Add synchronized extension function for Loggers (#40)

khronicle-core/api/khronicle-core.api

@@ -140,6 +140,10 @@ public abstract class com/juul/khronicle/SimpleLogger : com/juul/khronicle/Logge
 	public final fun warn (Ljava/lang/String;Ljava/lang/String;Lcom/juul/khronicle/ReadMetadata;Ljava/lang/Throwable;)V
 }
 
+public final class com/juul/khronicle/SynchronizedLoggerKt {
+	public static final fun synchronized (Lcom/juul/khronicle/Logger;)Lcom/juul/khronicle/Logger;
+}
+
 public abstract interface class com/juul/khronicle/TagGenerator {
 	public abstract fun getTag ()Ljava/lang/String;
 }

khronicle-core/src/commonMain/kotlin/SynchronizedLogger.kt

@@ -0,0 +1,37 @@
+package com.juul.khronicle
+
+import kotlinx.atomicfu.locks.reentrantLock
+import kotlinx.atomicfu.locks.withLock
+
+public fun Logger.synchronized(): Logger = SynchronizedLogger(this)
+
+private class SynchronizedLogger(
+    private val inner: Logger,
+) : Logger {
+
+    private val guard = reentrantLock()
+
+    override fun verbose(tag: String, message: String, metadata: ReadMetadata, throwable: Throwable?) {
+        guard.withLock { inner.verbose(tag, message, metadata, throwable) }
+    }
+
+    override fun debug(tag: String, message: String, metadata: ReadMetadata, throwable: Throwable?) {
+        guard.withLock { inner.debug(tag, message, metadata, throwable) }
+    }
+
+    override fun info(tag: String, message: String, metadata: ReadMetadata, throwable: Throwable?) {
+        guard.withLock { inner.info(tag, message, metadata, throwable) }
+    }
+
+    override fun warn(tag: String, message: String, metadata: ReadMetadata, throwable: Throwable?) {
+        guard.withLock { inner.warn(tag, message, metadata, throwable) }
+    }
+
+    override fun error(tag: String, message: String, metadata: ReadMetadata, throwable: Throwable?) {
+        guard.withLock { inner.error(tag, message, metadata, throwable) }
+    }
+
+    override fun assert(tag: String, message: String, metadata: ReadMetadata, throwable: Throwable?) {
+        guard.withLock { inner.assert(tag, message, metadata, throwable) }
+    }
+}