http://www.mongodb.org: The MongoDB Java Driver uber-artifact, containing the legacy driver, the mongodb-driver, mongodb-driver-core, and bson
  • Various (MongoDB) 
/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * 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.bson;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;


An interface wrapper around a java.nio.ByteBuffer which additionally is Closeable, so that pooled byte buffers know how.


This interface is not frozen yet, and methods may be added in a minor release, so beware implementing this yourself.


Since:3.0
/**
 * <p>An interface wrapper around a {@code java.nio.ByteBuffer} which additionally is {@code Closeable}, so that pooled byte buffers know
 * how.</p>
 *
 * <p>This interface is not frozen yet, and methods may be added in a minor release, so beware implementing this yourself.</p>
 *
 * @since 3.0
 */
public interface ByteBuf  {

    
Returns this buffer's capacity.

Returns:The capacity of this buffer
/**
     * Returns this buffer's capacity.
     *
     * @return The capacity of this buffer
     */
    int capacity();

    
Absolute put method (optional operation).


Writes the given byte into this buffer at the given index. 


Params:
  • index – The index at which the byte will be written
  • b –     The byte value to be written
Throws:
Returns:This buffer
/**
     * <p>Absolute <em>put</em> method <em>(optional operation)</em>.</p>
     *
     * <p>Writes the given byte into this buffer at the given index. </p>
     *
     * @param index The index at which the byte will be written
     * @param b     The byte value to be written
     * @return This buffer
     * @throws IndexOutOfBoundsException        If {@code index} is negative or not smaller than the buffer's limit
     * @throws java.nio.ReadOnlyBufferException If this buffer is read-only
     */
    ByteBuf put(int index, byte b);

    
Returns the number of elements between the current position and the limit.

Returns:The number of elements remaining in this buffer
/**
     * Returns the number of elements between the current position and the limit.
     *
     * @return The number of elements remaining in this buffer
     */
    int remaining();

    
Relative bulk put method  (optional operation). 


This method transfers bytes into this buffer from the given source array. If there are more bytes to be copied from the array than remain in this buffer, that is, if length > remaining(), then no bytes are transferred and a BufferOverflowException is thrown. 


Otherwise, this method copies length bytes from the given array into this buffer, starting at the given offset in the array and at the current position of this buffer. The position of this buffer is then incremented by length.


In other words, an invocation of this method of the form dst.put(src, off, len) has exactly the same effect as the loop



    for (int i = off; i < off + len; i++) {
        dst.put(a[i]);
    } 


except that it first checks that there is sufficient space in this buffer and it is potentially much more efficient. 


Params:
  • src –    The array from which bytes are to be read
  • offset – The offset within the array of the first byte to be read; must be non-negative and no larger than array.length
  • length – The number of bytes to be read from the given array; must be non-negative and no larger than array.length -
              offset
Throws:
Returns:This buffer
/**
     * <p>Relative bulk <em>put</em> method&nbsp;&nbsp;<em>(optional operation)</em>. </p>
     *
     * <p>This method transfers bytes into this buffer from the given source array.  If there are more bytes to be copied from the array
     * than remain in this buffer, that is, if {@code length > remaining()}, then no bytes are transferred and a {@link
     * java.nio.BufferOverflowException} is thrown. </p>
     *
     * <p>Otherwise, this method copies {@code length} bytes from the given array into this buffer, starting at the given offset in the
     * array and at the current position of this buffer.  The position of this buffer is then incremented by {@code length}.</p>
     *
     * <p>In other words, an invocation of this method of the form {@code dst.put(src, off, len)} has exactly the same effect as the
     * loop</p>
     * <pre>{@code
     *     for (int i = off; i < off + len; i++) {
     *         dst.put(a[i]);
     *     }}
     * </pre>
     *
     * <p>except that it first checks that there is sufficient space in this buffer and it is potentially much more efficient. </p>
     *
     * @param src    The array from which bytes are to be read
     * @param offset The offset within the array of the first byte to be read; must be non-negative and no larger than {@code array.length}
     * @param length The number of bytes to be read from the given array; must be non-negative and no larger than {@code array.length -
     *               offset}
     * @return This buffer
     * @throws java.nio.BufferOverflowException If there is insufficient space in this buffer
     * @throws IndexOutOfBoundsException        If the preconditions on the {@code offset} and {@code length} parameters do not hold
     * @throws java.nio.ReadOnlyBufferException If this buffer is read-only
     */
    ByteBuf put(byte[] src, int offset, int length);

    
States whether there are any elements between the current position and the limit.

