Add annotations and network events as labels in Stackdriver v1 API. (#591)

* Add annotations and network events as labels in v1 API.

* Fix minor comments.

Author: Bogdan Drutu

exporters/trace_stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverV1ExporterHandler.java

@@ -27,14 +27,19 @@
 import com.google.devtools.cloudtrace.v1.Trace;
 import com.google.devtools.cloudtrace.v1.TraceSpan;
 import com.google.devtools.cloudtrace.v1.Traces;
+import io.opencensus.common.Duration;
 import io.opencensus.common.Function;
 import io.opencensus.common.Functions;
 import io.opencensus.common.Timestamp;
+import io.opencensus.trace.Annotation;
 import io.opencensus.trace.AttributeValue;
+import io.opencensus.trace.NetworkEvent;
+import io.opencensus.trace.NetworkEvent.Type;
 import io.opencensus.trace.SpanContext;
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.export.SpanData;
+import io.opencensus.trace.export.SpanData.TimedEvent;
 import io.opencensus.trace.export.SpanExporter;
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -51,6 +56,8 @@ final class StackdriverV1ExporterHandler extends SpanExporter.Handler {
 
   private static final String STATUS_CODE = "g.co/status/code";
   private static final String STATUS_DESCRIPTION = "g.co/status/description";
+  private static final String ANNOTATION_LABEL = "ANNOTATION-";
+  private static final String NETWORK_EVENT_LABEL = "NETWORK-";
 
   private final String projectId;
   private final TraceServiceClient traceServiceClient;
@@ -95,6 +102,22 @@ private Trace generateTrace(SpanData spanData) {
       spanBuilder.putLabels(label.getKey(), attributeValueToString(label.getValue()));
     }
 
+    // Add Annotations as labels in the v1 API
+    int seq = 0;
+    for (TimedEvent<Annotation> annotation : spanData.getAnnotations().getEvents()) {
+      spanBuilder.putLabels(
+          ANNOTATION_LABEL + String.format("%03d", seq++),
+          renderAnnotation(annotation, spanData.getStartTimestamp()));
+    }
+
+    // Add NetworkEvents as labels in the v1 API
+    seq = 0;
+    for (TimedEvent<NetworkEvent> networkEvent : spanData.getNetworkEvents().getEvents()) {
+      spanBuilder.putLabels(
+          NETWORK_EVENT_LABEL + String.format("%03d", seq++),
+          renderNetworkEvents(networkEvent, spanData.getStartTimestamp()));
+    }
+
     // Add Status as labels in the v1 API.
     spanBuilder.putLabels(STATUS_CODE, spanData.getStatus().getCanonicalCode().toString());
     if (spanData.getStatus().getDescription() != null) {
@@ -132,6 +155,67 @@ private static TraceSpan.SpanKind toSpanKindProto(SpanData spanData) {
     return TraceSpan.SpanKind.SPAN_KIND_UNSPECIFIED;
   }
 
+  private static String renderNetworkEvents(TimedEvent<NetworkEvent> timedEvent, Timestamp start) {
+    StringBuilder stringBuilder = new StringBuilder();
+    renderDelay(stringBuilder, timedEvent.getTimestamp().subtractTimestamp(start));
+    NetworkEvent networkEvent = timedEvent.getEvent();
+    if (networkEvent.getType() == Type.RECV) {
+      stringBuilder.append("Received");
+    } else if (networkEvent.getType() == Type.SENT) {
+      stringBuilder.append("Sent");
+    } else {
+      stringBuilder.append("Unknown");
+    }
+    stringBuilder.append(" message_id=");
+    stringBuilder.append(networkEvent.getMessageId());
+    stringBuilder.append(" uncompressed_size=");
+    stringBuilder.append(networkEvent.getUncompressedMessageSize());
+    stringBuilder.append(" compressed_size=");
+    stringBuilder.append(networkEvent.getCompressedMessageSize());
+    if (networkEvent.getKernelTimestamp() != null) {
+      stringBuilder.append(" kernel_timestamp=");
+      stringBuilder.append(networkEvent.getKernelTimestamp().toString());
+    }
+    return stringBuilder.toString();
+  }
+
+  private static String renderAnnotation(TimedEvent<Annotation> timedEvent, Timestamp start) {
+    StringBuilder stringBuilder = new StringBuilder();
+    renderDelay(stringBuilder, timedEvent.getTimestamp().subtractTimestamp(start));
+    Annotation annotation = timedEvent.getEvent();
+    stringBuilder.append(annotation.getDescription());
+    if (!annotation.getAttributes().isEmpty()) {
+      stringBuilder.append(" ");
+      stringBuilder.append(renderAttributes(annotation.getAttributes()));
+    }
+    return stringBuilder.toString();
+  }
+
+  private static void renderDelay(StringBuilder stringBuilder, Duration delay) {
+    long delayUs = delay.getSeconds() * 1000000 + delay.getNanos() / 1000;
+    stringBuilder.append("[@");
+    stringBuilder.append(delayUs);
+    stringBuilder.append(" us] ");
+  }
+
+  private static String renderAttributes(Map<String, AttributeValue> attributes) {
+    StringBuilder stringBuilder = new StringBuilder();
+    stringBuilder.append("Attributes:{");
+    boolean first = true;
+    for (Map.Entry<String, AttributeValue> entry : attributes.entrySet()) {
+      if (first) {
+        first = false;
+      } else {
+        stringBuilder.append(", ");
+      }
+      stringBuilder.append(entry.getKey());
+      stringBuilder.append("=");
+      stringBuilder.append(attributeValueToString(entry.getValue()));
+    }
+    stringBuilder.append("}");
+    return stringBuilder.toString();
+  }
+
   private static com.google.protobuf.Timestamp toTimestampProto(Timestamp timestamp) {
     return com.google.protobuf.Timestamp.newBuilder()
         .setSeconds(timestamp.getSeconds())