Folder close idempotent

Signed-off-by: Jorge Bescos Gascon <[email protected]>

api/src/main/java/jakarta/mail/Folder.java

@@ -32,6 +32,7 @@
 import java.util.List;
 import java.util.Vector;
 import java.util.concurrent.Executor;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 /**
  * Folder is an abstract class that represents a folder for mail
@@ -102,6 +103,7 @@
 
 public abstract class Folder implements AutoCloseable {
 
+    private final AtomicBoolean closed = new AtomicBoolean(false);
     /**
      * The parent store.
      */
@@ -650,8 +652,13 @@ public abstract boolean delete(boolean recurse)
      */
     @Override
     public void close() throws MessagingException {
-        close(true);
-        q.terminateQueue();
+        if (!closed.getAndSet(true)) {
+            try {
+                close(true);
+            } finally {
+                q.terminateQueue();
+            }
+        }
     }
 
     /**

api/src/test/java/jakarta/mail/FolderTest.java

@@ -0,0 +1,163 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0, which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the
+ * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
+ * version 2 with the GNU Classpath Exception, which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ */
+
+package jakarta.mail;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Properties;
+
+import org.junit.Test;
+
+public class FolderTest {
+
+    @Test
+    public void closeIdempotent() throws MessagingException {
+        CustomFolder folder = new CustomFolder(new DummyStore(Session.getDefaultInstance(new Properties()), null));
+        folder.close();
+        folder.close();
+        assertEquals(1, folder.closedTimes);
+    }
+
+    private static class CustomFolder extends Folder {
+
+        private int closedTimes = 0;
+
+        protected CustomFolder(Store store) {
+            super(store);
+        }
+
+        @Override
+        public String getName() {
+            return null;
+        }
+
+        @Override
+        public String getFullName() {
+            return null;
+        }
+
+        @Override
+        public Folder getParent() throws MessagingException {
+            return null;
+        }
+
+        @Override
+        public boolean exists() throws MessagingException {
+            return false;
+        }
+
+        @Override
+        public Folder[] list(String pattern) throws MessagingException {
+            return null;
+        }
+
+        @Override
+        public char getSeparator() throws MessagingException {
+            return 0;
+        }
+
+        @Override
+        public int getType() throws MessagingException {
+            return 0;
+        }
+
+        @Override
+        public boolean create(int type) throws MessagingException {
+            return false;
+        }
+
+        @Override
+        public boolean hasNewMessages() throws MessagingException {
+            return false;
+        }
+
+        @Override
+        public Folder getFolder(String name) throws MessagingException {
+            return null;
+        }
+
+        @Override
+        public boolean delete(boolean recurse) throws MessagingException {
+            return false;
+        }
+
+        @Override
+        public boolean renameTo(Folder f) throws MessagingException {
+            return false;
+        }
+
+        @Override
+        public void open(int mode) throws MessagingException {
+        }
+
+        @Override
+        public void close(boolean expunge) throws MessagingException {
+            closedTimes++;
+        }
+
+        @Override
+        public boolean isOpen() {
+            return false;
+        }
+
+        @Override
+        public Flags getPermanentFlags() {
+            return null;
+        }
+
+        @Override
+        public int getMessageCount() throws MessagingException {
+            return 0;
+        }
+
+        @Override
+        public Message getMessage(int msgnum) throws MessagingException {
+            return null;
+        }
+
+        @Override
+        public void appendMessages(Message[] msgs) throws MessagingException {
+        }
+
+        @Override
+        public Message[] expunge() throws MessagingException {
+            return null;
+        }
+    }
+
+    private static class DummyStore extends Store {
+
+        protected DummyStore(Session session, URLName urlname) {
+            super(session, urlname);
+        }
+
+        @Override
+        public Folder getDefaultFolder() throws MessagingException {
+            return null;
+        }
+
+        @Override
+        public Folder getFolder(String name) throws MessagingException {
+            return null;
+        }
+
+        @Override
+        public Folder getFolder(URLName url) throws MessagingException {
+            return null;
+        }
+    }
+}