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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.io;

import java.nio.ByteBuffer;

/**
 * A {@link RetainableByteBuffer} pool.
 * Acquired buffers must be released by calling {@link RetainableByteBuffer#release()} otherwise the memory they hold will
 * be leaked.
 */
public interface RetainableByteBufferPool
{
    /**
     * Acquires a memory buffer from the pool.
     * @param size The size of the buffer. The returned buffer will have at least this capacity.
     * @param direct true if a direct memory buffer is needed, false otherwise.
     * @return a memory buffer with position and size set to 0.
     */
    RetainableByteBuffer acquire(int size, boolean direct);

    void clear();

    static RetainableByteBufferPool from(ByteBufferPool byteBufferPool)
    {
        return new NotRetainedByteBufferPool(byteBufferPool);
    }

    class NotRetainedByteBufferPool implements RetainableByteBufferPool
    {
        private final ByteBufferPool _byteBufferPool;

        public NotRetainedByteBufferPool(ByteBufferPool byteBufferPool)
        {
            _byteBufferPool = byteBufferPool;
        }

        @Override
        public RetainableByteBuffer acquire(int size, boolean direct)
        {
            ByteBuffer byteBuffer = _byteBufferPool.acquire(size, direct);
            RetainableByteBuffer retainableByteBuffer = new RetainableByteBuffer(byteBuffer, this::release);
            retainableByteBuffer.acquire();
            return retainableByteBuffer;
        }

        private void release(RetainableByteBuffer retainedBuffer)
        {
            _byteBufferPool.release(retainedBuffer.getBuffer());
        }

        @Override
        public void clear()
        {
        }

        @Override
        public String toString()
        {
            return String.format("NonRetainableByteBufferPool@%x{%s}", hashCode(), _byteBufferPool.toString());
        }
    }
}