From 74c581f5f388c17f7bde112f019b0bb70ff8a163 Mon Sep 17 00:00:00 2001
From: Jake Son <sonjeabin@gmail.com>
Date: Sat, 13 May 2023 21:02:30 +0900
Subject: [PATCH] feat: add circuit breaker support

---
 lib/builders/circuit-breaker.builder.ts | 13 +++++++++++++
 lib/decorators/constants.ts             |  1 +
 lib/supports/node-fetch.injector.ts     | 17 +++++++++++++++--
 lib/types/http-interface-config.ts      |  2 ++
 4 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 lib/builders/circuit-breaker.builder.ts

diff --git a/lib/builders/circuit-breaker.builder.ts b/lib/builders/circuit-breaker.builder.ts
new file mode 100644
index 0000000..fa0a105
--- /dev/null
+++ b/lib/builders/circuit-breaker.builder.ts
@@ -0,0 +1,13 @@
+import CircuitBreaker from 'opossum';
+
+export class CircuitBreakerBuilder {
+  constructor(private readonly options?: CircuitBreaker.Options) {}
+
+  async build(executor: () => Promise<Response>): Promise<Response> {
+    if (this.options == null) {
+      return await executor();
+    }
+
+    return await new CircuitBreaker(executor, this.options).fire();
+  }
+}
diff --git a/lib/decorators/constants.ts b/lib/decorators/constants.ts
index 879ad70..cea56a5 100644
--- a/lib/decorators/constants.ts
+++ b/lib/decorators/constants.ts
@@ -6,3 +6,4 @@ export const REQUEST_BODY_METADATA = Symbol('REQUEST_BODY_METADATA');
 export const REQUEST_FORM_METADATA = Symbol('REQUEST_FORM_METADATA');
 export const REQUEST_HEADER_METADATA = Symbol('REQUEST_HEADER_METADATA');
 export const RESPONSE_BODY_METADATA = Symbol('RESPONSE_BODY_METADATA');
+export const CIRCUIT_BREAKER_METADATA = Symbol('CIRCUIT_BREAKER_METADATA');
diff --git a/lib/supports/node-fetch.injector.ts b/lib/supports/node-fetch.injector.ts
index b4243af..26a4546 100644
--- a/lib/supports/node-fetch.injector.ts
+++ b/lib/supports/node-fetch.injector.ts
@@ -1,9 +1,11 @@
 import { Injectable, type OnModuleInit } from '@nestjs/common';
 import { DiscoveryService, MetadataScanner } from '@nestjs/core';
 import { type InstanceWrapper } from '@nestjs/core/injector/instance-wrapper';
+import { CircuitBreakerBuilder } from '../builders/circuit-breaker.builder';
 import { type HttpRequestBuilder } from '../builders/http-request.builder';
 import { type ResponseBodyBuilder } from '../builders/response-body.builder';
 import {
+  CIRCUIT_BREAKER_METADATA,
   HTTP_EXCHANGE_METADATA,
   HTTP_INTERFACE_METADATA,
   RESPONSE_BODY_METADATA,
@@ -43,14 +45,25 @@ export class NodeFetchInjector implements OnModuleInit {
         return;
       }
 
+      const circuitBreaker: CircuitBreakerBuilder =
+        Reflect.getMetadata(CIRCUIT_BREAKER_METADATA, prototype, methodName) ??
+        new CircuitBreakerBuilder(
+          this.httpInterfaceConfig?.circuitBreakerOption,
+        );
       const responseBodyBuilder: ResponseBodyBuilder<unknown> | undefined =
         Reflect.getMetadata(RESPONSE_BODY_METADATA, prototype, methodName);
 
       httpRequestBuilder.setBaseUrl(baseUrl);
 
       wrapper.instance[methodName] = async (...args: never[]) =>
-        await this.httpClient
-          .request(httpRequestBuilder.build(args), httpRequestBuilder.options)
+        await circuitBreaker
+          .build(
+            async () =>
+              await this.httpClient.request(
+                httpRequestBuilder.build(args),
+                httpRequestBuilder.options,
+              ),
+          )
           .then(async (response) => {
             if (responseBodyBuilder != null) {
               const res = await response.json();
diff --git a/lib/types/http-interface-config.ts b/lib/types/http-interface-config.ts
index b7598fd..d2e3cbf 100644
--- a/lib/types/http-interface-config.ts
+++ b/lib/types/http-interface-config.ts
@@ -1,8 +1,10 @@
 import { type ClassTransformOptions } from 'class-transformer';
+import type CircuitBreaker from 'opossum';
 import { type HttpClient } from './http-client.interface';
 
 export interface HttpInterfaceConfig {
   timeout?: number;
   httpClient?: HttpClient;
   transformOption?: ClassTransformOptions;
+  circuitBreakerOption?: CircuitBreaker.Options;
 }