| /* |
| * 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; |
| |
| abstract class BlockRevQueue extends AbstractRevQueue { |
| protected BlockFreeList free; |
| |
| /** |
| * Create an empty revision queue. |
| * |
| * @param firstParent |
| * whether only first-parent links should be followed when |
| * walking |
| */ |
| protected BlockRevQueue(boolean firstParent) { |
| super(firstParent); |
| free = new BlockFreeList(); |
| } |
| |
| BlockRevQueue(Generator s) throws MissingObjectException, |
| IncorrectObjectTypeException, IOException { |
| super(s.firstParent); |
| free = new BlockFreeList(); |
| outputType = s.outputType(); |
| s.shareFreeList(this); |
| for (;;) { |
| final RevCommit c = s.next(); |
| if (c == null) |
| break; |
| add(c); |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| * <p> |
| * Reconfigure this queue to share the same free list as another. |
| * <p> |
| * Multiple revision queues can be connected to the same free list, making |
| * it less expensive for applications to shuttle commits between them. This |
| * method arranges for the receiver to take from / return to the same free |
| * list as the supplied queue. |
| * <p> |
| * Free lists are not thread-safe. Applications must ensure that all queues |
| * sharing the same free list are doing so from only a single thread. |
| */ |
| @Override |
| public void shareFreeList(BlockRevQueue q) { |
| free = q.free; |
| } |
| |
| static final class BlockFreeList { |
| private Block next; |
| |
| Block newBlock() { |
| Block b = next; |
| if (b == null) |
| return new Block(); |
| next = b.next; |
| b.clear(); |
| return b; |
| } |
| |
| void freeBlock(Block b) { |
| b.next = next; |
| next = b; |
| } |
| |
| void clear() { |
| next = null; |
| } |
| } |
| |
| static final class Block { |
| static final int BLOCK_SIZE = 256; |
| |
| /** Next block in our chain of blocks; null if we are the last. */ |
| Block next; |
| |
| /** Our table of queued commits. */ |
| final RevCommit[] commits = new RevCommit[BLOCK_SIZE]; |
| |
| /** Next valid entry in {@link #commits}. */ |
| int headIndex; |
| |
| /** Next free entry in {@link #commits} for addition at. */ |
| int tailIndex; |
| |
| boolean isFull() { |
| return tailIndex == BLOCK_SIZE; |
| } |
| |
| boolean isEmpty() { |
| return headIndex == tailIndex; |
| } |
| |
| boolean canUnpop() { |
| return headIndex > 0; |
| } |
| |
| void add(RevCommit c) { |
| commits[tailIndex++] = c; |
| } |
| |
| void unpop(RevCommit c) { |
| commits[--headIndex] = c; |
| } |
| |
| RevCommit pop() { |
| return commits[headIndex++]; |
| } |
| |
| RevCommit peek() { |
| return commits[headIndex]; |
| } |
| |
| void clear() { |
| next = null; |
| headIndex = 0; |
| tailIndex = 0; |
| } |
| |
| void resetToMiddle() { |
| headIndex = tailIndex = BLOCK_SIZE / 2; |
| } |
| |
| void resetToEnd() { |
| headIndex = tailIndex = BLOCK_SIZE; |
| } |
| } |
| } |