[feat][misc] PIP-264 Annotation processor

pulsar-broker/pom.xml

@@ -660,6 +660,17 @@
         </executions>
       </plugin>
 
+      <plugin>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <configuration>
+          <annotationProcessors combine.children="append">
+            <annotationProcessor>
+              org.apache.pulsar.opentelemetry.MetricProcessor
+            </annotationProcessor>
+          </annotationProcessors>
+        </configuration>
+      </plugin>
+
       <plugin>
         <artifactId>maven-resources-plugin</artifactId>
         <executions>

pulsar-broker/src/main/java/org/apache/pulsar/broker/namespace/NamespaceService.java

@@ -105,6 +105,7 @@
 import org.apache.pulsar.common.util.collections.ConcurrentOpenHashMap;
 import org.apache.pulsar.metadata.api.MetadataCache;
 import org.apache.pulsar.metadata.api.MetadataStoreException;
+import org.apache.pulsar.opentelemetry.Metric;
 import org.apache.pulsar.opentelemetry.annotations.PulsarDeprecatedMetric;
 import org.apache.pulsar.policies.data.loadbalancer.AdvertisedListener;
 import org.apache.pulsar.policies.data.loadbalancer.LocalBrokerData;
@@ -350,6 +351,8 @@ private CompletableFuture<Optional<URL>> internalGetWebServiceUrl(@Nullable Serv
                 }
                 return CompletableFuture.completedFuture(Optional.empty());
             }
+
+            @Metric
             CompletableFuture<Optional<LookupResult>> future =
                     ExtensibleLoadManagerImpl.isLoadManagerExtensionEnabled(config)
                     ? loadManager.get().findBrokerServiceUrl(Optional.ofNullable(topic), bundle) :

pulsar-opentelemetry/pom.xml

@@ -95,6 +95,12 @@
       <artifactId>opentelemetry-sdk-testing</artifactId>
       <scope>test</scope>
     </dependency>
+
+    <dependency>
+      <groupId>com.google.auto.service</groupId>
+      <artifactId>auto-service</artifactId>
+      <version>1.1.1</version>
+    </dependency>
   </dependencies>
 
   <build>

pulsar-opentelemetry/src/main/java/org/apache/pulsar/opentelemetry/Metric.java

@@ -0,0 +1,26 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.opentelemetry;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+
+@Target({ElementType.LOCAL_VARIABLE, ElementType.FIELD})
+public @interface Metric {
+}

pulsar-opentelemetry/src/main/java/org/apache/pulsar/opentelemetry/MetricProcessor.java

@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.opentelemetry;
+
+import com.google.auto.service.AutoService;
+import java.util.Set;
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.Processor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.annotation.processing.SupportedSourceVersion;
+import javax.lang.model.element.TypeElement;
+import javax.tools.Diagnostic;
+
+@SupportedAnnotationTypes("org.apache.pulsar.opentelemetry.Metric")
+@SupportedSourceVersion(javax.lang.model.SourceVersion.RELEASE_8)
+@AutoService(Processor.class)
+public class MetricProcessor extends AbstractProcessor {
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+        processingEnv.getMessager().printMessage(Diagnostic.Kind.NOTE, "DMISCA Processing annotations");
+        for (var annotation: annotations) {
+            var elements = roundEnv.getElementsAnnotatedWith(annotation);
+            try {
+                var fileObject = processingEnv.getFiler().createSourceFile("dmisca-metric-processor-output");
+                try (var ignored = fileObject.openWriter()) {
+                    for (var element : elements) {
+                        processingEnv.getMessager().printMessage(
+                            Diagnostic.Kind.NOTE, "DMISCA Found annotated element: " + element, element);
+                        ignored.write("DMISCA Found annotated element: " + element);
+                        ignored.write('\n');
+                    }
+                }
+            } catch (Exception e) {
+                processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, e.getMessage());
+            }
+        }
+        return true;
+    }
+}

pulsar-opentelemetry/src/main/java/org/apache/pulsar/opentelemetry/OpenTelemetryService.java

@@ -21,6 +21,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import com.google.common.annotations.VisibleForTesting;
 import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.metrics.LongCounter;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdk;
 import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdkBuilder;
@@ -44,6 +45,9 @@ public class OpenTelemetryService implements Closeable {
 
     private final OpenTelemetrySdk openTelemetrySdk;
 
+    @Metric
+    private final LongCounter dummyCounter = null;
+
     /**
      * Instantiates the OpenTelemetry SDK. All attributes are overridden by system properties or environment
      * variables.