From 298bd124a2f094e321d2426a48af75b689d9bb6d Mon Sep 17 00:00:00 2001
From: ehmicky <ehmicky@gmail.com>
Date: Sun, 25 Aug 2019 17:39:21 +0200
Subject: [PATCH] Use time-resolution

---
 package-lock.json                      |  9 ++++
 package.json                           |  1 +
 src/resolution.js                      | 73 --------------------------
 src/run/runners/node/benchmark/bias.js |  5 +-
 4 files changed, 13 insertions(+), 75 deletions(-)
 delete mode 100644 src/resolution.js

diff --git a/package-lock.json b/package-lock.json
index 38e2167be..b29810dde 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -11847,6 +11847,15 @@
         "xtend": "~4.0.0"
       }
     },
+    "time-resolution": {
+      "version": "0.1.1",
+      "resolved": "https://registry.npmjs.org/time-resolution/-/time-resolution-0.1.1.tgz",
+      "integrity": "sha512-UnxHylIzHKuO2a4wnPHkTvAUq4vrUhLF9xroG62J6Qvk26ibKkU9LEt23cw9q2eEbZ+YP0+C4AtNORFw94nxOg==",
+      "requires": {
+        "core-js": "^3.2.1",
+        "precise-now": "^0.1.1"
+      }
+    },
     "time-stamp": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/time-stamp/-/time-stamp-1.1.0.tgz",
diff --git a/package.json b/package.json
index c884c12fd..a15a4ea16 100644
--- a/package.json
+++ b/package.json
@@ -65,6 +65,7 @@
     "slugify": "^1.3.4",
     "string-width": "^4.1.0",
     "strip-ansi": "^5.2.0",
+    "time-resolution": "^0.1.1",
     "uuid": "^3.3.3",
     "write-file-atomic": "^3.0.0",
     "yargs": "^14.0.0",
diff --git a/src/resolution.js b/src/resolution.js
deleted file mode 100644
index d99f50544..000000000
--- a/src/resolution.js
+++ /dev/null
@@ -1,73 +0,0 @@
-import now from 'precise-now'
-
-// Retrieve system's time resolution in nanoseconds.
-// If the resolution is <1ns, returns 1ns.
-// Time resolution depends on a combination of hardware and software factors.
-export const getTimeResolution = function() {
-  const times = getTimes(REPEAT)
-  return POSSIBLE_RESOLUTIONS.find(resolution =>
-    isTimeResolution(resolution, times),
-  )
-}
-
-// Run `now()` several times in a row.
-// We do it several times because there is a chance that the next resolution
-// would be hit otherwise. For example:
-//  - if resolution is 1ns, samples might (by chance) all be modulo 5ns
-//  - if resolution is 5ns, samples might (by chance) all be modulo 10ns
-// The probability for this to happen is:
-//  - if resolution is *1ns, `1 / 5 ** length`
-//  - if resolution is *5ns, `1 / 2 ** length`
-// So with `length` `100`, we get this error only once every `1e30` calls.
-// We must use imperative code because the loop size is unknown.
-/* eslint-disable fp/no-let, fp/no-loops, fp/no-mutation, fp/no-mutating-methods,
-max-depth */
-const getTimes = function(length) {
-  const times = []
-  let lastTime = 0
-
-  while (times.length < length) {
-    const time = now()
-
-    // If the resolution is very low, we need to perform `now()` several times
-    // until the result changes
-    if (time !== lastTime) {
-      lastTime = time
-      times.push(time)
-    }
-  }
-
-  return times
-}
-/* eslint-enable fp/no-let, fp/no-loops, fp/no-mutation, fp/no-mutating-methods,
-max-depth */
-
-const REPEAT = 1e2
-
-// Check among all `now()` if they fit a specific time resolution
-const isTimeResolution = function(resolution, times) {
-  return times.every(time => time % resolution === 0)
-}
-
-// Available time resolutions from 50ms, 10ms, 5ms, ... to 1ns.
-// In nanoseconds.
-const getPossibleResolutions = function() {
-  return Array.from({ length: MAX_RESOLUTION_EXPONENT }, getExponent).flatMap(
-    getPossibleResolution,
-  )
-}
-
-// 8 digits after nanoseconds, i.e. 99ms-10ms
-const MAX_RESOLUTION_EXPONENT = 8
-
-const getExponent = function(value, index) {
-  return MAX_RESOLUTION_EXPONENT - index - 1
-}
-
-const getPossibleResolution = function(exponent) {
-  const scale = 10 ** exponent
-  // eslint-disable-next-line no-magic-numbers
-  return [5 * scale, scale]
-}
-
-const POSSIBLE_RESOLUTIONS = getPossibleResolutions()
diff --git a/src/run/runners/node/benchmark/bias.js b/src/run/runners/node/benchmark/bias.js
index f42ce9a45..db65e823c 100644
--- a/src/run/runners/node/benchmark/bias.js
+++ b/src/run/runners/node/benchmark/bias.js
@@ -1,4 +1,5 @@
-import { getTimeResolution } from '../../../../resolution.js'
+import timeResolution from 'time-resolution'
+
 import { getMedian } from '../../../../stats/methods.js'
 
 import { benchmarkLoop } from './loop.js'
@@ -58,7 +59,7 @@ const getMinTime = function(nowBias) {
   return Math.max(minPrecisionTime, minNowBiasTime)
 }
 
-const TIME_RESOLUTION = getTimeResolution()
+const TIME_RESOLUTION = timeResolution()
 // The task loop must be at least `MIN_PRECISION` slower than time resolution
 const MIN_PRECISION = 1e2
 // The task loop must be at least `MIN_NOW_BIAS` slower than `nowBias`