Change hasRemoteParent to be Boolean where null means root Span. (#427)

Author: Bogdan Drutu

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

@@ -21,19 +21,20 @@ public abstract class Sampler {
   /**
    * Called during {@link Span} creation to make a sampling decision.
    *
-   * @param parentContext The parent {@code Span} {@link SpanContext}. May be {@code null} if this
+   * @param parentContext the parent span's {@link SpanContext}. {@code null} if this is a root
+   *     span.
+   * @param hasRemoteParent {@code true} if the parent {@code Span} is remote. {@code null} if this
    *     is a root span.
-   * @param remoteParent true if the parentContext is remote.
-   * @param traceId The {@link TraceId} for the new {@code Span}. This will be identical to that in
+   * @param traceId the {@link TraceId} for the new {@code Span}. This will be identical to that in
    *     the parentContext, unless this is a root span.
-   * @param spanId The span ID for the new {@code Span}.
-   * @param name The name of the new {@code Span}.
-   * @param parentLinks The parentLinks associated with the new {@code Span}.
+   * @param spanId the span ID for the new {@code Span}.
+   * @param name the name of the new {@code Span}.
+   * @param parentLinks the parentLinks associated with the new {@code Span}.
    * @return {@code true} if the {@code Span} is sampled.
    */
   public abstract boolean shouldSample(
       @Nullable SpanContext parentContext,
-      boolean remoteParent,
+      @Nullable Boolean hasRemoteParent,
       TraceId traceId,
       SpanId spanId,
       String name,

api/src/main/java/io/opencensus/trace/export/SpanData.java

@@ -44,7 +44,8 @@ public abstract class SpanData {
    * @param context the {@code SpanContext} of the {@code Span}.
    * @param parentSpanId the parent {@code SpanId} of the {@code Span}. {@code null} if the {@code
    *     Span} is a root.
-   * @param hasRemoteParent {@code true} if the parent is on a different process.
+   * @param hasRemoteParent {@code true} if the parent {@code Span} is remote. {@code null} if this
+   *     is a root span.
    * @param name the name of the {@code Span}.
    * @param startTimestamp the start {@code Timestamp} of the {@code Span}.
    * @param attributes the attributes associated with the {@code Span}.
@@ -61,7 +62,7 @@ public abstract class SpanData {
   public static SpanData create(
       SpanContext context,
       @Nullable SpanId parentSpanId,
-      boolean hasRemoteParent,
+      @Nullable Boolean hasRemoteParent,
       String name,
       Timestamp startTimestamp,
       Attributes attributes,
@@ -102,11 +103,14 @@ public static SpanData create(
   public abstract SpanId getParentSpanId();
 
   /**
-   * Returns {@code true} if the parent is on a different process.
+   * Returns {@code true} if the parent is on a different process. {@code null} if this is a root
+   * span.
    *
-   * @return {@code true} if the parent is on a different process.
+   * @return {@code true} if the parent is on a different process. {@code null} if this is a root
+   *     span.
    */
-  public abstract boolean getHasRemoteParent();
+  @Nullable
+  public abstract Boolean getHasRemoteParent();
 
   /**
    * Returns the name of this {@code Span}.

api/src/main/java/io/opencensus/trace/samplers/AlwaysSampleSampler.java

@@ -32,7 +32,7 @@ final class AlwaysSampleSampler extends Sampler {
   @Override
   public boolean shouldSample(
       @Nullable SpanContext parentContext,
-      boolean remoteParent,
+      @Nullable Boolean hasRemoteParent,
       TraceId traceId,
       SpanId spanId,
       String name,

api/src/main/java/io/opencensus/trace/samplers/NeverSampleSampler.java

@@ -32,7 +32,7 @@ final class NeverSampleSampler extends Sampler {
   @Override
   public boolean shouldSample(
       @Nullable SpanContext parentContext,
-      boolean remoteParent,
+      @Nullable Boolean hasRemoteParent,
       TraceId traceId,
       SpanId spanId,
       String name,

