c++ - 知道 libcurl 是否完成文件下载的可靠方法是什么？

Question

我写了这个基础类:

class SteamHTTP
{
public:
    SteamHTTP();
    virtual  ~SteamHTTP();

    void DownloadAllGames(const wxString& username, wxGauge* progress);

private:
    CURL* m_curl;
    std::stringstream m_currentRequestString;

private:
    static size_t write_func(char *ptr, size_t size, size_t nmemb, void *userdata);
    static int progress_func(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow);
};


SteamHTTP::SteamHTTP()
{
    m_curl = curl_easy_init();
}

SteamHTTP::~SteamHTTP()
{
    curl_easy_cleanup(m_curl);
}

size_t SteamHTTP::write_func(char *data, size_t size, size_t nmemb, void *userdata)
{
    SteamHTTP* ptr = reinterpret_cast<SteamHTTP*>(userdata);
    ptr->m_currentRequestString << data;
    return size*nmemb;
}

int SteamHTTP::progress_func(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow)
{
    wxGauge* ptr = reinterpret_cast<wxGauge*>(clientp);
    ptr->SetValue(dlnow * 100.0f / dlnow );
    return 0;
}

void SteamHTTP::DownloadAllGames(const wxString& username, wxGauge* gauge)
{
    std::string url;
    CURLcode result;

    // Build URL
    url = std::string("http://steamcommunity.com/id/") + username.mbc_str() + std::string("/games?tab=all&xml=1");

    // Set URL
    curl_easy_setopt(m_curl, CURLOPT_URL, url.c_str());

    // Follow redirection
    curl_easy_setopt(m_curl, CURLOPT_FOLLOWLOCATION, 1);

    // Data Callback
    curl_easy_setopt(m_curl, CURLOPT_WRITEFUNCTION, SteamHTTP::write_func);
    curl_easy_setopt(m_curl, CURLOPT_WRITEDATA, this);

    // Progress Callback
    curl_easy_setopt(m_curl, CURLOPT_PROGRESSFUNCTION, SteamHTTP::progress_func);
    curl_easy_setopt(m_curl, CURLOPT_PROGRESSDATA, gauge);
    curl_easy_setopt(m_curl, CURLOPT_NOPROGRESS, FALSE);

    // Perform
    result = curl_easy_perform(m_curl);
    if (result != 0){
        wxMessageBox(curl_easy_strerror(result), wxMessageBoxCaptionStr, wxICON_ERROR|wxOK);
    }
}

我遇到的困难是可靠地告诉 libcurl 何时实际完成。有回调吗？我需要它来解析下载的数据。

判断 libcurl 是否已完成以及我是否可以处理数据的最佳方法是什么？

p.s.:此代码正在进行中，还需要编写检查等。

Answer 1

当 curl_easy_perform() 返回时，它就完成了。它是如此简单。检查返回码以确定是否成功。