refactor: 주문 처리 직렬화를 마켓 큐로 단일화, 마켓 락 제거

[ohhalim]

Closes #117

목적

주문 처리의 동시성 직렬화 메커니즘을 마켓 큐 하나로 단일화하고, 중복이던 마켓 락을 제거한다.

배경 — 무엇이 문제였나

마켓 단위 직렬화(한 번에 하나씩 처리)를 보장하는 메커니즘이 2개 공존했다.

1. MarketOrderCommandQueue — 마켓당 워커 스레드 1개 (single-writer)
2. MarketOrderLockManager 의 ReentrantLock — 프로세서 내부에서 추가 획득

워커가 마켓당 1개이므로 큐만으로 이미 직렬화가 보장된다. 락이 실제로 의미를 갖던 곳은 큐를 거치지 않고 HTTP 스레드에서 오더북을 직접 변경하던 취소 경로 뿐이었다. 그 결과 "무엇이 동시성을 보장하는가"가 두 곳에 분산되어 흐름을 이해하기 어려웠다.

변경 전

flowchart TD
    C1["POST /orders (동기)"]
    C2["POST /orders/async (비동기)"]
    C3["POST /orders/{id}/cancel (취소)"]
    Q["MarketOrderCommandQueue<br/>워커 1개 — 직렬화 ①"]
    L["ReentrantLock — 직렬화 ② (중복)"]
    OB[("오더북")]

    C1 -->|submit| Q
    C2 -->|submitAsync| Q
    Q --> L
    C3 -.->|"큐 건너뜀"| L
    L --> OB

Loading

변경 후

flowchart TD
    C1["POST /orders (동기)"]
    C2["POST /orders/async (비동기)"]
    C3["POST /orders/{id}/cancel (취소)"]
    Q["MarketOrderCommandQueue<br/>워커 1개 — 유일한 직렬화 지점"]
    OB[("오더북")]

    C1 -->|submit| Q
    C2 -->|submitAsync| Q
    C3 -->|submit| Q
    Q --> OB

Loading

오더북을 변경하는 주체가 워커 스레드 하나뿐이므로 락이 필요 없다.

변경 사항 (커밋 단위)

1. MarketOrderCommandQueue: marketId/symbol 기반 submit 오버로드 추가
2. SyncOrderProcessor / AcceptedOrderProcessor: 마켓 락 획득·해제, releaseRegistered + afterCommit/afterCompletion 이중 해제 제거
3. OrderCancelService: 취소를 마켓 큐 경로로 전환 (오더북 변경 주체를 워커로 단일화, 응답은 기존대로 즉시 반환)
4. MarketOrderLockManager / MarketOrderLockService / MarketOrderLockScope 삭제

검증

• ./gradlew compileJava compileTestJava 통과
• OrderApiTest (동기 201+trades, self-trade, 취소, 비동기) 통과
• order + integration(오더북 복구, 매칭) 전체 통과
• 동기/비동기 API 계약 및 기존 테스트 변경 없음

후속 작업 (별도 PR)

• 라인 단위 계측(OrderCreateStageRecorder 등)을 경계 단위로 축소
• SyncOrderProcessor/AcceptedOrderProcessor 공통 로직 단일 핸들러로 통합

Summary by CodeRabbit

Refactor

• Improved order processing architecture for enhanced system performance during concurrent operations
• Streamlined order cancellation workflow and optimized internal concurrency mechanisms for greater reliability

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 77c012e7-325a-46ac-ab1c-61ccde3adbb4

📥 Commits

Reviewing files that changed from the base of the PR and between c33b93e and e2b31c0.

