Http Server in Cilk

Here’s the translation of the HTTP server example from Go to Cilk:

Our basic HTTP server example demonstrates how to create a simple web server using Cilk.

#include <cilk/cilk.h>
#include <iostream>
#include <string>
#include <map>
#include <vector>
#include <boost/asio.hpp>

using boost::asio::ip::tcp;

// A handler function to respond with "hello\n"
void hello(boost::asio::streambuf& request, tcp::iostream& stream) {
    stream << "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n";
    stream << "hello\n";
}

// A handler function to echo back all HTTP request headers
void headers(boost::asio::streambuf& request, tcp::iostream& stream) {
    stream << "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n";
    
    std::string s((std::istreambuf_iterator<char>(&request)), std::istreambuf_iterator<char>());
    std::istringstream iss(s);
    std::string line;
    
    while (std::getline(iss, line) && line != "\r") {
        stream << line << "\n";
    }
}

int main() {
    try {
        boost::asio::io_service io_service;
        tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), 8090));

        while (true) {
            tcp::iostream stream;
            boost::system::error_code ec;
            acceptor.accept(*stream.rdbuf(), ec);

            if (!ec) {
                boost::asio::streambuf request;
                boost::asio::read_until(stream, request, "\r\n");

                std::string request_line;
                std::istream request_stream(&request);
                std::getline(request_stream, request_line);

                std::string request_path;
                std::istringstream iss(request_line);
                iss >> request_path >> request_path;

                if (request_path == "/hello") {
                    cilk_spawn hello(request, stream);
                } else if (request_path == "/headers") {
                    cilk_spawn headers(request, stream);
                } else {
                    stream << "HTTP/1.1 404 Not Found\r\n\r\n";
                }
            }
        }
    }
    catch (std::exception& e) {
        std::cerr << "Exception: " << e.what() << "\n";
    }

    return 0;
}

This Cilk program creates a basic HTTP server that listens on port 8090. Here’s a breakdown of the code:

We include necessary headers for Cilk, standard C++ libraries, and Boost.Asio for networking.
We define two handler functions: hello and headers. These functions are similar to the handlers in the original example.
In the main function, we set up a TCP acceptor to listen for incoming connections.
We use a while loop to continuously accept new connections.
For each connection, we read the request line and determine which handler to call based on the request path.
We use cilk_spawn to potentially execute the handlers concurrently, which is similar to the concurrent nature of Go’s HTTP server.
The program uses Boost.Asio for networking, which provides an asynchronous model similar to Go’s net/http package.

To run the server:

$ g++ -fcilkplus -lboost_system -pthread http_server.cpp -o http_server
$ ./http_server &

You can then access the server using curl:

$ curl localhost:8090/hello
hello

This Cilk version provides similar functionality to the original Go example, using Cilk for potential parallelism and Boost.Asio for networking. The structure is adapted to fit C++ and Cilk paradigms while maintaining the core functionality of the HTTP server.

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Execing Processes in Cilk

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Http Server in Cilk