api/src/main/java/io/opencensus/trace/samplers/ProbabilitySampler.java

@@ -71,7 +71,7 @@ static ProbabilitySampler create(double probability) {
   @Override
   public final boolean shouldSample(
       @Nullable SpanContext parentContext,
-      boolean remoteParent,
+      @Nullable Boolean hasRemoteParent,
       TraceId traceId,
       SpanId spanId,
       String name,

api/src/test/java/io/opencensus/trace/export/SpanDataTest.java

@@ -126,7 +126,7 @@ public void spanData_RootActiveSpan() {
         SpanData.create(
             spanContext,
             null,
-            false,
+            null,
             SPAN_NAME,
             startTimestamp,
             attributes,
@@ -138,7 +138,7 @@ public void spanData_RootActiveSpan() {
             null);
     assertThat(spanData.getContext()).isEqualTo(spanContext);
     assertThat(spanData.getParentSpanId()).isNull();
-    assertThat(spanData.getHasRemoteParent()).isFalse();
+    assertThat(spanData.getHasRemoteParent()).isNull();
     assertThat(spanData.getName()).isEqualTo(SPAN_NAME);
     assertThat(spanData.getStartTimestamp()).isEqualTo(startTimestamp);
     assertThat(spanData.getAttributes()).isEqualTo(attributes);

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

@@ -40,7 +40,7 @@ final class SpanBuilderImpl extends SpanBuilder {
 
   private SpanImpl startSpanInternal(
       @Nullable SpanContext parent,
-      boolean hasRemoteParent,
+      @Nullable Boolean hasRemoteParent,
       String name,
       Sampler sampler,
       List<Span> parentLinks,
@@ -57,7 +57,7 @@ private SpanImpl startSpanInternal(
       traceId = TraceId.generateRandomId(random);
       traceOptionsBuilder = TraceOptions.builder();
       // This is a root span so no remote or local parent.
-      hasRemoteParent = false;
+      hasRemoteParent = null;
     } else {
       // New child span.
       traceId = parent.getTraceId();
@@ -123,19 +123,22 @@ private SpanBuilderImpl(
   @Override
   public SpanImpl startSpan() {
     SpanContext parentContext = remoteParentSpanContext;
-    boolean hasRemoteParent = parentContext != null;
+    Boolean hasRemoteParent = Boolean.TRUE;
     TimestampConverter timestampConverter = null;
-    if (!hasRemoteParent) {
+    if (remoteParentSpanContext == null) {
       // This is not a child of a remote Span. Get the parent SpanContext from the parent Span if
       // any.
       Span parent = this.parent;
+      hasRemoteParent = Boolean.FALSE;
       if (parent != null) {
         parentContext = parent.getContext();
         // Pass the timestamp converter from the parent to ensure that the recorded events are in
         // the right order. Implementation uses System.nanoTime() which is monotonically increasing.
         if (parent instanceof SpanImpl) {
           timestampConverter = ((SpanImpl) parent).getTimestampConverter();
         }
+      } else {
+        hasRemoteParent = null;
       }
     }
     return startSpanInternal(

impl_core/src/main/java/io/opencensus/trace/SpanImpl.java

@@ -44,7 +44,7 @@ public final class SpanImpl extends Span implements Element<SpanImpl> {
   // The parent SpanId of this span. Null if this is a root span.
   private final SpanId parentSpanId;
   // True if the parent is on a different process.
-  private final boolean hasRemoteParent;
+  private final Boolean hasRemoteParent;
   // Active trace params when the Span was created.
   private final TraceParams traceParams;
   // Handler called when the span starts and ends.
@@ -93,7 +93,8 @@ public final class SpanImpl extends Span implements Element<SpanImpl> {
    * @param options the options for the new span, importantly Options.RECORD_EVENTS.
    * @param name the displayed name for the new span.
    * @param parentSpanId the span_id of the parent span, or null if the new span is a root span.
-   * @param hasRemoteParent true if the parent span is in another process.
+   * @param hasRemoteParent {@code true} if the parentContext is remote. {@code null} if this is a
+   *     root span.
    * @param traceParams trace parameters like sampler and probability.
    * @param startEndHandler handler called when the span starts and ends.
    * @param timestampConverter null if the span is a root span or the parent is not sampled. If the
@@ -108,7 +109,7 @@ public static SpanImpl startSpan(
       @Nullable EnumSet<Options> options,
       String name,
       @Nullable SpanId parentSpanId,
-      boolean hasRemoteParent,
+      @Nullable Boolean hasRemoteParent,
       TraceParams traceParams,
       StartEndHandler startEndHandler,
       @Nullable TimestampConverter timestampConverter,
@@ -480,7 +481,7 @@ private SpanImpl(
       @Nullable EnumSet<Options> options,
       String name,
       @Nullable SpanId parentSpanId,
-      boolean hasRemoteParent,
+      @Nullable Boolean hasRemoteParent,
       TraceParams traceParams,
       StartEndHandler startEndHandler,
       @Nullable TimestampConverter timestampConverter,

