DateRevQueue.java

/*
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>,
 * Copyright (C) 2013, Gustaf Lundh <gustaf.lundh@sonymobile.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.revwalk;

import java.io.IOException;

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

/**
 * A queue of commits sorted by commit time order.
 */
public class DateRevQueue extends AbstractRevQueue {
    private static final int REBUILD_INDEX_COUNT = 1000;

    private Entry head;

    private Entry free;

    private int inQueue;

    private int sinceLastIndex;

    private Entry[] index;

    private int first;

    private int last = -1;

    /** Create an empty date queue. */
    public DateRevQueue() {
        super(false);
    }

    DateRevQueue(boolean firstParent) {
        super(firstParent);
    }

    DateRevQueue(Generator s) throws MissingObjectException,
            IncorrectObjectTypeException, IOException {
        super(s.firstParent);
        for (;;) {
            final RevCommit c = s.next();
            if (c == null)
                break;
            add(c);
        }
    }

    /** {@inheritDoc} */
    @Override
    public void add(RevCommit c) {
        sinceLastIndex++;
        if (++inQueue > REBUILD_INDEX_COUNT
                && sinceLastIndex > REBUILD_INDEX_COUNT)
            buildIndex();

        Entry q = head;
        final long when = c.commitTime;

        if (first <= last && index[first].commit.commitTime > when) {
            int low = first, high = last;
            while (low <= high) {
                int mid = (low + high) >>> 1;
                int t = index[mid].commit.commitTime;
                if (t < when)
                    high = mid - 1;
                else if (t > when)
                    low = mid + 1;
                else {
                    low = mid - 1;
                    break;
                }
            }
            low = Math.min(low, high);
            while (low > first && when == index[low].commit.commitTime)
                --low;
            q = index[low];
        }

        final Entry n = newEntry(c);
        if (q == null || (q == head && when > q.commit.commitTime)) {
            n.next = q;
            head = n;
        } else {
            Entry p = q.next;
            while (p != null && p.commit.commitTime > when) {
                q = p;
                p = q.next;
            }
            n.next = q.next;
            q.next = n;
        }
    }

    /** {@inheritDoc} */
    @Override
    public RevCommit next() {
        final Entry q = head;
        if (q == null)
            return null;

        if (index != null && q == index[first])
            index[first++] = null;
        inQueue--;

        head = q.next;
        freeEntry(q);
        return q.commit;
    }

    private void buildIndex() {
        sinceLastIndex = 0;
        first = 0;
        index = new Entry[inQueue / 100 + 1];
        int qi = 0, ii = 0;
        for (Entry q = head; q != null; q = q.next) {
            if (++qi % 100 == 0)
                index[ii++] = q;
        }
        last = ii - 1;
    }

    /**
     * Peek at the next commit, without removing it.
     *
     * @return the next available commit; null if there are no commits left.
     */
    public RevCommit peek() {
        return head != null ? head.commit : null;
    }

    /** {@inheritDoc} */
    @Override
    public void clear() {
        head = null;
        free = null;
        index = null;
        inQueue = 0;
        sinceLastIndex = 0;
        last = -1;
    }

    @Override
    boolean everbodyHasFlag(int f) {
        for (Entry q = head; q != null; q = q.next) {
            if ((q.commit.flags & f) == 0)
                return false;
        }
        return true;
    }

    @Override
    boolean anybodyHasFlag(int f) {
        for (Entry q = head; q != null; q = q.next) {
            if ((q.commit.flags & f) != 0)
                return true;
        }
        return false;
    }

    @Override
    int outputType() {
        return outputType | SORT_COMMIT_TIME_DESC;
    }

    /** {@inheritDoc} */
    @Override
    public String toString() {
        final StringBuilder s = new StringBuilder();
        for (Entry q = head; q != null; q = q.next)
            describe(s, q.commit);
        return s.toString();
    }

    private Entry newEntry(RevCommit c) {
        Entry r = free;
        if (r == null)
            r = new Entry();
        else
            free = r.next;
        r.commit = c;
        return r;
    }

    private void freeEntry(Entry e) {
        e.next = free;
        free = e;
    }

    static class Entry {
        Entry next;

        RevCommit commit;
    }
}