Add KeyPromiseQueue to Push and Job StatusHandlers (#7267)

* Add KeyPromiseQueue to Push and Job StatusHandlers

* Update CHANGELOG.md

* Update CHANGELOG.md

src/Adapters/Cache/RedisCacheAdapter.js

@@ -1,6 +1,6 @@
 import redis from 'redis';
-import logger from '../../../logger';
-import { KeyPromiseQueue } from './KeyPromiseQueue';
+import logger from '../../logger';
+import { KeyPromiseQueue } from '../../KeyPromiseQueue';
 
 const DEFAULT_REDIS_TTL = 30 * 1000; // 30 seconds in milliseconds
 const FLUSH_DB_KEY = '__flush_db__';

src/Adapters/Cache/RedisCacheAdapter/KeyPromiseQueue.js

@@ -1,43 +0,0 @@
-// KeyPromiseQueue is a simple promise queue
-// used to queue operations per key basis.
-// Once the tail promise in the key-queue fulfills,
-// the chain on that key will be cleared.
-export class KeyPromiseQueue {
-  constructor() {
-    this.queue = {};
-  }
-
-  enqueue(key, operation) {
-    const tuple = this.beforeOp(key);
-    const toAwait = tuple[1];
-    const nextOperation = toAwait.then(operation);
-    const wrappedOperation = nextOperation.then(result => {
-      this.afterOp(key);
-      return result;
-    });
-    tuple[1] = wrappedOperation;
-    return wrappedOperation;
-  }
-
-  beforeOp(key) {
-    let tuple = this.queue[key];
-    if (!tuple) {
-      tuple = [0, Promise.resolve()];
-      this.queue[key] = tuple;
-    }
-    tuple[0]++;
-    return tuple;
-  }
-
-  afterOp(key) {
-    const tuple = this.queue[key];
-    if (!tuple) {
-      return;
-    }
-    tuple[0]--;
-    if (tuple[0] <= 0) {
-      delete this.queue[key];
-      return;
-    }
-  }
-}