Returns:true if, and only if, there is at least one element remaining in this buffer
/**
     * States whether there are any elements between the current position and the limit.
     *
     * @return {@code true} if, and only if, there is at least one element remaining in this buffer
     */
    boolean hasRemaining();

    
Relative put method (optional operation).


Writes the given byte into this buffer at the current position, and then increments the position. 


Params:
  • b – The byte to be written
Throws:
Returns:This buffer
/**
     * <p>Relative <em>put</em> method <em>(optional operation)</em>.</p>
     *
     * <p>Writes the given byte into this buffer at the current position, and then increments the position. </p>
     *
     * @param b The byte to be written
     * @return This buffer
     * @throws java.nio.BufferOverflowException If this buffer's current position is not smaller than its limit
     * @throws java.nio.ReadOnlyBufferException If this buffer is read-only
     */
    ByteBuf put(byte b);

    
Flips this buffer.  The limit is set to the current position and then the position is set to zero.  If the mark is defined then it
is discarded.


After a sequence of channel-read or put operations, invoke this method to prepare for a sequence of channel-write or
relative get operations.  For example: 


buf.put(magic);    // Prepend header
in.read(buf);      // Read data into rest of buffer
buf.flip();        // Flip buffer
out.write(buf);    // Write header + data to channel



This method is often used in conjunction with the compact method when transferring data from one place to another. 


Returns:This buffer
/**
     * <p>Flips this buffer.  The limit is set to the current position and then the position is set to zero.  If the mark is defined then it
     * is discarded.</p>
     *
     * <p>After a sequence of channel-read or <em>put</em> operations, invoke this method to prepare for a sequence of channel-write or
     * relative <em>get</em> operations.  For example: </p>
     * <pre>
     * buf.put(magic);    // Prepend header
     * in.read(buf);      // Read data into rest of buffer
     * buf.flip();        // Flip buffer
     * out.write(buf);    // Write header + data to channel
     * </pre>
     * <p>This method is often used in conjunction with the {@link java.nio.ByteBuffer#compact compact} method when transferring data from
     * one place to another.  </p>
     *
     * @return This buffer
     */
    ByteBuf flip();

    
Returns the byte array that backs this buffer (optional operation).


Modifications to this buffer's content will cause the returned array's content to be modified, and vice versa.


Throws:
Returns:The array that backs this buffer
/**
     * <p>Returns the byte array that backs this buffer <em>(optional operation)</em>.</p>
     *
     * <p>Modifications to this buffer's content will cause the returned array's content to be modified, and vice versa.</p>
     *
     * @return The array that backs this buffer
     * @throws java.nio.ReadOnlyBufferException If this buffer is backed by an array but is read-only
     * @throws UnsupportedOperationException    If this buffer is not backed by an accessible array
     */
    byte[] array();

    
Returns this buffer's limit.

Returns:The limit of this buffer
/**
     * Returns this buffer's limit.
     *
     * @return The limit of this buffer
     */
    int limit();

    
Sets this buffer's position.  If the mark is defined and larger than the new position then it is discarded.

Params:
  • newPosition – The new position value; must be non-negative and no larger than the current limit
Throws:
Returns:This buffer
/**
     * Sets this buffer's position.  If the mark is defined and larger than the new position then it is discarded.
     *
     * @param newPosition The new position value; must be non-negative and no larger than the current limit
     * @return This buffer
     * @throws IllegalArgumentException If the preconditions on {@code newPosition} do not hold
     */
    ByteBuf position(int newPosition);

    
Clears this buffer.  The position is set to zero, the limit is set to the capacity, and the mark is discarded.


Invoke this method before using a sequence of channel-read or put operations to fill this buffer.  For example: 


buf.clear();     // Prepare buffer for reading
in.read(buf);    // Read data



This method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in
situations in which that might as well be the case. 


