirname.length + 1);
@@ -218,12 +218,12 @@ class Benchmark {
       throw new Error('Called start more than once in a single benchmark');
     }
     this._started = true;
-    this._time = process.hrtime();
+    this._time = process.hrtime.bigint();
   }
 
   end(operations) {
     // Get elapsed time now and do error checking later for accuracy.
-    const elapsed = process.hrtime(this._time);
+    const time = process.hrtime.bigint();
 
     if (!this._started) {
       throw new Error('called end without start');
@@ -237,16 +237,19 @@ class Benchmark {
     if (!process.env.NODEJS_BENCHMARK_ZERO_ALLOWED && operations <= 0) {
       throw new Error('called end() with operation count <= 0');
     }
-    if (elapsed[0] === 0 && elapsed[1] === 0) {
+
+    this._ended = true;
+
+    if (time === this._time) {
       if (!process.env.NODEJS_BENCHMARK_ZERO_ALLOWED)
         throw new Error('insufficient clock precision for short benchmark');
       // Avoid dividing by zero
-      elapsed[1] = 1;
+      this.report(operations && Number.MAX_VALUE, 0n);
+      return;
     }
 
-    this._ended = true;
-    const time = elapsed[0] + elapsed[1] / 1e9;
-    const rate = operations / time;
+    const elapsed = time - this._time;
+    const rate = operations / (Number(elapsed) / 1e9);
     this.report(rate, elapsed);
   }
 
@@ -255,12 +258,21 @@ class Benchmark {
       name: this.name,
       conf: this.config,
       rate,
-      time: elapsed[0] + elapsed[1] / 1e9,
+      time: nanoSecondsToString(elapsed),
       type: 'report',
     });
   }
 }
 
+function nanoSecondsToString(bigint) {
+  const str = bigint.toString();
+  const decimalPointIndex = str.length - 9;
+  if (decimalPointIndex < 0) {
+    return `0.${'0'.repeat(-decimalPointIndex)}${str}`;
+  }
+  return `${str.slice(0, decimalPointIndex)}.${str.slice(decimalPointIndex)}`;
+}
+
 function formatResult(data) {
   // Construct configuration string, " A=a, B=b, ..."
   let conf = '';