rebase (#33)

* issue #31 - Add MDC support: withLoggingContext

* Update ChangleLog.md

* Update ChangleLog.md

* Update README.md

* Rename ChangleLog.md to ChangeLog.md (#32)

Author: oshai

ChangleLog.md renamed to ChangeLog.md

@@ -1,3 +1,7 @@
+# 1.4.9
+* Add MDC Support [#31](https://github.com/MicroUtils/kotlin-logging/issues/31)
+* Upgrade to Kotlin 1.2.10.
+
 # 1.4.8
 * 1.4.7 was broken see issue [#30](https://github.com/MicroUtils/kotlin-logging/issues/30)
 

README.md

@@ -53,14 +53,14 @@ An `Android` example project with kotlin logging can be found in [kotlin-logging
 <dependency>
   <groupId>io.github.microutils</groupId>
   <artifactId>kotlin-logging</artifactId>
-  <version>1.4.7</version>
+  <version>1.4.9</version>
 </dependency>
 ```
 See full example in [kotlin-logging-example-maven](https://github.com/MicroUtils/kotlin-logging-example-maven).  
 
 ### Gradle
 ```Groovy
-compile 'io.github.microutils:kotlin-logging:1.4.7'
+compile 'io.github.microutils:kotlin-logging:1.4.9'
 ```
 
 Or alternatively, download jar from [github](https://github.com/MicroUtils/kotlin-logging/releases/latest) or [bintray](https://dl.bintray.com/microutils/kotlin-logging/io/github/microutils/kotlin-logging/) or [maven-central](http://repo1.maven.org/maven2/io/github/microutils/kotlin-logging/).

src/main/kotlin/mu/KotlinLoggingMDC.kt

@@ -0,0 +1,24 @@
+package mu
+
+import org.slf4j.MDC
+
+inline fun <T> withLoggingContext(pair: Pair<String, String>, body: () -> T): T =
+    MDC.putCloseable(pair.first, pair.second).use { body() }
+
+inline fun <T> withLoggingContext(vararg pair: Pair<String, String>, body: () -> T): T {
+  try {
+    pair.forEach { MDC.put(it.first, it.second) }
+    return body()
+  } finally {
+    pair.forEach { MDC.remove(it.first) }
+  }
+}
+
+inline fun <T> withLoggingContext(map: Map<String, String>, body: () -> T): T {
+  try {
+    map.forEach { MDC.put(it.key, it.value) }
+    return body()
+  } finally {
+    map.forEach { MDC.remove(it.key) }
+  }
+}

src/test/kotlin/mu/KotlinLoggingMDCTest.kt

@@ -0,0 +1,41 @@
+package mu
+
+import org.junit.Assert.*
+import org.junit.Test
+import org.slf4j.MDC
+
+class KotlinLoggingMDCTest {
+
+  @Test
+  fun `simple pair withLoggingContext`() {
+    assertNull(MDC.get("a"))
+    withLoggingContext("a" to "b") {
+      assertEquals("b", MDC.get("a"))
+    }
+    assertNull(MDC.get("a"))
+  }
+
+  @Test
+  fun `multiple pair withLoggingContext`() {
+    assertNull(MDC.get("a"))
+    assertNull(MDC.get("c"))
+    withLoggingContext("a" to "b", "c" to "d") {
+      assertEquals("b", MDC.get("a"))
+      assertEquals("d", MDC.get("c"))
+    }
+    assertNull(MDC.get("a"))
+    assertNull(MDC.get("c"))
+  }
+
+  @Test
+  fun `map withLoggingContext`() {
+    assertNull(MDC.get("a"))
+    assertNull(MDC.get("c"))
+    withLoggingContext(mapOf("a" to "b", "c" to "d")) {
+      assertEquals("b", MDC.get("a"))
+      assertEquals("d", MDC.get("c"))
+    }
+    assertNull(MDC.get("a"))
+    assertNull(MDC.get("c"))
+  }
+}