Handle concurrent order taking: refactor PerOrderIdMutex, move it to util/index.ts for more clean reusability [1/2] (#823)

* Move PerOrderIdMutex to util

* Code formatting

Author: Luquitasjeffrey

jobs/cancel_orders.ts

@@ -2,11 +2,14 @@ import { HasTelegram } from '../bot/start';
 import { User, Order } from '../models';
 import { cancelShowHoldInvoice, cancelAddInvoice } from '../bot/commands';
 import * as messages from '../bot/messages';
-import { getUserI18nContext, holdInvoiceExpirationInSecs } from '../util';
+import {
+  getUserI18nContext,
+  holdInvoiceExpirationInSecs,
+  PerOrderIdMutex,
+} from '../util';
 import { logger } from '../logger';
 import { CommunityContext } from '../bot/modules/community/communityContext';
 import * as OrderEvents from '../bot/modules/events/orders';
-import { PerOrderIdMutex } from '../ln/subscribe_invoice';
 
 const cancelOrders = async (bot: HasTelegram) => {
   try {

jobs/check_hold_invoice_expired.ts

@@ -1,9 +1,12 @@
 import { HasTelegram } from '../bot/start';
 import { Order, User, Dispute } from '../models';
-import { holdInvoiceExpirationInSecs, getUserI18nContext } from '../util';
+import {
+  holdInvoiceExpirationInSecs,
+  getUserI18nContext,
+  PerOrderIdMutex,
+} from '../util';
 import { logger } from '../logger';
 import { cancelHoldInvoice } from '../ln';
-import { PerOrderIdMutex } from '../ln/subscribe_invoice';
 import * as OrderEvents from '../bot/modules/events/orders';
 import * as messages from '../bot/messages';
 

ln/subscribe_invoice.ts

@@ -6,48 +6,20 @@ import { getInfo } from './info';
 import lnd from './connect';
 import * as messages from '../bot/messages';
 import * as ordersActions from '../bot/ordersActions';
-import { getUserI18nContext, getEmojiRate, decimalRound } from '../util';
+import {
+  getUserI18nContext,
+  getEmojiRate,
+  decimalRound,
+  PerOrderIdMutex,
+} from '../util';
 import { logger } from '../logger';
 import { HasTelegram } from '../bot/start';
 import { IOrder } from '../models/order';
-import { Mutex } from 'async-mutex';
-
-type LockCountedMutex = {
-  lockCount: number;
-  mutex: Mutex;
-};
 
 // Track pending reconnects to prevent duplicate resubscriptions
 // when both 'error' and 'end' events fire for the same invoice
 const pendingReconnects: Set<string> = new Set();
 
-class PerOrderIdMutex {
-  mutexes: Map<string, LockCountedMutex> = new Map();
-
-  async runExclusive(orderId: string, callback: () => Promise<any>) {
-    let mtx: LockCountedMutex;
-    if (!this.mutexes.has(orderId)) {
-      mtx = { lockCount: 1, mutex: new Mutex() };
-      this.mutexes.set(orderId, mtx);
-    } else {
-      mtx = this.mutexes.get(orderId)!;
-      mtx.lockCount++;
-    }
-    let ret: any;
-    try {
-      ret = await mtx.mutex.runExclusive(callback);
-    } finally {
-      mtx.lockCount--;
-      if (mtx.lockCount == 0) {
-        this.mutexes.delete(orderId);
-      }
-    }
-    return ret;
-  }
-
-  static instance = new PerOrderIdMutex();
-}
-
 const subscribeInvoice = async (
   bot: HasTelegram,
   id: string,
@@ -307,4 +279,4 @@ const payHoldInvoice = async (bot: HasTelegram, order: IOrder) => {
   }
 };
 
-export { subscribeInvoice, payHoldInvoice, PerOrderIdMutex };
+export { subscribeInvoice, payHoldInvoice };

util/index.ts

@@ -1,4 +1,5 @@
 import { I18nContext } from '@grammyjs/i18n';
+import { Mutex } from 'async-mutex';
 import { ICommunity, IOrderChannel } from '../models/community';
 import { IOrder } from '../models/order';
 import { UserDocument } from '../models/user';
@@ -604,6 +605,38 @@ const generateQRWithImage = async (request: string, randomImage: string) => {
   return canvas.toBuffer();
 };
 
+type LockCountedMutex = {
+  lockCount: number;
+  mutex: Mutex;
+};
+
+class PerOrderIdMutex {
+  mutexes: Map<string, LockCountedMutex> = new Map();
+
+  async runExclusive(orderId: string, callback: () => Promise<any>) {
+    let mtx: LockCountedMutex;
+    if (!this.mutexes.has(orderId)) {
+      mtx = { lockCount: 1, mutex: new Mutex() };
+      this.mutexes.set(orderId, mtx);
+    } else {
+      mtx = this.mutexes.get(orderId)!;
+      mtx.lockCount++;
+    }
+    let ret: any;
+    try {
+      ret = await mtx.mutex.runExclusive(callback);
+    } finally {
+      mtx.lockCount--;
+      if (mtx.lockCount == 0) {
+        this.mutexes.delete(orderId);
+      }
+    }
+    return ret;
+  }
+
+  static instance = new PerOrderIdMutex();
+}
+
 export {
   isIso4217,
   plural,
@@ -637,4 +670,5 @@ export {
   isOrderCreator,
   generateRandomImage,
   generateQRWithImage,
+  PerOrderIdMutex,
 };