主程序初始化

本文主要是介绍主程序初始化，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

比特币源码分析(三) - 主程序初始化

https://blog.csdn.net/yzpbright/article/details/81165546

本文是以一个整体的角度分析程序初始化过程中所做的操作，整个初始化过程如果要分开来细讲可以写好几篇，后面一系列文章会具体展开分析关键逻辑的源码。

主程序的入口函数main()在bitcoind.cpp文件中：

int main(int argc, char* argv[])
{SetupEnvironment();// Connect bitcoind signal handlersnoui_connect();return (AppInit(argc, argv) ? EXIT_SUCCESS : EXIT_FAILURE);
}

一步一步分析下。
一、SetupEnvironment() ，设置运行环境
二、noui_connect()，连接bitcoind信号处理器
三、AppInit(argc, argv)，应用初始化，这里有大量的初始化操作，接下来一步一步分析下这个函数的源码：

1.解析运行输入的参数，保存在 mapArgs 这个map容器中

    // If Qt is used, parameters/bitcoin.conf are parsed in qt/bitcoin.cpp's main()gArgs.ParseParameters(argc, argv);

2.处理查询帮助信息和版本信息的命令

    // Process help and version before taking care about datadirif (gArgs.IsArgSet("-?") || gArgs.IsArgSet("-h") ||  gArgs.IsArgSet("-help") || gArgs.IsArgSet("-version")){std::string strUsage = strprintf(_("%s Daemon"), _(PACKAGE_NAME)) + " " + _("version") + " " + FormatFullVersion() + "\n";if (gArgs.IsArgSet("-version")){strUsage += FormatParagraph(LicenseInfo());}else{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;}

3.检查应用的数据目录

        if (!fs::is_directory(GetDataDir(false))){fprintf(stderr, "Error: Specified data directory \"%s\" does not exist.\n", gArgs.GetArg("-datadir", "").c_str());return false;}

4.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;}

5.检查判断是主网还是测试网络，并设置区块链的全局参数

        // Check for -testnet or -regtest parameter (Params() calls are only valid after this clause)try {SelectParams(ChainNameFromCommandLine());} catch (const std::exception& e) {fprintf(stderr, "Error: %s\n", e.what());return false;}

6.设置server标识为true，即启用RPC服务

        // -server defaults to true for bitcoind but not for the GUI so do this heregArgs.SoftSetBoolArg("-server", true);

7.初始化日志

        // Set this early so that parameter interactions go to consoleInitLogging();

8.初始化参数交互，即根据规则将一些设置的参数转化为设置其他参数

       InitParameterInteraction();

8.建立Bitcoin Core的基础上下文环境

        if (!AppInitBasicSetup()){// InitError will have been called with detailed error, which ends up on consolereturn false;}

9.初始化参数交互，根据设置的参数做一些逻辑条件判断，根据情况显示相应的警告信息或者异常信息，也会有相关计算，将结果存储在内部变量中

        if (!AppInitParameterInteraction()){// InitError will have been called with detailed error, which ends up on consolereturn false;}

10.完整性检查

        if (!AppInitSanityChecks()){// InitError will have been called with detailed error, which ends up on consolereturn false;}

11.判断是否需要在后台运行(Daemonize)

        if (gArgs.GetBoolArg("-daemon", false)){#if HAVE_DECL_DAEMONfprintf(stdout, "Bitcoin server starting\n");// Daemonizeif (daemon(1, 0)) { // don't chdir (1), do close FDs (0)fprintf(stderr, "Error: daemon() failed: %s\n", strerror(errno));return false;}#elsefprintf(stderr, "Error: -daemon is not supported on this operating system\n");return false;#endif // HAVE_DECL_DAEMON}

12.锁住Bitcoin Core数据目录

        // Lock data directory after daemonizationif (!AppInitLockDataDirectory()){// If locking the data directory failed, exit immediatelyreturn false;}

13.Bitcoin Core的主要初始化工作

        fRet = AppInitMain();

14.监结束程序的请求，若有结束程序的请求，则完成结束程序的相关操作

    if (!fRet){Interrupt();} else {WaitForShutdown();}Shutdown();

P2P网络相关

CConnman
该类在src/net.h中声明，在src/net.cpp中实现。

class CConnman
{
public:

    enum NumConnections {
        CONNECTIONS_NONE = 0,
        CONNECTIONS_IN = (1U << 0),
        CONNECTIONS_OUT = (1U << 1),
        CONNECTIONS_ALL = (CONNECTIONS_IN | CONNECTIONS_OUT),
    };

    struct Options
    {
        ServiceFlags nLocalServices = NODE_NONE;
        int nMaxConnections = 0;
        int nMaxOutbound = 0;
        int nMaxAddnode = 0;
        int nMaxFeeler = 0;
        int nBestHeight = 0;
        CClientUIInterface* uiInterface = nullptr;
        NetEventsInterface* m_msgproc = nullptr;
        unsigned int nSendBufferMaxSize = 0;
        unsigned int nReceiveFloodSize = 0;
        uint64_t nMaxOutboundTimeframe = 0;
        uint64_t nMaxOutboundLimit = 0;
        std::vector<std::string> vSeedNodes;
        std::vector<CSubNet> vWhitelistedRange;
        std::vector<CService> vBinds, vWhiteBinds;
        bool m_use_addrman_outgoing = true;
        std::vector<std::string> m_specified_outgoing;
        std::vector<std::string> m_added_nodes;
    };

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该类是网络连接管理类，比较庞大，负责节点的启动、结束，推送消息，接收其他节点的连接等。

PeerLogicValidation
该类多重继承了两个接口类：CValidationInterface, 和 NetEventsInterface 。
CValidationInterface，主要是通知交易和区块相关的状态的改变。
NetEventsInterface，主要是处理从其他节点接收到的消息，发送消息，

/**
* Interface for message handling
*/
class NetEventsInterface
{
public:
    virtual bool ProcessMessages(CNode* pnode, std::atomic<bool>& interrupt) = 0;
    virtual bool SendMessages(CNode* pnode, std::atomic<bool>& interrupt) = 0;
    virtual void InitializeNode(CNode* pnode) = 0;
    virtual void FinalizeNode(NodeId id, bool& update_connection_time) = 0;
};

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除此之外，该类新增了几个方法，用于处理过期信息和剔除多余的对等节点

    void ConsiderEviction(CNode *pto, int64_t time_in_seconds);
    void CheckForStaleTipAndEvictPeers(const Consensus::Params &consensusParams);
    void EvictExtraOutboundPeers(int64_t time_in_seconds);

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