impl_core/src/test/java/io/opencensus/trace/SpanBuilderImplTest.java

@@ -61,7 +61,7 @@ public void startSpanNullParent() {
     assertThat(span.getContext().getTraceOptions().isSampled()).isTrue();
     SpanData spanData = span.toSpanData();
     assertThat(spanData.getParentSpanId()).isNull();
-    assertThat(spanData.getHasRemoteParent()).isFalse();
+    assertThat(spanData.getHasRemoteParent()).isNull();
     assertThat(spanData.getStartTimestamp()).isEqualTo(testClock.now());
     assertThat(spanData.getName()).isEqualTo(SPAN_NAME);
   }
@@ -78,7 +78,7 @@ public void startSpanNullParentWithRecordEvents() {
     assertThat(span.getContext().getTraceOptions().isSampled()).isFalse();
     SpanData spanData = span.toSpanData();
     assertThat(spanData.getParentSpanId()).isNull();
-    assertThat(spanData.getHasRemoteParent()).isFalse();
+    assertThat(spanData.getHasRemoteParent()).isNull();
   }
 
   @Test
@@ -99,12 +99,16 @@ public void startChildSpan() {
     assertThat(rootSpan.getContext().isValid()).isTrue();
     assertThat(rootSpan.getOptions().contains(Options.RECORD_EVENTS)).isTrue();
     assertThat(rootSpan.getContext().getTraceOptions().isSampled()).isTrue();
+    assertThat(((SpanImpl) rootSpan).toSpanData().getHasRemoteParent())
+        .isNull();
     Span childSpan =
         SpanBuilderImpl.createWithParent(SPAN_NAME, rootSpan, spanBuilderOptions).startSpan();
     assertThat(childSpan.getContext().isValid()).isTrue();
     assertThat(childSpan.getContext().getTraceId()).isEqualTo(rootSpan.getContext().getTraceId());
     assertThat(((SpanImpl) childSpan).toSpanData().getParentSpanId())
         .isEqualTo(rootSpan.getContext().getSpanId());
+    assertThat(((SpanImpl) childSpan).toSpanData().getHasRemoteParent())
+        .isFalse();
     assertThat(((SpanImpl) childSpan).getTimestampConverter())
         .isEqualTo(((SpanImpl) rootSpan).getTimestampConverter());
   }
@@ -118,7 +122,7 @@ public void startRemoteSpan_NullParent() {
     assertThat(span.getContext().getTraceOptions().isSampled()).isTrue();
     SpanData spanData = span.toSpanData();
     assertThat(spanData.getParentSpanId()).isNull();
-    assertThat(spanData.getHasRemoteParent()).isFalse();
+    assertThat(spanData.getHasRemoteParent()).isNull();
   }
 
   @Test
@@ -131,7 +135,7 @@ public void startRemoteSpanInvalidParent() {
     assertThat(span.getContext().getTraceOptions().isSampled()).isTrue();
     SpanData spanData = span.toSpanData();
     assertThat(spanData.getParentSpanId()).isNull();
-    assertThat(spanData.getHasRemoteParent()).isFalse();
+    assertThat(spanData.getHasRemoteParent()).isNull();
   }
 
   @Test