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[refactor] RefreshToken 시간복잡도 O(n) -> O(1) 으로 감소 #411

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[refactor] RefreshToken 시간복잡도 O(n) -> O(1) 으로 감소 #411

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15 changes: 5 additions & 10 deletions KkuMulKum.xcodeproj/project.pbxproj
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Original file line number Diff line number Diff line change
Expand Up @@ -2232,11 +2232,9 @@
ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
CODE_SIGN_ENTITLEMENTS = KkuMulKum/KkuMulKumDebug.entitlements;
CODE_SIGN_IDENTITY = "Apple Development";
"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
CODE_SIGN_STYLE = Manual;
CODE_SIGN_STYLE = Automatic;
CURRENT_PROJECT_VERSION = 1;
DEVELOPMENT_TEAM = "";
"DEVELOPMENT_TEAM[sdk=iphoneos*]" = D2DRA3F792;
DEVELOPMENT_TEAM = D2DRA3F792;
GENERATE_INFOPLIST_FILE = YES;
INFOPLIST_FILE = KkuMulKum/Resource/Info.plist;
INFOPLIST_KEY_CFBundleDisplayName = "꾸물꿈";
Expand All @@ -2257,7 +2255,6 @@
PRODUCT_BUNDLE_IDENTIFIER = KkuMulKum.yizihn;
PRODUCT_NAME = "$(TARGET_NAME)";
PROVISIONING_PROFILE_SPECIFIER = "";
"PROVISIONING_PROFILE_SPECIFIER[sdk=iphoneos*]" = KkumulkumDebug;
SUPPORTED_PLATFORMS = "iphoneos iphonesimulator";
SUPPORTS_MACCATALYST = NO;
SUPPORTS_MAC_DESIGNED_FOR_IPHONE_IPAD = NO;
Expand All @@ -2274,11 +2271,10 @@
ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
CODE_SIGN_ENTITLEMENTS = KkuMulKum/KkuMulKum.entitlements;
"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Distribution";
CODE_SIGN_STYLE = Manual;
CODE_SIGN_IDENTITY = "Apple Development";
CODE_SIGN_STYLE = Automatic;
CURRENT_PROJECT_VERSION = 1;
DEVELOPMENT_TEAM = "";
"DEVELOPMENT_TEAM[sdk=iphoneos*]" = D2DRA3F792;
DEVELOPMENT_TEAM = D2DRA3F792;
GENERATE_INFOPLIST_FILE = YES;
INFOPLIST_FILE = KkuMulKum/Resource/Info.plist;
INFOPLIST_KEY_CFBundleDisplayName = "꾸물꿈";
Expand All @@ -2300,7 +2296,6 @@
PRODUCT_BUNDLE_IDENTIFIER = KkuMulKum.yizihn;
PRODUCT_NAME = "$(TARGET_NAME)";
PROVISIONING_PROFILE_SPECIFIER = "";
"PROVISIONING_PROFILE_SPECIFIER[sdk=iphoneos*]" = KkumulkumRelease1;
SUPPORTED_PLATFORMS = "iphoneos iphonesimulator";
SUPPORTS_MACCATALYST = NO;
SUPPORTS_MAC_DESIGNED_FOR_IPHONE_IPAD = NO;
Expand Down
126 changes: 95 additions & 31 deletions KkuMulKum/Source/Core/Auth/TokenRefreshManager.swift
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Expand Up @@ -16,6 +16,16 @@ class TokenRefreshManager {
private var isRefreshing = false
private let queue = DispatchQueue(label: "com.TokenRefreshManager.queue")

// 대기 중인 콜백을 저장하는 배열
private var pendingCompletions: [(Result<String, Error>) -> Void] = []

// 디바운싱 매커니즘을 위한 work item
private var refreshWorkItem: DispatchWorkItem?

// 네트워크 요청 횟수를 추적하는 카운터
private var requestCount = 0
private let maxRequestRetries = 3
Comment on lines +25 to +27
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maxRequestRetries가 3인 기준이 궁금합니다.

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재시도 지연 시간이 0.2초, 0.4초, 0.8초로 증가하면서 총 1.4초까지만 대기하고자 하는 목적입니다 대부분 저 안에 해결이 될것이라 생각했고 대게 3-5회 정도 반복하는게 일시적인 문제를 해결할 수 있다고 생각했습니다


init(authService: AuthServiceProtocol, provider: MoyaProvider<AuthTargetType>) {
self.authService = authService
self.provider = provider
Expand All @@ -28,52 +38,106 @@ class TokenRefreshManager {
return
}

// 이미 토큰 리프레시 진행 중이면 대기열에 추가
if self.isRefreshing {
DispatchQueue.global().asyncAfter(deadline: .now() + 0.1) {
self.refreshToken(completion: completion)
}
self.pendingCompletions.append(completion)
return
}

self.isRefreshing = true

// 리프레시 토큰 확인
guard let currentRefreshToken = self.authService.getRefreshToken() else {
self.isRefreshing = false
completion(.failure(AuthError.tokenRefreshFailed))
return
}

self.provider.request(.refreshToken(refreshToken: currentRefreshToken)) { [weak self] result in
guard let self = self else {
completion(.failure(AuthError.tokenRefreshFailed))
return
}

self.queue.async {
self.isRefreshing = false

switch result {
case .success(let response):
do {
let reissueResponse = try response.map(ResponseBodyDTO<ReissueModel>.self)
if reissueResponse.success, let data = reissueResponse.data {
if self.authService.saveAccessToken(data.accessToken) &&
self.authService.saveRefreshToken(data.refreshToken) {
completion(.success(data.accessToken))
} else {
completion(.failure(AuthError.tokenRefreshFailed))
}
// 리프레시 진행 상태로 변경하고 현재 요청 추가
self.isRefreshing = true
self.pendingCompletions.append(completion)

