Promote ComponentLoader to opentelemetry-context, standardize SPI loading

Author: jack-berg

api/incubator/src/main/java/io/opentelemetry/api/incubator/config/DeclarativeConfigProperties.java

@@ -7,6 +7,7 @@
 
 import static io.opentelemetry.api.internal.ConfigUtil.defaultIfNull;
 
+import io.opentelemetry.context.ComponentLoader;
 import java.util.List;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -222,4 +223,9 @@ default List<DeclarativeConfigProperties> getStructuredList(
    * @return the configuration property keys
    */
   Set<String> getPropertyKeys();
+
+  /** Return a {@link ComponentLoader} that should be used to load SPIs. */
+  default ComponentLoader getComponentLoader() {
+    return ComponentLoader.forClassLoader(DeclarativeConfigProperties.class.getClassLoader());
+  }
 }

api/incubator/src/main/java/io/opentelemetry/api/incubator/config/EmptyDeclarativeConfigProperties.java

@@ -5,6 +5,7 @@
 
 package io.opentelemetry.api.incubator.config;
 
+import io.opentelemetry.context.ComponentLoader;
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
@@ -15,6 +16,8 @@ final class EmptyDeclarativeConfigProperties implements DeclarativeConfigPropert
 
   private static final EmptyDeclarativeConfigProperties INSTANCE =
       new EmptyDeclarativeConfigProperties();
+  private static final ComponentLoader COMPONENT_LOADER =
+      ComponentLoader.forClassLoader(EmptyDeclarativeConfigProperties.class.getClassLoader());
 
   private EmptyDeclarativeConfigProperties() {}
 
@@ -74,4 +77,9 @@ public List<DeclarativeConfigProperties> getStructuredList(String name) {
   public Set<String> getPropertyKeys() {
     return Collections.emptySet();
   }
+
+  @Override
+  public ComponentLoader getComponentLoader() {
+    return COMPONENT_LOADER;
+  }
 }

context/src/main/java/io/opentelemetry/context/ComponentLoader.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.context;
+
+import java.util.ServiceLoader;
+
+/** A loader for components that are discovered via SPI. */
+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);
+
+  /**
+   * Create an instance for the {@code classLoader} using {@link ServiceLoader#load(Class,
+   * ClassLoader)}.
+   */
+  static ComponentLoader forClassLoader(ClassLoader classLoader) {
+    return new ServiceLoaderComponentLoader(classLoader);
+  }
+}

context/src/main/java/io/opentelemetry/context/LazyStorage.java

@@ -39,7 +39,6 @@
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.ServiceLoader;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Function;
 import java.util.logging.Level;
@@ -103,9 +102,10 @@ static ContextStorage createStorage(AtomicReference<Throwable> deferredStorageFa
       return ContextStorage.defaultStorage();
     }
 
+    ComponentLoader componentLoader =
+        ComponentLoader.forClassLoader(LazyStorage.class.getClassLoader());
     List<ContextStorageProvider> providers = new ArrayList<>();
-    for (ContextStorageProvider provider :
-        ServiceLoader.load(ContextStorageProvider.class, LazyStorage.class.getClassLoader())) {
+    for (ContextStorageProvider provider : componentLoader.load(ContextStorageProvider.class)) {
       if (provider
           .getClass()
           .getName()

context/src/main/java/io/opentelemetry/context/ServiceLoaderComponentLoader.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.context;
+
+import java.util.ServiceLoader;
+
+class ServiceLoaderComponentLoader implements ComponentLoader {
+
+  private final ClassLoader classLoader;
+
+  ServiceLoaderComponentLoader(ClassLoader classLoader) {
+    this.classLoader = classLoader;
+  }
+
+  @Override
+  public <T> Iterable<T> load(Class<T> spiClass) {
+    return ServiceLoader.load(spiClass, classLoader);
+  }
+
+  @Override
+  public String toString() {
+    return "ServiceLoaderComponentLoader{classLoader=" + classLoader + "}";
+  }
+}

