perf: avoid creating monitor plugin chains when unnecessary (#1530)

Author: aaron-congo

wrapper/src/main/java/software/amazon/jdbc/util/monitoring/MonitorServiceImpl.java

@@ -17,9 +17,11 @@
 package software.amazon.jdbc.util.monitoring;
 
 import java.sql.SQLException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
@@ -197,25 +199,38 @@ public <T extends Monitor> T runIfAbsent(
       cacheContainer = monitorCaches.computeIfAbsent(monitorClass, k -> supplier.get());
     }
 
-    final ConnectionService connectionService =
-        getConnectionService(
-            storageService,
-            telemetryFactory,
-            defaultConnectionProvider,
-            originalUrl,
-            driverProtocol,
-            driverDialect,
-            dbDialect,
-            originalProps);
-
-    Monitor monitor = cacheContainer.getCache().computeIfAbsent(key, k -> {
-      MonitorItem monitorItem = new MonitorItem(() -> initializer.createMonitor(
-          connectionService,
-          connectionService.getPluginService()));
-      monitorItem.getMonitor().start();
-      return monitorItem;
-    }).getMonitor();
+    // Lambdas require references to outer variables to be final. We use this variable to check whether a SQLException
+    // occurred while attempting to create the monitor.
+    final List<SQLException> exceptionList = new ArrayList<>(1);
+    MonitorItem monitorItem = cacheContainer.getCache().computeIfAbsent(key, k -> {
+      try {
+        final ConnectionService connectionService =
+            getConnectionService(
+                storageService,
+                telemetryFactory,
+                defaultConnectionProvider,
+                originalUrl,
+                driverProtocol,
+                driverDialect,
+                dbDialect,
+                originalProps);
+        final MonitorItem monitorItemInner = new MonitorItem(() -> initializer.createMonitor(
+            connectionService,
+            connectionService.getPluginService())
+        );
+        monitorItemInner.getMonitor().start();
+        return monitorItemInner;
+      } catch (SQLException e) {
+        exceptionList.add(e);
+        return null;
+      }
+    });
+
+    if (!exceptionList.isEmpty()) {
+      throw exceptionList.get(0);
+    }
 
+    Monitor monitor = monitorItem.getMonitor();
     if (monitorClass.isInstance(monitor)) {
       return monitorClass.cast(monitor);
     }