Fix LatencyMetrics for DSE

CHANGELOG.md

@@ -10,6 +10,7 @@ Changelog for Management API, new PRs should update the `main / unreleased` sect
 ```
 
 ## unreleased
+* [BUGFIX] [#564](https://github.com/k8ssandra/management-api-for-apache-cassandra/issues/564) Fix LatencyMetrics for DSE
 
 ## v0.1.88 (2024-10-28)
 * [CHANGE] [#556](https://github.com/k8ssandra/management-api-for-apache-cassandra/issues/556) Update Management API dependencies to address CVEs

management-api-agent-common/src/main/java/io/k8ssandra/metrics/builder/CassandraMetricRegistryListener.java

@@ -528,12 +528,21 @@ public void onTimerRemoved(String name) {
    */
   private boolean isMicrosecondLatencyBuckets() {
 
-    // This should only catch Cassandra 4.1+ and 5+ versions. DSE 6.8 reports something like
-    // 4.0.0.6851 and 6.9 reports something like 4.0.0.693, both of which would follow C* 4.0.x
-    // nanosecond buckets
-    if (SERVER_MAJOR_VERSION > 4 || (SERVER_MAJOR_VERSION == 4 && SERVER_MINOR_VERSION > 0)) {
+    // Only Cassandra 4.1 and newer should use microsecond resolution.
+
+    boolean isCassandra = false;
+    try {
+      Class.forName("org.apache.cassandra.utils.CassandraVersion");
+      isCassandra = true;
+    } catch (ClassNotFoundException cfne) {
+      // DSE doesn't have CassandraVersion
+    }
+    if (isCassandra
+        && (SERVER_MAJOR_VERSION > 4 || (SERVER_MAJOR_VERSION == 4 && SERVER_MINOR_VERSION > 0))) {
+      logger.info("Server version indicates metrics are microsecond resolution");
       return true;
     }
+    logger.info("Server version indicates metrics are nanosecond resolution");
     return false;
   }
 }