Kotlin#119: first implementation of a SLF4J MDC Context

Author: abendt

integration/kotlinx-coroutines-slf4j/README.md

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+# Module kotlinx-coroutines-slf4j
+
+Integration with SLF4J [MDC](https://logback.qos.ch/manual/mdc.html).
+
+## Example
+
+Extends a given Coroutine context so that the SLF4J MDC context is passed into the coroutine.
+
+```kotlin
+MDC.put("kotlin", "rocks") // put a value into the MDC context
+
+launch(MDCContext(CommonPool)) {
+   logger.info { "..." }   // the MDC context will contain the mapping here
+}
+```
+
+# Package kotlinx.coroutines.experimental.slf4j
+
+Integration with SLF4J [MDC](https://logback.qos.ch/manual/mdc.html).

integration/kotlinx-coroutines-slf4j/build.gradle

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 dependencies {
     compile 'org.slf4j:slf4j-api:1.7.25'
+    testCompile 'io.github.microutils:kotlin-logging:1.5.4'
     testRuntime 'ch.qos.logback:logback-classic:1.2.3'
     testRuntime 'ch.qos.logback:logback-core:1.2.3'
 }

integration/kotlinx-coroutines-slf4j/src/test/kotlin/kotlinx/coroutines/experimental/slf4j/SimpleMDC.kt

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+package kotlinx.coroutines.experimental.slf4j
+
+import mu.KotlinLogging
+import org.slf4j.MDC
+
+fun main(args: Array<String>) {
+    val logger = KotlinLogging.logger {}
+
+    // You can put values in the MDC at any time. Before anything else
+    // we put the first name
+    MDC.put("first", "Dorothy")
+
+    // We now put the last name
+    MDC.put("last", "Parker")
+
+    // The most beautiful two words in the English language according
+    // to Dorothy Parker:
+    logger.info("Check enclosed.")
+    logger.debug("The most beautiful two words in English.")
+
+    MDC.put("first", "Richard")
+    MDC.put("last", "Nixon")
+    logger.info("I am not a crook.")
+    logger.info("Attributed to the former US president. 17 Nov 1973.")
+}

integration/kotlinx-coroutines-slf4j/src/test/resources/logback-test.xml

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+<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
+    <layout>
+        <Pattern>%X{first} %X{last} - %m%n</Pattern>
+    </layout>
+</appender>