Implement spec change to only accept Context as span parent.

api/src/main/java/io/opentelemetry/trace/DefaultTracer.java

@@ -67,43 +67,32 @@ static NoopSpanBuilder create(String spanName) {
     }
 
     private boolean isRootSpan;
-    @Nullable private SpanContext spanContext;
+    @Nullable private Context parent;
 
     @Override
     public Span startSpan() {
-      if (spanContext == null && !isRootSpan) {
-        spanContext = TracingContextUtils.getCurrentSpan().getContext();
+      if (parent == null) {
+        parent = Context.current();
+      }
+      if (isRootSpan) {
+        parent = TracingContextUtils.withSpan(DefaultSpan.getInvalid(), parent);
       }
 
-      return spanContext != null && !SpanContext.getInvalid().equals(spanContext)
-          ? new DefaultSpan(spanContext)
-          : DefaultSpan.getInvalid();
-    }
-
-    @Override
-    public NoopSpanBuilder setParent(Span parent) {
-      Utils.checkNotNull(parent, "parent");
-      spanContext = parent.getContext();
-      return this;
-    }
-
-    @Override
-    public NoopSpanBuilder setParent(SpanContext remoteParent) {
-      Utils.checkNotNull(remoteParent, "remoteParent");
-      spanContext = remoteParent;
-      return this;
+      return new DefaultSpan(TracingContextUtils.getSpan(parent).getContext());
     }
 
     @Override
     public NoopSpanBuilder setParent(Context context) {
       Utils.checkNotNull(context, "context");
-      spanContext = TracingContextUtils.getSpan(context).getContext();
+      isRootSpan = false; // TODO port this fix to mainline
+      parent = context;
       return this;
     }
 
     @Override
     public NoopSpanBuilder setNoParent() {
       isRootSpan = true;
+      parent = null;
       return this;
     }
 

api/src/main/java/io/opentelemetry/trace/Span.java

@@ -383,51 +383,6 @@ enum Kind {
    */
   interface Builder {
 
-    /**
-     * Sets the parent {@code Span} to use. If not set, the value of {@code Tracer.getCurrentSpan()}
-     * at {@link #startSpan()} time will be used as parent.
-     *
-     * <p>This <b>must</b> be used to create a {@code Span} when manual Context propagation is used
-     * OR when creating a root {@code Span} with a parent with an invalid {@link SpanContext}.
-     *
-     * <p>Observe this is the preferred method when the parent is a {@code Span} created within the
-     * process. Using its {@code SpanContext} as parent remains as a valid, albeit inefficient,
-     * operation.
-     *
-     * <p>If called multiple times, only the last specified value will be used. Observe that the
-     * state defined by a previous call to {@link #setNoParent()} will be discarded.
-     *
-     * @param parent the {@code Span} used as parent.
-     * @return this.
-     * @throws NullPointerException if {@code parent} is {@code null}.
-     * @see #setNoParent()
-     * @since 0.1.0
-     */
-    Builder setParent(Span parent);
-
-    /**
-     * Sets the parent {@link SpanContext} to use. If not set, the value of {@code
-     * Tracer.getCurrentSpan()} at {@link #startSpan()} time will be used as parent.
-     *
-     * <p>Similar to {@link #setParent(Span parent)} but this <b>must</b> be used to create a {@code
-     * Span} when the parent is in a different process. This is only intended for use by RPC systems
-     * or similar.
-     *
-     * <p>If no {@link SpanContext} is available, users must call {@link #setNoParent()} in order to
-     * create a root {@code Span} for a new trace.
-     *
-     * <p>If called multiple times, only the last specified value will be used. Observe that the
-     * state defined by a previous call to {@link #setNoParent()} will be discarded.
-     *
-     * @param remoteParent the {@link SpanContext} used as parent.
-     * @return this.
-     * @throws NullPointerException if {@code remoteParent} is {@code null}.
-     * @see #setParent(Span parent)
-     * @see #setNoParent()
-     * @since 0.1.0
-     */
-    Builder setParent(SpanContext remoteParent);
-
     /**
      * Sets the parent to use from the specified {@code Context}. If not set, the value of {@code
      * Tracer.getCurrentSpan()} at {@link #startSpan()} time will be used as parent.

