cache delegate

Signed-off-by: Gregor Zeitlinger <[email protected]>

Author: zeitlinger

integration-tests/it-spring-boot-smoke-test/pom.xml

@@ -74,6 +74,24 @@
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
             </plugin>
+            <plugin>
+                <groupId>com.diffplug.spotless</groupId>
+                <artifactId>spotless-maven-plugin</artifactId>
+                <version>2.43.0</version>
+                <configuration>
+                    <java>
+                        <googleJavaFormat/>
+                    </java>
+                </configuration>
+                <executions>
+                    <execution>
+                        <phase>verify</phase>
+                        <goals>
+                            <goal>check</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 

integration-tests/it-spring-boot-smoke-test/src/test/java/io/prometheus/metrics/it/springboot/ApplicationTest.java

@@ -1,33 +1,33 @@
 package io.prometheus.metrics.it.springboot;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 import io.prometheus.client.it.common.ExporterTest;
 import io.prometheus.metrics.expositionformats.generated.com_google_protobuf_4_28_3.Metrics;
-import org.junit.jupiter.api.Test;
-import org.springframework.boot.test.autoconfigure.actuate.observability.AutoConfigureObservability;
-import org.springframework.boot.test.context.SpringBootTest;
-
 import java.io.IOException;
 import java.net.URL;
 import java.util.List;
 import java.util.Optional;
-
-import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.autoconfigure.actuate.observability.AutoConfigureObservability;
+import org.springframework.boot.test.context.SpringBootTest;
 
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
 @AutoConfigureObservability
 class ApplicationTest {
   @Test
   public void testPrometheusProtobufFormat() throws IOException {
     ExporterTest.Response response =
-            ExporterTest.scrape(
+        ExporterTest.scrape(
             "GET",
             new URL("http://localhost:8080/actuator/prometheus"),
             "Accept",
             "application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited");
     assertThat(response.status).isEqualTo(200);
 
     List<Metrics.MetricFamily> metrics = response.protoBody();
-    Optional<Metrics.MetricFamily> metric = metrics.stream()
+    Optional<Metrics.MetricFamily> metric =
+        metrics.stream()
             .filter(m -> m.getName().equals("application_started_time_seconds"))
             .findFirst();
     assertThat(metric).isPresent();

prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusProtobufWriter.java

@@ -13,15 +13,11 @@
  */
 public class PrometheusProtobufWriter implements ExpositionFormatWriter {
 
-  @Nullable private final ExpositionFormatWriter delegate;
+  @Nullable private static final ExpositionFormatWriter DELEGATE = createProtobufWriter();
 
   public static final String CONTENT_TYPE =
       "application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited";
 
-  public PrometheusProtobufWriter() {
-    this.delegate = createProtobufWriter();
-  }
-
   @Nullable
   private static ExpositionFormatWriter createProtobufWriter() {
     try {
@@ -53,23 +49,23 @@ public String getContentType() {
 
   @Override
   public boolean isAvailable() {
-    return delegate != null;
+    return DELEGATE != null;
   }
 
   @Override
   public String toDebugString(MetricSnapshots metricSnapshots) {
     checkAvailable();
-    return delegate.toDebugString(metricSnapshots);
+    return DELEGATE.toDebugString(metricSnapshots);
   }
 
   @Override
   public void write(OutputStream out, MetricSnapshots metricSnapshots) throws IOException {
     checkAvailable();
-    delegate.write(out, metricSnapshots);
+    DELEGATE.write(out, metricSnapshots);
   }
 
   private void checkAvailable() {
-    if (delegate == null) {
+    if (DELEGATE == null) {
       throw new UnsupportedOperationException("Prometheus protobuf writer not available");
     }
   }