docs/apidiffs/current_vs_latest/opentelemetry-context.txt

@@ -1,2 +1,7 @@
 Comparing source compatibility of opentelemetry-context-1.52.0-SNAPSHOT.jar against opentelemetry-context-1.51.0.jar
-No changes.
++++  NEW INTERFACE: PUBLIC(+) ABSTRACT(+) io.opentelemetry.context.ComponentLoader  (not serializable)
+	+++  CLASS FILE FORMAT VERSION: 52.0 <- n.a.
+	+++  NEW SUPERCLASS: java.lang.Object
+	+++  NEW METHOD: PUBLIC(+) STATIC(+) io.opentelemetry.context.ComponentLoader forClassLoader(java.lang.ClassLoader)
+	+++  NEW METHOD: PUBLIC(+) ABSTRACT(+) java.lang.Iterable<T> load(java.lang.Class<T>)
+		GENERIC TEMPLATES: +++ T:java.lang.Object

docs/apidiffs/current_vs_latest/opentelemetry-exporter-otlp.txt

@@ -1,2 +1,19 @@
 Comparing source compatibility of opentelemetry-exporter-otlp-1.52.0-SNAPSHOT.jar against opentelemetry-exporter-otlp-1.51.0.jar
-No changes.
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.exporter.otlp.http.logs.OtlpHttpLogRecordExporterBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.exporter.otlp.http.logs.OtlpHttpLogRecordExporterBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.exporter.otlp.http.metrics.OtlpHttpMetricExporterBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.exporter.otlp.http.metrics.OtlpHttpMetricExporterBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporterBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporterBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.exporter.otlp.logs.OtlpGrpcLogRecordExporterBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.exporter.otlp.logs.OtlpGrpcLogRecordExporterBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporterBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporterBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporterBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporterBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)

docs/apidiffs/current_vs_latest/opentelemetry-sdk-extension-autoconfigure-spi.txt

@@ -1,2 +1,4 @@
 Comparing source compatibility of opentelemetry-sdk-extension-autoconfigure-spi-1.52.0-SNAPSHOT.jar against opentelemetry-sdk-extension-autoconfigure-spi-1.51.0.jar
-No changes.
+***  MODIFIED INTERFACE: PUBLIC ABSTRACT io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.context.ComponentLoader getComponentLoader()

docs/apidiffs/current_vs_latest/opentelemetry-sdk-extension-autoconfigure.txt

@@ -1,2 +1,4 @@
 Comparing source compatibility of opentelemetry-sdk-extension-autoconfigure-1.52.0-SNAPSHOT.jar against opentelemetry-sdk-extension-autoconfigure-1.51.0.jar
-No changes.
+***  MODIFIED CLASS: PUBLIC FINAL io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdkBuilder  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdkBuilder setComponentLoader(io.opentelemetry.context.ComponentLoader)

exporters/common/src/main/java/io/opentelemetry/exporter/internal/compression/CompressorUtil.java

@@ -8,9 +8,9 @@
 import static io.opentelemetry.api.internal.Utils.checkArgument;
 import static java.util.stream.Collectors.joining;
 
+import io.opentelemetry.context.ComponentLoader;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.ServiceLoader;
 import java.util.Set;
 import javax.annotation.Nullable;
 
@@ -48,7 +48,8 @@ public static Compressor validateAndResolveCompressor(String compressionMethod)
   private static Map<String, Compressor> buildCompressorRegistry() {
     Map<String, Compressor> compressors = new HashMap<>();
     for (CompressorProvider spi :
-        ServiceLoader.load(CompressorProvider.class, CompressorUtil.class.getClassLoader())) {
+        ComponentLoader.forClassLoader(CompressorUtil.class.getClassLoader())
+            .load(CompressorProvider.class)) {
       Compressor compressor = spi.getInstance();
       compressors.put(compressor.getEncoding(), compressor);
     }