| /* |
| * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com> |
| * and other copyright owners as documented in the project's IP log. |
| * |
| * This program and the accompanying materials are made available |
| * under the terms of the Eclipse Distribution License v1.0 which |
| * accompanies this distribution, is reproduced below, and is |
| * available at http://www.eclipse.org/org/documents/edl-v10.php |
| * |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that the following |
| * conditions are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * - Neither the name of the Eclipse Foundation, Inc. nor the |
| * names of its contributors may be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
| * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
| * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package org.eclipse.jgit.storage.file; |
| |
| import java.text.MessageFormat; |
| import java.util.Arrays; |
| |
| import org.eclipse.jgit.errors.CorruptObjectException; |
| import org.eclipse.jgit.internal.JGitText; |
| import org.eclipse.jgit.lib.ObjectId; |
| import org.eclipse.jgit.storage.file.PackIndex.MutableEntry; |
| |
| /** |
| * <p> |
| * Reverse index for forward pack index. Provides operations based on offset |
| * instead of object id. Such offset-based reverse lookups are performed in |
| * O(log n) time. |
| * </p> |
| * |
| * @see PackIndex |
| * @see PackFile |
| */ |
| public class PackReverseIndex { |
| /** Index we were created from, and that has our ObjectId data. */ |
| private final PackIndex index; |
| |
| /** |
| * (offset31, truly) Offsets accommodating in 31 bits. |
| */ |
| private final int offsets32[]; |
| |
| /** |
| * Offsets not accommodating in 31 bits. |
| */ |
| private final long offsets64[]; |
| |
| /** Position of the corresponding {@link #offsets32} in {@link #index}. */ |
| private final int nth32[]; |
| |
| /** Position of the corresponding {@link #offsets64} in {@link #index}. */ |
| private final int nth64[]; |
| |
| /** |
| * Create reverse index from straight/forward pack index, by indexing all |
| * its entries. |
| * |
| * @param packIndex |
| * forward index - entries to (reverse) index. |
| */ |
| public PackReverseIndex(final PackIndex packIndex) { |
| index = packIndex; |
| |
| final long cnt = index.getObjectCount(); |
| final long n64 = index.getOffset64Count(); |
| final long n32 = cnt - n64; |
| if (n32 > Integer.MAX_VALUE || n64 > Integer.MAX_VALUE |
| || cnt > 0xffffffffL) |
| throw new IllegalArgumentException( |
| JGitText.get().hugeIndexesAreNotSupportedByJgitYet); |
| |
| offsets32 = new int[(int) n32]; |
| offsets64 = new long[(int) n64]; |
| nth32 = new int[offsets32.length]; |
| nth64 = new int[offsets64.length]; |
| |
| int i32 = 0; |
| int i64 = 0; |
| for (final MutableEntry me : index) { |
| final long o = me.getOffset(); |
| if (o < Integer.MAX_VALUE) |
| offsets32[i32++] = (int) o; |
| else |
| offsets64[i64++] = o; |
| } |
| |
| Arrays.sort(offsets32); |
| Arrays.sort(offsets64); |
| |
| int nth = 0; |
| for (final MutableEntry me : index) { |
| final long o = me.getOffset(); |
| if (o < Integer.MAX_VALUE) |
| nth32[Arrays.binarySearch(offsets32, (int) o)] = nth++; |
| else |
| nth64[Arrays.binarySearch(offsets64, o)] = nth++; |
| } |
| } |
| |
| /** |
| * Search for object id with the specified start offset in this pack |
| * (reverse) index. |
| * |
| * @param offset |
| * start offset of object to find. |
| * @return object id for this offset, or null if no object was found. |
| */ |
| public ObjectId findObject(final long offset) { |
| if (offset <= Integer.MAX_VALUE) { |
| final int i32 = Arrays.binarySearch(offsets32, (int) offset); |
| if (i32 < 0) |
| return null; |
| return index.getObjectId(nth32[i32]); |
| } else { |
| final int i64 = Arrays.binarySearch(offsets64, offset); |
| if (i64 < 0) |
| return null; |
| return index.getObjectId(nth64[i64]); |
| } |
| } |
| |
| /** |
| * Search for the next offset to the specified offset in this pack (reverse) |
| * index. |
| * |
| * @param offset |
| * start offset of previous object (must be valid-existing |
| * offset). |
| * @param maxOffset |
| * maximum offset in a pack (returned when there is no next |
| * offset). |
| * @return offset of the next object in a pack or maxOffset if provided |
| * offset was the last one. |
| * @throws CorruptObjectException |
| * when there is no object with the provided offset. |
| */ |
| public long findNextOffset(final long offset, final long maxOffset) |
| throws CorruptObjectException { |
| if (offset <= Integer.MAX_VALUE) { |
| final int i32 = Arrays.binarySearch(offsets32, (int) offset); |
| if (i32 < 0) |
| throw new CorruptObjectException( |
| MessageFormat.format( |
| JGitText.get().cantFindObjectInReversePackIndexForTheSpecifiedOffset, |
| Long.valueOf(offset))); |
| |
| if (i32 + 1 == offsets32.length) { |
| if (offsets64.length > 0) |
| return offsets64[0]; |
| return maxOffset; |
| } |
| return offsets32[i32 + 1]; |
| } else { |
| final int i64 = Arrays.binarySearch(offsets64, offset); |
| if (i64 < 0) |
| throw new CorruptObjectException( |
| MessageFormat.format( |
| JGitText.get().cantFindObjectInReversePackIndexForTheSpecifiedOffset, |
| Long.valueOf(offset))); |
| |
| if (i64 + 1 == offsets64.length) |
| return maxOffset; |
| return offsets64[i64 + 1]; |
| } |
| } |
| } |