코드 3-10 TCPSocket에 Select 사용하기

fd_set* SocketUtil::FillSetFromVector(
    fd_set& outSet,
    const vector<TCPSocketPtr>* inSockets)
{
    if (inSockets)
    {
        FD_ZERO(&outSet);
        for (const TCPSocketPtr& socket : *inSockets)
        {
            FD_SET(socket->mSocket, &outSet);
        }
        return &outSet;
    }
    else return nullptr;
}
 
void SocketUtil::FillVectorFromSet(
    vector<TCPSocketPtr>* outSockets,
    const vector<TCPSocketPtr>* inSockets,
    const fd_set& inSet)
{
    if (inSockets && outSockets)
    {
        outSockets->clear();
        for (const TCPSocketPtr& socket : *inSockets)
        {
            if (FD_ISSET(socket->mSocket, &inSet))
                outSockets->push_back(socket);
        }
    }
}
 
int SocketUtil::Select(
    const vector<TCPSocketPtr>* inReadSet,
    vector<TCPSocketPtr>* outReadSet,
    const vector<TCPSocketPtr>* inWriteSet,
    vector<TCPSocketPtr>* outWriteSet,
    const vector<TCPSocketPtr>* inExceptSet,
    vector<TCPSocketPtr>* outExceptSet)
{
    // 받은 vector로 fd_set을 채움
    fd_set read, write, except;
    fd_set* readPtr = FillSetFromVector(read, inReadSet);
    fd_set* writePtr = FillSetFromVector(write, inWriteSet);
    fd_set* exceptPtr = FillSetFromVector(except, inExceptSet);
    int toRet = select(0, readPtr, writePtr, exceptPtr, nullptr);
 
    if (toRet > 0)
    {
        FillVectorFromSet(outReadSet, inReadSet, read);
        FillVectorFromSet(outWriteSet, inWriteSet, write);
        FillVectorFromSet(outExceptSet, inExceptSet, except);
    }
    return toRet;
}