Function main

example/http/client/crawl/http_crawl.cpp:342–405

};

int main(int argc, char* argv[])
{
    // Check command line arguments.
    if (argc != 2)
    {
        std::cerr <<
            "Usage: http-crawl <threads>\n" <<
            "Example:\n" <<
            "    http-crawl 100\n";
        return EXIT_FAILURE;
    }
    auto const threads = std::max<int>(1, std::atoi(argv[1]));

    // The io_context is used to aggregate the statistics
    net::io_context ioc;

    // The report holds the aggregated statistics
    crawl_report report{ioc};

    timer t;

    // Create and launch the worker threads.
    std::vector<std::thread> workers;
    workers.reserve(threads + 1);
    for(int i = 0; i < threads; ++i)
    {
        // Each worker will eventually add some data to the aggregated
        // report. Outstanding work is tracked in each worker to
        // represent the forthcoming delivery of this data by that
        // worker.
        auto reporting_work = net::require(
            ioc.get_executor(),
            net::execution::outstanding_work.tracked);

        workers.emplace_back(
            [&report, reporting_work] {
                // We use a separate io_context for each worker because
                // the asio resolver simulates asynchronous operation using
                // a dedicated worker thread per io_context, and we want to
                // do a lot of name resolutions in parallel.
                net::io_context ioc;
                std::make_shared<worker>(report, ioc)->run();
                ioc.run();
            });
    }

    // Add another thread to run the main io_context which
    // is used to aggregate the statistics
    workers.emplace_back(
    [&ioc]
    {
        ioc.run();
    });

    // Now block until all threads exit
    for(std::size_t i = 0; i < workers.size(); ++i)
        workers[i].join();