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- /*
- * Copyright (C) 2011, Google Inc.
- * 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.dht;
-
- import java.text.MessageFormat;
- import java.util.List;
-
- import org.eclipse.jgit.generated.storage.dht.proto.GitStore.ChunkMeta;
- import org.eclipse.jgit.generated.storage.dht.proto.GitStore.ChunkMeta.BaseChunk;
-
- class ChunkMetaUtil {
- static BaseChunk getBaseChunk(ChunkKey chunkKey, ChunkMeta meta,
- long position) throws DhtException {
- // Chunks are sorted by ascending relative_start order.
- // Thus for a pack sequence of: A B C, we have:
- //
- // -- C relative_start = 10,000
- // -- B relative_start = 20,000
- // -- A relative_start = 30,000
- //
- // Indicating that chunk C starts 10,000 bytes before us,
- // chunk B starts 20,000 bytes before us (and 10,000 before C),
- // chunk A starts 30,000 bytes before us (and 10,000 before B),
- //
- // If position falls within:
- //
- // -- C (10k), then position is between 0..10,000
- // -- B (20k), then position is between 10,000 .. 20,000
- // -- A (30k), then position is between 20,000 .. 30,000
-
- List<BaseChunk> baseChunks = meta.getBaseChunkList();
- int high = baseChunks.size();
- int low = 0;
- while (low < high) {
- final int mid = (low + high) >>> 1;
- final BaseChunk base = baseChunks.get(mid);
-
- if (position > base.getRelativeStart()) {
- low = mid + 1;
-
- } else if (mid == 0 || position == base.getRelativeStart()) {
- return base;
-
- } else if (baseChunks.get(mid - 1).getRelativeStart() < position) {
- return base;
-
- } else {
- high = mid;
- }
- }
-
- throw new DhtException(MessageFormat.format(
- DhtText.get().missingLongOffsetBase, chunkKey,
- Long.valueOf(position)));
- }
-
- static ChunkKey getNextFragment(ChunkMeta meta, ChunkKey chunkKey) {
- int cnt = meta.getFragmentCount();
- for (int i = 0; i < cnt - 1; i++) {
- ChunkKey key = ChunkKey.fromString(meta.getFragment(i));
- if (chunkKey.equals(key))
- return ChunkKey.fromString(meta.getFragment(i + 1));
- }
- return null;
- }
-
- private ChunkMetaUtil() {
- // Static utilities only, do not create instances.
- }
- }
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