| /* |
| * 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.spi; |
| |
| import java.util.Collection; |
| import java.util.Map; |
| import java.util.Set; |
| |
| import org.eclipse.jgit.generated.storage.dht.proto.GitStore.ChunkMeta; |
| import org.eclipse.jgit.storage.dht.AsyncCallback; |
| import org.eclipse.jgit.storage.dht.ChunkKey; |
| import org.eclipse.jgit.storage.dht.DhtException; |
| import org.eclipse.jgit.storage.dht.PackChunk; |
| import org.eclipse.jgit.storage.dht.StreamingCallback; |
| |
| /** |
| * Stores object data in compressed pack format. |
| * <p> |
| * Each chunk stores multiple objects, using the highly compressed and Git |
| * native pack file format. Chunks are sized during insertion, but average |
| * around 1 MB for historical chunks, and may be as small as a few KB for very |
| * recent chunks that were written in small bursts. |
| * <p> |
| * Objects whose compressed form is too large to fit into a single chunk are |
| * fragmented across multiple chunks, and the fragment information is used to |
| * put them back together in the correct order. Since the fragmenting occurs |
| * after data compression, random access to bytes of the large object is not |
| * currently possible. |
| * <p> |
| * Chunk keys are very well distributed, by embedding a uniformly random number |
| * at the start of the key, and also including a small time component. This |
| * layout permits chunks to be evenly spread across a cluster of disks or |
| * servers in a round-robin fashion (based on a hash of the leading bytes), but |
| * also offers some chance for older chunks to be located near each other and |
| * have that part of the storage system see less activity over time. |
| */ |
| public interface ChunkTable { |
| /** |
| * Asynchronously load one or more chunks |
| * <p> |
| * Callers are responsible for breaking up very large collections of chunk |
| * keys into smaller units, based on the reader's batch size option. Since |
| * chunks typically 1 MB each, 10-20 keys is a reasonable batch size, but |
| * depends on available JVM memory and performance of this method obtaining |
| * chunks from the database. |
| * |
| * @param options |
| * options to control reading. |
| * @param keys |
| * the chunk keys to obtain. |
| * @param callback |
| * receives the results when ready. If this is an instance of |
| * {@link StreamingCallback}, implementors should try to deliver |
| * results early. |
| */ |
| public void get(Context options, Set<ChunkKey> keys, |
| AsyncCallback<Collection<PackChunk.Members>> callback); |
| |
| /** |
| * Asynchronously load one or more chunk meta fields. |
| * <p> |
| * Usually meta is loaded by {@link #get(Context, Set, AsyncCallback)}, but |
| * some uses may require looking up the fragment data without having the |
| * entire chunk. |
| * |
| * @param options |
| * options to control reading. |
| * @param keys |
| * the chunk keys to obtain. |
| * @param callback |
| * receives the results when ready. If this is an instance of |
| * {@link StreamingCallback}, implementors should try to deliver |
| * results early. |
| */ |
| public void getMeta(Context options, Set<ChunkKey> keys, |
| AsyncCallback<Map<ChunkKey, ChunkMeta>> callback); |
| |
| /** |
| * Put some (or all) of a single chunk. |
| * <p> |
| * The higher level storage layer typically stores chunks in pieces. Its |
| * common to first store the data, then much later store the fragments and |
| * index. Sometimes all of the members are ready at once, and can be put |
| * together as a single unit. This method handles both approaches to storing |
| * a chunk. |
| * <p> |
| * Implementors must use a partial writing approach, for example: |
| * |
| * <pre> |
| * ColumnUpdateList list = ...; |
| * if (chunk.getChunkData() != null) |
| * list.addColumn("chunk_data", chunk.getChunkData()); |
| * if (chunk.getChunkIndex() != null) |
| * list.addColumn("chunk_index", chunk.getChunkIndex()); |
| * if (chunk.getFragments() != null) |
| * list.addColumn("fragments", chunk.getFragments()); |
| * createOrUpdateRow(chunk.getChunkKey(), list); |
| * </pre> |
| * |
| * @param chunk |
| * description of the chunk to be stored. |
| * @param buffer |
| * buffer to enqueue the put onto. |
| * @throws DhtException |
| * if the buffer flushed and an enqueued operation failed. |
| */ |
| public void put(PackChunk.Members chunk, WriteBuffer buffer) |
| throws DhtException; |
| |
| /** |
| * Completely remove a chunk and all of its data elements. |
| * <p> |
| * Chunk removal should occur as quickly as possible after the flush has |
| * completed, as the caller has already ensured the chunk is not in use. |
| * |
| * @param key |
| * key of the chunk to remove. |
| * @param buffer |
| * buffer to enqueue the remove onto. |
| * @throws DhtException |
| * if the buffer flushed and an enqueued operation failed. |
| */ |
| public void remove(ChunkKey key, WriteBuffer buffer) throws DhtException; |
| } |