Ensure MongoClient#close only actions on first call

JAVA-4215

Author: rozza

driver-legacy/src/main/com/mongodb/MongoClient.java

@@ -49,6 +49,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.stream.Collectors;
 
 import static com.mongodb.internal.connection.ServerAddressHelper.createServerAddress;
@@ -119,6 +120,7 @@ public class MongoClient implements Closeable {
     private final ConcurrentLinkedQueue<ServerCursorAndNamespace> orphanedCursors = new ConcurrentLinkedQueue<>();
     private final ExecutorService cursorCleaningService;
     private final MongoClientImpl delegate;
+    private final AtomicBoolean closed;
 
     /**
      * Gets the default codec registry.  It includes the following providers:
@@ -232,6 +234,7 @@ private MongoClient(final MongoClientSettings settings,
         delegate = new MongoClientImpl(settings, wrapMongoDriverInformation(mongoDriverInformation));
         this.options = options != null ? options : MongoClientOptions.builder(settings).build();
         cursorCleaningService = this.options.isCursorFinalizerEnabled() ? createCursorCleaningService() : null;
+        this.closed = new AtomicBoolean();
     }
 
     private static MongoDriverInformation wrapMongoDriverInformation(@Nullable final MongoDriverInformation mongoDriverInformation) {
@@ -764,9 +767,11 @@ public void dropDatabase(final String dbName) {
      * databases obtained from it can no longer be used.
      */
     public void close() {
-        delegate.close();
-        if (cursorCleaningService != null) {
-            cursorCleaningService.shutdownNow();
+        if (!closed.getAndSet(true)) {
+            delegate.close();
+            if (cursorCleaningService != null) {
+                cursorCleaningService.shutdownNow();
+            }
         }
     }
 

driver-reactive-streams/src/main/com/mongodb/reactivestreams/client/internal/MongoClientImpl.java

@@ -44,6 +44,7 @@
 import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static com.mongodb.assertions.Assertions.notNull;
 import static org.bson.internal.CodecRegistryHelper.createRegistry;
@@ -65,6 +66,7 @@ public final class MongoClientImpl implements MongoClient {
     private final ClientSessionHelper clientSessionHelper;
     private final MongoOperationPublisher<Document> mongoOperationPublisher;
     private final Crypt crypt;
+    private final AtomicBoolean closed;
 
     public MongoClientImpl(final MongoClientSettings settings, final Cluster cluster, @Nullable final Closeable externalResourceCloser) {
         this(settings, cluster, null, externalResourceCloser);
@@ -96,6 +98,7 @@ private MongoClientImpl(final MongoClientSettings settings, final Cluster cluste
                                                                      settings.getReadConcern(), settings.getWriteConcern(),
                                                                      settings.getRetryWrites(), settings.getRetryReads(),
                                                                      settings.getUuidRepresentation(), this.executor);
+        this.closed = new AtomicBoolean();
     }
 
     Cluster getCluster() {
@@ -126,16 +129,18 @@ public MongoDatabase getDatabase(final String name) {
 
     @Override
     public void close() {
-        if (crypt != null) {
-            crypt.close();
-        }
-        serverSessionPool.close();
-        cluster.close();
-        if (externalResourceCloser != null) {
-            try {
-                externalResourceCloser.close();
-            } catch (IOException e) {
-                LOGGER.warn("Exception closing resource", e);
+        if (!closed.getAndSet(true)) {
+            if (crypt != null) {
+                crypt.close();
+            }
+            serverSessionPool.close();
+            cluster.close();
+            if (externalResourceCloser != null) {
+                try {
+                    externalResourceCloser.close();
+                } catch (IOException e) {
+                    LOGGER.warn("Exception closing resource", e);
+                }
             }
         }
     }

driver-sync/src/main/com/mongodb/client/internal/MongoClientDelegate.java

@@ -46,6 +46,7 @@
 import org.bson.codecs.configuration.CodecRegistry;
 
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static com.mongodb.MongoException.TRANSIENT_TRANSACTION_ERROR_LABEL;
 import static com.mongodb.MongoException.UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL;
@@ -64,6 +65,7 @@ final class MongoClientDelegate {
     @Nullable
     private final ServerApi serverApi;
     private final CodecRegistry codecRegistry;
+    private final AtomicBoolean closed;
 
     MongoClientDelegate(final Cluster cluster, final CodecRegistry codecRegistry,
                         final Object originator, @Nullable final OperationExecutor operationExecutor,
@@ -75,6 +77,7 @@ final class MongoClientDelegate {
         this.operationExecutor = operationExecutor == null ? new DelegateOperationExecutor() : operationExecutor;
         this.crypt = crypt;
         this.serverApi = serverApi;
+        this.closed = new AtomicBoolean();
     }
 
     public OperationExecutor getOperationExecutor() {
@@ -109,11 +112,13 @@ public ClientSession createClientSession(final ClientSessionOptions options, fin
     }
 
     public void close() {
-        if (crypt != null) {
-            crypt.close();
+        if (!closed.getAndSet(true)) {
+            if (crypt != null) {
+                crypt.close();
+            }
+            serverSessionPool.close();
+            cluster.close();
         }
-        serverSessionPool.close();
-        cluster.close();
     }
 
     public Cluster getCluster() {