Implement spec change to only accept Context as span parent.

api/src/jmh/java/io/opentelemetry/trace/propagation/HttpTraceContextInjectBenchmark.java

@@ -24,7 +24,6 @@
 import io.opentelemetry.trace.TraceFlags;
 import io.opentelemetry.trace.TraceId;
 import io.opentelemetry.trace.TraceState;
-import io.opentelemetry.trace.TracingContextUtils;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -93,7 +92,7 @@ private static SpanContext createTestSpanContext(String traceId, String spanId)
   private static List<Context> createContexts(List<SpanContext> spanContexts) {
     List<Context> contexts = new ArrayList<>();
     for (SpanContext context : spanContexts) {
-      contexts.add(TracingContextUtils.withSpan(DefaultSpan.create(context), Context.ROOT));
+      contexts.add(DefaultSpan.createInContext(context, Context.ROOT));
     }
     return contexts;
   }

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

@@ -16,6 +16,7 @@
 
 package io.opentelemetry.trace;
 
+import io.grpc.Context;
 import io.opentelemetry.common.AttributeValue;
 import io.opentelemetry.common.Attributes;
 import javax.annotation.concurrent.Immutable;
@@ -31,8 +32,10 @@
 @Immutable
 public final class DefaultSpan implements Span {
 
-  private static final DefaultSpan INVALID = new DefaultSpan(SpanContext.getInvalid());
+  private static final DefaultSpan INVALID =
+      new DefaultSpan(SpanContext.getInvalid(), Context.ROOT);
 
+  // TODO: Do we need to change this to getInvalid(Context parent)?
   /**
    * Returns a {@link DefaultSpan} with an invalid {@link SpanContext}.
    *
@@ -44,20 +47,27 @@ public static Span getInvalid() {
   }
 
   /**
-   * Creates an instance of this class with the {@link SpanContext}.
+   * Creates an instance of this class with a (parent) {@link Context}.
    *
-   * @param spanContext the {@code SpanContext}.
+   * @param spanContext the {@link SpanContext}.
+   * @param parent the (parent) {@link Context}.
    * @return a {@link DefaultSpan}.
    * @since 0.1.0
    */
-  public static Span create(SpanContext spanContext) {
-    return new DefaultSpan(spanContext);
+  public static Span create(SpanContext spanContext, Context parent) {
+    return new DefaultSpan(spanContext, parent);
+  }
+
+  public static Context createInContext(SpanContext spanContext, Context parent) {
+    return TracingContextUtils.withSpan(create(spanContext, parent), parent);
   }
 
   private final SpanContext spanContext;
+  private final Context parent;
 
-  DefaultSpan(SpanContext spanContext) {
+  DefaultSpan(SpanContext spanContext, Context parent) {
     this.spanContext = spanContext;
+    this.parent = parent;
   }
 
   @Override
@@ -116,6 +126,11 @@ public SpanContext getContext() {
     return spanContext;
   }
 
+  @Override
+  public Context getParent() {
+    return parent;
+  }
+
   @Override
   public boolean isRecording() {
     return false;

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(), parent);
     }
 
     @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

@@ -283,6 +283,14 @@ enum Kind {
    */
   SpanContext getContext();
 
+  /**
+   * Returns the parent {@code Context} associated with this {@code Span}.
+   *
+   * @return the parent {@code Context} associated with this {@code Span}.
+   * @since 0.8.0
+   */
+  Context getParent();
+
   /**
    * Returns {@code true} if this {@code Span} records tracing events (e.g. {@link
    * #addEvent(String)}, {@link #setAttribute(String, long)}).
@@ -383,51 +391,6 @@ 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/main/java/io/opentelemetry/trace/propagation/HttpTraceContext.java

@@ -130,7 +130,7 @@ private static <C> void injectImpl(SpanContext spanContext, C carrier, Setter<C>
       return context;
     }
 
