updates to supporting classes

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/trace/SpanHolder.java

@@ -1,16 +1,23 @@
 package org.springframework.cloud.sleuth.trace;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 /**
  * @author Spencer Gibb
  */
 public class SpanHolder {
 	private static final ThreadLocal<Span> currentSpan = new ThreadLocal<>();
+	private static final Log log = LogFactory.getLog(SpanHolder.class);
 
-	public Span getCurrentSpan() {
+	public static Span getCurrentSpan() {
 		return currentSpan.get();
 	}
 
-	public void setCurrentSpan(Span span) {
+	public static void setCurrentSpan(Span span) {
+		if (log.isTraceEnabled()) {
+			log.trace("Setting current span " + span);
+		}
 		currentSpan.set(span);
 	}
 }

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/trace/TraceScope.java

@@ -1,6 +1,7 @@
 package org.springframework.cloud.sleuth.trace;
 
 import lombok.Data;
+import lombok.extern.apachecommons.CommonsLog;
 
 import java.io.Closeable;
 import java.io.IOException;
@@ -9,6 +10,7 @@ import java.io.IOException;
  * @author Spencer Gibb
  */
 @Data
+@CommonsLog
 public class TraceScope implements Closeable {
 	/**
 	 * the span for this scope
@@ -30,13 +32,44 @@ public class TraceScope implements Closeable {
 	 * @return the same Span object
 	 */
 	public Span detach() {
-		//TODO: implement detach
+		if (detached) {
+			error("Tried to detach trace span " + span + " but " +
+					"it has already been detached.");
+		}
+		detached = true;
+
+		Span cur = SpanHolder.getCurrentSpan();
+		if (cur != span) {
+			error("Tried to detach trace span " + span + " but " +
+					"it is not the current span for the " +
+					Thread.currentThread().getName() + " thread.  You have " +
+					"probably forgotten to close or detach " + cur);
+		} else {
+			SpanHolder.setCurrentSpan(savedSpan);
+		}
 		return span;
 	}
 
 	@Override
 	public void close() throws IOException {
-		span.stop();
-		//TODO: set savedSpan to currentSpan in SpanHolder
+		if (detached) {
+			return;
+		}
+		detached = true;
+		Span cur = SpanHolder.getCurrentSpan();
+		if (cur != span) {
+			error("Tried to close trace span " + span + " but " +
+					"it is not the current span for the " +
+					Thread.currentThread().getName() + " thread.  You have " +
+					"probably forgotten to close or detach " + cur);
+		} else {
+			span.stop();
+			SpanHolder.setCurrentSpan(savedSpan);
+		}
+	}
+
+	private void error(String msg) {
+		log.error(msg);
+		throw new RuntimeException(msg);
 	}
 }