| /* |
| * 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.util.zip.DataFormatException; |
| import java.util.zip.Inflater; |
| |
| import org.eclipse.jgit.internal.storage.pack.PackOutputStream; |
| |
| /** |
| * A window of data currently stored within a cache. |
| * <p> |
| * All bytes in the window can be assumed to be "immediately available", that is |
| * they are very likely already in memory, unless the operating system's memory |
| * is very low and has paged part of this process out to disk. Therefore copying |
| * bytes from a window is very inexpensive. |
| * </p> |
| */ |
| abstract class ByteWindow { |
| protected final Pack pack; |
| |
| protected final long start; |
| |
| protected final long end; |
| |
| /** |
| * Constructor for ByteWindow. |
| * |
| * @param p |
| * a {@link org.eclipse.jgit.internal.storage.file.Pack}. |
| * @param s |
| * where the byte window starts in the pack file |
| * @param n |
| * size of the byte window |
| */ |
| protected ByteWindow(Pack p, long s, int n) { |
| pack = p; |
| start = s; |
| end = start + n; |
| } |
| |
| final int size() { |
| return (int) (end - start); |
| } |
| |
| final boolean contains(Pack neededPack, long neededPos) { |
| return pack == neededPack && start <= neededPos && neededPos < end; |
| } |
| |
| /** |
| * Copy bytes from the window to a caller supplied buffer. |
| * |
| * @param pos |
| * offset within the file to start copying from. |
| * @param dstbuf |
| * destination buffer to copy into. |
| * @param dstoff |
| * offset within <code>dstbuf</code> to start copying into. |
| * @param cnt |
| * number of bytes to copy. This value may exceed the number of |
| * bytes remaining in the window starting at offset |
| * <code>pos</code>. |
| * @return number of bytes actually copied; this may be less than |
| * <code>cnt</code> if <code>cnt</code> exceeded the number of |
| * bytes available. |
| */ |
| final int copy(long pos, byte[] dstbuf, int dstoff, int cnt) { |
| return copy((int) (pos - start), dstbuf, dstoff, cnt); |
| } |
| |
| /** |
| * Copy bytes from the window to a caller supplied buffer. |
| * |
| * @param pos |
| * offset within the window to start copying from. |
| * @param dstbuf |
| * destination buffer to copy into. |
| * @param dstoff |
| * offset within <code>dstbuf</code> to start copying into. |
| * @param cnt |
| * number of bytes to copy. This value may exceed the number of |
| * bytes remaining in the window starting at offset |
| * <code>pos</code>. |
| * @return number of bytes actually copied; this may be less than |
| * <code>cnt</code> if <code>cnt</code> exceeded the number of |
| * bytes available. |
| */ |
| protected abstract int copy(int pos, byte[] dstbuf, int dstoff, int cnt); |
| |
| abstract void write(PackOutputStream out, long pos, int cnt) |
| throws IOException; |
| |
| final int setInput(long pos, Inflater inf) throws DataFormatException { |
| return setInput((int) (pos - start), inf); |
| } |
| |
| /** |
| * Set the input |
| * |
| * @param pos |
| * position |
| * @param inf |
| * an {@link java.util.zip.Inflater} object. |
| * @return size of the byte window |
| * @throws java.util.zip.DataFormatException |
| * if any. |
| */ |
| protected abstract int setInput(int pos, Inflater inf) |
| throws DataFormatException; |
| } |