From b5f56ccac747619913cf45133124b37600efacce Mon Sep 17 00:00:00 2001
From: HaloFour <HaloFour@users.noreply.github.com>
Date: Sat, 7 Aug 2021 22:17:40 -0400
Subject: [PATCH] Adds getParentSpanContext to ReadableSpan interface (#3454)

* Adds getParentSpanContext to ReadableSpan

* Unit tests
---
 .../opentelemetry-sdk-trace.txt                  |  3 +++
 .../io/opentelemetry/sdk/trace/ReadableSpan.java |  8 ++++++++
 .../sdk/trace/RecordEventsReadableSpan.java      |  9 +++++----
 .../sdk/trace/RecordEventsReadableSpanTest.java  | 16 ++++++++++++++++
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/docs/apidiffs/current_vs_latest/opentelemetry-sdk-trace.txt b/docs/apidiffs/current_vs_latest/opentelemetry-sdk-trace.txt
index 1806a13b6f..8e86b36a5d 100644
--- a/docs/apidiffs/current_vs_latest/opentelemetry-sdk-trace.txt
+++ b/docs/apidiffs/current_vs_latest/opentelemetry-sdk-trace.txt
@@ -1,4 +1,7 @@
 Comparing source compatibility of  against 
+**** MODIFIED INTERFACE: PUBLIC ABSTRACT io.opentelemetry.sdk.trace.ReadableSpan  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++* NEW METHOD: PUBLIC(+) ABSTRACT(+) io.opentelemetry.api.trace.SpanContext getParentSpanContext()
 ***! MODIFIED INTERFACE: PUBLIC ABSTRACT io.opentelemetry.sdk.trace.samplers.SamplingResult  (not serializable)
 	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
 	+++! NEW METHOD: PUBLIC(+) STATIC(+) io.opentelemetry.sdk.trace.samplers.SamplingResult drop()
diff --git a/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/ReadableSpan.java b/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/ReadableSpan.java
index 20cc052cce..ec086c1783 100644
--- a/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/ReadableSpan.java
+++ b/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/ReadableSpan.java
@@ -23,6 +23,14 @@ public interface ReadableSpan {
    */
   SpanContext getSpanContext();
 
+  /**
+   * Returns the parent {@link SpanContext} of the {@link Span}, or {@link SpanContext#getInvalid()}
+   * if this is a root span.
+   *
+   * @return the parent {@link SpanContext} of the {@link Span}
+   */
+  SpanContext getParentSpanContext();
+
   /**
    * Returns the name of the {@code Span}.
    *
diff --git a/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpan.java b/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpan.java
index 42bea711b5..5113ead4df 100644
--- a/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpan.java
+++ b/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpan.java
@@ -202,6 +202,11 @@ final class RecordEventsReadableSpan implements ReadWriteSpan {
     return context;
   }
 
+  @Override
+  public SpanContext getParentSpanContext() {
+    return parentSpanContext;
+  }
+
   /**
    * Returns the name of the {@code Span}.
    *
@@ -451,10 +456,6 @@ final class RecordEventsReadableSpan implements ReadWriteSpan {
     }
   }
 
-  SpanContext getParentSpanContext() {
-    return parentSpanContext;
-  }
-
   Resource getResource() {
     return resource;
   }
diff --git a/sdk/trace/src/test/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpanTest.java b/sdk/trace/src/test/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpanTest.java
index 8e6308e589..7cb8c04511 100644
--- a/sdk/trace/src/test/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpanTest.java
+++ b/sdk/trace/src/test/java/io/opentelemetry/sdk/trace/RecordEventsReadableSpanTest.java
@@ -214,10 +214,26 @@ class RecordEventsReadableSpanTest {
     } finally {
       span.end();
     }
+    assertThat(span.getParentSpanContext().isValid()).isFalse();
     SpanData spanData = span.toSpanData();
     assertThat(SpanId.isValid(spanData.getParentSpanId())).isFalse();
   }
 
+  @Test
+  void toSpanData_ChildSpan() {
+    RecordEventsReadableSpan span = createTestSpan(SpanKind.INTERNAL);
+    try {
+      spanDoWork(span, null, null);
+    } finally {
+      span.end();
+    }
+    assertThat(span.getParentSpanContext().isValid()).isTrue();
+    assertThat(span.getParentSpanContext().getTraceId()).isEqualTo(traceId);
+    assertThat(span.getParentSpanContext().getSpanId()).isEqualTo(parentSpanId);
+    SpanData spanData = span.toSpanData();
+    assertThat(spanData.getParentSpanId()).isEqualTo(parentSpanId);
+  }
+
   @Test
   void toSpanData_WithInitialAttributes() {
     RecordEventsReadableSpan span = createTestSpanWithAttributes(attributes);