fix(MongoInstance): add a timeout for the "launch" promise

re #710

Author: hasezoey

packages/mongodb-memory-server-core/src/util/MongoInstance.ts

@@ -14,6 +14,7 @@ import { lt } from 'semver';
 import { EventEmitter } from 'events';
 import { MongoClient, MongoClientOptions, MongoNetworkError } from 'mongodb';
 import {
+  GenericMMSError,
   KeyFileMissingError,
   StartBinaryFailedError,
   StdoutInstanceError,
@@ -165,6 +166,12 @@ export interface MongoMemoryInstanceOpts extends MongoMemoryInstanceOptsBase {
    * @default undefined
    */
   keyfileLocation?: string;
+  /**
+   * Define a custom timeout for when out of some reason the binary cannot get started correctly
+   * Time in MS
+   * @default 10000 10 seconds
+   */
+  launchTimeout?: number;
 }
 
 export enum MongoInstanceEvents {
@@ -336,12 +343,30 @@ export class MongoInstance extends EventEmitter implements ManagerBase {
     this.isInstanceReady = false;
     this.isReplSet = false;
 
-    const launch: Promise<void> = new Promise((res, rej) => {
+    let timeout: NodeJS.Timeout;
+
+    const launch: Promise<void> = new Promise<void>((res, rej) => {
       this.once(MongoInstanceEvents.instanceReady, res);
       this.once(MongoInstanceEvents.instanceError, rej);
       this.once(MongoInstanceEvents.instanceClosed, function launchInstanceClosed() {
         rej(new Error('Instance Exited before being ready and without throwing an error!'));
       });
+
+      // extra conditions just to be sure that the custom defined timeout is valid
+      const timeoutTime =
+        !!this.instanceOpts.launchTimeout && this.instanceOpts.launchTimeout >= 1000
+          ? this.instanceOpts.launchTimeout
+          : 1000 * 10; // default 10 seconds
+
+      timeout = setTimeout(() => {
+        const err = new GenericMMSError(`Instance failed to start within ${timeoutTime}ms`);
+        this.emit(MongoInstanceEvents.instanceError, err);
+
+        rej(err);
+      }, timeoutTime);
+    }).finally(() => {
+      // always clear the timeout after the promise somehow resolves
+      clearTimeout(timeout);
     });
 
     const mongoBin = await MongoBinary.getPath(this.binaryOpts);

packages/mongodb-memory-server-core/src/util/__tests__/MongoInstance.test.ts

@@ -4,7 +4,12 @@ import * as dbUtil from '../utils';
 import MongodbInstance, { MongoInstanceEvents } from '../MongoInstance';
 import resolveConfig, { ResolveConfigVariables } from '../resolveConfig';
 import getPort from 'get-port';
-import { StartBinaryFailedError, StdoutInstanceError, UnexpectedCloseError } from '../errors';
+import {
+  GenericMMSError,
+  StartBinaryFailedError,
+  StdoutInstanceError,
+  UnexpectedCloseError,
+} from '../errors';
 import { assertIsError } from '../../__tests__/testUtils/test_utils';
 
 jest.setTimeout(100000); // 10s
@@ -17,6 +22,7 @@ beforeEach(() => {
 
 afterEach(() => {
   tmpDir.removeCallback();
+  jest.restoreAllMocks();
 });
 
 describe('MongodbInstance', () => {
@@ -597,5 +603,42 @@ describe('MongodbInstance', () => {
         expect(event.message).toMatchSnapshot();
       });
     });
+
+    it('"start" should emit a "instanceError" when timeout is reached and throw a error', async () => {
+      mongod.instanceOpts['launchTimeout'] = 1000;
+
+      jest.spyOn(mongod, '_launchMongod').mockImplementation(
+        // @ts-expect-error The following is not meant to work, but in this test we dont care about that result, only that it never fires any events
+        () => {
+          return { pid: 0 }; // required for a direct check afterwards
+        }
+      );
+      jest.spyOn(mongod, '_launchKiller').mockImplementation(
+        // @ts-expect-error The following is not meant to work, but in this test we dont care about that result, only that it never fires any events
+        () => undefined
+      );
+      jest.spyOn(mongod, 'stop').mockImplementation(
+        // @ts-expect-error The following is not meant to work, but in this test we dont care about that result, only that it never fires any events
+        () => undefined
+      );
+
+      try {
+        await mongod.start();
+        fail('Expected "start" to throw');
+      } catch (err) {
+        // this error could be thrown through "once => instanceError" or from the timeout directly, but it does not matter where it gets thrown from
+        expect(err).toBeInstanceOf(GenericMMSError);
+        assertIsError(err);
+        expect(err.message).toMatchSnapshot();
+
+        expect(events.size).toEqual(1);
+
+        const event = events.get(MongoInstanceEvents.instanceError)?.[0];
+        expect(event).toBeInstanceOf(GenericMMSError);
+        assertIsError(event);
+        expect(event.message).toStrictEqual(err.message);
+        expect(err).toBe(event); // reference compare, because these 2 values should be the same
+      }
+    });
   });
 });

packages/mongodb-memory-server-core/src/util/__tests__/__snapshots__/MongoInstance.test.ts.snap

@@ -17,6 +17,8 @@ exports[`MongodbInstance test events "closeHandler" should emit "instanceError"
 
 exports[`MongodbInstance test events "closeHandler" should emit "instanceError" with non-0 or non-12 code 2`] = `"Instance closed unexpectedly with code \\"null\\" and signal \\"SIG\\""`;
 
+exports[`MongodbInstance test events "start" should emit a "instanceError" when timeout is reached and throw a error 1`] = `"Instance failed to start within 1000ms"`;
+
 exports[`MongodbInstance test events checkErrorInLine() should emit "instanceError" when shared libraries fail to load 1`] = `"Instance failed to start because a library is missing or cannot be opened: \\"libcrypto.so.1.1\\""`;
 
 exports[`MongodbInstance test events stdoutHandler() should emit "instanceError" when "excepetion in initAndListen" is thrown DBException in initAndListen 1`] = `