SdkTracerProviderBuilder.addSpanProcessorFirst added

Author: onurkybsi

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/SdkTracerProviderBuilder.java

@@ -151,10 +151,27 @@ public SdkTracerProviderBuilder setSampler(Sampler sampler) {
    * @return this
    */
   public SdkTracerProviderBuilder addSpanProcessor(SpanProcessor spanProcessor) {
+    requireNonNull(spanProcessor, "spanProcessor");
     spanProcessors.add(spanProcessor);
     return this;
   }
 
+  /**
+   * Add a SpanProcessor to the beginning of the span pipeline that will be built. {@link
+   * SpanProcessor} will be called each time a {@link Span} is started or ended.
+   *
+   * <p>The {@code spanProcessor} must be thread-safe and return immediately (no remote calls, as
+   * contention free as possible).
+   *
+   * @param spanProcessor the processor to be added to the beginning of the span pipeline.
+   * @return this
+   */
+  public SdkTracerProviderBuilder addSpanProcessorFirst(SpanProcessor spanProcessor) {
+    requireNonNull(spanProcessor, "spanProcessor");
+    spanProcessors.add(0, spanProcessor);
+    return this;
+  }
+
   /**
    * Set the tracer configurator, which computes {@link TracerConfig} for each {@link
    * InstrumentationScopeInfo}.

sdk/trace/src/test/java/io/opentelemetry/sdk/trace/SdkTracerProviderBuilderTest.java

@@ -6,10 +6,12 @@
 package io.opentelemetry.sdk.trace;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
 
 import io.opentelemetry.api.common.AttributeKey;
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.sdk.resources.Resource;
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
 public class SdkTracerProviderBuilderTest {
@@ -28,4 +30,23 @@ void addResource() {
         .extracting("sharedState")
         .hasFieldOrPropertyWithValue("resource", Resource.getDefault().merge(customResource));
   }
+
+  @Test
+  void addSpanProcessorFirst() {
+    SpanProcessor firstProcessor = mock(SpanProcessor.class);
+    SpanProcessor anotherProcessor = mock(SpanProcessor.class);
+
+    SdkTracerProvider sdkTracerProvider =
+        SdkTracerProvider.builder()
+            .addSpanProcessor(anotherProcessor)
+            .addSpanProcessorFirst(firstProcessor)
+            .build();
+
+    assertThat(sdkTracerProvider)
+        .extracting("sharedState")
+        .extracting("activeSpanProcessor")
+        .extracting("spanProcessorsAll", InstanceOfAssertFactories.list(SpanProcessor.class))
+        .hasSize(2)
+        .containsExactly(firstProcessor, anotherProcessor);
+  }
 }