设置InternetConnect的httpRequest连接数

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这几天在写http断点下传的实现，遇到问题:

* 开多个httpConnect, 每个Connect对应一个httpRequest, 如果超过4个httpConnect, sendHttpRequest时，阻塞住了.

只有前面的httpConnect任务完成后，被阻塞线程的sendHttpRequest才返回.

* 如果是下载不同服务器的文件, 则不会出现sendHttpRequest阻塞.

同事在stackoverflow上找到资料, 可以设置连接同一个服务器httpConnect的连接数为指定值，解决了这个问题。

整理一下。

HINTERNET   FCHttpRequest::create_connect(){    std::wstring        strTemp = L"";    HINTERNET           hConnect = NULL;    INTERNET_PORT       nPort = INTERNET_DEFAULT_HTTP_PORT;    CLsStopWatchTick    watch;    if (m_tmp_scheme == INTERNET_SCHEME_HTTPS)    {        nPort = INTERNET_DEFAULT_HTTPS_PORT;    }    watch.start();    hConnect = InternetConnect(m_http_session.GetHandle(), m_tmp_host.c_str(), nPort, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);    strTemp = ns_base::StringFormatV(        L"create_connect() : [FCHttpRequest = 0x%p][TID = %d] : hConnect = 0x%p\r\n",         this,        ::GetCurrentThreadId(),        hConnect);    watch.StopAndShow(strTemp.c_str(), TRUE);    if (NULL != hConnect)    {        /// 试验过了, 在程序开始设置 HINTERNE 为NULL, 那种http连接数, 是没用的        /// 只有在InternetConnect 所在线程中, 对有效httpConnect设置指定连接数, 才有效        SetHttpMaxConnectNumberEx(hConnect);    }    return hConnect;}

void FCHttpRequest::SetHttpMaxConnectNumberEx(HINTERNET hHandle){    BOOL    bRc = FALSE;    DWORD   dwErr = 0;    DWORD   dwHttpConnectMax = 50/*5 * 5 * 2 + 10*/; ///< (5条任务，一个任务5条线程) * 2 + 10(备用数目)    DWORD   dwRecvBufLen = 0;    BOOL    bRcOld = FALSE;    DWORD   dwHttpConnectOld = 0;   ///< INTERNET_OPTION_MAX_CONNS_PER_SERVER's cnt    BOOL    bRcOld10 = FALSE;    DWORD   dwHttpConnectOld10 = 0; ///< INTERNET_OPTION_MAX_CONNS_PER_1_0_SERVER's cnt    dwHttpConnectOld = 0;    bRc = GetHttpMaxConnectNumberEx(hHandle, INTERNET_OPTION_MAX_CONNS_PER_SERVER, dwHttpConnectOld);    dwErr = ::GetLastError();    _ASSERT(bRc);    dwHttpConnectOld10 = 0;    bRc = GetHttpMaxConnectNumberEx(hHandle, INTERNET_OPTION_MAX_CONNS_PER_1_0_SERVER, dwHttpConnectOld10);    dwErr = ::GetLastError();    _ASSERT(bRc);    /// 设置不成功, 设置成功的，取出来还是原来的值.    bRc = InternetSetOption(hHandle,INTERNET_OPTION_MAX_CONNS_PER_SERVER,&dwHttpConnectMax,sizeof(DWORD));    dwErr = ::GetLastError();//    _ASSERT(bRc); ///< 虽然为FALSE, 但是已经有效果了    bRc = InternetSetOption(hHandle,INTERNET_OPTION_MAX_CONNS_PER_1_0_SERVER,&dwHttpConnectMax,sizeof(DWORD));    dwErr = ::GetLastError();//    _ASSERT(bRc);  ///< 虽然为FALSE, 但是已经有效果了    /// 这里得到的连接数, 也是旧的, 但是从程序运行效果上看，已经生效了    dwHttpConnectOld = 0;    bRc = GetHttpMaxConnectNumberEx(hHandle, INTERNET_OPTION_MAX_CONNS_PER_SERVER, dwHttpConnectOld);    dwErr = ::GetLastError();    _ASSERT(bRc);    /// 这里得到的连接数, 也是旧的, 但是从程序运行效果上看，已经生效了    dwHttpConnectOld10 = 0;    bRc = GetHttpMaxConnectNumberEx(hHandle, INTERNET_OPTION_MAX_CONNS_PER_1_0_SERVER, dwHttpConnectOld10);    dwErr = ::GetLastError();    _ASSERT(bRc);}

BOOL FCHttpRequest::GetHttpMaxConnectNumberEx(HINTERNET hHandle, DWORD dwOption, DWORD& dwCnt){    BOOL    bRc = FALSE;    DWORD   dwRecvBufLen = 0;    dwCnt = 0;    bRc = InternetQueryOption(        NULL,         dwOption,         NULL,         &dwRecvBufLen);    if (!bRc)    {        _ASSERT(dwRecvBufLen == sizeof(DWORD));        bRc = ::InternetQueryOption(            NULL,             dwOption,            (LPVOID)&dwCnt,             &dwRecvBufLen);        _ASSERT(bRc);    }    return bRc;}

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