feat: StartTime 기록용 MDC 유틸 및 테스트 추가

common/utils/src/main/kotlin/com/sangdol/common/utils/MdcStartTimeUtil.kt

@@ -0,0 +1,25 @@
+package com.sangdol.common.utils
+
+import org.slf4j.MDC
+
+object MdcStartTimeUtil {
+    const val MDC_START_TIME_KEY = "start_time"
+
+    fun extractDurationMsOrNull(): Long? {
+        return extractOrNull()?.let { System.currentTimeMillis() - it }
+    }
+
+    fun setCurrentTime() {
+        extractOrNull() ?: run {
+            MDC.put(MDC_START_TIME_KEY, System.currentTimeMillis().toString())
+        }
+    }
+
+    fun clear() {
+        MDC.remove(MDC_START_TIME_KEY)
+    }
+
+    private fun extractOrNull(): Long? {
+        return MDC.get(MDC_START_TIME_KEY)?.toLong()
+    }
+}

common/utils/src/test/kotlin/com/sangdol/common/utils/MdcPrincipalIdUtilTest.kt

@@ -25,4 +25,4 @@ class MdcPrincipalIdUtilTest : StringSpec({
             MdcPrincipalIdUtil.extractAsOptionalLongOrEmpty() shouldBe Optional.empty()
         }
     }
-})
+})

common/utils/src/test/kotlin/com/sangdol/common/utils/MdcStartTimeUtilTest.kt

@@ -0,0 +1,34 @@
+package com.sangdol.common.utils
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.nulls.shouldNotBeNull
+import io.kotest.matchers.shouldBe
+
+class MdcStartTimeUtilTest : FunSpec({
+
+    test("기존에 등록된 startTime 값을 기준으로 duration_ms를 구한다.") {
+        MdcStartTimeUtil.setCurrentTime()
+        MdcStartTimeUtil.extractDurationMsOrNull().shouldNotBeNull()
+        MdcStartTimeUtil.clear()
+    }
+
+    test("기존에 등록된 startTime 값이 없으면 duration_ms는 null이다.") {
+        MdcStartTimeUtil.extractDurationMsOrNull() shouldBe null
+    }
+
+    test("현재 시간을 등록한다.") {
+        MdcStartTimeUtil.setCurrentTime()
+        MdcStartTimeUtil.extractDurationMsOrNull().shouldNotBeNull()
+        MdcStartTimeUtil.clear()
+    }
+
+    test("등록된 시간을 지운다.") {
+        MdcStartTimeUtil.setCurrentTime().also {
+            MdcStartTimeUtil.extractDurationMsOrNull().shouldNotBeNull()
+        }
+
+        MdcStartTimeUtil.clear().also {
+            MdcStartTimeUtil.extractDurationMsOrNull() shouldBe null
+        }
+    }
+})