org.eclipse.jgit.storage.dht/src/org/eclipse/jgit/storage/dht/ChunkKey.java

/*
 * 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
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 *   disclaimer in the documentation and/or other materials provided
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 *   names of its contributors may be used to endorse or promote
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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package org.eclipse.jgit.storage.dht;

import static org.eclipse.jgit.storage.dht.KeyUtils.format32;
import static org.eclipse.jgit.storage.dht.KeyUtils.parse32;
import static org.eclipse.jgit.util.RawParseUtils.decode;

import java.text.MessageFormat;

import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;

/** Unique identifier of a {@link PackChunk} in the DHT. */
public final class ChunkKey implements RowKey {
	static final int KEYLEN = 52;

	/**
	 * @param repo
	 * @param chunk
	 * @return the key
	 */
	public static ChunkKey create(RepositoryKey repo, ObjectId chunk) {
		return new ChunkKey(repo.asInt(), chunk);
	}

	/**
	 * @param key
	 * @return the key
	 */
	public static ChunkKey fromBytes(byte[] key) {
		return fromBytes(key, 0, key.length);
	}

	/**
	 * @param key
	 * @param ptr
	 * @param len
	 * @return the key
	 */
	public static ChunkKey fromBytes(byte[] key, int ptr, int len) {
		if (len != KEYLEN)
			throw new IllegalArgumentException(MessageFormat.format(
					DhtText.get().invalidChunkKey, decode(key, ptr, ptr + len)));

		int repo = parse32(key, ptr + 3);
		ObjectId chunk = ObjectId.fromString(key, ptr + 12);
		return new ChunkKey(repo, chunk);
	}

	/**
	 * @param key
	 * @return the key
	 */
	public static ChunkKey fromString(String key) {
		return fromBytes(Constants.encodeASCII(key));
	}

	private final int repo;

	private final ObjectId chunk;

	ChunkKey(int repo, ObjectId chunk) {
		this.repo = repo;
		this.chunk = chunk;
	}

	/** @return the repository that contains the chunk. */
	public RepositoryKey getRepositoryKey() {
		return RepositoryKey.fromInt(repo);
	}

	int getRepositoryId() {
		return repo;
	}

	/** @return unique SHA-1 describing the chunk. */
	public ObjectId getChunkHash() {
		return chunk;
	}

	public byte[] asBytes() {
		byte[] r = new byte[KEYLEN];
		chunk.copyTo(r, 12);
		format32(r, 3, repo);
		// bucket is the leading 2 digits of the SHA-1.
		r[11] = '.';
		r[2] = '.';
		r[1] = r[12 + 1];
		r[0] = r[12 + 0];
		return r;
	}

	public String asString() {
		return decode(asBytes());
	}

	@Override
	public int hashCode() {
		return chunk.hashCode();
	}

	@Override
	public boolean equals(Object other) {
		if (this == other)
			return true;
		if (other instanceof ChunkKey) {
			ChunkKey thisChunk = this;
			ChunkKey otherChunk = (ChunkKey) other;
			return thisChunk.repo == otherChunk.repo
					&& thisChunk.chunk.equals(otherChunk.chunk);
		}
		return false;
	}

	@Override
	public String toString() {
		return "chunk:" + asString();
	}
}