Implement spec change to only accept Context as span parent.

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

@@ -79,20 +79,6 @@ public Span startSpan() {
           : 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;
-    }
-
     @Override
     public NoopSpanBuilder setParent(Context context) {
       Utils.checkNotNull(context, "context");

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

@@ -399,51 +399,6 @@ 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

@@ -82,15 +82,23 @@ 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

@@ -20,6 +20,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
+import io.grpc.Context;
 import io.opentelemetry.common.Attributes;
 import io.opentelemetry.trace.Span.Kind;
 import org.junit.jupiter.api.Test;
@@ -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

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

@@ -21,10 +21,13 @@
 import static io.opentelemetry.common.AttributesKeys.longKey;
 import static io.opentelemetry.common.AttributesKeys.stringKey;
 
+import io.grpc.Context;
 import io.opentelemetry.common.AttributeKey;
 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;
@@ -192,11 +195,13 @@ public Span start() {
     if (ignoreActiveSpan && parentSpan == null && parentSpanContext == null) {
       builder.setNoParent();
     } else if (parentSpan != null) {
-      builder.setParent(parentSpan.getSpan());
+      builder.setParent(TracingContextUtils.withSpan(parentSpan.getSpan(), Context.ROOT));
       SpanContextShim contextShim = spanContextTable().get(parentSpan);
       distContext = contextShim == null ? null : contextShim.getCorrelationContext();
     } else if (parentSpanContext != null) {
-      builder.setParent(parentSpanContext.getSpanContext());
+      builder.setParent(
+          TracingContextUtils.withSpan(
+              DefaultSpan.create(parentSpanContext.getSpanContext()), Context.ROOT));
       distContext = parentSpanContext.getCorrelationContext();
     }
 

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

@@ -58,14 +58,13 @@ final class SpanBuilderSdk implements Span.Builder {
   private final IdsGenerator idsGenerator;
   private final Clock clock;
 
-  @Nullable private Span parent;
-  @Nullable private SpanContext remoteParent;
+  @Nullable private Context parent;
   private Kind spanKind = Kind.INTERNAL;
   @Nullable private AttributesMap attributes;
   @Nullable private List<io.opentelemetry.trace.Link> links;
   private int totalNumberOfLinksAdded = 0;
-  private ParentType parentType = ParentType.CURRENT_CONTEXT;
   private long startEpochNanos = 0;
+  private boolean isRootSpan;
 
   SpanBuilderSdk(
       String spanName,
@@ -84,34 +83,18 @@ final class SpanBuilderSdk implements Span.Builder {
     this.clock = clock;
   }
 
-  @Override
-  public Span.Builder setParent(Span parent) {
-    this.parent = Objects.requireNonNull(parent, "parent");
-    this.remoteParent = null;
-    this.parentType = ParentType.EXPLICIT_PARENT;
-    return this;
-  }
-
-  @Override
-  public Span.Builder setParent(SpanContext remoteParent) {
-    this.remoteParent = Objects.requireNonNull(remoteParent, "remoteParent");
-    this.parent = null;
-    this.parentType = ParentType.EXPLICIT_REMOTE_PARENT;
-    return this;
-  }
-
   @Override
   public Span.Builder setParent(Context context) {
     Objects.requireNonNull(context, "context");
-    setParent(TracingContextUtils.getSpan(context));
+    this.isRootSpan = false;
+    this.parent = context;
     return this;
   }
 
   @Override
   public Span.Builder setNoParent() {
-    this.parentType = ParentType.NO_PARENT;
+    this.isRootSpan = true;
     this.parent = null;
-    this.remoteParent = null;
     return this;
   }
 
@@ -206,17 +189,20 @@ public Span.Builder setStartTimestamp(long startTimestamp) {
 
   @Override
   public Span startSpan() {
-    SpanContext parentContext = parent(parentType, parent, remoteParent);
+    final Context parentContext =
+        isRootSpan ? Context.ROOT : parent == null ? Context.current() : parent;
+    final Span parentSpan = TracingContextUtils.getSpan(parentContext);
+    final SpanContext parentSpanContext = parentSpan.getContext();
     String traceId;
     String spanId = idsGenerator.generateSpanId();
     TraceState traceState = TraceState.getDefault();
-    if (!parentContext.isValid()) {
+    if (!parentSpanContext.isValid()) {
       // New root span.
       traceId = idsGenerator.generateTraceId();
     } else {
       // New child span.
-      traceId = parentContext.getTraceIdAsHexString();
-      traceState = parentContext.getTraceState();
+      traceId = parentSpanContext.getTraceIdAsHexString();
+      traceState = parentSpanContext.getTraceState();
     }
     List<io.opentelemetry.trace.Link> immutableLinks =
         links == null
@@ -230,7 +216,12 @@ public Span startSpan() {
         traceConfig
             .getSampler()
             .shouldSample(
-                parentContext, traceId, spanName, spanKind, immutableAttributes, immutableLinks);
+                parentSpanContext,
+                traceId,
+                spanName,
+                spanKind,
+                immutableAttributes,
+                immutableLinks);
     Sampler.Decision samplingDecision = samplingResult.getDecision();
 