Returns:This buffer
/**
     * <p>Clears this buffer.  The position is set to zero, the limit is set to the capacity, and the mark is discarded.</p>
     *
     * <p>Invoke this method before using a sequence of channel-read or <em>put</em> operations to fill this buffer.  For example: </p>
     *
     * <pre>
     * buf.clear();     // Prepare buffer for reading
     * in.read(buf);    // Read data
     * </pre>
     * <p>This method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in
     * situations in which that might as well be the case. </p>
     *
     * @return This buffer
     */
    ByteBuf clear();

    
Modifies this buffer's byte order.

Params:
Returns:This buffer
/**
     * Modifies this buffer's byte order.
     *
     * @param byteOrder The new byte order, either {@link ByteOrder#BIG_ENDIAN BIG_ENDIAN} or {@link ByteOrder#LITTLE_ENDIAN LITTLE_ENDIAN}
     * @return This buffer
     */
    ByteBuf order(ByteOrder byteOrder);

    
Relative get method.  Reads the byte at this buffer's current position, and then increments the position.

Throws:
Returns:The byte at the buffer's current position
/**
     * Relative <em>get</em> method.  Reads the byte at this buffer's current position, and then increments the position.
     *
     * @return The byte at the buffer's current position
     * @throws java.nio.BufferUnderflowException If the buffer's current position is not smaller than its limit
     */
    byte get();

    
Absolute get method.  Reads the byte at the given index.

Params:
  • index – The index from which the byte will be read
Throws:
Returns:The byte at the given index
/**
     * Absolute <em>get</em> method.  Reads the byte at the given index.
     *
     * @param index The index from which the byte will be read
     * @return The byte at the given index
     * @throws IndexOutOfBoundsException If {@code index} is negative or not smaller than the buffer's limit
     */
    byte get(int index);

    
Relative bulk get method.


This method transfers bytes from this buffer into the given destination array. An invocation of this method of the form 
src.get(a) behaves in exactly the same way as the invocation:


src.get(a, 0, a.length)



Params:
  • bytes – the destination byte array
Throws:
Returns:This buffer
/**
     * <p>Relative bulk {@code get} method.</p>
     *
     * <p>This method transfers bytes from this buffer into the given destination array.  An invocation of this method of the form {@code
     * src.get(a)} behaves in exactly the same way as the invocation:</p>
     *
     * <pre>
     * src.get(a, 0, a.length)
     * </pre>
     *
     * @param bytes the destination byte array
     * @return This buffer
     * @throws java.nio.BufferUnderflowException If there are fewer than {@code length} bytes remaining in this buffer
     */
    ByteBuf get(byte[] bytes);

    
Absolute bulk get method.


This method transfers bytes from this buffer into the given destination array. An invocation of this method of the form 
src.get(a) behaves in exactly the same way as the invocation:


src.get(index, a, 0, a.length)



Params:
  • index – The index from which the bytes will be read
  • bytes – the destination byte array
Throws:
Returns:This buffer
/**
     * <p>Absolute bulk {@code get} method.</p>
     *
     * <p>This method transfers bytes from this buffer into the given destination array.  An invocation of this method of the form {@code
     * src.get(a)} behaves in exactly the same way as the invocation:</p>
     *
     * <pre>
     * src.get(index, a, 0, a.length)
     * </pre>
     *
     * @param index The index from which the bytes will be read
     * @param bytes the destination byte array
     * @return This buffer
     * @throws java.nio.BufferUnderflowException If there are fewer than {@code length} bytes remaining in this buffer
     */
    ByteBuf get(int index, byte[] bytes);

    
Relative bulk get method.

 This method transfers bytes from this buffer into the given
destination array.  If there are fewer bytes remaining in the
buffer than are required to satisfy the request, that is, if
length > remaining(), then no bytes are transferred and a BufferUnderflowException is thrown. 
 Otherwise, this method copies length bytes from this buffer into the given array, starting at the current position of this buffer and at the given offset in the array. The position of this buffer is then incremented by length. 
 In other words, an invocation of this method of the form
src.get(dst, off, len)
has exactly the same effect as the loop


    for (int i = off; i < off + len; i++)
        dst[i] = src.get();
 

except that it first checks that there are sufficient bytes in
this buffer and it is potentially much more efficient.

