fix: MDC 복사가 종료 신호를 건너뛰어 다음 시퀀스가 이전 Context 로 로그를 남기는 문제 수정

Foundation/org.egovframe.rte.fdl.reactive/src/main/java/org/egovframe/rte/fdl/reactive/logging/EgovMdcContextConfig.java

@@ -110,11 +110,13 @@ public void onNext(T t) {
 
         @Override
         public void onError(Throwable throwable) {
+            copyToMdc(coreSubscriber.currentContext());
             coreSubscriber.onError(throwable);
         }
 
         @Override
         public void onComplete() {
+            copyToMdc(coreSubscriber.currentContext());
             coreSubscriber.onComplete();
         }
 

Foundation/org.egovframe.rte.fdl.reactive/src/test/java/org/egovframe/rte/fdl/reactive/logging/EgovMdcContextConfigTest.java

@@ -0,0 +1,85 @@
+package org.egovframe.rte.fdl.reactive.logging;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.MDC;
+import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Scheduler;
+import reactor.core.scheduler.Schedulers;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class EgovMdcContextConfigTest {
+
+    private final EgovMdcContextConfig config = new EgovMdcContextConfig();
+
+    /** 시퀀스의 상류 절반이 도는, 재사용되는 스레드 */
+    private Scheduler worker;
+
+    /** publishOn 으로 하류 절반을 넘겨받는 스레드 */
+    private Scheduler consumer;
+
+    @BeforeEach
+    public void setUp() {
+        worker = Schedulers.newSingle("mdc-worker");
+        consumer = Schedulers.newSingle("mdc-consumer");
+        config.contextOperatorHook();
+        MDC.clear();
+    }
+
+    @AfterEach
+    public void tearDown() {
+        config.cleanupHook();
+        worker.dispose();
+        consumer.dispose();
+        MDC.clear();
+    }
+
+    /**
+     * userId=A 를 worker 스레드의 MDC 에 남긴 뒤, 같은 worker 스레드에서 값 없이 완료되는
+     * 시퀀스를 구독한다. 두 번째 시퀀스의 종료 콜백은 자신의 Context 값인 B 를 봐야 한다.
+     */
+    @Test
+    public void completionOfNextSequenceSeesItsOwnContext() {
+        Mono.just("a").hide()
+                .subscribeOn(worker)
+                .publishOn(consumer)
+                .contextWrite(context -> context.put("userId", "A"))
+                .block();
+
+        AtomicReference<String> seen = new AtomicReference<>();
+        Mono.empty()
+                .subscribeOn(worker)
+                .doOnTerminate(() -> seen.set(MDC.get("userId")))
+                .contextWrite(context -> context.put("userId", "B"))
+                .block();
+
+        assertEquals("B", seen.get());
+    }
+
+    /**
+     * 두 번째 시퀀스가 값 없이 에러로 끝나는 경우도 마찬가지다.
+     */
+    @Test
+    public void errorOfNextSequenceSeesItsOwnContext() {
+        Mono.just("a").hide()
+                .subscribeOn(worker)
+                .publishOn(consumer)
+                .contextWrite(context -> context.put("userId", "A"))
+                .block();
+
+        AtomicReference<String> seen = new AtomicReference<>();
+        Mono<Object> error = Mono.error(new IllegalStateException("boom")).hide()
+                .subscribeOn(worker)
+                .doOnTerminate(() -> seen.set(MDC.get("userId")))
+                .contextWrite(context -> context.put("userId", "B"));
+        assertThrows(IllegalStateException.class, error::block);
+
+        assertEquals("B", seen.get());
+    }
+
+}