区块链研习社比特币源码研读班
今天研读第四步，AppInit初始化

一总体结构图

image.png

二AppInit函数

bool AppInit(int argc, char* argv[])
{
    boost::thread_group threadGroup;
    CScheduler scheduler;

    bool fRet = false;

   //《1 解析main函数的命令行参数，放入gArgs变量中
    gArgs.ParseParameters(argc, argv);

    if (gArgs.IsArgSet("-?") || gArgs.IsArgSet("-h") ||  gArgs.IsArgSet("-help") || gArgs.IsArgSet("-version"))
    {
        //《2 打印信息增加包名，版本信息
        std::string strUsage = strprintf(_("%s Daemon"), _(PACKAGE_NAME)) + " " + _("version") + " " + FormatFullVersion() + "\n";

        
        if (gArgs.IsArgSet("-version"))
        {
            //《3 打印信息增加搬迁证书信息信息
            strUsage += FormatParagraph(LicenseInfo());
        }
        else
        {
           //《4 增加命令行参数使用帮助信息
            strUsage += "\n" + _("Usage:") + "\n" +
                  "  bitcoind [options]                     " + strprintf(_("Start %s Daemon"), _(PACKAGE_NAME)) + "\n";

            strUsage += "\n" + HelpMessage(HMM_BITCOIND);
        }

        fprintf(stdout, "%s", strUsage.c_str());
        return true;
    }

    try
    {
        //《5 检查区块数据保存目录是否存在
        if (!fs::is_directory(GetDataDir(false)))
        {
            fprintf(stderr, "Error: Specified data directory \"%s\" does not exist.\n", gArgs.GetArg("-datadir", "").c_str());
            return false;
        }
         //《6 读取配置文件
        try
        {
            gArgs.ReadConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME));
        } catch (const std::exception& e) {
            fprintf(stderr,"Error reading configuration file: %s\n", e.what());
            return false;
        }

        //《7  检查测试参数有效
        try {
            SelectParams(ChainNameFromCommandLine());
        } catch (const std::exception& e) {
            fprintf(stderr, "Error: %s\n", e.what());
            return false;
        }

        // 《8  检查命令行的引导参数有异常，必须带- 或 /
        for (int i = 1; i < argc; i++) {
            if (!IsSwitchChar(argv[i][0])) {
                fprintf(stderr, "Error: Command line contains unexpected token '%s', see bitcoind -h for a list of options.\n", argv[i]);
                exit(EXIT_FAILURE);
            }
        }

        // 《8 bitcoind 命令行，启用server参数为默认值true
        gArgs.SoftSetBoolArg("-server", true);
        // Set this early so that parameter interactions go to console

        InitLogging();//初始化日志格式
        InitParameterInteraction();//初始化交互参数
        if (!AppInitBasicSetup())//设置异常报告重定向， 启动网络，中断处理等
        {
            // InitError will have been called with detailed error, which ends up on console
            exit(EXIT_FAILURE);
        }

         //《9 应用程序初始化参数交互
        if (!AppInitParameterInteraction())
        {
            // InitError will have been called with detailed error, which ends up on console
            exit(EXIT_FAILURE);
        }

       //《10  应用程序参数完整性检查
        if (!AppInitSanityChecks())
        {
            // InitError will have been called with detailed error, which ends up on console
            exit(EXIT_FAILURE);
        }

        //《11  开启守护进程
        if (gArgs.GetBoolArg("-daemon", false))
        {
#if HAVE_DECL_DAEMON
            fprintf(stdout, "Bitcoin server starting\n");

            // Daemonize
            if (daemon(1, 0)) { // don't chdir (1), do close FDs (0)
                fprintf(stderr, "Error: daemon() failed: %s\n", strerror(errno));
                return false;
            }
#else
            fprintf(stderr, "Error: -daemon is not supported on this operating system\n");
            return false;
#endif // HAVE_DECL_DAEMON
        }

        // 《12  开启守护进程后，锁住区块数据文件夹
        if (!AppInitLockDataDirectory())
        {
            // If locking the data directory failed, exit immediately
            exit(EXIT_FAILURE);
        }
        fRet = AppInitMain(threadGroup, scheduler);//初始化线程池和调度器
    }
    catch (const std::exception& e) {
        PrintExceptionContinue(&e, "AppInit()");
    } catch (...) {
        PrintExceptionContinue(nullptr, "AppInit()");
    }

    if (!fRet)
    {
        //初始化初始化线程池和调度器失败，主动退出
        Interrupt(threadGroup); //中断线程池
        threadGroup.join_all();//等待所有线程退出
    } else {
        WaitForShutdown(&threadGroup);//等待threadGroup句柄可用，既等待程序正常退出
    }
    Shutdown(); //关闭程序

    return fRet;
}