Ringbuffer.java

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/**
 * Author: Sven Gothel <sgothel@jausoft.com>
 * Copyright (c) 2020 Gothel Software e.K.
 * Copyright (c) 2013 Gothel Software e.K.
 * Copyright (c) 2013 JogAmp Community.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package org.jau.util;
 
import java.io.PrintStream;
 
/**
 * Ring buffer interface, a.k.a circular buffer.
 * <p>
 * Caller can chose whether to block until get / put is able to proceed or not.
 * </p>
 * <p>
 * Caller can chose whether to pass an empty array and clear references at get,
 * or using a preset array for circular access of same objects.
 * </p>
 * <p>
 * Synchronization and hence thread safety details belong to the implementation.
 * </p>
 */
public interface Ringbuffer<T> {
 
    /** Returns a short string representation incl. size/capacity and internal r/w index (impl. dependent). */
    @Override
    public String toString();
 
    /** Debug functionality - Dumps the contents of the internal array. */
    public void dump(PrintStream stream, String prefix);
 
    /** Returns the net capacity of this ring buffer. */
    public int capacity();
 
    /**
     * Resets the read and write position according to an empty ring buffer
     * and set all ring buffer slots to <code>null</code>.
     * <p>
     * {@link #isEmpty()} will return <code>true</code> after calling this method.
     * </p>
     */
    public void clear();
 
    /**
     * Resets the read and write position according to a full ring buffer
     * and fill all slots w/ elements of array <code>copyFrom</code>.
     * <p>
     * Array's <code>copyFrom</code> elements will be copied into the internal array,
     * hence it's length must be equal to {@link #capacity()}.
     * </p>
     * @param copyFrom Mandatory array w/ length {@link #capacity()} to be copied into the internal array.
     * @throws IllegalArgumentException if <code>copyFrom</code> is <code>null</code>.
     * @throws IllegalArgumentException if <code>copyFrom</code>'s length is different from {@link #capacity()}.
     */
    public void resetFull(T[] copyFrom) throws IllegalArgumentException;
 
    /** Returns the number of elements in this ring buffer. */
    public int size();
 
    /** Returns the number of free slots available to put.  */
    public int getFreeSlots();
 
    /** Returns true if this ring buffer is empty, otherwise false. */
    public boolean isEmpty();
 
    /** Returns true if this ring buffer is full, otherwise false. */
    public boolean isFull();
 
    /**
     * Dequeues the oldest enqueued element if available, otherwise null.
     * <p>
     * The returned ring buffer slot will be set to <code>null</code> to release the reference
     * and move ownership to the caller.
     * </p>
     * <p>
     * Method is non blocking and returns immediately;.
     * </p>
     * @return the oldest put element if available, otherwise null.
     */
    public T get();
 
    /**
     * Dequeues the oldest enqueued element.
     * <p>
     * The returned ring buffer slot will be set to <code>null</code> to release the reference
     * and move ownership to the caller.
     * </p>
     * <p>
     * Methods blocks until an element becomes available via put.
     * </p>
     * @return the oldest put element
     * @throws InterruptedException
     */
    public T getBlocking() throws InterruptedException;
 
    /**
     * Peeks the next element at the read position w/o modifying pointer, nor blocking.
     * @return <code>null</code> if empty, otherwise the element which would be read next.
     */
    public T peek();
 
    /**
     * Peeks the next element at the read position w/o modifying pointer, but w/ blocking.
     * @return <code>null</code> if empty, otherwise the element which would be read next.
     */
    public T peekBlocking() throws InterruptedException;
 
    /**
     * Enqueues the given element.
     * <p>
     * Returns true if successful, otherwise false in case buffer is full.
     * </p>
     * <p>
     * Method is non blocking and returns immediately;.
     * </p>
     */
    public boolean put(T e);
 
    /**
     * Enqueues the given element.
     * <p>
     * Method blocks until a free slot becomes available via get.
     * </p>
     * @throws InterruptedException
     */
    public void putBlocking(T e) throws InterruptedException;
 
    /**
     * Enqueues the same element at it's write position, if not full.
     * <p>
     * Returns true if successful, otherwise false in case buffer is full.
     * </p>
     * <p>
     * If <code>blocking</code> is true, method blocks until a free slot becomes available via get.
     * </p>
     * @param blocking if true, wait until a free slot becomes available via get.
     * @throws InterruptedException
     */
    public boolean putSame(boolean blocking) throws InterruptedException;
 
    /**
     * Blocks until at least <code>count</code> free slots become available.
     * @throws InterruptedException
     */
    public void waitForFreeSlots(int count) throws InterruptedException;
 
    /**
     * Grows an empty ring buffer, increasing it's capacity about the amount.
     * <p>
     * Growing an empty ring buffer increases it's size about the amount, i.e. renders it not empty.
     * The new elements are inserted at the read position, able to be read out via {@link #get()} etc.
     * </p>
     *
     * @param newElements array of new full elements the empty buffer shall grow about.
     * @throws IllegalStateException if buffer is not empty
     * @throws IllegalArgumentException if newElements is null
     */
    public void growEmptyBuffer(T[] newElements) throws IllegalStateException, IllegalArgumentException;
 
    /**
     * Grows a full ring buffer, increasing it's capacity about the amount.
     * <p>
     * Growing a full ring buffer leaves the size intact, i.e. renders it not full.
     * New <code>null</code> elements are inserted at the write position, able to be written to via {@link #put(Object)} etc.
     * </p>
     * @param amount the amount of elements the buffer shall grow about
     *
     * @throws IllegalStateException if buffer is not full
     * @throws IllegalArgumentException if amount is < 0
     */
    public void growFullBuffer(int amount) throws IllegalStateException, IllegalArgumentException;
}