add ComponentLoader to support more auto configuration scenarios

buildSrc/src/main/kotlin/otel.japicmp-conventions.gradle.kts

@@ -115,6 +115,8 @@ if (!project.hasProperty("otel.release") && !project.name.startsWith("bom")) {
         // Reproduce defaults from https://github.com/melix/japicmp-gradle-plugin/blob/09f52739ef1fccda6b4310cf3f4b19dc97377024/src/main/java/me/champeau/gradle/japicmp/report/ViolationsGenerator.java#L130
         // with some changes.
         val exclusions = mutableListOf<String>()
+        // Generics are not detected correctly
+        exclusions.add("CLASS_GENERIC_TEMPLATE_CHANGED")
         // Allow new default methods on interfaces
         exclusions.add("METHOD_NEW_DEFAULT")
         // Allow adding default implementations for default methods

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/AutoConfiguredOpenTelemetrySdkBuilder.java

@@ -13,6 +13,7 @@
 import io.opentelemetry.context.propagation.TextMapPropagator;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.OpenTelemetrySdkBuilder;
+import io.opentelemetry.sdk.autoconfigure.internal.ComponentLoader;
 import io.opentelemetry.sdk.autoconfigure.internal.SpiHelper;
 import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizer;
 import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizerProvider;
@@ -368,6 +369,13 @@ public AutoConfiguredOpenTelemetrySdkBuilder setServiceClassLoader(
     return this;
   }
 
+  /** Sets the {@link ComponentLoader} to be used to load SPI implementations. */
+  AutoConfiguredOpenTelemetrySdkBuilder setComponentLoader(ComponentLoader componentLoader) {
+    requireNonNull(componentLoader, "componentLoader");
+    this.spiHelper = SpiHelper.create(componentLoader);
+    return this;
+  }
+
   /**
    * Returns a new {@link AutoConfiguredOpenTelemetrySdk} holding components auto-configured using
    * the settings of this {@link AutoConfiguredOpenTelemetrySdkBuilder}.

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/TracerProviderConfiguration.java

@@ -173,21 +173,13 @@ static Sampler configureSampler(String sampler, ConfigProperties config, SpiHelp
       case "always_off":
         return Sampler.alwaysOff();
       case "traceidratio":
-        {
-          double ratio =
-              config.getDouble("otel.traces.sampler.arg", DEFAULT_TRACEIDRATIO_SAMPLE_RATIO);
-          return Sampler.traceIdRatioBased(ratio);
-        }
+        return ratioSampler(config);
       case PARENTBASED_ALWAYS_ON:
         return Sampler.parentBased(Sampler.alwaysOn());
       case "parentbased_always_off":
         return Sampler.parentBased(Sampler.alwaysOff());
       case "parentbased_traceidratio":
-        {
-          double ratio =
-              config.getDouble("otel.traces.sampler.arg", DEFAULT_TRACEIDRATIO_SAMPLE_RATIO);
-          return Sampler.parentBased(Sampler.traceIdRatioBased(ratio));
-        }
+        return Sampler.parentBased(ratioSampler(config));
       case "parentbased_jaeger_remote":
         Sampler jaegerRemote = spiSamplersManager.getByName("jaeger_remote");
         if (jaegerRemote == null) {
@@ -205,5 +197,10 @@ static Sampler configureSampler(String sampler, ConfigProperties config, SpiHelp
     }
   }
 
+  private static Sampler ratioSampler(ConfigProperties config) {
+    double ratio = config.getDouble("otel.traces.sampler.arg", DEFAULT_TRACEIDRATIO_SAMPLE_RATIO);
+    return Sampler.traceIdRatioBased(ratio);
+  }
+
   private TracerProviderConfiguration() {}
 }

