feat(aws-stream-handler): add flag to customize callbackWaitsForEmpty…

…EventLoop (#264)
H4ad · Sep 17, 2024 · 30a59f9 · 30a59f9
1 parent 53d431b
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diff --git a/src/handlers/aws/aws-stream.handler.ts b/src/handlers/aws/aws-stream.handler.ts
@@ -58,6 +58,22 @@ declare const awslambda: {
   };
 };
 
+/**
+ * The interface that customizes the {@link AwsStreamHandler}
+ *
+ * @breadcrumb Handlers / AwsStreamHandler
+ * @public
+ */
+export type AwsStreamHandlerOptions = {
+  /**
+   * Set the value of the property `callbackWaitsForEmptyEventLoop`, you can set to `false` to fix issues with long execution due to not cleaning the event loop ([ref](https://github.com/H4ad/serverless-adapter/issues/264)).
+   * In the next release, this value will be changed to `false`.
+   *
+   * @defaultValue undefined
+   */
+  callbackWaitsForEmptyEventLoop?: boolean;
+};
+
 /**
  * The interface that describes the internal context used by the {@link AwsStreamHandler}
  *
@@ -89,6 +105,17 @@ export class AwsStreamHandler<TApp> extends BaseHandler<
   AWSStreamResponseMetadata,
   void
 > {
+  //#region Constructor
+
+  /**
+   * Construtor padrão
+   */
+  constructor(private readonly options?: AwsStreamHandlerOptions) {
+    super();
+  }
+
+  //#endregion
+
   //#region Public Methods
 
   /**
@@ -114,6 +141,12 @@ export class AwsStreamHandler<TApp> extends BaseHandler<
     log: ILogger,
   ): ServerlessHandler<Promise<void>> {
     return awslambda.streamifyResponse(async (event, response, context) => {
+      if (this.options?.callbackWaitsForEmptyEventLoop !== undefined) {
+        // TODO(h4ad): Set the following property to false by default
+        context.callbackWaitsForEmptyEventLoop =
+          this.options.callbackWaitsForEmptyEventLoop;
+      }
+
       const streamContext = { response, context };
 
       this.onReceiveRequest(

diff --git a/test/handlers/aws-stream.handler.spec.ts b/test/handlers/aws-stream.handler.spec.ts
@@ -435,4 +435,80 @@ describe('AwsStreamHandler', () => {
       }),
     );
   });
+
+  it('callbackWaitsForEmptyEventLoop should not be modified', async () => {
+    const app = express();
+
+    app.get('/', (_, res) => {
+      res.json({ ok: true });
+    });
+
+    const expressFramework = new ExpressFramework();
+
+    const handler = awsStreamHandler.getHandler(
+      app,
+      expressFramework,
+      adapters,
+      resolver,
+      binarySettings,
+      respondWithErrors,
+      logger,
+    );
+
+    const event = createApiGatewayV2('GET', '/', {}, { test: 'true' });
+    const defaultValueForCallback = Symbol('1');
+    const context = {
+      test: Symbol('unique'),
+      callbackWaitsForEmptyEventLoop: defaultValueForCallback,
+    };
+
+    const writable = new WritableMock();
+
+    await handler(event, writable, context);
+
+    expect(context).toHaveProperty(
+      'callbackWaitsForEmptyEventLoop',
+      defaultValueForCallback,
+    );
+  });
+
+  describe('callbackWaitsForEmptyEventLoop should be changed', () => {
+    for (const value of [true, false]) {
+      it(`to ${value}`, async () => {
+        const app = express();
+
+        app.get('/', (_, res) => {
+          res.json({ ok: true });
+        });
+
+        const expressFramework = new ExpressFramework();
+        const customAwsHandler = new AwsStreamHandler({
+          callbackWaitsForEmptyEventLoop: value,
+        });
+
+        const handler = customAwsHandler.getHandler(
+          app,
+          expressFramework,
+          adapters,
+          resolver,
+          binarySettings,
+          respondWithErrors,
+          logger,
+        );
+
+        const event = createApiGatewayV2('GET', '/', {}, { test: 'true' });
+        const defaultValueForCallback = Symbol('test');
+        const context = {
+          test: Symbol('unique'),
+          callbackWaitsForEmptyEventLoop: defaultValueForCallback,
+        };
+
+        const writable = new WritableMock();
+
+        await handler(event, writable, context);
+
+        expect(context).toHaveProperty('callbackWaitsForEmptyEventLoop', value);
+      });
+    }
+  });
 });
diff --git a/www/docs/main/handlers/aws.mdx b/www/docs/main/handlers/aws.mdx
@@ -83,6 +83,31 @@ export const handler = ServerlessAdapter.new(app)
 
 As you see, we only have to change the `setHandler`, `setResolver` and `setAdapter` methods, that's all!
 
+### My execution is taking too long
+
+Well, maybe is caused because your event loop is not empty when the request finishes, in this case, you can set `callbackWaitsForEmptyEventLoop=false` on [AwsStreamHandler](../../api/handlers/AwsStreamHandler).
+
+
+```ts title="index.ts"
+import { ServerlessAdapter } from '@h4ad/serverless-adapter';
+import { AwsStreamHandler } from '@h4ad/serverless-adapter/handlers/aws';
+import { DummyResolver } from '@h4ad/serverless-adapter/resolvers/dummy';
+import { ApiGatewayV2Adapter } from '@h4ad/serverless-adapter/adapters/aws';
+import app from './app';
+
+export const handler = ServerlessAdapter.new(app)
+  .setHandler(new AwsStreamHandler({ callbackWaitsForEmptyEventLoop: false }))
+  .setResolver(new DummyResolver())
+  .setAdapter(new ApiGatewayV2Adapter())
+  // continue to set the other options here.
+  //.addAdapter(new AlbAdapter())
+  //.addAdapter(new SQSAdapter())
+  //.addAdapter(new SNSAdapter())
+  //.setFramework(new ExpressFramework())
+  // after put all methods necessary, just call the build method.
+  .build();
+```
+
 ### Can I use SQS and other services?
 
 Well, I don't know, but you can try. At least with `SQS` I was able to get the messages, but I couldn't use the `partial batch response` feature.