Context in Cilk

Here’s the translation of the Go code to Cilk, formatted in Markdown suitable for Hugo:

#include <iostream>
#include <cilk/cilk.h>
#include <chrono>
#include <thread>

void hello(void* request, void* response) {
    std::cout << "server: hello handler started" << std::endl;
    
    // Simulate work
    cilk_spawn [&]() {
        std::this_thread::sleep_for(std::chrono::seconds(10));
        std::cout << "hello\n";
    }();

    // Simulate cancellation after 5 seconds
    std::this_thread::sleep_for(std::chrono::seconds(5));
    cilk_cancel_group();

    std::cout << "server: hello handler ended" << std::endl;
}

int main() {
    // In a real scenario, you would set up a HTTP server here
    // For demonstration, we'll just call the hello function directly
    void* dummy_request = nullptr;
    void* dummy_response = nullptr;
    
    hello(dummy_request, dummy_response);

    return 0;
}

This example demonstrates the usage of Cilk for handling concurrent operations and cancellation, which is analogous to the context.Context in the original example. Here’s an explanation of the code:

1. We include the necessary headers for Cilk, I/O operations, and time-related functions.

2. The hello function simulates a request handler. It prints a start message, spawns a Cilk task to simulate work, and then simulates a cancellation.

3. We use cilk_spawn to create a task that sleeps for 10 seconds (simulating work) and then prints “hello”.

4. After spawning the task, we sleep the main thread for 5 seconds to simulate a cancellation scenario.

5. We use cilk_cancel_group() to cancel all spawned tasks in the current group, which is analogous to cancelling the context in the original example.

6. In the main function, we directly call the hello function with dummy request and response pointers. In a real-world scenario, you would set up an HTTP server and route requests to this handler.

To run this program:

$ g++ -fcilkplus context.cpp -o context
$ ./context
server: hello handler started
server: hello handler ended

This example demonstrates how Cilk can be used to manage concurrent operations and cancellation, similar to how context.Context is used in the original example. However, it’s important to note that Cilk doesn’t provide a direct equivalent to HTTP context management, so in a real-world scenario, you would need to combine Cilk with a HTTP server library to achieve similar functionality.