api/src/test/java/io/opentelemetry/trace/DefaultTracerTest.java

@@ -81,15 +81,23 @@ void testInProcessContext() {
 
   @Test
   void testSpanContextPropagationExplicitParent() {
-    Span span = defaultTracer.spanBuilder(SPAN_NAME).setParent(spanContext).startSpan();
+    Span span =
+        defaultTracer
+            .spanBuilder(SPAN_NAME)
+            .setParent(TracingContextUtils.withSpan(DefaultSpan.create(spanContext), Context.ROOT))
+            .startSpan();
     assertThat(span.getContext()).isSameAs(spanContext);
   }
 
   @Test
   void testSpanContextPropagation() {
     DefaultSpan parent = new DefaultSpan(spanContext);
 
-    Span span = defaultTracer.spanBuilder(SPAN_NAME).setParent(parent).startSpan();
+    Span span =
+        defaultTracer
+            .spanBuilder(SPAN_NAME)
+            .setParent(TracingContextUtils.withSpan(parent, Context.ROOT))
+            .startSpan();
     assertThat(span.getContext()).isSameAs(spanContext);
   }
 

api/src/test/java/io/opentelemetry/trace/SpanBuilderTest.java

@@ -19,6 +19,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
+import io.grpc.Context;
 import io.opentelemetry.common.AttributeValue;
 import io.opentelemetry.common.Attributes;
 import io.opentelemetry.trace.Span.Kind;
@@ -32,8 +33,8 @@ class SpanBuilderTest {
   void doNotCrash_NoopImplementation() {
     Span.Builder spanBuilder = tracer.spanBuilder("MySpanName");
     spanBuilder.setSpanKind(Kind.SERVER);
-    spanBuilder.setParent(DefaultSpan.getInvalid());
-    spanBuilder.setParent(DefaultSpan.getInvalid().getContext());
+    spanBuilder.setParent(TracingContextUtils.withSpan(DefaultSpan.create(null), Context.ROOT));
+    spanBuilder.setParent(Context.ROOT);
     spanBuilder.setNoParent();
     spanBuilder.addLink(DefaultSpan.getInvalid().getContext());
     spanBuilder.addLink(DefaultSpan.getInvalid().getContext(), Attributes.empty());
@@ -61,15 +62,9 @@ public Attributes getAttributes() {
   }
 
   @Test
-  void setParent_NullSpan() {
+  void setParent_NullContext() {
     Span.Builder spanBuilder = tracer.spanBuilder("MySpanName");
-    assertThrows(NullPointerException.class, () -> spanBuilder.setParent((Span) null));
-  }
-
-  @Test
-  void setParent_NullSpanContext() {
-    Span.Builder spanBuilder = tracer.spanBuilder("MySpanName");
-    assertThrows(NullPointerException.class, () -> spanBuilder.setParent((SpanContext) null));
+    assertThrows(NullPointerException.class, () -> spanBuilder.setParent(null));
   }
 
   @Test

exporters/jaeger/src/test/java/io/opentelemetry/exporters/jaeger/AdapterTest.java

@@ -305,7 +305,7 @@ private static SpanData getSpanData(long startMs, long endMs) {
         .setHasEnded(true)
         .setTraceId(TraceId.fromLowerBase16(TRACE_ID, 0))
         .setSpanId(SpanId.fromLowerBase16(SPAN_ID, 0))
-        .setParentSpanId(SpanId.fromLowerBase16(PARENT_SPAN_ID, 0))
+        .setParent(SpanId.fromLowerBase16(PARENT_SPAN_ID, 0), false)
         .setName("GET /api/endpoint")
         .setStartEpochNanos(TimeUnit.MILLISECONDS.toNanos(startMs))
         .setEndEpochNanos(TimeUnit.MILLISECONDS.toNanos(endMs))

exporters/otlp/src/test/java/io/opentelemetry/exporters/otlp/SpanAdapterTest.java

