fix: refactor client-metrics list and ttl-list to TypeScript (#1080)

Co-authored-by: Ivar Conradi Østhus <ivarconr@gmail.com>

src/lib/services/client-metrics/index.ts

@@ -22,12 +22,13 @@ import {
     IMetricsBucket,
 } from '../../types/model';
 import { clientRegisterSchema } from './register-schema';
+
 import {
     minutesToMilliseconds,
     parseISO,
     secondsToMilliseconds,
 } from 'date-fns';
-import TTLList = require('./ttl-list');
+import TTLList from './ttl-list';
 
 export default class ClientMetricsService {
     globalCount = 0;
@@ -38,13 +39,13 @@ export default class ClientMetricsService {
 
     lastMinuteProjection = new Projection();
 
-    lastHourList = new TTLList({
+    lastHourList = new TTLList<IMetricCounts>({
         interval: secondsToMilliseconds(10),
     });
 
     logger = null;
 
-    lastMinuteList = new TTLList({
+    lastMinuteList = new TTLList<IMetricCounts>({
         interval: secondsToMilliseconds(10),
         expireType: 'minutes',
         expireAmount: 1,

src/lib/services/client-metrics/list.test.ts

@@ -1,9 +1,7 @@
-'use strict';
-
-const List = require('./list');
+import List from './list';
 
 function getList() {
-    const list = new List();
+    const list = new List<number>();
     list.add(1);
     list.add(2);
     list.add(3);

src/lib/services/client-metrics/list.ts

@@ -1,31 +1,41 @@
 /* eslint-disable no-param-reassign */
 /* eslint-disable max-classes-per-file */
 
-'use strict';
+import { EventEmitter } from 'events';
 
-const { EventEmitter } = require('events');
+class Node<T> {
+    value: T | null;
 
-class Node {
-    constructor(value) {
+    prev: Node<T> | null;
+
+    next: Node<T> | null;
+
+    constructor(value: T) {
         this.value = value;
         this.next = null;
     }
 
-    link(next) {
+    link(next: Node<T>) {
         this.next = next;
         next.prev = this;
         return this;
     }
 }
 
-module.exports = class List extends EventEmitter {
+type IteratorFn<T, U = unknown> = (cursor: Node<T>) => U;
+
+export default class List<T> extends EventEmitter {
+    private start: Node<T> | null;
+
+    private tail: Node<T> | null;
+
     constructor() {
         super();
         this.start = null;
         this.tail = null;
     }
 
-    add(obj) {
+    add(obj: T): Node<T> {
         const node = new Node(obj);
         if (this.start) {
             this.start = node.link(this.start);
@@ -36,7 +46,7 @@ module.exports = class List extends EventEmitter {
         return node;
     }
 
-    iterate(fn) {
+    iterate(fn: IteratorFn<T>): void {
         if (!this.start) {
             return;
         }
@@ -51,7 +61,7 @@ module.exports = class List extends EventEmitter {
         }
     }
 
-    iterateReverse(fn) {
+    iterateReverse(fn: IteratorFn<T>): void {
         if (!this.tail) {
             return;
         }
@@ -66,7 +76,7 @@ module.exports = class List extends EventEmitter {
         }
     }
 
-    reverseRemoveUntilTrue(fn) {
+    reverseRemoveUntilTrue(fn: IteratorFn<T, boolean>): void {
         if (!this.tail) {
             return;
         }
@@ -98,7 +108,7 @@ module.exports = class List extends EventEmitter {
         }
     }
 
-    toArray() {
+    toArray(): T[] {
         const result = [];
 
         if (this.start) {
@@ -125,4 +135,4 @@ module.exports = class List extends EventEmitter {
 
     //     return result;
     // }
-};
+}

src/lib/services/client-metrics/ttl-list.test.ts

@@ -1,11 +1,9 @@
-'use strict';
-
-const TTLList = require('./ttl-list');
-const { addMilliseconds } = require('date-fns');
+import { addMilliseconds } from 'date-fns';
+import TTLList from './ttl-list';
 
 test('should emit expire', (done) => {
     jest.useFakeTimers('modern');
-    const list = new TTLList({
+    const list = new TTLList<{ n: number }>({
         interval: 20,
         expireAmount: 10,
         expireType: 'milliseconds',
@@ -25,7 +23,7 @@ test('should emit expire', (done) => {
 test('should slice off list', () => {
     jest.useFakeTimers('modern');
 
-    const list = new TTLList({
+    const list = new TTLList<{ n: string }>({
         interval: 10,
         expireAmount: 10,
         expireType: 'milliseconds',
@@ -69,7 +67,7 @@ test('should slice off list', () => {
 test('should add item created in the past but expiring in the future', () => {
     jest.useFakeTimers('modern');
 
-    const list = new TTLList({
+    const list = new TTLList<{ n: string }>({
         interval: 10,
         expireAmount: 10,
         expireType: 'milliseconds',

src/lib/services/client-metrics/ttl-list.ts

@@ -1,21 +1,38 @@
-'use strict';
-
-const { EventEmitter } = require('events');
-const List = require('./list');
-const {
+import { EventEmitter } from 'events';
+import List from './list';
+import {
     add,
-    isFuture,
     addMilliseconds,
     secondsToMilliseconds,
-} = require('date-fns');
+    Duration,
+    isFuture,
+} from 'date-fns';
+
+interface ConstructorArgs {
+    interval: number;
+    expireAmount: number;
+    expireType: keyof Duration | 'milliseconds';
+}
 
 // this list must have entries with sorted ttl range
-module.exports = class TTLList extends EventEmitter {
+export default class TTLList<T> extends EventEmitter {
+    private readonly interval: number;
+
+    private readonly expireAmount: number;
+
+    private readonly expireType: keyof Duration | 'milliseconds';
+
+    public list: List<{ ttl: Date; value: T }>;
+
+    private timer: NodeJS.Timeout;
+
+    private readonly getExpiryFrom: (timestamp) => Date;
+
     constructor({
         interval = secondsToMilliseconds(1),
         expireAmount = 1,
         expireType = 'hours',
-    } = {}) {
+    }: Partial<ConstructorArgs> = {}) {
         super();
         this.interval = interval;
         this.expireAmount = expireAmount;
@@ -37,7 +54,7 @@ module.exports = class TTLList extends EventEmitter {
         this.startTimer();
     }
 
-    startTimer() {
+    startTimer(): void {
         if (this.list) {
             this.timer = setTimeout(() => {
                 if (this.list) {
@@ -48,7 +65,7 @@ module.exports = class TTLList extends EventEmitter {
         }
     }
 
-    add(value, timestamp = new Date()) {
+    add(value: T, timestamp = new Date()): void {
         const ttl = this.getExpiryFrom(timestamp);
         if (isFuture(ttl)) {
             this.list.add({ ttl, value });
@@ -57,14 +74,14 @@ module.exports = class TTLList extends EventEmitter {
         }
     }
 
-    timedCheck() {
+    timedCheck(): void {
         this.list.reverseRemoveUntilTrue(({ value }) => isFuture(value.ttl));
         this.startTimer();
     }
 
-    destroy() {
+    destroy(): void {
         clearTimeout(this.timer);
         this.timer = null;
         this.list = null;
     }
-};
+}