第五步：tracker全局变量g_groups初始化(part 4)--tracker_load_groups_new函数分析

|------tracker_load_data        
    |-----tracker_load_groups_new
        |-----tracker_load_groups_new
        |-----tracker_save_groups
        |-----iniloadFormFile
        |-----tracker_mem_add_group_ex
        |-----iniFreeContext
    |-----tracker_load_storage_new
    |-----tracker_malloc_all_group_path_mbs
    |-----tracker_load_sync_timestamps

tracker_load_groups_new函数：

//从storage_groups_new.dat获取group数据
static int tracker_load_groups_new(FDFSGroups *pGroups, const char *data_path)
{
    IniContext iniContext; //保存从配置文件中读取信息
    FDFSGroupInfo *pGroup;
    char *group_name;
    int group_count;
    int result;
    int i;
    char section_name[64];
    TrackerClientInfo clientInfo;
    bool bInserted;

    if (!fileExists(STORAGE_GROUPS_LIST_FILENAME_NEW) && \//若_new不存在，并且_old存在
         fileExists(STORAGE_GROUPS_LIST_FILENAME_OLD))
    {
        logDebug("file: "__FILE__", line: %d, " \
            "convert old data file %s to new data file %s", \
            __LINE__, STORAGE_GROUPS_LIST_FILENAME_OLD, \
            STORAGE_GROUPS_LIST_FILENAME_NEW);
        if ((result=tracker_load_groups_old(pGroups, data_path)) == 0)//从_old文件中读取配置
        {
            if ((result=tracker_save_groups()) == 0)//把_old文件变成_new文件
            {
                unlink(STORAGE_GROUPS_LIST_FILENAME_OLD); //删除_old文件
            }
        }

        return result;
    }

    if ((result=iniLoadFromFile(STORAGE_GROUPS_LIST_FILENAME_NEW, \
            &iniContext)) != 0)//从新的group文件中获取配置信息，并保存到inicontext结构中
    {
        return result;
    }

    group_count = iniGetIntValue(GROUP_SECTION_NAME_GLOBAL, \//获取集群中group的数目
                GROUP_ITEM_GROUP_COUNT, \
                        &iniContext, -1);
    if (group_count < 0)
    {
        iniFreeContext(&iniContext);
        logError("file: "__FILE__", line: %d, " \
            "in the file \"%s/%s\", " \
            "item \"%s\" is not found", \
            __LINE__, data_path, \
            STORAGE_GROUPS_LIST_FILENAME_NEW, \
            GROUP_ITEM_GROUP_COUNT);
        return ENOENT;
    }

    for (i=1; i<=group_count; i++)//依次获取section name，如Group001
    {
        sprintf(section_name, "%s"GROUP_SECTION_NO_FORMAT, \
            GROUP_SECTION_NAME_PREFIX, i);

        group_name = iniGetStrValue(section_name, \//从section name中获取group name
                GROUP_ITEM_GROUP_NAME, &iniContext);
        if (group_name == NULL)
        {
            logError("file: "__FILE__", line: %d, " \
                "in the file \"%s/%s\", " \
                "item \"%s\" is not found", \
                __LINE__, data_path, \
                STORAGE_GROUPS_LIST_FILENAME_NEW, \
                GROUP_ITEM_GROUP_NAME);
            result = ENOENT;
            break;
        }

        memset(&clientInfo, 0, sizeof(TrackerClientInfo));
        if ((result=tracker_mem_add_group_ex(pGroups, &clientInfo, \//从pGroups中找到一个group，若没有找到，
                group_name, false, &bInserted)) != 0) //则，创建一个group，放入到pGroups中
        {
            break;
        }

        if (!bInserted)
        {
            logError("file: "__FILE__", line: %d, " \
                "in the file \"%s/%s\", " \
                "group \"%s\" is duplicate", \
                __LINE__, data_path, \
                STORAGE_GROUPS_LIST_FILENAME_NEW, \
                group_name);
            result = errno != 0 ? errno : EEXIST;
            break;
        }

        pGroup = clientInfo.pGroup;
        pGroup->storage_port = iniGetIntValue(section_name, \
            GROUP_ITEM_STORAGE_PORT, &iniContext, 0);
        pGroup->storage_http_port = iniGetIntValue(section_name, \
            GROUP_ITEM_STORAGE_HTTP_PORT, &iniContext, 0);
        pGroup->store_path_count = iniGetIntValue(section_name, \
            GROUP_ITEM_STORE_PATH_COUNT, &iniContext, 0);
        pGroup->subdir_count_per_path = iniGetIntValue(section_name, \
            GROUP_ITEM_SUBDIR_COUNT_PER_PATH, &iniContext, 0);
    }

    iniFreeContext(&iniContext);  //释放iniContext空间

    return result;
}

tracker_load_groups_new函数执行逻辑：
（1） 从配置文件中读取group配置信息并写入到group对象中。
（2） 为了兼容老的版本，先调用tracker_load_groups_old函数读取老的配置文件，并把数据写入新的配置文件。
（3） 读取新配置文件中的数据到iniContext结构中，再从iniContext中读取数据。
（4） 调用tracker_mem_add_group_ex函数把读取的数据写入到group对象中，tracker_mem_add_group_ex函数将在下一节详细分析。