RevCommitList.java

/*
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> 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;
import org.eclipse.jgit.revwalk.filter.RevFilter;

/**
 * An ordered list of {@link org.eclipse.jgit.revwalk.RevCommit} subclasses.
 *
 * @param <E>
 *            type of subclass of RevCommit the list is storing.
 */
public class RevCommitList<E extends RevCommit> extends RevObjectList<E> {
    private RevWalk walker;

    /** {@inheritDoc} */
    @Override
    public void clear() {
        super.clear();
        walker = null;
    }

    /**
     * Apply a flag to all commits matching the specified filter.
     * <p>
     * Same as <code>applyFlag(matching, flag, 0, size())</code>, but without
     * the incremental behavior.
     *
     * @param matching
     *            the filter to test commits with. If the filter includes a
     *            commit it will have the flag set; if the filter does not
     *            include the commit the flag will be unset.
     * @param flag
     *            the flag to apply (or remove). Applications are responsible
     *            for allocating this flag from the source RevWalk.
     * @throws java.io.IOException
     *             revision filter needed to read additional objects, but an
     *             error occurred while reading the pack files or loose objects
     *             of the repository.
     * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
     *             revision filter needed to read additional objects, but an
     *             object was not of the correct type. Repository corruption may
     *             have occurred.
     * @throws org.eclipse.jgit.errors.MissingObjectException
     *             revision filter needed to read additional objects, but an
     *             object that should be present was not found. Repository
     *             corruption may have occurred.
     */
    public void applyFlag(RevFilter matching, RevFlag flag)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException {
        applyFlag(matching, flag, 0, size());
    }

    /**
     * Apply a flag to all commits matching the specified filter.
     * <p>
     * This version allows incremental testing and application, such as from a
     * background thread that needs to periodically halt processing and send
     * updates to the UI.
     *
     * @param matching
     *            the filter to test commits with. If the filter includes a
     *            commit it will have the flag set; if the filter does not
     *            include the commit the flag will be unset.
     * @param flag
     *            the flag to apply (or remove). Applications are responsible
     *            for allocating this flag from the source RevWalk.
     * @param rangeBegin
     *            first commit within the list to begin testing at, inclusive.
     *            Must not be negative, but may be beyond the end of the list.
     * @param rangeEnd
     *            last commit within the list to end testing at, exclusive. If
     *            smaller than or equal to <code>rangeBegin</code> then no
     *            commits will be tested.
     * @throws java.io.IOException
     *             revision filter needed to read additional objects, but an
     *             error occurred while reading the pack files or loose objects
     *             of the repository.
     * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
     *             revision filter needed to read additional objects, but an
     *             object was not of the correct type. Repository corruption may
     *             have occurred.
     * @throws org.eclipse.jgit.errors.MissingObjectException
     *             revision filter needed to read additional objects, but an
     *             object that should be present was not found. Repository
     *             corruption may have occurred.
     */
    public void applyFlag(final RevFilter matching, final RevFlag flag,
            int rangeBegin, int rangeEnd) throws MissingObjectException,
            IncorrectObjectTypeException, IOException {
        final RevWalk w = flag.getRevWalk();
        rangeEnd = Math.min(rangeEnd, size());
        while (rangeBegin < rangeEnd) {
            int index = rangeBegin;
            Block s = contents;
            while (s.shift > 0) {
                final int i = index >> s.shift;
                index -= i << s.shift;
                s = (Block) s.contents[i];
            }

            while (rangeBegin++ < rangeEnd && index < BLOCK_SIZE) {
                final RevCommit c = (RevCommit) s.contents[index++];
                if (matching.include(w, c))
                    c.add(flag);
                else
                    c.remove(flag);
            }
        }
    }

    /**
     * Remove the given flag from all commits.
     * <p>
     * Same as <code>clearFlag(flag, 0, size())</code>, but without the
     * incremental behavior.
     *
     * @param flag
     *            the flag to remove. Applications are responsible for
     *            allocating this flag from the source RevWalk.
     */
    public void clearFlag(RevFlag flag) {
        clearFlag(flag, 0, size());
    }

    /**
     * Remove the given flag from all commits.
     * <p>
     * This method is actually implemented in terms of:
     * <code>applyFlag(RevFilter.NONE, flag, rangeBegin, rangeEnd)</code>.
     *
     * @param flag
     *            the flag to remove. Applications are responsible for
     *            allocating this flag from the source RevWalk.
     * @param rangeBegin
     *            first commit within the list to begin testing at, inclusive.
     *            Must not be negative, but may be beyond the end of the list.
     * @param rangeEnd
     *            last commit within the list to end testing at, exclusive. If
     *            smaller than or equal to <code>rangeBegin</code> then no
     *            commits will be tested.
     */
    public void clearFlag(final RevFlag flag, final int rangeBegin,
            final int rangeEnd) {
        try {
            applyFlag(RevFilter.NONE, flag, rangeBegin, rangeEnd);
        } catch (IOException e) {
            // Never happen. The filter we use does not throw any
            // exceptions, for any reason.
        }
    }

    /**
     * Find the next commit that has the given flag set.
     *
     * @param flag
     *            the flag to test commits against.
     * @param begin
     *            first commit index to test at. Applications may wish to begin
     *            at 0, to test the first commit in the list.
     * @return index of the first commit at or after index <code>begin</code>
     *         that has the specified flag set on it; -1 if no match is found.
     */
    public int indexOf(RevFlag flag, int begin) {
        while (begin < size()) {
            int index = begin;
            Block s = contents;
            while (s.shift > 0) {
                final int i = index >> s.shift;
                index -= i << s.shift;
                s = (Block) s.contents[i];
            }

            while (begin++ < size() && index < BLOCK_SIZE) {
                final RevCommit c = (RevCommit) s.contents[index++];
                if (c.has(flag))
                    return begin;
            }
        }
        return -1;
    }

