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 handlers
noui_connect();
return (AppInit(argc, argv) ? EXIT_SUCCESS : EXIT_FAILURE);
}
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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);
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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 datadir
if (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;
}
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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;
}
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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;
}
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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;
}
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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 here
gArgs.SoftSetBoolArg("-server", true);
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7.初始化日志
// Set this early so that parameter interactions go to console
InitLogging();
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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();
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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 console
return false;
}
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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 console
return false;
}
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10.完整性检查
if (!AppInitSanityChecks())
{
// InitError will have been called with detailed error, which ends up on console
return false;
}
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11.判断是否需要在后台运行(Daemonize)
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.锁住Bitcoin Core数据目录
// Lock data directory after daemonization
if (!AppInitLockDataDirectory())
{
// If locking the data directory failed, exit immediately
return false;
}
13.Bitcoin Core的主要初始化工作
fRet = AppInitMain();
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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);