ReachabilityChecker.java

/*
 * Copyright (C) 2019, Google LLC. 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.revwalk;

import java.io.IOException;
import java.util.Collection;
import java.util.Optional;
import java.util.stream.Stream;

import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;

/**
 * Check if a commit is reachable from a collection of starting commits.
 * <p>
 * Note that this checks the reachability of commits (and tags). Trees, blobs or
 * any other object will cause IncorrectObjectTypeException exceptions.
 *
 * @since 5.4
 */
public interface ReachabilityChecker {

    /**
     * Check if all targets are reachable from the {@code starter} commits.
     * <p>
     * Caller should parse the objectIds (preferably with
     * {@code walk.parseCommit()} and handle missing/incorrect type objects
     * before calling this method.
     *
     * @param targets
     *            commits to reach.
     * @param starters
     *            known starting points.
     * @return An unreachable target if at least one of the targets is
     *         unreachable. An empty optional if all targets are reachable from
     *         the starters.
     *
     * @throws MissingObjectException
     *             if any of the incoming objects doesn't exist in the
     *             repository.
     * @throws IncorrectObjectTypeException
     *             if any of the incoming objects is not a commit or a tag.
     * @throws IOException
     *             if any of the underlying indexes or readers can not be
     *             opened.
     *
     * @deprecated see {{@link #areAllReachable(Collection, Stream)}
     */
    @Deprecated
    default Optional<RevCommit> areAllReachable(Collection<RevCommit> targets,
                       Collection<RevCommit> starters) throws MissingObjectException,
            IncorrectObjectTypeException, IOException {
        return areAllReachable(targets, starters.stream());
    }

    /**
     * Check if all targets are reachable from the {@code starter} commits.
     * <p>
     * Caller should parse the objectIds (preferably with
     * {@code walk.parseCommit()} and handle missing/incorrect type objects
     * before calling this method.
     *
     * @param targets
     *            commits to reach.
     * @param starters
     *            known starting points.
     * @return An unreachable target if at least one of the targets is
     *         unreachable. An empty optional if all targets are reachable from
     *         the starters.
     *
     * @throws MissingObjectException
     *             if any of the incoming objects doesn't exist in the
     *             repository.
     * @throws IncorrectObjectTypeException
     *             if any of the incoming objects is not a commit or a tag.
     * @throws IOException
     *             if any of the underlying indexes or readers can not be
     *             opened.
     * @since 5.6
     */
    Optional<RevCommit> areAllReachable(Collection<RevCommit> targets,
            Stream<RevCommit> starters)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException;
}