Save baggage in span

jaeger-core/src/main/java/com/uber/jaeger/Span.java

@@ -118,6 +118,13 @@ public List<LogData> getLogs() {
   public Span setBaggageItem(String key, String value) {
     synchronized (this) {
       this.context = this.context.withBaggageItem(key, value);
+      if (context.isSampled()) {
+        Map<String, String> fields = new HashMap<String, String>();
+        fields.put("event", "baggage");
+        fields.put("key", key);
+        fields.put("value", value);
+        return this.log(fields);
+      }
     }
     return this;
   }

jaeger-core/src/test/java/com/uber/jaeger/SpanTest.java

@@ -36,6 +36,7 @@
 import io.opentracing.tag.Tags;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import org.junit.Before;
@@ -77,6 +78,9 @@ public void testSetAndGetBaggageItem() {
     String key = "some.BAGGAGE";
     span.setBaggageItem(key, expected);
     assertEquals(expected, span.getBaggageItem(key));
+
+    // Ensure the baggage was logged
+    this.assertBaggageLogs(span, key, expected);
   }
 
   @Test
@@ -291,12 +295,14 @@ public void testSpanDetectsSamplingPriorityLessThanZero() {
   public void testBaggageOneReference() {
     io.opentracing.Span parent = tracer.buildSpan("foo").start();
     parent.setBaggageItem("foo", "bar");
+    this.assertBaggageLogs(parent, "foo", "bar");
 
     io.opentracing.Span child = tracer.buildSpan("foo")
         .asChildOf(parent)
         .start();
 
     child.setBaggageItem("a", "a");
+    this.assertBaggageLogs(child, "a", "a");
 
     assertNull(parent.getBaggageItem("a"));
     assertEquals("a", child.getBaggageItem("a"));
@@ -307,15 +313,18 @@ public void testBaggageOneReference() {
   public void testBaggageMultipleReferences() {
     io.opentracing.Span parent1 = tracer.buildSpan("foo").start();
     parent1.setBaggageItem("foo", "bar");
+    this.assertBaggageLogs(parent1, "foo", "bar");
     io.opentracing.Span parent2 = tracer.buildSpan("foo").start();
     parent2.setBaggageItem("foo2", "bar");
+    this.assertBaggageLogs(parent2, "foo2", "bar");
 
     io.opentracing.Span child = tracer.buildSpan("foo")
         .asChildOf(parent1)
         .addReference(References.FOLLOWS_FROM, parent2.context())
         .start();
 
     child.setBaggageItem("a", "a");
+    this.assertBaggageLogs(child, "a", "a");
 
     assertNull(parent1.getBaggageItem("a"));
     assertNull(parent2.getBaggageItem("a"));
@@ -338,4 +347,15 @@ public void testImmutableBaggage() {
     baggageIter.next();
     assertFalse(baggageIter.hasNext());
   }
+
+  private void assertBaggageLogs(io.opentracing.Span span, String key, String value) {
+    Span sp = (Span)span;
+    List<LogData> logs = sp.getLogs();
+    assertEquals(1, logs.size());
+    Map<String, ?> fields = logs.get(0).getFields();
+    assertEquals(3, fields.size());
+    assertEquals("baggage", fields.get("event"));
+    assertEquals(key, fields.get("key"));
+    assertEquals(value, fields.get("value"));
+  }
 }

jaeger-core/src/test/java/com/uber/jaeger/reporters/protocols/JaegerThriftSpanConverterTest.java

@@ -124,11 +124,12 @@ public void testConvertSpan() {
     Span span = tracer.buildSpan("operation-name").start();
     span = span.log(1, "key", "value");
     span = span.log(1, fields);
+    span = span.setBaggageItem("foo", "bar");
 
     com.uber.jaeger.thriftjava.Span thriftSpan = JaegerThriftSpanConverter.convertSpan((com.uber.jaeger.Span) span);
 
     assertEquals("operation-name", thriftSpan.getOperationName());
-    assertEquals(2, thriftSpan.getLogs().size());
+    assertEquals(3, thriftSpan.getLogs().size());
     Log thriftLog = thriftSpan.getLogs().get(0);
     assertEquals(1, thriftLog.getTimestamp());
     assertEquals(2, thriftLog.getFields().size());
@@ -145,6 +146,18 @@ public void testConvertSpan() {
     thriftTag = thriftLog.getFields().get(0);
     assertEquals("k", thriftTag.getKey());
     assertEquals("v", thriftTag.getVStr());
+
+    thriftLog = thriftSpan.getLogs().get(2);
+    assertEquals(3, thriftLog.getFields().size());
+    thriftTag = thriftLog.getFields().get(0);
+    assertEquals("event", thriftTag.getKey());
+    assertEquals("baggage", thriftTag.getVStr());
+    thriftTag = thriftLog.getFields().get(1);
+    assertEquals("value", thriftTag.getKey());
+    assertEquals("bar", thriftTag.getVStr());
+    thriftTag = thriftLog.getFields().get(2);
+    assertEquals("key", thriftTag.getKey());
+    assertEquals("foo", thriftTag.getVStr());
   }
 
   @Test