BranchTrackingStatus.java

/*
 * Copyright (C) 2011, Robin Stocker <robin@nibor.org>
 * Copyright (C) 2012, Matthias Sohn <matthias.sohn@sap.com> 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.lib;

import java.io.IOException;

import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.revwalk.RevWalkUtils;
import org.eclipse.jgit.revwalk.filter.RevFilter;

/**
 * Status of a branch's relation to its remote-tracking branch.
 */
public class BranchTrackingStatus {

    /**
     * Compute the tracking status for the <code>branchName</code> in
     * <code>repository</code>.
     *
     * @param repository
     *            the git repository to compute the status from
     * @param branchName
     *            the local branch
     * @return the tracking status, or null if it is not known
     * @throws java.io.IOException
     */
    public static BranchTrackingStatus of(Repository repository, String branchName)
            throws IOException {

        String shortBranchName = Repository.shortenRefName(branchName);
        String fullBranchName = Constants.R_HEADS + shortBranchName;
        BranchConfig branchConfig = new BranchConfig(repository.getConfig(),
                shortBranchName);

        String trackingBranch = branchConfig.getTrackingBranch();
        if (trackingBranch == null)
            return null;

        Ref tracking = repository.exactRef(trackingBranch);
        if (tracking == null)
            return null;

        Ref local = repository.exactRef(fullBranchName);
        if (local == null)
            return null;

        try (RevWalk walk = new RevWalk(repository)) {

            RevCommit localCommit = walk.parseCommit(local.getObjectId());
            RevCommit trackingCommit = walk.parseCommit(tracking.getObjectId());

            walk.setRevFilter(RevFilter.MERGE_BASE);
            walk.markStart(localCommit);
            walk.markStart(trackingCommit);
            RevCommit mergeBase = walk.next();

            walk.reset();
            walk.setRevFilter(RevFilter.ALL);
            int aheadCount = RevWalkUtils.count(walk, localCommit, mergeBase);
            int behindCount = RevWalkUtils.count(walk, trackingCommit,
                    mergeBase);

            return new BranchTrackingStatus(trackingBranch, aheadCount,
                    behindCount);
        }
    }

    private final String remoteTrackingBranch;

    private final int aheadCount;

    private final int behindCount;

    private BranchTrackingStatus(String remoteTrackingBranch, int aheadCount,
            int behindCount) {
        this.remoteTrackingBranch = remoteTrackingBranch;
        this.aheadCount = aheadCount;
        this.behindCount = behindCount;
    }

    /**
     * Get full remote-tracking branch name
     *
     * @return full remote-tracking branch name
     */
    public String getRemoteTrackingBranch() {
        return remoteTrackingBranch;
    }

    /**
     * Get number of commits that the local branch is ahead of the
     * remote-tracking branch
     *
     * @return number of commits that the local branch is ahead of the
     *         remote-tracking branch
     */
    public int getAheadCount() {
        return aheadCount;
    }

    /**
     * Get number of commits that the local branch is behind of the
     * remote-tracking branch
     *
     * @return number of commits that the local branch is behind of the
     *         remote-tracking branch
     */
    public int getBehindCount() {
        return behindCount;
    }
}