    /**
     * Find the next commit that has the given flag set.
     *
     * @param flag
     *            the flag to test commits against.
     * @param begin
     *            first commit index to test at. Applications may wish to begin
     *            at <code>size()-1</code>, to test the last commit in the
     *            list.
     * @return index of the first commit at or before index <code>begin</code>
     *         that has the specified flag set on it; -1 if no match is found.
     */
    public int lastIndexOf(RevFlag flag, int begin) {
        begin = Math.min(begin, size() - 1);
        while (begin >= 0) {
            int index = begin;
            Block s = contents;
            while (s.shift > 0) {
                final int i = index >> s.shift;
                index -= i << s.shift;
                s = (Block) s.contents[i];
            }

            while (begin-- >= 0 && index >= 0) {
                final RevCommit c = (RevCommit) s.contents[index--];
                if (c.has(flag))
                    return begin;
            }
        }
        return -1;
    }

    /**
     * Set the revision walker this list populates itself from.
     *
     * @param w
     *            the walker to populate from.
     * @see #fillTo(int)
     */
    public void source(RevWalk w) {
        walker = w;
    }

    /**
     * Is this list still pending more items?
     *
     * @return true if {@link #fillTo(int)} might be able to extend the list
     *         size when called.
     */
    public boolean isPending() {
        return walker != null;
    }

    /**
     * Ensure this list contains at least a specified number of commits.
     * <p>
     * The revision walker specified by {@link #source(RevWalk)} is pumped until
     * the given number of commits are contained in this list. If there are
     * fewer total commits available from the walk then the method will return
     * early. Callers can test the final size of the list by {@link #size()} to
     * determine if the high water mark specified was met.
     *
     * @param highMark
     *            number of commits the caller wants this list to contain when
     *            the fill operation is complete.
     * @throws java.io.IOException
     *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
     * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
     *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
     * @throws org.eclipse.jgit.errors.MissingObjectException
     *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
     */
    @SuppressWarnings("unchecked")
    public void fillTo(int highMark) throws MissingObjectException,
            IncorrectObjectTypeException, IOException {
        if (walker == null || size > highMark)
            return;

        RevCommit c = walker.next();
        if (c == null) {
            walker = null;
            return;
        }
        enter(size, (E) c);
        add((E) c);

        while (size <= highMark) {
            int index = size;
            Block s = contents;
            while (index >> s.shift >= BLOCK_SIZE) {
                s = new Block(s.shift + BLOCK_SHIFT);
                s.contents[0] = contents;
                contents = s;
            }
            while (s.shift > 0) {
                final int i = index >> s.shift;
                index -= i << s.shift;
                if (s.contents[i] == null)
                    s.contents[i] = new Block(s.shift - BLOCK_SHIFT);
                s = (Block) s.contents[i];
            }

            final Object[] dst = s.contents;
            while (size <= highMark && index < BLOCK_SIZE) {
                c = walker.next();
                if (c == null) {
                    walker = null;
                    return;
                }
                enter(size++, (E) c);
                dst[index++] = c;
            }
        }
    }

    /**
     * Ensures all commits until the given commit are loaded. The revision
     * walker specified by {@link #source(RevWalk)} is pumped until the
     * specified commit is loaded. Callers can test the final size of the list
     * by {@link #size()} to determine if the high water mark specified was met.
     * <p>
     *
     * @param commitToLoad
     *            commit the caller wants this list to contain when the fill
     *            operation is complete.
     * @param highMark
     *            maximum number of commits the caller wants this list to
     *            contain when the fill operation is complete. If highMark is 0
     *            the walk is pumped until the specified commit or the end of
     *            the walk is reached.
     * @throws java.io.IOException
     *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
     * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
     *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
     * @throws org.eclipse.jgit.errors.MissingObjectException
     *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
     */
    @SuppressWarnings("unchecked")
    public void fillTo(RevCommit commitToLoad, int highMark)
            throws MissingObjectException, IncorrectObjectTypeException,
            IOException {
        if (walker == null || commitToLoad == null
                || (highMark > 0 && size > highMark))
            return;

        RevCommit c = walker.next();
        if (c == null) {
            walker = null;
            return;
        }
        enter(size, (E) c);
        add((E) c);

        while ((highMark == 0 || size <= highMark) && !c.equals(commitToLoad)) {
            int index = size;
            Block s = contents;
            while (index >> s.shift >= BLOCK_SIZE) {
                s = new Block(s.shift + BLOCK_SHIFT);
                s.contents[0] = contents;
                contents = s;
            }
            while (s.shift > 0) {
                final int i = index >> s.shift;
                index -= i << s.shift;
                if (s.contents[i] == null)
                    s.contents[i] = new Block(s.shift - BLOCK_SHIFT);
                s = (Block) s.contents[i];
            }

            final Object[] dst = s.contents;
            while ((highMark == 0 || size <= highMark) && index < BLOCK_SIZE
                    && !c.equals(commitToLoad)) {
                c = walker.next();
                if (c == null) {
                    walker = null;
                    return;
                }
                enter(size++, (E) c);
                dst[index++] = c;
            }
        }
    }

    /**
     * Optional callback invoked when commits enter the list by fillTo.
     * <p>
     * This method is only called during {@link #fillTo(int)}.
     *
     * @param index
     *            the list position this object will appear at.
     * @param e
     *            the object being added (or set) into the list.
     */
    protected void enter(int index, E e) {
        // Do nothing by default.
    }
}