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jsync.io is a non-blocking, event-driven networking framework for Java

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/*
 * Copyright (c) 2011-2013 The original author or authors
 * ------------------------------------------------------
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Apache License v2.0 which accompanies this distribution.
 *
 *     The Eclipse Public License is available at
 *     http://www.eclipse.org/legal/epl-v10.html
 *
 *     The Apache License v2.0 is available at
 *     http://www.opensource.org/licenses/apache2.0.php
 *
 * You may elect to redistribute this code under either of these licenses.
 */
package io.jsync.streams;

import io.jsync.Handler;

/**
 * Allows to set a {@link Handler} which is notified once the write queue is drained again.
 * This way you can stop writing once the write queue consumes to much memory and so prevent
 * an OutOfMemoryError.
 *
 * @author Norman Maurer
 */
public interface DrainSupport {

    /**
     * Set the maximum size of the write queue to {@code maxSize}. You will still be able to write to the stream even
     * if there is more than {@code maxSize} bytes in the write queue. This is used as an indicator by classes such as
     * {@code Pump} to provide flow control.
     */
    T setWriteQueueMaxSize(int maxSize);

    /**
     * This will return {@code true} if there are more bytes in the write queue than the value set using {@link
     * #setWriteQueueMaxSize}
     */
    boolean writeQueueFull();

    /**
     * Set a drain handler on the stream. If the write queue is full, then the handler will be called when the write
     * queue has been reduced to maxSize / 2. See {@link Pump} for an example of this being used.
     */
    T drainHandler(Handler handler);
}