Params:
  • bytes – 
        The array into which bytes are to be written
  • offset –  The offset within the array of the first byte to be written; must be non-negative and no larger than dst.length
  • length –  The maximum number of bytes to be written to the given array; must be non-negative and no larger than dst.length - offset
Throws:
Returns: This buffer
/**
     * Relative bulk <i>get</i> method.
     *
     * <p> This method transfers bytes from this buffer into the given
     * destination array.  If there are fewer bytes remaining in the
     * buffer than are required to satisfy the request, that is, if
     * <code style="white-space:nowrap">length &gt; remaining()</code>, then no
     * bytes are transferred and a {@link java.nio.BufferUnderflowException} is
     * thrown.
     *
     * <p> Otherwise, this method copies {@code length} bytes from this
     * buffer into the given array, starting at the current position of this
     * buffer and at the given offset in the array.  The position of this
     * buffer is then incremented by {@code length}.
     *
     * <p> In other words, an invocation of this method of the form
     * <code style="white-space:nowrap">src.get(dst, off, len)</code>
     * has exactly the same effect as the loop
     *
     * <pre>
     * {@code
     *     for (int i = off; i < off + len; i++)
     *         dst[i] = src.get();
     * }
     * </pre>
     *
     * except that it first checks that there are sufficient bytes in
     * this buffer and it is potentially much more efficient.
     *
     * @param  bytes
     *         The array into which bytes are to be written
     *
     * @param  offset
     *         The offset within the array of the first byte to be
     *         written; must be non-negative and no larger than
     *         {@code dst.length}
     *
     * @param  length
     *         The maximum number of bytes to be written to the given
     *         array; must be non-negative and no larger than
     *         {@code dst.length - offset}
     *
     * @return  This buffer
     *
     * @throws java.nio.BufferUnderflowException
     *          If there are fewer than {@code length} bytes
     *          remaining in this buffer
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the {@code offset} and {@code length}
     *          parameters do not hold
     */
    ByteBuf get(byte[] bytes, int offset, int length);

    
Absolute bulk get method.

 This method transfers bytes from this buffer into the given destination array. If there are fewer bytes remaining in the buffer than are required to satisfy the request, that is, if length &gt; remaining, then no bytes are transferred and a BufferUnderflowException is thrown.


 Otherwise, this method copies length bytes from this buffer into the given array, starting at the given index buffer and at the given offset in the array.


 In other words, an invocation of this method of the form src.get(dst, off, len) has exactly the same effect as the loop 



    for (int i = off; i < off + len; i++)
        dst[i] = src.get(i);
 

except that it first checks that there are sufficient bytes in this buffer and it is potentially much more efficient.

Params:
  • index –  The index from which the bytes will be read
  • bytes –  The array into which bytes are to be written
  • offset – The offset within the array of the first byte to be written; must be non-negative and no larger than dst.length
  • length – The maximum number of bytes to be written to the given array; must be non-negative and no larger than dst.length - offset
Throws:
Returns:This buffer
/**
     * Absolute bulk <i>get</i> method.
     *
     * <p> This method transfers bytes from this buffer into the given destination array.  If there are fewer bytes remaining in the buffer
     * than are required to satisfy the request, that is, if {@code length &gt; remaining}, then no bytes are
     * transferred and a {@link java.nio.BufferUnderflowException} is thrown.</p>
     *
     * <p> Otherwise, this method copies {@code length} bytes from this buffer into the given array, starting at the given index buffer
     * and at the given offset in the array.</p>
     *
     * <p> In other words, an invocation of this method of the form {@code src.get(dst, off, len)} has exactly the same
     * effect as the loop </p>
     * <pre>
     * {@code
     *     for (int i = off; i < off + len; i++)
     *         dst[i] = src.get(i);
     * }
     * </pre>
     *
     * except that it first checks that there are sufficient bytes in this buffer and it is potentially much more efficient.
     *
     * @param index  The index from which the bytes will be read
     * @param bytes  The array into which bytes are to be written
     * @param offset The offset within the array of the first byte to be written; must be non-negative and no larger than
     *               {@code dst.length}
     * @param length The maximum number of bytes to be written to the given array; must be non-negative and no larger than
     *               {@code dst.length - offset}
     * @return This buffer
     * @throws java.nio.BufferUnderflowException If there are fewer than {@code length} bytes remaining in this buffer
     * @throws IndexOutOfBoundsException         If the preconditions on the {@code offset} and {@code length} parameters do not hold
     */
    ByteBuf get(int index, byte[] bytes, int offset, int length);

