jgit/org.eclipse.jgit.storage.dht/src/org/eclipse/jgit/storage/dht/spi/RepositoryIndexTable.java

/*
 * Copyright (C) 2011, Google Inc.
 * and other copyright owners as documented in the project's IP log.
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 * 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
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package org.eclipse.jgit.storage.dht.spi;

import java.util.concurrent.TimeoutException;

import org.eclipse.jgit.storage.dht.DhtException;
import org.eclipse.jgit.storage.dht.RepositoryKey;
import org.eclipse.jgit.storage.dht.RepositoryName;

/**
 * Maps a repository name from a URL, to the internal {@link RepositoryKey}.
 * <p>
 * The internal identifier is used for all data storage, as its part of the row
 * keys for each data row that makes up the repository. By using an internal
 * key, repositories can be efficiently renamed in O(1) time, without changing
 * existing data rows.
 */
public interface RepositoryIndexTable {
	/**
	 * Find a repository by name.
	 *
	 * @param name
	 *            name of the repository, from the URL.
	 * @return the internal key; null if not found.
	 * @throws DhtException
	 * @throws TimeoutException
	 */
	public RepositoryKey get(RepositoryName name) throws DhtException,
			TimeoutException;

	/**
	 * Atomically record the association of name to identifier.
	 * <p>
	 * This method must use some sort of transaction system to ensure the name
	 * either points at {@code key} when complete, or fails fast with an
	 * exception if the name is used by a different key. This may require
	 * running some sort of lock management service in parallel to the database.
	 *
	 * @param name
	 *            name of the repository.
	 * @param key
	 *            internal key used to find the repository's data.
	 * @throws DhtException
	 * @throws TimeoutException
	 */
	public void putUnique(RepositoryName name, RepositoryKey key)
			throws DhtException, TimeoutException;

	/**
	 * Remove the association of a name to an identifier.
	 * <p>
	 * This method must use some sort of transaction system to ensure the name
	 * is removed only if it currently references {@code key}. This may require
	 * running some sort of lock management service in parallel to the database.
	 *
	 * @param name
	 *            name of the repository.
	 * @param key
	 *            internal key defining the repository.
	 * @throws DhtException
	 * @throws TimeoutException
	 */
	public void remove(RepositoryName name, RepositoryKey key)
			throws DhtException, TimeoutException;
}