/*
编写一个程序, 创建多个线程, 每个线程负责对一个共享链表进行搜索操作。要求实现线程间的同步, 确保每个线程搜索链表时不会干扰其他线程的工作。
*/
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

typedef struct node
{
    char name[32];
    struct node *next;
} Node;

Node *head; // 定义头节点

void *find(void *data)
{
    int n = 0; // 标识待查询内容在链表中的索引号
    char *name = (char *)data;
    pthread_mutex_lock(&mutex);
    // 查询
    Node *p = head->next;
    while (p != NULL)
    {
        if (strcmp(p->name, name) == 0)
        {
            printf("%s 在链表的索引为 %d\n", name, n);
            pthread_mutex_unlock(&mutex);

            return NULL;
        }

        n++;
        p = p->next;
    }
    printf("%s 在链表中未找到\n", name);
    pthread_mutex_unlock(&mutex);

    return NULL;
}

// 添加节点
void add_node(Node *head, char *name)
{
    Node *p = head;
    while (p->next != NULL)
        p = p->next;
    Node *new_node = (Node *)malloc(sizeof(Node));
    if (NULL == new_node)
    {
        perror("malloc error");
        return;
    }
    memset(new_node, 0, sizeof(Node)); // 初始化新节点为默认值
    strcpy(new_node->name, name);
    p->next = new_node;
}

int main(int argc, char const *argv[])
{
    head = (Node *)malloc(sizeof(Node));
    if (NULL == head)
    {
        perror("malloc error");
        return 1;
    }
    memset(head, 0, sizeof(Node));

    add_node(head, "a");
    add_node(head, "b");
    add_node(head, "c");
    add_node(head, "d");

    // 待查询字符表，包含查询的字符顺序
    char *alphabet[4] = {"a", "e", "d", "b"};

    pthread_t t[4];
    for (int i = 0; i < 4; i++)
    {
        pthread_create(&t[i], NULL, find, (void *)alphabet[i]);
    }

    for (int i = 0; i < 4; i++)
    {
        pthread_join(t[i], NULL);
    }

    pthread_mutex_destroy(&mutex);

    return 0;
}