    
 Relative get method for reading a long value. 
 
Reads the next eight bytes at this buffer's current position,
composing them into a long value according to the current byte order, and then increments the position by eight.  


Throws:
Returns:The long value at the buffer's current position
/**
     * <p> Relative <em>get</em> method for reading a long value. </p> <p>Reads the next eight bytes at this buffer's current position,
     * composing them into a long value according to the current byte order, and then increments the position by eight.  </p>
     *
     * @return The long value at the buffer's current position
     * @throws java.nio.BufferUnderflowException If there are fewer than eight bytes remaining in this buffer
     */
    long getLong();

    
Absolute get method for reading a long value.

 Reads eight bytes at the given index, composing them into a long value according to the current byte order.  


Params:
  • index – The index from which the bytes will be read
Throws:
Returns:The long value at the given index
/**
     * Absolute <i>get</i> method for reading a long value.
     *
     * <p> Reads eight bytes at the given index, composing them into a long value according to the current byte order.  </p>
     *
     * @param  index The index from which the bytes will be read
     *
     * @return The long value at the given index
     *
     * @throws IndexOutOfBoundsException If {@code index} is negative or not smaller than the buffer's limit, minus seven
     */
    long getLong(int index);

    
Relative get method for reading a double value.


Reads the next eight bytes at this buffer's current position, composing them into a double value according to the current byte
order, and then increments the position by eight.  


Throws:
Returns:The double value at the buffer's current position
/**
     * <p>Relative <em>get</em> method for reading a double value.</p>
     *
     * <p>Reads the next eight bytes at this buffer's current position, composing them into a double value according to the current byte
     * order, and then increments the position by eight.  </p>
     *
     * @return The double value at the buffer's current position
     * @throws java.nio.BufferUnderflowException If there are fewer than eight bytes remaining in this buffer
     */
    double getDouble();

    
Absolute get method for reading a double value.

 Reads eight bytes at the given index, composing them into a double value
according to the current byte order.  


Params:
  • index – The index from which the bytes will be read
Throws:
Returns:The double value at the given index
/**
     * Absolute <em>get</em> method for reading a double value.
     *
     * <p> Reads eight bytes at the given index, composing them into a double value
     * according to the current byte order.  </p>
     *
     * @param index The index from which the bytes will be read
     * @return The double value at the given index
     * @throws IndexOutOfBoundsException If {@code index} is negative or not smaller than the buffer's limit, minus seven
     */
    double getDouble(int index);

    
Relative get method for reading an int value.


Reads the next four bytes at this buffer's current position, composing them into an int value according to the current byte order,
and then increments the position by four.  


Throws:
Returns:The int value at the buffer's current position
/**
     * <p>Relative <em>get</em> method for reading an int value.</p>
     *
     * <p>Reads the next four bytes at this buffer's current position, composing them into an int value according to the current byte order,
     * and then increments the position by four.  </p>
     *
     * @return The int value at the buffer's current position
     * @throws java.nio.BufferUnderflowException If there are fewer than four bytes remaining in this buffer
     */
    int getInt();

    
Absolute get method for reading an int value. 
 Reads four bytes at the given index, composing them into a int value
according to the current byte order.  


Params:
  • index – The index from which the bytes will be read
Throws:
Returns:The int value at the given index
/**
     * Absolute <em>get</em> method for reading an int value. <p> Reads four bytes at the given index, composing them into a int value
     * according to the current byte order.  </p>
     *
     * @param index The index from which the bytes will be read
     * @return The int value at the given index
     * @throws IndexOutOfBoundsException If {@code index} is negative or not smaller than the buffer's limit, minus three
     */
    int getInt(int index);

    
Returns this buffer's position.

