add support of onError for circuit Breaker

genesys · Nov 23, 2020 · 7ae4bfd · 7ae4bfd
1 parent a85781f
commit 7ae4bfd
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Showing 2 changed files with 37 additions and 1 deletion.
diff --git a/src/module/breaker/index.ts b/src/module/breaker/index.ts
@@ -1,6 +1,8 @@
 import { Module, ModuleOptions } from '..';
 import { Circuit } from '../../circuit';
 
+type ErrorCallback = (err: any) => boolean;
+
 export class BreakerError extends Error {
   constructor(message: string) {
     super(message);
@@ -30,6 +32,7 @@ export interface SlidingWindowBreakerOptions extends ModuleOptions {
   slowCallRateThreshold?:                  number;
   slowCallDurationThreshold?:              number;
   permittedNumberOfCallsInHalfOpenState?:  number;
+  onError?:                                ErrorCallback;
 }
 
 export enum SlidingWindowRequestResult {
@@ -53,6 +56,7 @@ export abstract class SlidingWindowBreaker<T> extends Module implements BreakerN
   private openTimeout = 0;
   private nbCallsInHalfOpenedState: number;
   private callsInHalfOpenedState: SlidingWindowRequestResult[];
+  public onError: ErrorCallback;
 
   constructor (options?: SlidingWindowBreakerOptions) {
     super(options);
@@ -73,6 +77,7 @@ export abstract class SlidingWindowBreaker<T> extends Module implements BreakerN
     this.nbCallsInHalfOpenedState = 0;
     this.callsInHalfOpenedState = [];
     this.callsInClosedState = [];
+    this.onError = options?.onError || (() => true);
   }
 
   private reinitializeCounters (): void {
@@ -143,7 +148,9 @@ export abstract class SlidingWindowBreaker<T> extends Module implements BreakerN
         return {requestResult: requestResp, response: res};
       })
       .catch((err: any) => {
-        return {requestResult: SlidingWindowRequestResult.FAILURE, response: err};
+        const shouldReportFailure = this.onError(err);
+        const returnedValue = shouldReportFailure ? SlidingWindowRequestResult.FAILURE : SlidingWindowRequestResult.SUCCESS;
+        return {requestResult: returnedValue, response: err};
       });
   }
 

diff --git a/test/unit/module/breaker/sliding-count-breaker.spec.ts b/test/unit/module/breaker/sliding-count-breaker.spec.ts
@@ -182,4 +182,33 @@ describe('Sliding Count Breaker', () => {
     await expect(circuit.fn(failureAsync).execute('dummy')).rejects.toEqual('dummy');
     expect(slidingCountBreaker.state).toEqual(Mollitia.BreakerState.OPENED);
   });
+  it('No switch to Open when failures but failure reported as success', async () => {
+    const slidingCountBreaker = new Mollitia.SlidingCountBreaker({
+      slidingWindowSize: 2,
+      minimumNumberOfCalls: 2,
+      failureRateThreshold: 60,
+      openStateDelay: 20,
+      onError: (err) => {
+        if (err === 'credentials-issue') {
+          return false;
+        } else {
+          return true;
+        }
+      }
+    });
+    const circuit = new Mollitia.Circuit({
+      options: {
+        modules: [
+          slidingCountBreaker
+        ]
+      }
+    });
+    await circuit.fn(failureAsync).execute('credentials-issue');
+    await circuit.fn(failureAsync).execute('credentials-issue');
+    expect(slidingCountBreaker.state).toEqual(Mollitia.BreakerState.CLOSED);
+    await circuit.fn(failureAsync).execute('real-issue').catch(()=>{ });
+    expect(slidingCountBreaker.state).toEqual(Mollitia.BreakerState.CLOSED);
+    await circuit.fn(failureAsync).execute('real-issue').catch(()=>{ });
+    expect(slidingCountBreaker.state).toEqual(Mollitia.BreakerState.OPENED);
+  });
 });