C++11 Async cURL

来源：互联网发布：h网络是什么意思编辑：程序博客网时间：2024/06/05 11:12
https://gist.github.com/owickstrom/3218376
#include <iostream>#include <curl/curl.h>#include <math.h>#include <vector>#include <future>#include <boost/format.hpp>#define logbase(a, b) (log(a)/log(b))using namespace std;using boost::format;const char *fileSizes[] = {"byte", "K", "MB", "GB", "TB"};const int numFileSizes = 5;// adds chunk size to sumsize_t addChunkSize(char *ptr, size_t size, size_t nmemb, void *data){    auto acc = (long *)data;    auto chunkSize = size * nmemb;    *acc += chunkSize;    return chunkSize;}// returns a formatted string (number of bytes, K, MB, GB or TB)string getSizeString(long fsize){    int fmtIndex;    format fmter;        if(fsize == 0 || (fmtIndex = (int)floor(logbase(fsize, 1024))) == 0)    {        fmter = format("%ld %s") % fsize % fileSizes[0];    }    else    {        fmtIndex = (fmtIndex >= numFileSizes) ? numFileSizes : fmtIndex;        fmter = format("%.2f %s")            % (fsize / pow(1024, fmtIndex))            % fileSizes[fmtIndex];    }    return fmter.str();}void usage(string name){    cout << "Usage: " << name << " url1 url2 url3 ...\n";}int main(int argc, const char * argv[]){    long acc = 0L;    auto results = vector<future<long>>();        // if no urls    if(argc == 1)    {        usage(string(argv[0]));        exit(1);    }        for(int i = 1; i < argc; i++)    {        const char *url = argv[i];                // create future using a lambda and push it to the result vector        results.push_back(async(launch::async,        [url]() -> long        {            CURL *curl;            CURLcode res;            long siteSize = 0;                        curl = curl_easy_init();                        if(curl) {                // setup                curl_easy_setopt(curl, CURLOPT_URL, url);                // pass the siteSize pointer along (received by addChunkSize)                curl_easy_setopt(curl, CURLOPT_WRITEDATA, &siteSize);                // callback for downloaded chunks                curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, addChunkSize);                                // make the request                res = curl_easy_perform(curl);                                // something failed                if(res != CURLE_OK)                {                    cerr    << "\rWebsite size fetch failed for " << url << ": "                            << curl_easy_strerror(res) << "\n";                    siteSize = 0;                }                // successful                else                {                    cerr    << "\rSize of " << url << ": "                            << getSizeString(siteSize) << "\n";                }                                // cleanup                curl_easy_cleanup(curl);            }                        return siteSize;        }));    }        // gather results from futures    for(auto &result : results)    {        acc += result.get();    }        cerr << "\nTotal size of websites: " << getSizeString(acc) << "\n";    return 0;}
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