Demo: Process supervision

Buildable, runnable, verifiable, and synchronized with the repository source.

1. Example Scope

Key calls are explained with English comments, and the page includes run commands, validation steps, and adjustable settings.

2. Build and Run

cmake --build build --target sttnet_process_supervisor --parallel
./build/examples/sttnet_process_supervisor

3. Validation

./build/examples/sttnet_process_supervisor

Expected: Several supervised child runs over seven seconds

4. Complete Source

#include <sttnet.h>

#include <chrono>
#include <iostream>
#include <thread>
#include <unistd.h>

int main()
{
    using stt::system::Process;

    // sec=2 creates a helper process that launches the worker again two seconds
    // after each exit. The helper is tied to this parent on Linux, so it stops
    // when the parent program ends.
    const bool started = Process::startProcess(
        [] {
            const char message[] = "supervised child ran once\n";
            // write() is used because the child exits with _exit(), which does not
            // flush C++ iostream buffers.
            ::write(STDOUT_FILENO, message, sizeof(message) - 1);
            std::this_thread::sleep_for(std::chrono::milliseconds(300));
        },
        2);

    if(!started)
    {
        std::cerr << "failed to create supervisor\n";
        return 1;
    }

    std::cout << "parent pid=" << ::getpid()
              << "; observe several child runs for seven seconds" << std::endl;
    std::this_thread::sleep_for(std::chrono::seconds(7));

    // This is supervision, not full daemonization: Process::startProcess() does
    // not call setsid(), change the working directory, or redirect standard I/O.
    return 0;
}