| /* |
| * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> |
| * and other copyright owners as documented in the project's IP log. |
| * |
| * This program and the accompanying materials are made available |
| * under the terms of the Eclipse Distribution License v1.0 which |
| * accompanies this distribution, is reproduced below, and is |
| * available at http://www.eclipse.org/org/documents/edl-v10.php |
| * |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that the following |
| * conditions are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * - Neither the name of the Eclipse Foundation, Inc. nor the |
| * names of its contributors may be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
| * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
| * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| 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; |
| } |
| } |
| } |