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- /*
- * 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(final 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(final 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(final RevObject c) {
- objects[tailIndex++] = c;
- }
-
- RevObject pop() {
- return objects[headIndex++];
- }
-
- void clear() {
- next = null;
- headIndex = 0;
- tailIndex = 0;
- }
- }
- }
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