address review comments

- Switch to joint 8-arg AsyncMetricEntityStateBase.create() API
- Add TehutiMetricName inner enum, use getMetricName() instead of string
literal
- Fix Javadoc: joint registration IS possible and is now used

Author: m-nagarajan

services/venice-server/src/main/java/com/linkedin/venice/stats/DiskHealthStats.java

@@ -5,9 +5,11 @@
 import com.linkedin.davinci.storage.DiskHealthCheckService;
 import com.linkedin.venice.stats.dimensions.VeniceMetricsDimensions;
 import com.linkedin.venice.stats.metrics.AsyncMetricEntityStateBase;
+import com.linkedin.venice.stats.metrics.TehutiMetricNameEnum;
 import io.opentelemetry.api.common.Attributes;
 import io.tehuti.metrics.MetricsRepository;
 import io.tehuti.metrics.stats.AsyncGauge;
+import java.util.Collections;
 import java.util.Map;
 import java.util.function.LongSupplier;
 
@@ -16,33 +18,36 @@
  * {@code DiskHealthStats} measures the disk health conditions based on the periodic tests ran by
  * the {@link DiskHealthCheckService}. Reports 1 if healthy, 0 if unhealthy.
  *
- * <p>Tehuti and OTel both poll the same {@link DiskHealthCheckService#isDiskHealthy()} method.
- * They cannot share a single registration because Tehuti uses {@link AsyncGauge} (polled by
- * Tehuti's async executor) while OTel uses {@link AsyncMetricEntityStateBase} (polled by the
- * OTel SDK's PeriodicMetricReader).
+ * <p>Uses the joint Tehuti+OTel API: a single {@link AsyncMetricEntityStateBase} registration
+ * binds both the Tehuti {@link AsyncGauge} and the OTel ASYNC_GAUGE to the same
+ * {@link DiskHealthCheckService#isDiskHealthy()} callback.
  */
 public class DiskHealthStats extends AbstractVeniceStats {
+  /** Tehuti metric name for the disk health sensor. */
+  enum TehutiMetricName implements TehutiMetricNameEnum {
+    DISK_HEALTHY
+  }
+
   public DiskHealthStats(
       MetricsRepository metricsRepository,
       DiskHealthCheckService diskHealthCheckService,
       String name,
       String clusterName) {
     super(metricsRepository, name);
 
-    // Shared callback: 1 = healthy, 0 = unhealthy
-    LongSupplier healthCallback = () -> diskHealthCheckService.isDiskHealthy() ? 1 : 0;
-
-    // Tehuti: AsyncGauge
-    registerSensor(new AsyncGauge((ignored, ignored2) -> healthCallback.getAsLong(), "disk_healthy"));
-
-    // OTel: ASYNC_GAUGE with CLUSTER_NAME
     OpenTelemetryMetricsSetup.OpenTelemetryMetricsSetupInfo otelData =
         OpenTelemetryMetricsSetup.builder(metricsRepository).setClusterName(clusterName).build();
     Map<VeniceMetricsDimensions, String> baseDimensionsMap = otelData.getBaseDimensionsMap();
     Attributes baseAttributes = otelData.getBaseAttributes();
+
+    LongSupplier healthCallback = () -> diskHealthCheckService.isDiskHealthy() ? 1 : 0;
     AsyncMetricEntityStateBase.create(
         DISK_HEALTH_STATUS.getMetricEntity(),
         otelData.getOtelRepository(),
+        this::registerSensorIfAbsent,
+        TehutiMetricName.DISK_HEALTHY,
+        Collections.singletonList(
+            new AsyncGauge((ig, ig2) -> healthCallback.getAsLong(), TehutiMetricName.DISK_HEALTHY.getMetricName())),
         baseDimensionsMap,
         baseAttributes,
         healthCallback);