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/internal/AutoConfigureUtil.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.sdk.autoconfigure.internal;
 
 import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdk;
+import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdkBuilder;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -30,4 +31,34 @@ public static ConfigProperties getConfig(
           "Error calling getConfig on AutoConfiguredOpenTelemetrySdk", e);
     }
   }
+
+  /** Sets the {@link ComponentLoader} to be used in the auto-configuration process. */
+  public static void setComponentLoader(
+      AutoConfiguredOpenTelemetrySdkBuilder builder, ComponentLoader componentLoader) {
+    try {
+      Method method =
+          AutoConfiguredOpenTelemetrySdkBuilder.class.getDeclaredMethod(
+              "setComponentLoader", ComponentLoader.class);
+      method.setAccessible(true);
+      method.invoke(builder, componentLoader);
+    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
+      throw new IllegalStateException(
+          "Error calling setComponentLoader on AutoConfiguredOpenTelemetrySdkBuilder", e);
+    }
+  }
+
+  /** Sets the {@link ConfigProperties} to be used in the auto-configuration process. */
+  public static void setConfigProperties(
+      AutoConfiguredOpenTelemetrySdkBuilder builder, ConfigProperties config) {
+    try {
+      Method method =
+          AutoConfiguredOpenTelemetrySdkBuilder.class.getDeclaredMethod(
+              "setConfig", ConfigProperties.class);
+      method.setAccessible(true);
+      method.invoke(builder, config);
+    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
+      throw new IllegalStateException(
+          "Error calling setConfig on AutoConfiguredOpenTelemetrySdkBuilder", e);
+    }
+  }
 }

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/internal/ComponentLoader.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure.internal;
+
+import io.opentelemetry.sdk.autoconfigure.spi.Ordered;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+/**
+ * A loader for components that are discovered via SPI.
+ *
+ * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
+ * at any time.
+ */
+public interface ComponentLoader {
+  /**
+   * Load implementations of an SPI.
+   *
+   * @param spiClass the SPI class
+   * @param <T> the SPI type
+   * @return iterable of SPI implementations
+   */
+  <T> Iterable<T> load(Class<T> spiClass);
+
+  /**
+   * Load implementations of an ordered SPI (i.e. implements {@link Ordered}).
+   *
+   * @param spiClass the SPI class
+   * @param <T> the SPI type
+   * @return list of SPI implementations, in order
+   */
+  default <T extends Ordered> List<T> loadOrdered(Class<T> spiClass) {
+    return StreamSupport.stream(load(spiClass).spliterator(), false)
+        .sorted(Comparator.comparing(Ordered::order))
+        .collect(Collectors.toList());
+  }
+}

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/internal/SpiHelper.java

@@ -10,7 +10,6 @@
 import io.opentelemetry.sdk.autoconfigure.spi.internal.AutoConfigureListener;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Comparator;
 import java.util.HashMap;
 import java.util.IdentityHashMap;
 import java.util.List;
@@ -27,20 +26,22 @@
  */
 public final class SpiHelper {
 
-  private final ClassLoader classLoader;
-  private final SpiFinder spiFinder;
+  private final ComponentLoader componentLoader;
   private final Set<AutoConfigureListener> listeners =
       Collections.newSetFromMap(new IdentityHashMap<>());
 
-  // Visible for testing
-  SpiHelper(ClassLoader classLoader, SpiFinder spiFinder) {
-    this.classLoader = classLoader;
-    this.spiFinder = spiFinder;
+  private SpiHelper(ComponentLoader componentLoader) {
+    this.componentLoader = componentLoader;
   }
 
   /** Create a {@link SpiHelper} which loads SPIs using the {@code classLoader}. */
   public static SpiHelper create(ClassLoader classLoader) {
-    return new SpiHelper(classLoader, ServiceLoader::load);
+    return new SpiHelper(new ServiceLoaderComponentLoader(classLoader));
+  }
+
+  /** Create a {@link SpiHelper} which loads SPIs using the {@code componentLoader}. */
+  public static SpiHelper create(ComponentLoader componentLoader) {
+    return new SpiHelper(componentLoader);
   }
 
   /**
@@ -82,9 +83,7 @@ public <T, S> NamedSpiManager<T> loadConfigurable(
    * @return list of SPI implementations, in order
    */
   public <T extends Ordered> List<T> loadOrdered(Class<T> spiClass) {
-    List<T> result = load(spiClass);
-    result.sort(Comparator.comparing(Ordered::order));
-    return result;
+    return init(componentLoader.loadOrdered(spiClass));
   }
 