@@ -59,7 +59,7 @@ void toProtoSpan() {
                 .setHasEnded(true)
                 .setTraceId(TRACE_ID)
                 .setSpanId(SPAN_ID)
-                .setParentSpanId(SpanId.getInvalid())
+                .setParent(SpanId.getInvalid(), false)
                 .setName("GET /api/endpoint")
                 .setKind(Kind.SERVER)
                 .setStartEpochNanos(12345)

exporters/zipkin/src/test/java/io/opentelemetry/exporters/zipkin/ZipkinSpanExporterEndToEndHttpTest.java

@@ -155,11 +155,10 @@ private static TestSpanData.Builder buildStandardSpan() {
     return TestSpanData.newBuilder()
         .setTraceId(TraceId.fromLowerBase16(TRACE_ID, 0))
         .setSpanId(SpanId.fromLowerBase16(SPAN_ID, 0))
-        .setParentSpanId(SpanId.fromLowerBase16(PARENT_SPAN_ID, 0))
+        .setParent(SpanId.fromLowerBase16(PARENT_SPAN_ID, 0), false)
         .setTraceFlags(TraceFlags.builder().setIsSampled(true).build())
         .setStatus(Status.OK)
         .setKind(Kind.SERVER)
-        .setHasRemoteParent(true)
         .setName(SPAN_NAME)
         .setStartEpochNanos(START_EPOCH_NANOS)
         .setAttributes(attributes)

exporters/zipkin/src/test/java/io/opentelemetry/exporters/zipkin/ZipkinSpanExporterTest.java

@@ -313,11 +313,10 @@ private static TestSpanData.Builder buildStandardSpan() {
     return TestSpanData.newBuilder()
         .setTraceId(TraceId.fromLowerBase16(TRACE_ID, 0))
         .setSpanId(SpanId.fromLowerBase16(SPAN_ID, 0))
-        .setParentSpanId(SpanId.fromLowerBase16(PARENT_SPAN_ID, 0))
+        .setParent(SpanId.fromLowerBase16(PARENT_SPAN_ID, 0), true)
         .setTraceFlags(TraceFlags.builder().setIsSampled(true).build())
         .setStatus(Status.OK)
         .setKind(Kind.SERVER)
-        .setHasRemoteParent(true)
         .setName("Recv.helloworld.Greeter.SayHello")
         .setStartEpochNanos(1505855794_194009601L)
         .setAttributes(attributes)

opentracing_shim/src/main/java/io/opentelemetry/opentracingshim/SpanBuilderShim.java

@@ -16,10 +16,13 @@
 
 package io.opentelemetry.opentracingshim;
 
+import io.grpc.Context;
 import io.opentelemetry.common.AttributeValue;
 import io.opentelemetry.correlationcontext.CorrelationContext;
+import io.opentelemetry.trace.DefaultSpan;
 import io.opentelemetry.trace.Span.Kind;
 import io.opentelemetry.trace.Status;
+import io.opentelemetry.trace.TracingContextUtils;
 import io.opentracing.Span;
 import io.opentracing.SpanContext;
 import io.opentracing.Tracer.SpanBuilder;
@@ -183,11 +186,15 @@ public Span start() {
     if (ignoreActiveSpan && parentSpan == null && parentSpanContext == null) {
       builder.setNoParent();
     } else if (parentSpan != null) {
-      builder.setParent(parentSpan.getSpan());
+      // Note: We ignore the (potentially stored) parentSpan's (grand)parent context here.
+      builder.setParent(TracingContextUtils.withSpan(parentSpan.getSpan(), Context.current()));
       SpanContextShim contextShim = spanContextTable().get(parentSpan);
       distContext = contextShim == null ? null : contextShim.getCorrelationContext();
     } else if (parentSpanContext != null) {
-      builder.setParent(parentSpanContext.getSpanContext());
+      // TODO: This might be wonky
+      builder.setParent(
+          TracingContextUtils.withSpan(
+              DefaultSpan.create(parentSpanContext.getSpanContext()), Context.current()));
       distContext = parentSpanContext.getCorrelationContext();
     }
 

sdk/tracing/src/main/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpan.java

