How does this project work? about refresh-token-sample HOT 2 CLOSED

class AuthInterceptor @Inject constructor(...) : Interceptor {
  private val mutex = Mutex()

  override fun intercept(chain: Interceptor.Chain): Response {
    val currentToken = getCurrentTokenFromLocalSource()
 
    val originalResponse = ...
  
    if (!isHttpUnauthorizedCode()) {
       // ignored
       return ...
    }

    // refresh-token logic starts here...
    
    // `withLock` will only allow one `block {}` to execute 
    val newToken: String? = mutex.withLock block@{
       // `maybeUpdatedToken` can be `currentToken` or `refreshed-token by other block {}`
       val maybeUpdatedToken = getCurrentTokenFromLocalSource()
       
       when {
           // [FAILED] already logged out! -> `refresh-token-request by other block {}` failed.
          maybeUpdatedToken == null -> null
          // [SUCCESS] refreshed by another request -> `refresh-token-request by other block {}` succeed,
          // so we don't need to make another request anymore (one is enough!).
          maybeUpdatedToken != token -> maybeUpdatedToken
          // else: means other `block {}`s are blocking while this block is executing -> will make `refresh-token-request`
          else -> {
              val newToken = callRefreshTokenApi()
              if (HTTP_OK) {
                  saveToken(newToken)
                  newToken // return newToken as result
              } else if (HTTP_UNAUTHORIZED) {
                  clearUserAndToken() // means logout...
                  null
              } else {
                  // other errors, don't clearUserAndToken()
                  null 
              }
          }
    }

    return if (newToken != null) {
       retryRequestWithNewToken(newToken)
    } else {
       originalResponse
    }
  }
}