   /**
@@ -95,27 +94,46 @@ public <T extends Ordered> List<T> loadOrdered(Class<T> spiClass) {
    * @return list of SPI implementations
    */
   public <T> List<T> load(Class<T> spiClass) {
+    return init(componentLoader.load(spiClass));
+  }
+
+  /**
+   * Load implementations of an SPI.
+   *
+   * @param components the SPI implementations
+   * @param <T> the SPI type
+   * @return list of SPI implementations
+   */
+  private <T> List<T> init(Iterable<T> components) {
     List<T> result = new ArrayList<>();
-    for (T service : spiFinder.load(spiClass, classLoader)) {
-      maybeAddListener(service);
-      result.add(service);
+    for (T service : components) {
+      result.add(maybeAddListener(service));
     }
     return result;
   }
 
-  private void maybeAddListener(Object object) {
+  private <T> T maybeAddListener(T object) {
     if (object instanceof AutoConfigureListener) {
       listeners.add((AutoConfigureListener) object);
     }
+    return object;
   }
 
   /** Return the set of SPIs loaded which implement {@link AutoConfigureListener}. */
   public Set<AutoConfigureListener> getListeners() {
     return Collections.unmodifiableSet(listeners);
   }
 
-  // Visible for testing
-  interface SpiFinder {
-    <T> Iterable<T> load(Class<T> spiClass, ClassLoader classLoader);
+  private static class ServiceLoaderComponentLoader implements ComponentLoader {
+    private final ClassLoader classLoader;
+
+    private ServiceLoaderComponentLoader(ClassLoader classLoader) {
+      this.classLoader = classLoader;
+    }
+
+    @Override
+    public <T> Iterable<T> load(Class<T> spiClass) {
+      return ServiceLoader.load(spiClass, classLoader);
+    }
   }
 }

sdk-extensions/autoconfigure/src/test/java/io/opentelemetry/sdk/autoconfigure/AutoConfiguredOpenTelemetrySdkTest.java

@@ -20,6 +20,7 @@
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.when;
 
 import io.github.netmikey.logunit.api.LogCapturer;
@@ -36,7 +37,9 @@
 import io.opentelemetry.context.propagation.TextMapPropagator;
 import io.opentelemetry.internal.testing.slf4j.SuppressLogger;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.autoconfigure.internal.ComponentLoader;
 import io.opentelemetry.sdk.autoconfigure.internal.SpiHelper;
+import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizerProvider;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigurationException;
 import io.opentelemetry.sdk.autoconfigure.spi.internal.AutoConfigureListener;
@@ -315,6 +318,33 @@ void builder_addSpanProcessorCustomizer() {
     verifyNoInteractions(spanExporter1);
   }
 
+  @Test
+  void builder_addAutoConfigurationCustomizerProviderUsingComponentLoader() {
+    AutoConfigurationCustomizerProvider customizerProvider =
+        mock(AutoConfigurationCustomizerProvider.class);
+
+    SpiHelper spiHelper =
+        SpiHelper.create(AutoConfiguredOpenTelemetrySdkBuilder.class.getClassLoader());
+
+    builder
+        .setComponentLoader(
+            new ComponentLoader() {
+              @SuppressWarnings("unchecked")
+              @Override
+              public <T> Iterable<T> load(Class<T> spiClass) {
+                if (spiClass.equals(AutoConfigurationCustomizerProvider.class)) {
+                  return Collections.singletonList((T) customizerProvider);
+                }
+                return spiHelper.load(spiClass);
+              }
+            })
+        .build();
+
+    verify(customizerProvider).customize(any());
+
+    verifyNoMoreInteractions(customizerProvider);
+  }
+
   @Test
   void builder_addPropertiesSupplier() {
     AutoConfiguredOpenTelemetrySdk autoConfigured =

sdk-extensions/autoconfigure/src/test/java/io/opentelemetry/sdk/autoconfigure/internal/SpiHelperTest.java

@@ -11,6 +11,7 @@
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -28,11 +29,11 @@ public class SpiHelperTest {
 
