Breakout ResourceHolder from AwsXrayRemoteSamplerProvider

aws-xray/build.gradle.kts

@@ -16,6 +16,7 @@ dependencies {
   implementation("io.opentelemetry:opentelemetry-semconv")
 
   annotationProcessor("com.google.auto.service:auto-service")
+  testImplementation("com.google.auto.service:auto-service")
   compileOnly("com.google.auto.service:auto-service-annotations")
 
   annotationProcessor("com.google.auto.value:auto-value")

aws-xray/src/main/java/io/opentelemetry/contrib/awsxray/AwsXrayRemoteSamplerProvider.java

@@ -13,18 +13,13 @@
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
 import java.util.Map;
-import javax.annotation.Nullable;
 
 @AutoService(ConfigurableSamplerProvider.class)
 public class AwsXrayRemoteSamplerProvider implements ConfigurableSamplerProvider {
 
   @Override
   public Sampler createSampler(ConfigProperties config) {
-    Resource resource = ResourceHolder.resource;
-    if (resource == null) {
-      // Should never be the case in practice.
-      resource = Resource.getDefault();
-    }
+    Resource resource = io.opentelemetry.contrib.awsxray.ResourceHolder.getResource();
     AwsXrayRemoteSamplerBuilder builder = AwsXrayRemoteSampler.newBuilder(resource);
 
     Map<String, String> params = config.getMap("otel.traces.sampler.arg");
@@ -42,21 +37,15 @@ public String getName() {
     return "xray";
   }
 
-  // Currently the only way to read the Resource from autoconfiguration. Best would be if the SPI
-  // could return a Function<SamplerFactoryArgs, Sampler> where SamplerFactoryArgs has
-  // SDK-constructed components like Resource and Clock.
+  /** Deprecated in favor of {@link io.opentelemetry.contrib.awsxray.ResourceHolder}. */
+  @Deprecated
   @AutoService(AutoConfigurationCustomizerProvider.class)
   public static final class ResourceHolder implements AutoConfigurationCustomizerProvider {
 
-    @Nullable static volatile Resource resource;
-
+    @Deprecated
     @Override
     public void customize(AutoConfigurationCustomizer autoConfiguration) {
-      autoConfiguration.addResourceCustomizer(
-          (resource, config) -> {
-            ResourceHolder.resource = resource;
-            return resource;
-          });
+      // No-op
     }
   }
 }

aws-xray/src/main/java/io/opentelemetry/contrib/awsxray/ResourceHolder.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.awsxray;
+
+import com.google.auto.service.AutoService;
+import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizer;
+import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizerProvider;
+import io.opentelemetry.sdk.resources.Resource;
+import javax.annotation.Nullable;
+
+/**
+ * Currently the only way to read the Resource from autoconfiguration. Best would be if the SPI
+ * could return a {@code Function<SamplerFactoryArgs, Sampler>} where SamplerFactoryArgs has
+ * SDK-constructed components like Resource and Clock.
+ */
+@AutoService(AutoConfigurationCustomizerProvider.class)
+public final class ResourceHolder implements AutoConfigurationCustomizerProvider {
+
+  @Nullable static volatile Resource resource;
+
+  @Override
+  public void customize(AutoConfigurationCustomizer autoConfiguration) {
+    autoConfiguration.addResourceCustomizer(
+        (resource, config) -> {
+          ResourceHolder.resource = resource;
+          return resource;
+        });
+  }
+
+  /**
+   * Returns held resource, unless resource is null, in which case {@link Resource#getDefault()} is
+   * returned. This should not happen in practice, as {@link #customize} should be automatically
+   * run, populating {@link #resource}.
+   */
+  public static Resource getResource() {
+    Resource resourceReference = resource;
+    if (resourceReference == null) {
+      // Should never be the case in practice.
+      resourceReference = Resource.getDefault();
+    }
+    return resourceReference;
+  }
+}

aws-xray/src/test/java/io/opentelemetry/contrib/awsxray/ResourceHolderTest.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.awsxray;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizer;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.resources.Resource;
+import java.util.function.BiFunction;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for {@link ResourceHolder}. Note that there isn't a great way to test the "default"
+ * fallback logic, as when the test suite is run, the customize logic appears to be invoked.
+ */
+public class ResourceHolderTest {
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void testCustomized() {
+    Resource customizedResource = Resource.create(Attributes.empty());
+    AutoConfigurationCustomizer mockCustomizer = mock(AutoConfigurationCustomizer.class);
+    ResourceHolder resourceHolder = new ResourceHolder();
+    when(mockCustomizer.addResourceCustomizer(any()))
+        .thenAnswer(
+            invocation -> {
+              BiFunction<Resource, ConfigProperties, Resource> biFunction =
+                  (BiFunction<Resource, ConfigProperties, Resource>) invocation.getArguments()[0];
+              assertThat(biFunction.apply(customizedResource, null)).isEqualTo(customizedResource);
+              return mockCustomizer;
+            });
+    resourceHolder.customize(mockCustomizer);
+    assertThat(ResourceHolder.getResource()).isEqualTo(customizedResource);
+  }
+}