Add Tracestate into SpanContext. (#1359)

* Add Tracestate into SpanContext.

* Remove empty constructor from Tracestate.Builder

* Add info in the changelog.

Author: Bogdan Drutu

CHANGELOG.md

@@ -7,8 +7,9 @@
   on recording exemplars.
 - Reduce the default limit on `Link`s per `Span` to 32 (was 128 before).
 - Add Spring support for `@Traced` annotation and java.sql.PreparedStatements 
-  tracing
+  tracing.
 - Allow custom prefix for Stackdriver metrics in `StackdriverStatsConfiguration`.
+- Add support to handle the Tracestate in the SpanContext.
 
 ## 0.15.0 - 2018-06-20
 - Expose the factory methods of MonitoredResource.

api/src/main/java/io/opencensus/trace/SpanContext.java

@@ -30,17 +30,19 @@
  */
 @Immutable
 public final class SpanContext {
+  private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
   private final TraceId traceId;
   private final SpanId spanId;
   private final TraceOptions traceOptions;
+  private final Tracestate tracestate;
 
   /**
    * The invalid {@code SpanContext}.
    *
    * @since 0.5
    */
   public static final SpanContext INVALID =
-      new SpanContext(TraceId.INVALID, SpanId.INVALID, TraceOptions.DEFAULT);
+      new SpanContext(TraceId.INVALID, SpanId.INVALID, TraceOptions.DEFAULT, TRACESTATE_DEFAULT);
 
   /**
    * Creates a new {@code SpanContext} with the given identifiers and options.
@@ -49,10 +51,26 @@ public final class SpanContext {
    * @param spanId the span identifier of the span context.
    * @param traceOptions the trace options for the span context.
    * @return a new {@code SpanContext} with the given identifiers and options.
-   * @since 0.5
+   * @deprecated use {@link #create(TraceId, SpanId, TraceOptions, Tracestate)}.
    */
+  @Deprecated
   public static SpanContext create(TraceId traceId, SpanId spanId, TraceOptions traceOptions) {
-    return new SpanContext(traceId, spanId, traceOptions);
+    return create(traceId, spanId, traceOptions, TRACESTATE_DEFAULT);
+  }
+
+  /**
+   * Creates a new {@code SpanContext} with the given identifiers and options.
+   *
+   * @param traceId the trace identifier of the span context.
+   * @param spanId the span identifier of the span context.
+   * @param traceOptions the trace options for the span context.
+   * @param tracestate the trace state for the span context.
+   * @return a new {@code SpanContext} with the given identifiers and options.
+   * @since 0.16
+   */
+  public static SpanContext create(
+      TraceId traceId, SpanId spanId, TraceOptions traceOptions, Tracestate tracestate) {
+    return new SpanContext(traceId, spanId, traceOptions, tracestate);
   }
 
   /**
@@ -76,15 +94,25 @@ public SpanId getSpanId() {
   }
 
   /**
-   * Returns the trace options associated with this {@code SpanContext}.
+   * Returns the {@code TraceOptions} associated with this {@code SpanContext}.
    *
-   * @return the trace options associated with this {@code SpanContext}.
+   * @return the {@code TraceOptions} associated with this {@code SpanContext}.
    * @since 0.5
    */
   public TraceOptions getTraceOptions() {
     return traceOptions;
   }
 
+  /**
+   * Returns the {@code Tracestate} associated with this {@code SpanContext}.
+   *
+   * @return the {@code Tracestate} associated with this {@code SpanContext}.
+   * @since 0.5
+   */
+  public Tracestate getTracestate() {
+    return tracestate;
+  }
+
   /**
    * Returns true if this {@code SpanContext} is valid.
    *
@@ -127,9 +155,11 @@ public String toString() {
         + "}";
   }
 
-  private SpanContext(TraceId traceId, SpanId spanId, TraceOptions traceOptions) {
+  private SpanContext(
+      TraceId traceId, SpanId spanId, TraceOptions traceOptions, Tracestate tracestate) {
     this.traceId = traceId;
     this.spanId = spanId;
     this.traceOptions = traceOptions;
+    this.tracestate = tracestate;
   }
 }

api/src/main/java/io/opencensus/trace/Tracestate.java

@@ -81,7 +81,7 @@ public String get(String key) {
    * @since 0.16
    */
   public static Builder builder() {
-    return new Builder();
+    return new Builder(Builder.EMPTY);
   }
 
   /**
@@ -108,10 +108,6 @@ public static final class Builder {
     // subclass (the auto-value generate class).
     private static final Tracestate EMPTY = create(Collections.<Entry>emptyList());
 
