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C++负载均衡远程调用学习之HOOK注册机制

news 来源：原创 2025/5/3 6:14:03

1.larV0.7-hook流程的说明

2.larV0.7-TCP_server集成链接HOOK函数

3.larV0.7-TCP_client集成链接HOOK注册功能

1.larV0.7-hook流程的说明

### 7.1 数据库表相关查询方法实现

        我们先实现一些基本的数据表达查询方法：

> lars_dns/src/dns_route.cpp

```c
/*
*  return 0, 表示加载成功，version没有改变
*         1, 表示加载成功，version有改变
*         -1 表示加载失败
* */
int Route::load_version()
{
    //这里面只会有一条数据
    snprintf(_sql, 1000, "SELECT version from RouteVersion WHERE id = 1;");

    int ret = mysql_real_query(&_db_conn, _sql, strlen(_sql));
    if (ret)
    {
        fprintf(stderr, "load version error: %s\n", mysql_error(&_db_conn));
        return -1;
    }

    MYSQL_RES *result = mysql_store_result(&_db_conn);
    if (!result)
    {
        fprintf(stderr, "mysql store result: %s\n", mysql_error(&_db_conn));
        return -1;
    }

    long line_num = mysql_num_rows(result);
    if (line_num == 0)
    {
        fprintf(stderr, "No version in table RouteVersion: %s\n", mysql_error(&_db_conn));
        return -1;
    }

    MYSQL_ROW row = mysql_fetch_row(result);
    //得到version

    long new_version = atol(row[0]);

    if (new_version == this->_version)
    {
        //加载成功但是没有修改
        return 0;
    }
    this->_version = new_version;
    printf("now route version is %ld\n", this->_version);

    mysql_free_result(result);

    return 1;
}

2.larV0.7-TCP_server集成链接HOOK函数

//加载RouteData到_temp_pointer
int Route::load_route_data()
{
    _temp_pointer->clear();

    snprintf(_sql, 100, "SELECT * FROM RouteData;");

    int ret = mysql_real_query(&_db_conn, _sql, strlen(_sql));
    if (ret)
    {
        fprintf(stderr, "load version error: %s\n", mysql_error(&_db_conn));
        return -1;
    }

    MYSQL_RES *result = mysql_store_result(&_db_conn);
    if (!result)
    {
        fprintf(stderr, "mysql store result: %s\n", mysql_error(&_db_conn));
        return -1;
    }

    long line_num = mysql_num_rows(result);
    MYSQL_ROW row;
    for (long i = 0;i < line_num; ++i)
    {
        row = mysql_fetch_row(result);
        int modid = atoi(row[1]);
        int cmdid = atoi(row[2]);
        unsigned ip = atoi(row[3]);
        int port = atoi(row[4]);

        uint64_t key = ((uint64_t)modid << 32) + cmdid;
        uint64_t value = ((uint64_t)ip << 32) + port;

        (*_temp_pointer)[key].insert(value);
    }
    printf("load data to tmep succ! size is %lu\n", _temp_pointer->size());

    mysql_free_result(result);

    return 0;
}

3.larV0.7-TCP_client集成链接HOOK注册功能

//将temp_pointer的数据更新到data_pointer
void Route::swap()
{
    pthread_rwlock_wrlock(&_map_lock);
    route_map *temp = _data_pointer;
    _data_pointer = _temp_pointer;
    _temp_pointer = temp;
    pthread_rwlock_unlock(&_map_lock);
}

//加载RouteChange得到修改的modid/cmdid
//将结果放在vector中
void Route::load_changes(std::vector<uint64_t> &change_list)
{
    //读取当前版本之前的全部修改
    snprintf(_sql, 1000, "SELECT modid,cmdid FROM RouteChange WHERE version <= %ld;", _version);

    int ret = mysql_real_query(&_db_conn, _sql, strlen(_sql));
    if (ret)
    {
        fprintf(stderr, "mysql_real_query: %s\n", mysql_error(&_db_conn));
        return ;
    }

    MYSQL_RES *result = mysql_store_result(&_db_conn);
    if (!result)
    {
        fprintf(stderr, "mysql_store_result %s\n", mysql_error(&_db_conn));
        return ;
    }

    long lineNum = mysql_num_rows(result);
    if (lineNum == 0)
    {
        fprintf(stderr,  "No version in table ChangeLog: %s\n", mysql_error(&_db_conn));
        return ;
    }
    MYSQL_ROW row;
    for (long i = 0;i < lineNum; ++i)
    {
        row = mysql_fetch_row(result);
        int modid = atoi(row[0]);
        int cmdid = atoi(row[1]);
        uint64_t key = (((uint64_t)modid) << 32) + cmdid;
        change_list.push_back(key);
    }
    mysql_free_result(result);
}