Returns:The position of this buffer
/**
     * Returns this buffer's position.
     *
     * @return The position of this buffer
     */
    int position();

    
Sets this buffer's limit.  If the position is larger than the new limit then it is set to the new limit.  If the mark is defined and
larger than the new limit then it is discarded.

Params:
  • newLimit – The new limit value; must be non-negative and no larger than this buffer's capacity
Throws:
Returns:This buffer
/**
     * Sets this buffer's limit.  If the position is larger than the new limit then it is set to the new limit.  If the mark is defined and
     * larger than the new limit then it is discarded.
     *
     * @param newLimit The new limit value; must be non-negative and no larger than this buffer's capacity
     * @return This buffer
     * @throws IllegalArgumentException If the preconditions on {@code newLimit} do not hold
     */
    ByteBuf limit(int newLimit);


    
Creates a new, read-only byte buffer that shares this buffer's content.


The content of the new buffer will be that of this buffer.  Changes to this buffer's content will be visible in the new buffer;
the new buffer itself, however, will be read-only and will not allow the shared content to be modified.  The two buffers' position,
limit, and mark values will be independent.


The new buffer's capacity, limit, position, and mark values will be identical to those of this buffer.


Returns:The new, read-only byte buffer
/**
     * <p>Creates a new, read-only byte buffer that shares this buffer's content.</p>
     *
     * <p>The content of the new buffer will be that of this buffer.  Changes to this buffer's content will be visible in the new buffer;
     * the new buffer itself, however, will be read-only and will not allow the shared content to be modified.  The two buffers' position,
     * limit, and mark values will be independent.</p>
     *
     * <p>The new buffer's capacity, limit, position, and mark values will be identical to those of this buffer.</p>
     *
     * @return The new, read-only byte buffer
     */
    ByteBuf asReadOnly();


    
Creates a new byte buffer that shares this buffer's content.


The content of the new buffer will be that of this buffer.  Changes to this buffer's content will be visible in the new buffer,
and vice versa; the two buffers' position, limit, and mark values will be independent.


The new buffer's capacity, limit, position, and mark values will be identical to those of this buffer.  The new buffer will be
direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only. 


Returns:The new byte buffer
/**
     * <p>Creates a new byte buffer that shares this buffer's content.</p>
     *
     * <p>The content of the new buffer will be that of this buffer.  Changes to this buffer's content will be visible in the new buffer,
     * and vice versa; the two buffers' position, limit, and mark values will be independent.</p>
     *
     * <p>The new buffer's capacity, limit, position, and mark values will be identical to those of this buffer.  The new buffer will be
     * direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only. </p>
     *
     * @return The new byte buffer
     */
    ByteBuf duplicate();

    
Gets the underlying NIO ByteBuffer. Changes made directly to the returned buffer will be reflected in this instance, and vice versa, so be careful. This method should really only be used so that the underlying buffer can be passed directly to a socket channel. 
Returns:the underlying ByteBuffer
/**
     * Gets the underlying NIO {@code ByteBuffer}.  Changes made directly to the returned buffer will be reflected in this instance, and
     * vice versa, so be careful.  This method should really only be used so that the underlying buffer can be passed directly to a socket
     * channel.
     *
     * @return the underlying ByteBuffer
     */
    ByteBuffer asNIO();

    
Gets the current reference count, which starts at 0.

Returns:the current count, which must be greater than or equal to 0
/**
     * Gets the current reference count, which starts at 0.
     *
     * @return the current count, which must be greater than or equal to 0
     */
    int getReferenceCount();

    
Retain an additional reference to this object.  All retained references must be released, or there will be a leak.

Returns:this
/**
     * Retain an additional reference to this object.  All retained references must be released, or there will be a leak.
     *
     * @return this
     */
    ByteBuf retain();

    
Release a reference to this object.

Throws:
  • IllegalStateException – if the reference count is already 0
/**
     * Release a reference to this object.
     * @throws java.lang.IllegalStateException if the reference count is already 0
     */
    void release();
}