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- /*
- * 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;
- }
- }
- }
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