-    private Builder() {
-      this(EMPTY);
-    }
-
     private Builder(Tracestate parent) {
       Utils.checkNotNull(parent, "parent");
       this.parent = parent;

api/src/test/java/io/opencensus/trace/SpanContextTest.java

@@ -32,16 +32,20 @@ public class SpanContextTest {
       new byte[] {0, 0, 0, 0, 0, 0, 0, '0', 0, 0, 0, 0, 0, 0, 0, 0};
   private static final byte[] firstSpanIdBytes = new byte[] {0, 0, 0, 0, 0, 0, 0, 'a'};
   private static final byte[] secondSpanIdBytes = new byte[] {'0', 0, 0, 0, 0, 0, 0, 0};
+  private static final Tracestate firstTracestate = Tracestate.builder().set("foo", "bar").build();
+  private static final Tracestate secondTracestate = Tracestate.builder().set("foo", "baz").build();
   private static final SpanContext first =
       SpanContext.create(
           TraceId.fromBytes(firstTraceIdBytes),
           SpanId.fromBytes(firstSpanIdBytes),
-          TraceOptions.DEFAULT);
+          TraceOptions.DEFAULT,
+          firstTracestate);
   private static final SpanContext second =
       SpanContext.create(
           TraceId.fromBytes(secondTraceIdBytes),
           SpanId.fromBytes(secondSpanIdBytes),
-          TraceOptions.builder().setIsSampled(true).build());
+          TraceOptions.builder().setIsSampled(true).build(),
+          secondTracestate);
 
   @Test
   public void invalidSpanContext() {
@@ -86,6 +90,12 @@ public void getTraceOptions() {
         .isEqualTo(TraceOptions.builder().setIsSampled(true).build());
   }
 
+  @Test
+  public void getTracestate() {
+    assertThat(first.getTracestate()).isEqualTo(firstTracestate);
+    assertThat(second.getTracestate()).isEqualTo(secondTracestate);
+  }
+
   @Test
   public void spanContext_EqualsAndHashCode() {
     EqualsTester tester = new EqualsTester();
@@ -98,13 +108,15 @@ public void spanContext_EqualsAndHashCode() {
         SpanContext.create(
             TraceId.fromBytes(firstTraceIdBytes),
             SpanId.fromBytes(firstSpanIdBytes),
-            TraceOptions.builder().setIsSampled(false).build()));
+            TraceOptions.builder().setIsSampled(false).build(),
+            firstTracestate));
     tester.addEqualityGroup(
         second,
         SpanContext.create(
             TraceId.fromBytes(secondTraceIdBytes),
             SpanId.fromBytes(secondSpanIdBytes),
-            TraceOptions.builder().setIsSampled(true).build()));
+            TraceOptions.builder().setIsSampled(true).build(),
+            secondTracestate));
     tester.testEquals();
   }
 

benchmarks/src/jmh/java/io/opencensus/benchmarks/trace/propagation/BinaryPropagationImplBenchmark.java

@@ -20,6 +20,7 @@
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import io.opencensus.trace.Tracing;
 import io.opencensus.trace.propagation.BinaryFormat;
 import io.opencensus.trace.propagation.SpanContextParseException;
@@ -41,7 +42,8 @@ public class BinaryPropagationImplBenchmark {
   private static final SpanId spanId = SpanId.fromBytes(spanIdBytes);
   private static final byte[] traceOptionsBytes = new byte[] {1};
   private static final TraceOptions traceOptions = TraceOptions.fromBytes(traceOptionsBytes);
-  private static final SpanContext spanContext = SpanContext.create(traceId, spanId, traceOptions);
+  private static final SpanContext spanContext =
+      SpanContext.create(traceId, spanId, traceOptions, Tracestate.builder().build());
   private static final BinaryFormat binaryFormat =
       Tracing.getPropagationComponent().getBinaryFormat();
   private static final byte[] spanContextBinary = binaryFormat.toByteArray(spanContext);

contrib/appengine_standard_util/src/main/java/io/opencensus/contrib/appengine/standard/util/AppEngineCloudTraceContextUtils.java

@@ -24,6 +24,7 @@
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import java.nio.ByteBuffer;
 
 /**
@@ -37,6 +38,7 @@ public final class AppEngineCloudTraceContextUtils {
       TraceIdProto.newBuilder().setHi(0).setLo(0).build().toByteArray();
   private static final long INVALID_SPAN_ID = 0L;
   private static final long INVALID_TRACE_MASK = 0L;
+  private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
 
   @VisibleForTesting
   static final CloudTraceContext INVALID_CLOUD_TRACE_CONTEXT =
@@ -64,7 +66,8 @@ public static SpanContext fromCloudTraceContext(CloudTraceContext cloudTraceCont
       return SpanContext.create(
           TraceId.fromBytes(traceIdBuf.array()),
           SpanId.fromBytes(spanIdBuf.array()),
-          TraceOptions.builder().setIsSampled(cloudTraceContext.isTraceEnabled()).build());
+          TraceOptions.builder().setIsSampled(cloudTraceContext.isTraceEnabled()).build(),
+          TRACESTATE_DEFAULT);
     } catch (com.google.protobuf.InvalidProtocolBufferException e) {
       throw new RuntimeException(e);
     }

contrib/http_util/src/main/java/io/opencensus/contrib/http/util/CloudTraceFormat.java

