feat(queue): add getDebounceJobId method (#2717)

docs/gitbook/guide/jobs/debouncing.md

@@ -44,6 +44,14 @@ This mode is particularly useful for jobs that have a long running time or those
 Any manual deletion will disable the debouncing. For example, when calling _job.remove_ method.
 {% endhint %}
 
+## Get Debounce Job Id
+
+If you need to know which is the job id that started the debounce state. You can call **getDebounceJobId** method.
+
+```typescript
+const jobId = await myQueue.getDebounceJobId('customValue');
+```
+
 ## Remove Debounce Key
 
 If you need to stop debouncing before ttl finishes or before finishing a job. You can call **removeDebounceKey** method.

src/classes/queue-getters.ts

@@ -113,6 +113,17 @@ export class QueueGetters<
     return this.scripts.getRateLimitTtl(maxJobs);
   }
 
+  /**
+   * Get jobId that starts debounced state.
+   *
+   * @param id - debounce identifier
+   */
+  async getDebounceJobId(id: string): Promise<string | null> {
+    const client = await this.client;
+
+    return client.get(`${this.keys.de}:${id}`);
+  }
+
   /**
    * Job counts by type
    *

tests/test_flow.ts

@@ -252,6 +252,103 @@ describe('flows', () => {
     }).timeout(8000);
   });
 
+  describe('when child is debounced when added again with same debounce id', function () {
+    describe('when ttl is not provided', function () {
+      it('waits until job is finished before removing debounce key', async function () {
+        const parentQueueName = `parent-queue-${v4()}`;
+
+        const flow = new FlowProducer({ connection, prefix });
+        const queueEvents = new QueueEvents(queueName, { connection, prefix });
+        await queueEvents.waitUntilReady();
+
+        const worker = new Worker(
+          queueName,
+          async job => {
+            await delay(100);
+
+            const jobIdFromDebounceKey = await queue.getDebounceJobId(
+              'debounce_id',
+            );
+            expect(jobIdFromDebounceKey).to.be.equal(job.id);
+
+            await flow.add({
+              name: 'parent',
+              data: {},
+              queueName: parentQueueName,
+              children: [
+                {
+                  queueName,
+                  name: 'child0',
+                  data: {},
+                  opts: {
+                    debounce: {
+                      id: 'debounce_id',
+                    },
+                  },
+                },
+              ],
+            });
+
+            await delay(100);
+          },
+          {
+            autorun: false,
+            connection,
+            prefix,
+          },
+        );
+        await worker.waitUntilReady();
+
+        const { children } = await flow.add({
+          name: 'parent',
+          data: {},
+          queueName: parentQueueName,
+          children: [
+            {
+              queueName,
+              name: 'child0',
+              data: {},
+              opts: {
+                debounce: {
+                  id: 'debounce_id',
+                },
+              },
+            },
+          ],
+        });
+
+        let debouncedCounter = 0;
+
+        const completing = new Promise<void>(resolve => {
+          queueEvents.once('completed', ({ jobId }) => {
+            expect(children![0].job.id).to.be.equal(jobId);
+            resolve();
+          });
+
+          queueEvents.on('debounced', ({ jobId }) => {
+            debouncedCounter++;
+          });
+        });
+
+        worker.run();
+
+        await completing;
+
+        const jobIdFromDebounceKey = await queue.getDebounceJobId(
+          'debounce_id',
+        );
+        expect(jobIdFromDebounceKey).to.be.null;
+
+        expect(debouncedCounter).to.be.equal(1);
+
+        await worker.close();
+        await queueEvents.close();
+        await flow.close();
+        await removeAllQueueData(new IORedis(redisHost), parentQueueName);
+      });
+    });
+  });
+
   it('should process children before the parent', async () => {
     const name = 'child-job';
     const values = [