/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.io.memory;

import static org.neo4j.io.memory.ByteBuffers.allocate;
import static org.neo4j.io.memory.ByteBuffers.releaseBuffer;
import static org.neo4j.memory.EmptyMemoryTracker.INSTANCE;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import org.neo4j.memory.MemoryTracker;

/**
 * Autocloseable container for heap byte buffer that will release memory from memory tracker on close.
 */
public final class HeapScopedBuffer implements ScopedBuffer {
    public static final HeapScopedBuffer EMPTY_BUFFER =
            new HeapScopedBuffer(allocate(0, ByteOrder.LITTLE_ENDIAN, INSTANCE).asReadOnlyBuffer(), INSTANCE);

    private final ByteBuffer buffer;
    private final MemoryTracker memoryTracker;
    private boolean closed;

    public HeapScopedBuffer(int capacity, ByteOrder byteOrder, MemoryTracker memoryTracker) {
        this(allocate(capacity, byteOrder, memoryTracker), memoryTracker);
    }

    private HeapScopedBuffer(ByteBuffer buffer, MemoryTracker memoryTracker) {
        this.buffer = buffer;
        this.memoryTracker = memoryTracker;
    }

    @Override
    public ByteBuffer getBuffer() {
        return buffer;
    }

    @Override
    public void close() {
        if (!closed) {
            releaseBuffer(buffer, memoryTracker);
            closed = true;
        }
    }
}
