feat(effects): limit retries to 10 by default (#2376)

Closes #2303

Author: alex-okrushko

modules/effects/spec/effects_error_handler.spec.ts

@@ -1,20 +1,21 @@
-import { ErrorHandler, Provider } from '@angular/core';
+import { ErrorHandler, Provider, Type } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
 import { Action, Store } from '@ngrx/store';
-import { Observable, of } from 'rxjs';
+import { Observable, of, throwError } from 'rxjs';
 import { catchError } from 'rxjs/operators';
 import { createEffect, EFFECTS_ERROR_HANDLER, EffectsModule } from '..';
+import * as effectsSrc from '../src/effects_error_handler';
 
 describe('Effects Error Handler', () => {
   let subscriptionCount: number;
   let globalErrorHandler: jasmine.Spy;
   let storeNext: jasmine.Spy;
 
-  function makeEffectTestBed(...providers: Provider[]) {
+  function makeEffectTestBed(effect: Type<any>, ...providers: Provider[]) {
     subscriptionCount = 0;
 
     TestBed.configureTestingModule({
-      imports: [EffectsModule.forRoot([ErrorEffect])],
+      imports: [EffectsModule.forRoot([effect])],
       providers: [
         {
           provide: Store,
@@ -38,8 +39,14 @@ describe('Effects Error Handler', () => {
     storeNext = store.next;
   }
 
+  it('should retry on infinite error up to 10 times', () => {
+    makeEffectTestBed(AlwaysErrorEffect);
+
+    expect(globalErrorHandler.calls.count()).toBe(10);
+  });
+
   it('should retry and notify error handler when effect error handler is not provided', () => {
-    makeEffectTestBed();
+    makeEffectTestBed(ErrorEffect);
 
     // two subscriptions expected:
     // 1. Initial subscription to the effect (this will error)
@@ -62,7 +69,7 @@ describe('Effects Error Handler', () => {
         );
       });
 
-    makeEffectTestBed({
+    makeEffectTestBed(ErrorEffect, {
       provide: EFFECTS_ERROR_HANDLER,
       useValue: effectsErrorHandlerSpy,
     });
@@ -84,6 +91,10 @@ describe('Effects Error Handler', () => {
     });
   }
 
+  class AlwaysErrorEffect {
+    effect$ = createEffect(() => throwError('always an error'));
+  }
+
   /**
    * This observable factory returns an observable that will never emit, but the first subscriber will get an immediate
    * error. All subsequent subscribers will just get an observable that does not emit.

modules/effects/src/effects_error_handler.ts

@@ -8,17 +8,25 @@ export type EffectsErrorHandler = <T extends Action>(
   errorHandler: ErrorHandler
 ) => Observable<T>;
 
-export const defaultEffectsErrorHandler: EffectsErrorHandler = <
-  T extends Action
->(
+const MAX_NUMBER_OF_RETRY_ATTEMPTS = 10;
+
+export function defaultEffectsErrorHandler<T extends Action>(
   observable$: Observable<T>,
-  errorHandler: ErrorHandler
-): Observable<T> => {
+  errorHandler: ErrorHandler,
+  retryAttemptLeft: number = MAX_NUMBER_OF_RETRY_ATTEMPTS
+): Observable<T> {
   return observable$.pipe(
     catchError(error => {
       if (errorHandler) errorHandler.handleError(error);
+      if (retryAttemptLeft <= 1) {
+        return observable$; // last attempt
+      }
       // Return observable that produces this particular effect
-      return defaultEffectsErrorHandler(observable$, errorHandler);
+      return defaultEffectsErrorHandler(
+        observable$,
+        errorHandler,
+        retryAttemptLeft - 1
+      );
     })
   );
-};
+}

modules/effects/src/index.ts

@@ -3,7 +3,10 @@ export { EffectConfig } from './models';
 export { Effect } from './effect_decorator';
 export { getEffectsMetadata } from './effects_metadata';
 export { mergeEffects } from './effects_resolver';
-export { EffectsErrorHandler } from './effects_error_handler';
+export {
+  EffectsErrorHandler,
+  defaultEffectsErrorHandler,
+} from './effects_error_handler';
 export { EffectsMetadata, CreateEffectMetadata } from './models';
 export { Actions, ofType } from './actions';
 export { EffectsModule } from './effects_module';

projects/ngrx.io/content/guide/effects/lifecycle.md

@@ -43,7 +43,8 @@ export class LogEffects {
 Starting with version 8, when an error happens in the effect's main stream it is
 reported using Angular's `ErrorHandler`, and the source effect is
 **automatically** resubscribed to (instead of completing), so it continues to
-listen to all dispatched Actions.
+listen to all dispatched Actions. By default, effects are resubscribed up to 10
+errors.
 
 Generally, errors should be handled by users. However, for the cases where errors were missed,
 this new behavior adds an additional safety net.
@@ -96,7 +97,8 @@ The behavior of the default resubscription handler can be customized
 by providing a custom handler using the `EFFECTS_ERROR_HANDLER` injection token.
 
 This allows you to provide a custom behavior, such as only retrying on
-certain "retryable" errors, or with maximum number of retries.
+certain "retryable" errors, or change the maximum number of retries (it's set to
+10 by default).
 
 <code-example header="customise-error-handler.effects.ts">
 import { ErrorHandler, NgModule } from '@angular/core';