// 디바운싱 구현: 짧은 시간 동안 추가 요청을 모아서 한 번에 처리
self.refreshWorkItem?.cancel()

let workItem = DispatchWorkItem { [weak self] in
guard let self = self else { return }
self.performTokenRefresh(with: currentRefreshToken)
}

self.refreshWorkItem = workItem

// 20ms 지연으로 짧은 시간 내 다수 요청을 하나로 통합
DispatchQueue.global().asyncAfter(deadline: .now() + 0.02, execute: workItem)
}
}

private func performTokenRefresh(with refreshToken: String) {
requestCount += 1
provider.request(.refreshToken(refreshToken: refreshToken)) { [weak self] result in
guard let self = self else { return }

self.queue.async {
Comment on lines +74 to +77
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위 작업은 글로벌 큐(Concurrent)에서 실행되고, 네트워크 작업이기 때문에 백그라운드에서 실행되는데 이 때 커스텀 직렬 큐로 하위 작업을 실행시켜야 하는지 잘 몰라서 여쭤보고 싶습니다.

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공유 상태(isRefreshing, pendingCompletions 등)를 업데이트하기위해 하위작업으로 동기화 시켜주는 작업입니다

switch result {
case .success(let response):
do {
let reissueResponse = try response.map(ResponseBodyDTO<ReissueModel>.self)
if reissueResponse.success, let data = reissueResponse.data {
if self.authService.saveAccessToken(data.accessToken) &&
self.authService.saveRefreshToken(data.refreshToken) {
self.handleSuccess(data.accessToken)
} else {
completion(.failure(AuthError.tokenRefreshFailed))
self.handleFailure(AuthError.tokenRefreshFailed)
}
} catch {
completion(.failure(error))
} else {
self.handleFailure(AuthError.tokenRefreshFailed)
}
case .failure(let error):
completion(.failure(error))
} catch {
self.handleFailure(error)
}

case .failure(let error):
// 지수 백오프 알고리즘으로 재시도
if self.shouldRetry() {
// 지수 백오프: 2^n * 100ms 대기
let delay = pow(2.0, Double(self.requestCount)) * 0.1
DispatchQueue.global().asyncAfter(deadline: .now() + delay) { [weak self] in
guard let self = self,
let currentRefreshToken = self.authService.getRefreshToken() else { return }
Comment on lines +102 to +103
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else 문은 개행 부탁드려요.

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갱!

self.performTokenRefresh(with: currentRefreshToken)
}
} else {
self.handleFailure(error)
}
}
}
}
}

// 성공 처리 - 모든 대기 콜백에 성공 결과 전달
private func handleSuccess(_ token: String) {
// 삽입 순서 보존 알고리즘 적용 (FIFO)
let callbacks = self.pendingCompletions
self.pendingCompletions = []
self.isRefreshing = false
self.requestCount = 0

DispatchQueue.main.async {
callbacks.forEach { $0(.success(token)) }
}
Comment on lines +117 to +124
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어차피 배열의 아이템마다 어떠한 동작을 수행하고, 배열을 비워야 한다면 아래와 같은 코드도 가능할 것 같습니다.

while let callback = self.pendingCompletions.popLast() {
    DispatchQueue.main.async {
        callback(.success(token))
    }
}
self.isRefreshing = false
self.requestCount = 0

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좋은 의견입니다 하지만 해당 코드로 진행했을때 극단적으로 생각해서 중간에 값이 변경될 가능성이 있지 않을까요? (원자성X) 그리고 현재 코드는 단일 비동기 블록으로 처리하는 반면 제안주신 코드는 각 콜백마다 비동기 작업을 예약하는 형식이여서 스케쥴링 오버헤드가 좀더 발생할 여지가 있지 않을까요?
(물론 아주 극단적이고 아주아주 미미할것이라는건 알고있습니다,,)

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오 확실히 그러한 부분도 있을 수 있겠군요.
동시성 프로그래밍 속에서 race condition을 고려하면서 짜는 건 너무 어려운 것 같습니다.

지훈님의 TokenRefreshManager 또한 여러 DispatchQueue의 콜백이 존재하다 보니, 어떤 큐에서 어떻게 동작하는지 파악해야 하는 부분이 있네요.
이렇기 때문에 Actor 클래스가 등장한게 아닐까 싶습니다.
TokenRefreshManager를 Actor로 구현해 보시는 것도 쿨럭,,

}

// 실패 처리 - 모든 대기 콜백에 실패 결과 전달
private func handleFailure(_ error: Error) {
let callbacks = self.pendingCompletions
self.pendingCompletions = []
self.isRefreshing = false
self.requestCount = 0

DispatchQueue.main.async {
callbacks.forEach { $0(.failure(error)) }
}
Comment on lines +134 to +136
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콜백에 성공 신호를 메인 큐에서 전달하는 이유가 궁금합니다.

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코드트리를 최대한 평평하게 하기 위함이였습니다만,, 글로벌 큐에서 작업을 했어도 되었을 작업이였습니다.
성능개선에만 집중하다보니 이상한 코드가 나와버렷네요

}

// 재시도 여부 결정 로직
private func shouldRetry() -> Bool {
return requestCount < maxRequestRetries
}
Comment on lines +139 to +142
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계산 속성으로 구현해도 좋을 듯 하네요.

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좋은생각이에요!

}