wilk#23 add quicksort example

examples/quicksort.ts

@@ -0,0 +1,92 @@
+/**
+ * This example sorts a large array using the quicksort algorithm
+ * It uses microjob to divide the load between 8 jobs
+ */
+
+import { start, job, stop } from '../src/job'
+
+// utility function to generate random numbers
+const ranges = [100, 1000, 10000, 100000, 1000000]
+function randomNumber(): Number {
+  const numb = Math.random()
+  const range = Math.floor(Math.random() * 10) % ranges.length
+  return Math.floor(numb * ranges[range])
+}
+
+// swap, partition and quickSort are used in conjunction inside the job
+function swap(arr, i, j) {
+  const temp = arr[i]
+  arr[i] = arr[j]
+  arr[j] = temp
+}
+
+function partition(arr, pivot, left, right) {
+  const pivotValue = arr[pivot]
+  let partitionIndex = left
+
+  for (let i = left; i < right; i++) {
+    if (arr[i] < pivotValue) {
+      swap(arr, i, partitionIndex)
+      partitionIndex++
+    }
+  }
+  swap(arr, right, partitionIndex)
+
+  return partitionIndex
+}
+
+function quickSort(arr, left, right) {
+  let pivot, partitionIndex
+
+  if (left < right) {
+    pivot = right
+    partitionIndex = partition(arr, pivot, left, right)
+
+    quickSort(arr, left, partitionIndex - 1)
+    quickSort(arr, partitionIndex + 1, right)
+  }
+
+  return arr
+}
+
+// prepare the main dataset and split it into subsets with the same length
+const MAX_LEN = 1000
+const largeArray = Array.from({ length: MAX_LEN }).map(randomNumber)
+const WORKERS = 8
+const datasets = []
+const PART = MAX_LEN / WORKERS
+
+for (let i = 0; i < WORKERS; i++) {
+  datasets.push(largeArray.slice(i * PART, (i * PART) + PART))
+}
+
+const main = async () => {
+  await start({ maxWorkers: WORKERS })
+
+  // sort the datasets separately
+  const promises = datasets.map(data => job(dataset => quickSort(dataset, 0, dataset.length - 1), { data, ctx: { swap, partition, quickSort } }))
+
+  const results = await Promise.all(promises)
+  // merge the resulting arrays
+  const arr = results.reduce((acc, list) => {
+    acc.push(...list)
+    return acc
+  }, [])
+
+  // and do the last sort
+  const sorted = quickSort(arr, 0, arr.length - 1)
+
+  await stop()
+
+  console.log('*** UNSORTED ARRAY SLICES ***')
+  console.log(largeArray.slice(0, 10))
+  console.log(largeArray.slice(500, 510))
+  console.log(largeArray.slice(900, 910))
+
+  console.log('*** SORTED ARRAY SLICES ***')
+  console.log(sorted.slice(0, 10))
+  console.log(sorted.slice(500, 510))
+  console.log(sorted.slice(900, 910))
+}
+
+main()