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/*
 * Copyright (c) 2017, 2023 Oracle and/or its affiliates and others.
 * 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.servlet;

import java.io.IOException;
import java.util.EventListener;

/**
 *
 * Callback notification mechanism that signals to the developer it's possible to write content without blocking.
 *
 * @since Servlet 3.1
 */
public interface WriteListener extends EventListener {

    /**
     * When an instance of the WriteListener is registered with a {@link ServletOutputStream}, this method will be invoked
     * by the container the first time when it is possible to write data. Subsequently the container will invoke this method
     * if and only if the {@link jakarta.servlet.ServletOutputStream#isReady()} method has been called and has returned a
     * value of false. a write operation has subsequently become possible and any previous call to this method
     * has returned to the container.
     *
     * @throws IOException if an I/O related error has occurred during processing
     */
    void onWritePossible() throws IOException;

    /**
     * Invoked when an error occurs writing data using the non-blocking APIs.
     *
     * @param t the throwable to indicate why the write operation failed
     */
    void onError(final Throwable t);

}