-    return TracingContextUtils.withSpan(DefaultSpan.create(spanContext), context);
+    return DefaultSpan.createInContext(spanContext, context);
   }
 
   private static <C> SpanContext extractImpl(C carrier, Getter<C> getter) {

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(DefaultSpan.createInContext(spanContext, Context.ROOT))
+            .startSpan();
     assertThat(span.getContext()).isSameAs(spanContext);
   }
 
   @Test
   void testSpanContextPropagation() {
-    DefaultSpan parent = new DefaultSpan(spanContext);
+    DefaultSpan parent = new DefaultSpan(spanContext, Context.ROOT);
 
-    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);
   }
 
@@ -108,15 +116,17 @@ void testSpanContextPropagation_nullContext() {
 
   @Test
   void testSpanContextPropagation_fromContext() {
-    Context context = TracingContextUtils.withSpan(new DefaultSpan(spanContext), Context.current());
+    Context context =
+        TracingContextUtils.withSpan(
+            new DefaultSpan(spanContext, Context.current()), Context.current());
 
     Span span = defaultTracer.spanBuilder(SPAN_NAME).setParent(context).startSpan();
     assertThat(span.getContext()).isSameAs(spanContext);
   }
 
   @Test
   void testSpanContextPropagationCurrentSpan() {
-    DefaultSpan parent = new DefaultSpan(spanContext);
+    DefaultSpan parent = new DefaultSpan(spanContext, Context.ROOT);
     try (Scope scope = defaultTracer.withSpan(parent)) {
       Span span = defaultTracer.spanBuilder(SPAN_NAME).startSpan();
       assertThat(span.getContext()).isSameAs(spanContext);
@@ -125,8 +135,7 @@ void testSpanContextPropagationCurrentSpan() {
 
   @Test
   void testSpanContextPropagationCurrentSpanContext() {
-    Context context =
-        TracingContextUtils.withSpan(DefaultSpan.create(spanContext), Context.current());
+    Context context = DefaultSpan.createInContext(spanContext, Context.current());
     try (Scope scope = ContextUtils.withScopedContext(context)) {
       Span span = defaultTracer.spanBuilder(SPAN_NAME).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(DefaultSpan.createInContext(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_EmptyContext() {
     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

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

@@ -32,7 +32,7 @@ void testGetCurrentSpan_Default() {
 
   @Test
   void testGetCurrentSpan_SetSpan() {
-    Span span = DefaultSpan.create(SpanContext.getInvalid());
+    Span span = DefaultSpan.create(SpanContext.getInvalid(), Context.current());
     Context orig = TracingContextUtils.withSpan(span, Context.current()).attach();
     try {
       assertThat(TracingContextUtils.getCurrentSpan()).isSameAs(span);
@@ -49,7 +49,7 @@ void testGetSpan_DefaultContext() {
 
   @Test
   void testGetSpan_ExplicitContext() {
-    Span span = DefaultSpan.create(SpanContext.getInvalid());
+    Span span = DefaultSpan.create(SpanContext.getInvalid(), Context.current());
     Context context = TracingContextUtils.withSpan(span, Context.current());
     assertThat(TracingContextUtils.getSpan(context)).isSameAs(span);
   }
@@ -62,7 +62,7 @@ void testGetSpanWithoutDefault_DefaultContext() {
 
   @Test
   void testGetSpanWithoutDefault_ExplicitContext() {
-    Span span = DefaultSpan.create(SpanContext.getInvalid());
+    Span span = DefaultSpan.create(SpanContext.getInvalid(), Context.current());
     Context context = TracingContextUtils.withSpan(span, Context.current());
     assertThat(TracingContextUtils.getSpanWithoutDefault(context)).isSameAs(span);
   }

api/src/test/java/io/opentelemetry/trace/propagation/HttpTraceContextTest.java

@@ -67,7 +67,7 @@ private static SpanContext getSpanContext(Context context) {
   }
 
   private static Context withSpanContext(SpanContext spanContext, Context context) {
-    return TracingContextUtils.withSpan(DefaultSpan.create(spanContext), context);
+    return DefaultSpan.createInContext(spanContext, context);
   }
 
   @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)