Redis源码分析（一）_adlist.c

最新推荐文章于 2022-03-25 16:54:51 发布

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最新推荐文章于 2022-03-25 16:54:51 发布

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分类专栏：【Redis】文章标签： redis 源码分析

本文链接：https://blog.youkuaiyun.com/u013139008/article/details/79638470

本文主要探讨Redis源码中adlist.c模块，重点关注结点的void *value字段的灵活处理，包括自定义复制、释放和匹配操作。此外，文章还提到通过宏函数增强链表的基本操作，如获取长度、头尾结点，以及采用迭代器实现的遍历功能。同时，资源管理是关键，如创建和释放链表、迭代器的配对使用确保了内存的正确管理。

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/* adlist.c - A generic doubly linked list implementation
 *
 * Copyright (c) 2006-2010, Salvatore Sanfilippo <antirez at gmail dot com>
 * 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 Redis 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.
 */
#ifdef _WIN32
#include "Win32_Interop/Win32_Portability.h"
#include "Win32_Interop/win32_types.h"
#endif

#include <stdlib.h>
#include "adlist.h"
#include "zmalloc.h"

/* Create a new list. The created list can be freed with
 * AlFreeList(), but private value of every node need to be freed
 * by the user before to call AlFreeList().
 *
 * On error, NULL is returned. Otherwise the pointer to the new list. */
list *listCreate(void)
{
    struct list *list;

    // 申请的内存的大小是sizeof(*list)，不是sizeof(list)，后者是指针大小
    if ((list = zmalloc(sizeof(*list))) == NULL)
        return NULL;

    // 对list结构体的所有成员进行赋初值
    list->head = list->tail = NULL;
    list->len = 0;
    list->dup = NULL;
    list->free = NULL;
    list->match = NULL;
    return list;
}

/* Free the whole list.
 *
 * This function can't fail. */
void listRelease(list *list)
{
    PORT_ULONG len;
    listNode *current, *next;

    current = list->head;
    len = list->len;
    w