순환 참조 문제 해결

[daadaadaah]

순환 참조 문제 : AppConfig 순환 참조 문제

에러 메시지

Description:

The dependencies of some of the beans in the application context form a cycle:

   localMethodExecutionTimeLoggingAspect defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/common/aop/LocalMethodExecutionTimeLoggingAspect.class]
      ↓
   discordNotificationService defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/service/notification/DiscordNotificationService.class]
      ↓
   restTemplateHttpClient defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/infrastructure/resttemplate/RestTemplateHttpClient.class]
┌─────┐
|  appConfig defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/common/config/AppConfig.class]
↑     ↓
|  gitHubApiLoggingInterceptor defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/infrastructure/resttemplate/interceptor/GitHubApiLoggingInterceptor.class]
↑     ↓
|  logDirectSaveGoogleSheetsService defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/service/log/LogDirectSaveGoogleSheetsService.class]
↑     ↓
|  logGoogleSheetsRepository defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/repository/log/LogGoogleSheetsRepository.class]
↑     ↓
|  googleSheetsClient defined in file [/Users/daheekwak/Desktop/review-study-app/out/production/classes/com/example/review_study_app/infrastructure/googlesheets/GoogleSheetsClient.class]
└─────┘

Action:

Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans. As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.

Process finished with exit code 1

해결 과정

1. 에러 메시지 해석

• Spring의 기본 설정에서는 Bean간의 순환 참조를 허용되지 않는데, Bean간의 순환 참조 문제가 발생해서 애플리케이션이 실행되지 못했다.

2. 어떤 순환 참조가 형성되었는지 파악

• 다음과 같이 그림을 그려보며, 어떻게 순환 참조가 발생했는지 파악했습니다.

3. 왜 순환 참조가 일어나는지 파악

• 순환 참조가 발생한 이유는 AppConfig 클래스이 여러 책임을 동시에 맡았기 때문이었습니다. (SRP 원칙 위반!)
• AppConfig 클래스는 RestTemplate과 Google Sheets 관련 설정을 모두 관리하고 있었으며, 이로 인해 의존성 간의 순환이 발생하게 된 것이었습니다.

4. 어떻게 순환 참조 문제를 해결할 것인지

• 따라서, AppConfig 클래스에서 Google Sheets 관련 설정을 분리하면, AppConfig 클래스는 SRP 원칙에 따라 RestTemplate 관련 설정만 관리하게 되어 순환 참조 문제가 해결될 것이라고 생각했습니다.

• 이에, 코드를 다음과 같이 AppConfig에서 Google Sheets 관련 설정을 분리하고, 이를 관리해 줄 GoogleSheetsConfig를 만들었습니다.

  @Configuration
  public class AppConfig {
  
  private final GitHubApiLoggingInterceptor gitHubApiLoggingInterceptor;
  
  @Autowired
  public AppConfig(
      GitHubApiLoggingInterceptor gitHubApiLoggingInterceptor
  ) {
      this.gitHubApiLoggingInterceptor = gitHubApiLoggingInterceptor;
  }
  
  @Bean
  public RestTemplate restTemplate() {
      RestTemplate restTemplate = new RestTemplate();
      // ... 생략
      restTemplate.setInterceptors(Collections.singletonList(gitHubApiLoggingInterceptor));
      // ... 생략
      return restTemplate;
  }
  }

@Configuration
public class GoogleSheetsConfig {

    @Bean
    public Sheets sheets(GoogleSheetsFactory googleSheetsFactory) {
        return googleSheetsFactory.createSheets();
    }
}

결과 (관련 commit)

• 그 결과, 다음과 같이 순환 참조가 끊어지면서 1번째 순환 참조 문제를 해결했습니다.

[daadaadaah]

2번째 순환 참조 문제 관련 코드

@Autowired
public DiscordNotificationService(
    RestTemplateHttpClient restTemplateHttpClient
) {
    this.restTemplateHttpClient = restTemplateHttpClient;
}

@Autowired
public RestTemplateHttpClient(
   RestTemplate restTemplate
) {
     this.restTemplate = restTemplate;
}

@Configuration
public class AppConfig {

    @Autowired
    public AppConfig(
        GitHubApiLoggingInterceptor gitHubApiLoggingInterceptor
    ) {
        this.gitHubApiLoggingInterceptor = gitHubApiLoggingInterceptor;
    }

    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        // ... 생략
        return restTemplate;
    }
}

@Autowired
public GitHubApiLoggingInterceptor(
    LogService logService
) {
    this.logService = logService;
}

@Autowired
public LogDirectSaveGoogleSheetsService(
    NotificationService notificationService
) {
    this.notificationService = notificationService;
}

@Autowired
public DiscordNotificationService(
   RestTemplateHttpClient restTemplateHttpClient
) {
    this.restTemplateHttpClient = restTemplateHttpClient;
}