Adds zipkin.internal.Span2

This adds an internal copy of the new span data structure defined in
issue 1499. This is starting internal to ease review and allow
incremental progress. The first consumer will be dependency linking.

benchmarks/src/main/java/zipkin/benchmarks/SpanBenchmarks.java

@@ -34,6 +34,7 @@
 import zipkin.Endpoint;
 import zipkin.Span;
 import zipkin.TraceKeys;
+import zipkin.internal.Span2;
 import zipkin.internal.Util;
 
 @Measurement(iterations = 5, time = 1)
@@ -50,9 +51,11 @@ public class SpanBenchmarks {
       Endpoint.builder().serviceName("app").ipv4(172 << 24 | 17 << 16 | 2).port(8080).build();
 
   final Span.Builder sharedBuilder;
+  final Span2.Builder shared2Builder;
 
   public SpanBenchmarks() {
     sharedBuilder = buildClientOnlySpan(Span.builder()).toBuilder();
+    shared2Builder = buildClientOnlySpan2().toBuilder();
   }
 
   @Benchmark
@@ -104,6 +107,39 @@ public Span buildClientOnlySpan_clear() {
     return buildClientOnlySpan(sharedBuilder.clear());
   }
 
+  @Benchmark
+  public Span2 buildClientOnlySpan2() {
+    return buildClientOnlySpan2(Span2.builder());
+  }
+
+  static Span2 buildClientOnlySpan2(Span2.Builder builder) {
+    return builder
+      .traceId(traceId)
+      .parentId(traceId)
+      .id(spanId)
+      .name("get")
+      .kind(Span2.Kind.CLIENT)
+      .localEndpoint(frontend)
+      .remoteEndpoint(backend)
+      .timestamp(1472470996199000L)
+      .duration(207000L)
+      .addAnnotation(1472470996238000L, Constants.WIRE_SEND)
+      .addAnnotation(1472470996403000L, Constants.WIRE_RECV)
+      .putTag(TraceKeys.HTTP_PATH, "/api")
+      .putTag("clnt/finagle.version", "6.45.0")
+      .build();
+  }
+
+  @Benchmark
+  public Span2 buildClientOnlySpan2_clear() {
+    return buildClientOnlySpan2(shared2Builder.clear());
+  }
+
+  @Benchmark
+  public Span2 buildClientOnlySpan2_clone() {
+    return shared2Builder.clone().build();
+  }
+
   @Benchmark
   public Span buildRpcSpan() {
     return Span.builder() // web calls app

zipkin/pom.xml

@@ -33,6 +33,12 @@
   </properties>
 
   <dependencies>
+    <dependency>
+      <groupId>com.google.auto.value</groupId>
+      <artifactId>auto-value</artifactId>
+      <scope>provided</scope>
+    </dependency>
+
     <dependency>
       <groupId>com.google.code.gson</groupId>
       <artifactId>gson</artifactId>