比特币源码阅读(CRPCTable)

1.CRPCTable的作用和相关方法实现

1.1.作用：维持所能执行的RPC命令集合

src/rpc/server.h

/**
 * Bitcoin RPC command dispatcher.
 */
class CRPCTable
{
private:
    std::map<std::string, const CRPCCommand*> mapCommands;
public:
    CRPCTable();
    const CRPCCommand* operator[](const std::string& name) const;
    std::string help(const std::string& name, const JSONRPCRequest& helpreq) const;

    /**
     * Execute a method.
     * @param request The JSONRPCRequest to execute
     * @returns Result of the call.
     * @throws an exception (UniValue) when an error happens.
     */
    UniValue execute(const JSONRPCRequest &request) const;

    /**
    * Returns a list of registered commands
    * @returns List of registered commands.
    */
    std::vector<std::string> listCommands() const;


    /**
     * Appends a CRPCCommand to the dispatch table.
     *
     * Returns false if RPC server is already running (dump concurrency protection).
     *
     * Commands cannot be overwritten (returns false).
     *
     * Commands with different method names but the same callback function will
     * be considered aliases, and only the first registered method name will
     * show up in the help text command listing. Aliased commands do not have
     * to have the same behavior. Server and client code can distinguish
     * between calls based on method name, and aliased commands can also
     * register different names, types, and numbers of parameters.
     */
    bool appendCommand(const std::string& name, const CRPCCommand* pcmd);
};

1.2.operator[]的实现：

src/rpc/server.cpp

const CRPCCommand *CRPCTable::operator[](const std::string &name) const
{
    std::map<std::string, const CRPCCommand*>::const_iterator it = mapCommands.find(name);
    if (it == mapCommands.end())
        return nullptr;
    return (*it).second;
}

1.3.往CRPCTable添加命令：

src/rpc/server.cpp

bool CRPCTable::appendCommand(const std::string& name, const CRPCCommand* pcmd)
{
    if (IsRPCRunning())
        return false;

    // don't allow overwriting for now
    std::map<std::string, const CRPCCommand*>::const_iterator it = mapCommands.find(name);
    if (it != mapCommands.end())
        return false;

    mapCommands[name] = pcmd;  //operator[]
    return true;
}

1.4. 命令的执行

src/rpc/server.cpp

UniValue CRPCTable::execute(const JSONRPCRequest &request) const
{
    // Return immediately if in warmup
    {
        LOCK(cs_rpcWarmup);
        if (fRPCInWarmup)
            throw JSONRPCError(RPC_IN_WARMUP, rpcWarmupStatus);
    }

    // Find method
    const CRPCCommand *pcmd = tableRPC[request.strMethod];
    if (!pcmd)
        throw JSONRPCError(RPC_METHOD_NOT_FOUND, "Method not found");

    g_rpcSignals.PreCommand(*pcmd);

    try
    {
        // Execute, convert arguments to array if necessary
        if (request.params.isObject()) {
            return pcmd->actor(transformNamedArguments(request, pcmd->argNames));
        } else {
            return pcmd->actor(request);
        }
    }
    catch (const std::exception& e)
    {
        throw JSONRPCError(RPC_MISC_ERROR, e.what());
    }
}

2. 往CRPCTable添加RPC命令的调用堆栈

2.1. bitcoind命令入口main函数

src/bitcoind.cpp

int main(int argc, char* argv[])
{
    return (AppInit(argc, argv) ? EXIT_SUCCESS : EXIT_FAILURE);
}

2.2. AppInit函数

src/bitcoind.cpp

static bool AppInit(int argc, char* argv[])
{
  fRet = AppInitMain();
}

2.3. AppInitMain函数

src/init.cpp

bool AppInitMain()
{
  RegisterAllCoreRPCCommands(tableRPC);
}

2.4. RegisterAllCoreRPCCommands函数

src/rpc/register.h

static inline void RegisterAllCoreRPCCommands(CRPCTable &t)
{
    RegisterBlockchainRPCCommands(t);
    RegisterNetRPCCommands(t);
    RegisterMiscRPCCommands(t);
    RegisterMiningRPCCommands(t);
    RegisterRawTransactionRPCCommands(t);
}