@@ -25,6 +25,7 @@
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import io.opencensus.trace.propagation.SpanContextParseException;
 import io.opencensus.trace.propagation.TextFormat;
 import java.nio.ByteBuffer;
@@ -77,6 +78,7 @@ final class CloudTraceFormat extends TextFormat {
   // 32-digit TRACE_ID + 1 digit SPAN_ID_DELIMITER + at least 1 digit SPAN_ID
   static final int MIN_HEADER_SIZE = SPAN_ID_START_POS + 1;
   static final int CLOUD_TRACE_IS_SAMPLED = 0x1;
+  private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
 
   @Override
   public List<String> fields() {
@@ -125,7 +127,7 @@ public List<String> fields() {
           traceOptions = OPTIONS_SAMPLED;
         }
       }
-      return SpanContext.create(traceId, spanId, traceOptions);
+      return SpanContext.create(traceId, spanId, traceOptions, TRACESTATE_DEFAULT);
     } catch (IllegalArgumentException e) {
       throw new SpanContextParseException("Invalid input", e);
     }

impl_core/src/main/java/io/opencensus/implcore/trace/SpanBuilderImpl.java

@@ -31,6 +31,7 @@
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import io.opencensus.trace.config.TraceConfig;
 import io.opencensus.trace.config.TraceParams;
 import java.util.Collections;
@@ -41,8 +42,9 @@
 
 /** Implementation of the {@link SpanBuilder}. */
 final class SpanBuilderImpl extends SpanBuilder {
-  private final Options options;
+  private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
 
+  private final Options options;
   private final String name;
   @Nullable private final Span parent;
   @Nullable private final SpanContext remoteParentSpanContext;
@@ -66,6 +68,8 @@ private SpanImpl startSpanInternal(
     SpanId spanId = SpanId.generateRandomId(random);
     SpanId parentSpanId = null;
     TraceOptions.Builder traceOptionsBuilder;
+    // TODO(bdrutu): Handle tracestate correctly not just propagate.
+    Tracestate tracestate = TRACESTATE_DEFAULT;
     if (parent == null || !parent.isValid()) {
       // New root span.
       traceId = TraceId.generateRandomId(random);
@@ -77,6 +81,7 @@ private SpanImpl startSpanInternal(
       traceId = parent.getTraceId();
       parentSpanId = parent.getSpanId();
       traceOptionsBuilder = TraceOptions.builder(parent.getTraceOptions());
+      tracestate = parent.getTracestate();
     }
     traceOptionsBuilder.setIsSampled(
         makeSamplingDecision(
@@ -95,7 +100,7 @@ private SpanImpl startSpanInternal(
     }
     SpanImpl span =
         SpanImpl.startSpan(
-            SpanContext.create(traceId, spanId, traceOptions),
+            SpanContext.create(traceId, spanId, traceOptions, tracestate),
             spanOptions,
             name,
             kind,

impl_core/src/main/java/io/opencensus/implcore/trace/propagation/B3Format.java

@@ -23,6 +23,7 @@
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import io.opencensus.trace.propagation.SpanContextParseException;
 import io.opencensus.trace.propagation.TextFormat;
 import java.util.Arrays;
@@ -38,6 +39,7 @@
  * href=https://github.com/openzipkin/b3-propagation>b3-propagation</a>.
  */
 final class B3Format extends TextFormat {
+  private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
   @VisibleForTesting static final String X_B3_TRACE_ID = "X-B3-TraceId";
   @VisibleForTesting static final String X_B3_SPAN_ID = "X-B3-SpanId";
   @VisibleForTesting static final String X_B3_PARENT_SPAN_ID = "X-B3-ParentSpanId";
@@ -103,7 +105,7 @@ public List<String> fields() {
           || FLAGS_VALUE.equals(getter.get(carrier, X_B3_FLAGS))) {
         traceOptions = TraceOptions.builder().setIsSampled(true).build();
       }
-      return SpanContext.create(traceId, spanId, traceOptions);
+      return SpanContext.create(traceId, spanId, traceOptions, TRACESTATE_DEFAULT);
     } catch (IllegalArgumentException e) {
       throw new SpanContextParseException("Invalid input.", e);
     }

impl_core/src/main/java/io/opencensus/implcore/trace/propagation/BinaryFormatImpl.java

@@ -23,6 +23,7 @@
 import io.opencensus.trace.SpanId;
 import io.opencensus.trace.TraceId;
 import io.opencensus.trace.TraceOptions;
+import io.opencensus.trace.Tracestate;
 import io.opencensus.trace.propagation.BinaryFormat;
 import io.opencensus.trace.propagation.SpanContextParseException;
 
@@ -61,6 +62,7 @@
  * </ul>
  */
 final class BinaryFormatImpl extends BinaryFormat {
+  private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
   private static final byte VERSION_ID = 0;
   private static final int VERSION_ID_OFFSET = 0;
   // The version_id/field_id size in bytes.
@@ -141,6 +143,6 @@ public SpanContext fromByteArray(byte[] bytes) throws SpanContextParseException
       }
       traceOptions = TraceOptions.fromBytes(bytes, pos + ID_SIZE);
     }
-    return SpanContext.create(traceId, spanId, traceOptions);
+    return SpanContext.create(traceId, spanId, traceOptions, TRACESTATE_DEFAULT);
   }
 }