common/utils/build.gradle.kts

@@ -0,0 +1,5 @@
+dependencies {
+    implementation("org.slf4j:slf4j-api:2.0.17")
+
+    testImplementation("ch.qos.logback:logback-classic:1.5.18")
+}

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

@@ -0,0 +1,26 @@
+package com.sangdol.common.utils
+
+import org.slf4j.MDC
+import java.util.*
+
+object MdcPrincipalIdUtil {
+    const val MDC_PRINCIPAL_ID_KEY = "principal_id"
+
+    fun extractAsLongOrNull(): Long? {
+        return MDC.get(MDC_PRINCIPAL_ID_KEY)?.toLong()
+    }
+
+    fun extractAsOptionalLongOrEmpty(): Optional<Long> {
+        return MDC.get(MDC_PRINCIPAL_ID_KEY)?.let {
+            Optional.of(it.toLong())
+        } ?: Optional.empty()
+    }
+
+    fun set(id: String) {
+        MDC.put(MDC_PRINCIPAL_ID_KEY, id)
+    }
+
+    fun clear() {
+        MDC.remove(MDC_PRINCIPAL_ID_KEY)
+    }
+}

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

@@ -0,0 +1,28 @@
+package com.sangdol.common.utils
+
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+import java.util.*
+
+class MdcPrincipalIdUtilTest : StringSpec({
+
+    val id = 1872847943L
+
+    "값을 설정한다." {
+        MdcPrincipalIdUtil.set(id.toString()).also {
+            MdcPrincipalIdUtil.extractAsLongOrNull() shouldBe id
+            MdcPrincipalIdUtil.extractAsOptionalLongOrEmpty() shouldBe Optional.of(id)
+        }
+    }
+
+    "값을 제거한다." {
+        MdcPrincipalIdUtil.set(id.toString()).also {
+            MdcPrincipalIdUtil.extractAsLongOrNull() shouldBe id
+        }
+
+        MdcPrincipalIdUtil.clear().also {
+            MdcPrincipalIdUtil.extractAsLongOrNull() shouldBe null
+            MdcPrincipalIdUtil.extractAsOptionalLongOrEmpty() shouldBe Optional.empty()
+        }
+    }
+})