/**
 * Copyright 2007-2016, Kaazing Corporation. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.mina.core.future;


/**
 * An {@link IoFuture} for asynchronous write requests.
 *
 * <h3>Example</h3>
 * <pre>
 * IoSession session = ...;
 * WriteFuture future = session.write(...);
 * // Wait until the message is completely written out to the O/S buffer.
 * future.join();
 * if( future.isWritten() )
 * {
 *     // The message has been written successfully.
 * }
 * else
 * {
 *     // The messsage couldn't be written out completely for some reason.
 *     // (e.g. Connection is closed)
 * }
 * </pre>
 *
 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
 */
public interface WriteFuture extends IoFuture {
    /**
     * Returns <tt>true</tt> if the write operation is finished successfully.
     */
    boolean isWritten();
    
    /**
     * Returns the cause of the write failure if and only if the write
     * operation has failed due to an {@link Exception}.  Otherwise,
     * <tt>null</tt> is returned.
     */
    Throwable getException();

    /**
     * Sets the message is written, and notifies all threads waiting for
     * this future.  This method is invoked by MINA internally.  Please do
     * not call this method directly.
     */
    void setWritten();
    
    /**
     * Sets the cause of the write failure, and notifies all threads waiting
     * for this future.  This method is invoked by MINA internally.  Please
     * do not call this method directly.
     */
    void setException(Throwable cause);

    /**
     * Wait for the asynchronous operation to complete.
     * The attached listeners will be notified when the operation is 
     * completed.
     * 
     * @return the created {@link WriteFuture}
     * @throws InterruptedException
     */
    WriteFuture await() throws InterruptedException;

    /**
     * {@inheritDoc}
     */
    WriteFuture awaitUninterruptibly();

    /**
     * {@inheritDoc}
     */
    WriteFuture addListener(IoFutureListener<?> listener);

    /**
     * {@inheritDoc}
     */
    WriteFuture removeListener(IoFutureListener<?> listener);
}
