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- /*
- * Copyright (C) 2012, Google Inc. 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 org.eclipse.jgit.lib.AnyObjectId;
- import org.eclipse.jgit.lib.ObjectIdOwnerMap;
-
- import com.googlecode.javaewah.EWAHCompressedBitmap;
-
- /**
- * Base implementation of the PackBitmapIndex.
- */
- abstract class BasePackBitmapIndex extends PackBitmapIndex {
- private final ObjectIdOwnerMap<StoredBitmap> bitmaps;
-
- BasePackBitmapIndex(ObjectIdOwnerMap<StoredBitmap> bitmaps) {
- this.bitmaps = bitmaps;
- }
-
- /** {@inheritDoc} */
- @Override
- public EWAHCompressedBitmap getBitmap(AnyObjectId objectId) {
- StoredBitmap sb = bitmaps.get(objectId);
- return sb != null ? sb.getBitmap() : null;
- }
-
- ObjectIdOwnerMap<StoredBitmap> getBitmaps() {
- return bitmaps;
- }
-
- /**
- * Data representation of the bitmap entry restored from a pack index. The
- * commit of the bitmap is the map key.
- */
- static final class StoredBitmap extends ObjectIdOwnerMap.Entry {
- private volatile Object bitmapContainer;
- private final int flags;
-
- StoredBitmap(AnyObjectId objectId, EWAHCompressedBitmap bitmap,
- StoredBitmap xorBitmap, int flags) {
- super(objectId);
- this.bitmapContainer = xorBitmap == null
- ? bitmap
- : new XorCompressedBitmap(bitmap, xorBitmap);
- this.flags = flags;
- }
-
- /**
- * Computes and returns the full bitmap.
- *
- * @return the full bitmap
- */
- EWAHCompressedBitmap getBitmap() {
- EWAHCompressedBitmap bitmap = getBitmapWithoutCaching();
- // Cache the result.
- bitmapContainer = bitmap;
- return bitmap;
- }
-
- /**
- * Compute and return the full bitmap, do NOT cache the expanded bitmap,
- * which saves memory and should only be used during bitmap creation in
- * garbage collection.
- *
- * @return the full bitmap
- */
- EWAHCompressedBitmap getBitmapWithoutCaching() {
- // Fast path to immediately return the expanded result.
- Object r = bitmapContainer;
- if (r instanceof EWAHCompressedBitmap)
- return (EWAHCompressedBitmap) r;
-
- // Expand the bitmap but not cache the result.
- XorCompressedBitmap xb = (XorCompressedBitmap) r;
- EWAHCompressedBitmap out = xb.bitmap;
- for (;;) {
- r = xb.xorBitmap.bitmapContainer;
- if (r instanceof EWAHCompressedBitmap) {
- out = out.xor((EWAHCompressedBitmap) r);
- out.trim();
- return out;
- }
- xb = (XorCompressedBitmap) r;
- out = out.xor(xb.bitmap);
- }
- }
-
- /** @return the flags associated with the bitmap */
- int getFlags() {
- return flags;
- }
- }
-
- private static final class XorCompressedBitmap {
- final EWAHCompressedBitmap bitmap;
- final StoredBitmap xorBitmap;
-
- XorCompressedBitmap(EWAHCompressedBitmap b, StoredBitmap xb) {
- bitmap = b;
- xorBitmap = xb;
- }
- }
- }
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