| /* |
| * 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; |
| |
| class BlockObjQueue { |
| private BlockFreeList free; |
| |
| private Block head; |
| |
| private Block tail; |
| |
| /** Create an empty queue. */ |
| BlockObjQueue() { |
| free = new BlockFreeList(); |
| } |
| |
| void add(RevObject c) { |
| Block b = tail; |
| if (b == null) { |
| b = free.newBlock(); |
| b.add(c); |
| head = b; |
| tail = b; |
| return; |
| } else if (b.isFull()) { |
| b = free.newBlock(); |
| tail.next = b; |
| tail = b; |
| } |
| b.add(c); |
| } |
| |
| RevObject next() { |
| final Block b = head; |
| if (b == null) |
| return null; |
| |
| final RevObject c = b.pop(); |
| if (b.isEmpty()) { |
| head = b.next; |
| if (head == null) |
| tail = null; |
| free.freeBlock(b); |
| } |
| return c; |
| } |
| |
| 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; |
| } |
| } |
| |
| static final class Block { |
| private 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 objects. */ |
| final RevObject[] objects = new RevObject[BLOCK_SIZE]; |
| |
| /** Next valid entry in {@link #objects}. */ |
| int headIndex; |
| |
| /** Next free entry in {@link #objects} for addition at. */ |
| int tailIndex; |
| |
| boolean isFull() { |
| return tailIndex == BLOCK_SIZE; |
| } |
| |
| boolean isEmpty() { |
| return headIndex == tailIndex; |
| } |
| |
| void add(RevObject c) { |
| objects[tailIndex++] = c; |
| } |
| |
| RevObject pop() { |
| return objects[headIndex++]; |
| } |
| |
| void clear() { |
| next = null; |
| headIndex = 0; |
| tailIndex = 0; |
| } |
| } |
| } |