Add config option defaulted to true

Author: franz1981

extensions/mongodb-client/runtime/src/main/java/io/quarkus/mongodb/runtime/MongoClientConfig.java

@@ -190,4 +190,21 @@ public interface MongoClientConfig {
      */
     Optional<UuidRepresentation> uuidRepresentation();
 
+    enum TransportConfig {
+        /**
+         * Uses a Netty-based transport re-using the existing Netty event loops.
+         */
+        NETTY,
+        /**
+         * Uses an asynchronous transport running async I/O tasks on a dedicated thread pool owned by the driver.
+         */
+        ASYNC
+    }
+
+    /**
+     * Configures the transport.
+     */
+    @WithDefault("netty")
+    TransportConfig transport();
+
 }

extensions/mongodb-client/runtime/src/main/java/io/quarkus/mongodb/runtime/MongoClients.java

@@ -51,10 +51,10 @@
 import com.mongodb.connection.ClusterConnectionMode;
 import com.mongodb.connection.ClusterSettings;
 import com.mongodb.connection.ConnectionPoolSettings;
-import com.mongodb.connection.NettyTransportSettings;
 import com.mongodb.connection.ServerSettings;
 import com.mongodb.connection.SocketSettings;
 import com.mongodb.connection.SslSettings;
+import com.mongodb.connection.TransportSettings;
 import com.mongodb.event.CommandListener;
 import com.mongodb.event.ConnectionPoolListener;
 import com.mongodb.reactivestreams.client.ReactiveContextProvider;
@@ -261,15 +261,19 @@ private MongoClientSettings createMongoConfiguration(String name, MongoClientCon
 
         MongoClientSettings.Builder settings = MongoClientSettings.builder();
 
+        switch (config.transport()) {
+            case NETTY:
+                // we supports just NIO for now
+                if (!vertx.isNativeTransportEnabled()) {
+                    configureNettyTransport(settings);
+                }
+                break;
+            case ASYNC:
+                // no-op since this is the default behaviour
+                break;
+        }
+
         if (isReactive) {
-            // we supports just NIO for now
-            if (!vertx.isNativeTransportEnabled()) {
-                var nettyStreaming = NettyTransportSettings.nettyBuilder()
-                        .allocator(VertxByteBufAllocator.POOLED_ALLOCATOR)
-                        .eventLoopGroup(vertx.nettyEventLoopGroup())
-                        .socketChannelClass(NioSocketChannel.class).build();
-                settings.transportSettings(nettyStreaming);
-            }
             reactiveContextProviders.stream().findAny().ifPresent(settings::contextProvider);
         }
 
@@ -344,6 +348,14 @@ private MongoClientSettings createMongoConfiguration(String name, MongoClientCon
         return settings.build();
     }
 
+    private void configureNettyTransport(MongoClientSettings.Builder settings) {
+        var nettyStreaming = TransportSettings.nettyBuilder()
+                .allocator(VertxByteBufAllocator.POOLED_ALLOCATOR)
+                .eventLoopGroup(vertx.nettyEventLoopGroup())
+                .socketChannelClass(NioSocketChannel.class).build();
+        settings.transportSettings(nettyStreaming);
+    }
+
     private boolean doesNotHaveClientNameQualifier(Bean<?> bean) {
         for (Annotation qualifier : bean.getQualifiers()) {
             if (qualifier.annotationType().equals(MongoClientName.class)) {