     SpanContext spanContext =
@@ -263,11 +254,11 @@ public <T> void consume(AttributeKey<T> key, T value) {
         spanName,
         instrumentationLibraryInfo,
         spanKind,
-        parentContext.getSpanIdAsHexString(),
-        parentContext.isRemote(),
+        parentSpanContext.getSpanIdAsHexString(),
+        parentSpanContext.isRemote(),
         traceConfig,
         spanProcessor,
-        getClock(parentSpan(parentType, parent), clock),
+        getClock(parentSpan, clock),
         resource,
         recordedAttributes,
         immutableLinks,
@@ -289,37 +280,4 @@ private static Clock getClock(Span parent, Clock clock) {
       return MonotonicClock.create(clock);
     }
   }
-
-  private static SpanContext parent(
-      ParentType parentType, Span explicitParent, SpanContext remoteParent) {
-    switch (parentType) {
-      case NO_PARENT:
-        return SpanContext.getInvalid();
-      case CURRENT_CONTEXT:
-        return TracingContextUtils.getCurrentSpan().getContext();
-      case EXPLICIT_PARENT:
-        return explicitParent.getContext();
-      case EXPLICIT_REMOTE_PARENT:
-        return remoteParent;
-    }
-    throw new IllegalStateException("Unknown parent type");
-  }
-
-  private static Span parentSpan(ParentType parentType, Span explicitParent) {
-    switch (parentType) {
-      case CURRENT_CONTEXT:
-        return TracingContextUtils.getCurrentSpan();
-      case EXPLICIT_PARENT:
-        return explicitParent;
-      default:
-        return DefaultSpan.getInvalid();
-    }
-  }
-
-  private enum ParentType {
-    CURRENT_CONTEXT,
-    EXPLICIT_PARENT,
-    EXPLICIT_REMOTE_PARENT,
-    NO_PARENT,
-  }
 }

sdk/tracing/src/test/java/io/opentelemetry/sdk/trace/SpanBuilderSdkTest.java

@@ -74,14 +74,7 @@ void setSpanKind_null() {
   @Test
   void setParent_null() {
     assertThrows(
-        NullPointerException.class, () -> tracerSdk.spanBuilder(SPAN_NAME).setParent((Span) null));
-  }
-
-  @Test
-  void setRemoteParent_null() {
-    assertThrows(
-        NullPointerException.class,
-        () -> tracerSdk.spanBuilder(SPAN_NAME).setParent((SpanContext) null));
+        NullPointerException.class, () -> tracerSdk.spanBuilder(SPAN_NAME).setParent(null));
   }
 
   @Test
@@ -600,7 +593,7 @@ void noParent() {
             tracerSdk
                 .spanBuilder(SPAN_NAME)
                 .setNoParent()
-                .setParent(parent)
+                .setParent(Context.current())
                 .setNoParent()
                 .startSpan();
         try {
@@ -623,7 +616,11 @@ void noParent_override() {
     try {
       RecordEventsReadableSpan span =
           (RecordEventsReadableSpan)
-              tracerSdk.spanBuilder(SPAN_NAME).setNoParent().setParent(parent).startSpan();
+              tracerSdk
+                  .spanBuilder(SPAN_NAME)
+                  .setNoParent()
+                  .setParent(TracingContextUtils.withSpan(parent, Context.current()))
+                  .startSpan();
       try {
         assertThat(span.getContext().getTraceIdAsHexString())
             .isEqualTo(parent.getContext().getTraceIdAsHexString());
@@ -635,7 +632,7 @@ void noParent_override() {
                 tracerSdk
                     .spanBuilder(SPAN_NAME)
                     .setNoParent()
-                    .setParent(parent.getContext())
+                    .setParent(TracingContextUtils.withSpan(parent, Context.current()))
                     .startSpan();
         try {
           assertThat(span2.getContext().getTraceIdAsHexString())
@@ -661,7 +658,7 @@ void overrideNoParent_remoteParent() {
               tracerSdk
                   .spanBuilder(SPAN_NAME)
                   .setNoParent()
-                  .setParent(parent.getContext())
+                  .setParent(TracingContextUtils.withSpan(parent, Context.current()))
                   .startSpan();
       try {
         assertThat(span.getContext().getTraceIdAsHexString())
@@ -747,7 +744,10 @@ void parent_invalidContext() {
 
     RecordEventsReadableSpan span =
         (RecordEventsReadableSpan)
-            tracerSdk.spanBuilder(SPAN_NAME).setParent(parent.getContext()).startSpan();
+            tracerSdk
+                .spanBuilder(SPAN_NAME)
+                .setParent(TracingContextUtils.withSpan(parent, Context.current()))
+                .startSpan();
     try {
       assertThat(span.getContext().getTraceIdAsHexString())
           .isNotEqualTo(parent.getContext().getTraceIdAsHexString());
@@ -768,9 +768,9 @@ void startTimestamp_null() {
   @Test
   void parent_clockIsSame() {
     Span parent = tracerSdk.spanBuilder(SPAN_NAME).startSpan();
-    try {
+    try (Scope scope = tracerSdk.withSpan(parent)) {
       RecordEventsReadableSpan span =
-          (RecordEventsReadableSpan) tracerSdk.spanBuilder(SPAN_NAME).setParent(parent).startSpan();
+          (RecordEventsReadableSpan) tracerSdk.spanBuilder(SPAN_NAME).startSpan();
 
       assertThat(span.getClock()).isSameAs(((RecordEventsReadableSpan) parent).getClock());
     } finally {