   @Test
   public void canRetrieveByName() {
-    SpiHelper.SpiFinder mockFinder = mock(SpiHelper.SpiFinder.class);
-    when(mockFinder.load(any(), any()))
+    ComponentLoader mockLoader = spy(ComponentLoader.class);
+    when(mockLoader.load(any()))
         .thenReturn(Collections.singletonList(new SpiExampleProviderImplementation()));
 
-    SpiHelper spiHelper = new SpiHelper(SpiHelperTest.class.getClassLoader(), mockFinder);
+    SpiHelper spiHelper = SpiHelper.create(mockLoader);
 
     NamedSpiManager<SpiExample> spiProvider =
         spiHelper.loadConfigurable(
@@ -49,10 +50,10 @@ public void canRetrieveByName() {
   public void instantiatesImplementationsLazily() {
     SpiExampleProvider mockProvider = mock(SpiExampleProvider.class);
     when(mockProvider.getName()).thenReturn("lazy-init-example");
-    SpiHelper.SpiFinder mockFinder = mock(SpiHelper.SpiFinder.class);
-    when(mockFinder.load(any(), any())).thenReturn(Collections.singletonList(mockProvider));
+    ComponentLoader mockLoader = spy(ComponentLoader.class);
+    when(mockLoader.load(any())).thenReturn(Collections.singletonList(mockProvider));
 
-    SpiHelper spiHelper = new SpiHelper(SpiHelperTest.class.getClassLoader(), mockFinder);
+    SpiHelper spiHelper = SpiHelper.create(mockLoader);
 
     NamedSpiManager<SpiExample> spiProvider =
         spiHelper.loadConfigurable(
@@ -68,11 +69,11 @@ public void instantiatesImplementationsLazily() {
 
   @Test
   public void onlyInstantiatesOnce() {
-    SpiHelper.SpiFinder mockFinder = mock(SpiHelper.SpiFinder.class);
-    when(mockFinder.load(any(), any()))
+    ComponentLoader mockLoader = mock(ComponentLoader.class);
+    when(mockLoader.load(any()))
         .thenReturn(Collections.singletonList(new SpiExampleProviderImplementation()));
 
-    SpiHelper spiHelper = new SpiHelper(SpiHelperTest.class.getClassLoader(), mockFinder);
+    SpiHelper spiHelper = SpiHelper.create(mockLoader);
 
     NamedSpiManager<SpiExample> spiProvider =
         spiHelper.loadConfigurable(
@@ -93,10 +94,10 @@ public void failureToInitializeThrows() {
     when(mockProvider.getName()).thenReturn("init-failure-example");
     when(mockProvider.createSpiExample(any())).thenThrow(new RuntimeException());
 
-    SpiHelper.SpiFinder mockFinder = mock(SpiHelper.SpiFinder.class);
-    when(mockFinder.load(any(), any())).thenReturn(Collections.singletonList(mockProvider));
+    ComponentLoader mockLoader = spy(ComponentLoader.class);
+    when(mockLoader.load(any())).thenReturn(Collections.singletonList(mockProvider));
 
-    SpiHelper spiHelper = new SpiHelper(SpiHelperTest.class.getClassLoader(), mockFinder);
+    SpiHelper spiHelper = SpiHelper.create(mockLoader);
 
     NamedSpiManager<SpiExample> spiProvider =
         spiHelper.loadConfigurable(
@@ -120,11 +121,10 @@ void loadsOrderedSpi() {
     when(spi2.order()).thenReturn(0);
     when(spi3.order()).thenReturn(1);
 
-    SpiHelper.SpiFinder mockFinder = mock(SpiHelper.SpiFinder.class);
-    when(mockFinder.load(ResourceProvider.class, SpiHelper.class.getClassLoader()))
-        .thenReturn(asList(spi1, spi2, spi3));
+    ComponentLoader mockLoader = spy(ComponentLoader.class);
+    when(mockLoader.load(ResourceProvider.class)).thenReturn(asList(spi1, spi2, spi3));
 
-    SpiHelper spiHelper = new SpiHelper(SpiHelperTest.class.getClassLoader(), mockFinder);
+    SpiHelper spiHelper = SpiHelper.create(mockLoader);
 
     List<ResourceProvider> loadedSpi = spiHelper.loadOrdered(ResourceProvider.class);