ByteBufferWindow.java

/*
 * Copyright (C) 2008-2009, Google Inc.
 * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.internal.storage.file;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.zip.DataFormatException;
import java.util.zip.Inflater;

import org.eclipse.jgit.internal.storage.pack.PackOutputStream;

/**
 * A window for accessing git packs using a {@link ByteBuffer} for storage.
 *
 * @see ByteWindow
 */
final class ByteBufferWindow extends ByteWindow {
    private final ByteBuffer buffer;

    ByteBufferWindow(Pack pack, long o, ByteBuffer b) {
        super(pack, o, b.capacity());
        buffer = b;
    }

    /** {@inheritDoc} */
    @Override
    protected int copy(int p, byte[] b, int o, int n) {
        final ByteBuffer s = buffer.slice();
        s.position(p);
        n = Math.min(s.remaining(), n);
        s.get(b, o, n);
        return n;
    }

    @Override
    void write(PackOutputStream out, long pos, int cnt)
            throws IOException {
        final ByteBuffer s = buffer.slice();
        s.position((int) (pos - start));

        while (0 < cnt) {
            byte[] buf = out.getCopyBuffer();
            int n = Math.min(cnt, buf.length);
            s.get(buf, 0, n);
            out.write(buf, 0, n);
            cnt -= n;
        }
    }

    /** {@inheritDoc} */
    @Override
    protected int setInput(int pos, Inflater inf)
            throws DataFormatException {
        final ByteBuffer s = buffer.slice();
        s.position(pos);
        final byte[] tmp = new byte[Math.min(s.remaining(), 512)];
        s.get(tmp, 0, tmp.length);
        inf.setInput(tmp, 0, tmp.length);
        return tmp.length;
    }
}