From f64e11996f56869c486ba5bb97d7d2de999b9200 Mon Sep 17 00:00:00 2001
From: ehmicky <ehmicky@gmail.com>
Date: Mon, 27 May 2019 10:00:00 +0200
Subject: [PATCH] Add benchmarking

---
 benchmarks/array.js   |  7 +++++++
 benchmarks/main.js    | 22 +++++++++++-----------
 benchmarks/mean.js    | 12 ++++++++++++
 benchmarks/measure.js | 13 +++++++++++++
 benchmarks/print.js   | 15 +++++++++++++++
 benchmarks/promise.js | 18 ++++++++++++++++++
 benchmarks/results.js | 23 +++++++++++++++++++++++
 7 files changed, 99 insertions(+), 11 deletions(-)
 create mode 100644 benchmarks/array.js
 create mode 100644 benchmarks/mean.js
 create mode 100644 benchmarks/measure.js
 create mode 100644 benchmarks/print.js
 create mode 100644 benchmarks/promise.js
 create mode 100644 benchmarks/results.js

diff --git a/benchmarks/array.js b/benchmarks/array.js
new file mode 100644
index 0000000..d1f936d
--- /dev/null
+++ b/benchmarks/array.js
@@ -0,0 +1,7 @@
+export const getArray = function(length) {
+  return Array.from({ length }, getIndex)
+}
+
+const getIndex = function(value, index) {
+  return index
+}
diff --git a/benchmarks/main.js b/benchmarks/main.js
index 905e0b1..1baa4a8 100644
--- a/benchmarks/main.js
+++ b/benchmarks/main.js
@@ -1,13 +1,13 @@
 import testCartesian from '../src/main.js'
 
-const getIndex = function(value, index) {
-  return index
-}
-
-const getArray = function(length) {
-  return new Array({ length }, getIndex)
-}
-
-const DATA = [[getArray(5)], [getArray(10), getArray(10)]]
-
-console.log(testCartesian(DATA[1]))
+import { printResults } from './print.js'
+import { getArray } from './array.js'
+
+printResults(
+  [
+    { variant: 'simple', args: [getArray(5)] },
+    { variant: 'complex', args: [getArray(100), getArray(100)] },
+  ],
+  [{ name: 'test-cartesian', func: testCartesian }],
+  { count: 1e4 },
+)
diff --git a/benchmarks/mean.js b/benchmarks/mean.js
new file mode 100644
index 0000000..e91f55c
--- /dev/null
+++ b/benchmarks/mean.js
@@ -0,0 +1,12 @@
+// Calculate the mean of an array of integers
+export const mean = function(array) {
+  return sum(array) / array.length
+}
+
+const sum = function(array) {
+  return array.reduce(add, 0)
+}
+
+const add = function(memo, number) {
+  return memo + number
+}
diff --git a/benchmarks/measure.js b/benchmarks/measure.js
new file mode 100644
index 0000000..c87049d
--- /dev/null
+++ b/benchmarks/measure.js
@@ -0,0 +1,13 @@
+import { performance } from 'perf_hooks'
+
+import { promiseThen } from './promise.js'
+
+// Measure how long a sync or async function take to execute
+export const measure = function(func) {
+  const start = performance.now()
+  return promiseThen(func(), () => {
+    const end = performance.now()
+    const duration = end - start
+    return duration
+  })
+}
diff --git a/benchmarks/print.js b/benchmarks/print.js
new file mode 100644
index 0000000..57ae729
--- /dev/null
+++ b/benchmarks/print.js
@@ -0,0 +1,15 @@
+import { getResults } from './results.js'
+
+export const printResults = function(variants, funcs, { count }) {
+  const results = getResults(variants, funcs, { count })
+  results.forEach(printResult)
+}
+
+const printResult = function({ variant, name, duration }) {
+  // eslint-disable-next-line no-console, no-restricted-globals
+  console.log(
+    `${variant} ${name}: ${Math.round(duration * MICROSECS_TO_NANOSECS)}ns`,
+  )
+}
+
+const MICROSECS_TO_NANOSECS = 1e3
diff --git a/benchmarks/promise.js b/benchmarks/promise.js
new file mode 100644
index 0000000..4e6b0e8
--- /dev/null
+++ b/benchmarks/promise.js
@@ -0,0 +1,18 @@
+// Like `promise.then()` except if `value` is not a promise
+export const promiseThen = function(value, func) {
+  if (isPromise(value)) {
+    // eslint-disable-next-line promise/prefer-await-to-then
+    return value.then(func)
+  }
+
+  return func()
+}
+
+const isPromise = function(value) {
+  return (
+    typeof value === 'object' &&
+    value !== null &&
+    // eslint-disable-next-line promise/prefer-await-to-then
+    typeof value.then === 'function'
+  )
+}
diff --git a/benchmarks/results.js b/benchmarks/results.js
new file mode 100644
index 0000000..2ea60bf
--- /dev/null
+++ b/benchmarks/results.js
@@ -0,0 +1,23 @@
+import { getArray } from './array.js'
+import { measure } from './measure.js'
+import { mean } from './mean.js'
+
+export const getResults = function(variants, funcs, { count }) {
+  const countA = getArray(count)
+  return variants.flatMap(({ variant, args }) =>
+    getVariantResult({ variant, args, funcs, count: countA }),
+  )
+}
+
+const getVariantResult = function({ variant, args, funcs, count }) {
+  return funcs.map(({ name, func }) =>
+    getResult({ variant, args, name, func, count }),
+  )
+}
+
+const getResult = function({ variant, args, name, func, count }) {
+  const funcA = func.bind(null, ...args)
+  const durations = count.map(() => measure(funcA))
+  const duration = mean(durations)
+  return { variant, name, duration, durations, count }
+}