curl multi接口示例

API请参考：http://curl.haxx.se/libcurl/c/libcurl-multi.html

官网sample参考：http://curl.haxx.se/libcurl/c/multi-single.html

下面是自己的一个multi接口select IO复用采集例子：

void CMultiGather::PerformRequests()
{
    int nStillRunnings = 0;
    while(CURLM_CALL_MULTI_PERFORM==
        curl_multi_perform(m_pMultiCURL, &nStillRunnings));
    if(0 == nStillRunnings)
    {
        usleep(10000);
        return;
    }

    //fd_set for read,write and exception
    fd_set fdread;
    fd_set fdwrite;
    fd_set fdexcep;
    FD_ZERO(&fdread);
    FD_ZERO(&fdwrite);
    FD_ZERO(&fdexcep);

    //fdset & select
    int maxfd = 0;
    long nTimeout = 0;
    CURLMcode nRetCode = curl_multi_fdset(m_pMultiCURL, &fdread, &fdwrite, &fdexcep, &maxfd);
    assert(nRetCode == CURLM_OK);
    nRetCode = curl_multi_timeout(m_pMultiCURL, &nTimeout);
    assert(nRetCode == CURLM_OK);
    if (nTimeout == -1 || nTimeout > 5000)
        nTimeout = 2000;

    if (maxfd == -1)
    {
        usleep(nTimeout*1000);
    }
    else
    {
        struct timeval T;
        T.tv_sec = nTimeout/1000;
        T.tv_usec = (nTimeout%1000)*1000;
        int rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &T);
        //assert(rc >= 0);
        if(rc > 0)
        {
            while(CURLM_CALL_MULTI_PERFORM ==
                curl_multi_perform(m_pMultiCURL, &nStillRunnings));
        }
    }
    /* check whether some conns are timeout or not.*/
    map<TConnInfo*,int>::iterator it = m_mConnStatus.begin();
    for(; it != m_mConnStatus.end(); it++)
    {
        TConnInfo* pConn = it->first;
        assert(pConn != NULL);
        if(it->second == CONN_BUSY)
        {
            assert(pConn->nStartTime > 0);
            time_t nTime = time(0) - pConn->nStartTime;
            if(nTime > pConn->pRequest->m_nTransferTimeout)
            {
                curl_multi_remove_handle(m_pMultiCURL, pConn->pEasyCURL);
                SaveConn(pConn, CURLE_OPERATION_TIMEDOUT);
                m_qFreeConn.push(pConn);
                pConn->nStartTime = 0;
                m_mConnStatus[pConn] = 0;
            }
        }
    }
}