📒 Files selected for processing (7)

• src/main/java/com/coinflow/order/service/cancel/OrderCancelService.java
• src/main/java/com/coinflow/order/service/command/MarketOrderCommandQueue.java
• src/main/java/com/coinflow/order/service/lock/MarketOrderLockManager.java
• src/main/java/com/coinflow/order/service/lock/MarketOrderLockScope.java
• src/main/java/com/coinflow/order/service/lock/MarketOrderLockService.java
• src/main/java/com/coinflow/order/service/processor/AcceptedOrderProcessor.java
• src/main/java/com/coinflow/order/service/processor/SyncOrderProcessor.java

💤 Files with no reviewable changes (4)

• src/main/java/com/coinflow/order/service/lock/MarketOrderLockService.java
• src/main/java/com/coinflow/order/service/lock/MarketOrderLockScope.java
• src/main/java/com/coinflow/order/service/lock/MarketOrderLockManager.java
• src/main/java/com/coinflow/order/service/processor/SyncOrderProcessor.java

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📝 Walkthrough

Walkthrough

Three per-market ReentrantLock classes (MarketOrderLockManager, MarketOrderLockService, MarketOrderLockScope) are deleted. MarketOrderCommandQueue gains a raw-identifier submit overload. OrderCancelService, AcceptedOrderProcessor, and SyncOrderProcessor all drop their lock service dependency and constructor parameters.

Changes

Lock Infrastructure Removal and Queue-Only Serialization

Layer / File(s)	Summary
MarketOrderCommandQueue new submit overload src/main/java/com/coinflow/order/service/command/MarketOrderCommandQueue.java	Adds submit(Long marketId, String marketSymbol, OrderSide, Supplier) overload; the existing submit(Market, ...) delegates into it, centralizing worker lookup on raw identifiers.
OrderCancelService migrated to queue src/main/java/com/coinflow/order/service/cancel/OrderCancelService.java	Replaces MarketOrderLockService injection with MarketOrderCommandQueue; cancelOrder now queues work via the new overload and runs transactionTemplate.execute inside the queued callback.
AcceptedOrderProcessor lock removal src/main/java/com/coinflow/order/service/processor/AcceptedOrderProcessor.java	Removes MarketOrderLockService field, constructor parameter, AtomicBoolean release flag, and all explicit lock acquisition/release; afterCommit/afterCompletion callbacks no longer touch any market lock.
SyncOrderProcessor lock removal src/main/java/com/coinflow/order/service/processor/SyncOrderProcessor.java	Removes MarketOrderLockService field, constructor parameter, MarketOrderLockScope acquisition, AtomicBoolean tracking, and the finally-block release; simplifies executeInTransaction and registerOrderBookSynchronization signatures; moves recordAfterCommitFinished into afterCommit.
Deleted lock classes src/main/java/com/coinflow/order/service/lock/MarketOrderLockManager.java, .../MarketOrderLockService.java, .../MarketOrderLockScope.java	MarketOrderLockManager (concurrent ReentrantLock map), MarketOrderLockService (acquire methods), and MarketOrderLockScope (release with double-release guard) are fully deleted.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• ohhalim/CoinFlow#79: Introduced MarketOrderCommandQueue as the queue-based per-market serialization mechanism that this PR now adopts as the sole serialization path.
• ohhalim/CoinFlow#101: Added OrderCancelService with MarketOrderLockService-based locking, which this PR directly replaces with MarketOrderCommandQueue.

Poem

🐇 Hoppity-hop, the locks fall away,
One queue to rule them all today!
No more ReentrantLock to find,
The market worker speaks one mind.
Submit, commit, and hop along —
The pipeline sings a simpler song! 🎵

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: refactoring order processing serialization to use the market queue exclusively and removing the market lock mechanism.
Linked Issues check	✅ Passed	All key coding objectives from issue #117 are met: market lock classes removed, order cancellations routed through the market queue, and dual serialization mechanisms consolidated into the queue-based approach.
Out of Scope Changes check	✅ Passed	All changes are directly aligned with the PR objectives and issue #117 scope. No extraneous modifications detected outside the specified refactoring boundaries.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/refactor-order-single-path

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