@@ -17,6 +17,7 @@
 package io.opentelemetry.sdk.trace;
 
 import com.google.common.collect.EvictingQueue;
+import io.grpc.Context;
 import io.opentelemetry.common.AttributeValue;
 import io.opentelemetry.common.Attributes;
 import io.opentelemetry.common.ReadableAttributes;
@@ -36,6 +37,7 @@
 import io.opentelemetry.trace.SpanId;
 import io.opentelemetry.trace.Status;
 import io.opentelemetry.trace.Tracer;
+import io.opentelemetry.trace.TracingContextUtils;
 import io.opentelemetry.trace.attributes.SemanticAttributes;
 import java.io.PrintWriter;
 import java.io.StringWriter;
@@ -59,10 +61,8 @@ final class RecordEventsReadableSpan implements ReadWriteSpan {
   private final TraceConfig traceConfig;
   // Contains the identifiers associated with this Span.
   private final SpanContext context;
-  // The parent SpanId of this span. Invalid if this is a root span.
-  private final SpanId parentSpanId;
-  // True if the parent is on a different process.
-  private final boolean hasRemoteParent;
+  // Parent context.
+  private final Context parent;
   // Handler called when the span starts and ends.
   private final SpanProcessor spanProcessor;
   // The displayed name of the span.
@@ -112,8 +112,7 @@ private RecordEventsReadableSpan(
       String name,
       InstrumentationLibraryInfo instrumentationLibraryInfo,
       Kind kind,
-      SpanId parentSpanId,
-      boolean hasRemoteParent,
+      Context parent,
       TraceConfig traceConfig,
       SpanProcessor spanProcessor,
       Clock clock,
@@ -124,8 +123,7 @@ private RecordEventsReadableSpan(
       long startEpochNanos) {
     this.context = context;
     this.instrumentationLibraryInfo = instrumentationLibraryInfo;
-    this.parentSpanId = parentSpanId;
-    this.hasRemoteParent = hasRemoteParent;
+    this.parent = parent;
     this.links = links;
     this.totalRecordedLinks = totalRecordedLinks;
     this.name = name;
@@ -146,10 +144,7 @@ private RecordEventsReadableSpan(
    * @param context supplies the trace_id and span_id for the newly started span.
    * @param name the displayed name for the new span.
    * @param kind the span kind.
-   * @param parentSpanId the span_id of the parent span, or {@code Span.INVALID} if the new span is
-   *     a root span.
-   * @param hasRemoteParent {@code true} if the parentContext is remote. {@code false} if this is a
-   *     root span.
+   * @param parent parent Context.
    * @param traceConfig trace parameters like sampler and probability.
    * @param spanProcessor handler called when the span starts and ends.
    * @param clock the clock used to get the time.
@@ -163,8 +158,7 @@ static RecordEventsReadableSpan startSpan(
       String name,
       InstrumentationLibraryInfo instrumentationLibraryInfo,
       Kind kind,
-      SpanId parentSpanId,
-      boolean hasRemoteParent,
+      Context parent,
       TraceConfig traceConfig,
       SpanProcessor spanProcessor,
       Clock clock,
@@ -179,8 +173,7 @@ static RecordEventsReadableSpan startSpan(
             name,
             instrumentationLibraryInfo,
             kind,
-            parentSpanId,
-            hasRemoteParent,
+            parent,
             traceConfig,
             spanProcessor,
             clock,
@@ -508,7 +501,7 @@ private Status getStatusWithDefault() {
   }
 
   SpanId getParentSpanId() {
-    return parentSpanId;
+    return TracingContextUtils.getSpan(parent).getContext().getSpanId();
   }
 
   Resource getResource() {
@@ -524,13 +517,17 @@ long getStartEpochNanos() {
   }
 
   boolean hasRemoteParent() {
-    return hasRemoteParent;
+    return TracingContextUtils.getSpan(parent).getContext().isRemote();
   }
 
   int getTotalRecordedLinks() {
     return totalRecordedLinks;
   }
 
+  Context getParent() {
+    return parent;
+  }
+
   @GuardedBy("lock")
   private List<Link> getImmutableLinks() {
     if (links.isEmpty()) {
@@ -613,7 +610,7 @@ public String toString() {
     sb.append(", spanId=");
     sb.append(context.getSpanId());
     sb.append(", parentSpanId=");
-    sb.append(parentSpanId);
+    sb.append(getParentSpanId());
     sb.append(", name=");
     sb.append(name);
     sb.append(", kind=");