waitpid, C++ (gcc)

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#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <vector>
#include <chrono>
#include <thread>
#include <random>
#include <iostream>

class fork_storage
{
public:
    fork_storage() noexcept
    {
        m_pid = fork();
    }

fork_storage(const fork_storage&) = delete;
    fork_storage& operator=(const fork_storage&) = delete;
    fork_storage& operator=(fork_storage&& rhv) = delete;

fork_storage(fork_storage&& src) noexcept
    {
        m_pid = src.pid();
        src.reset();
    }

~fork_storage()
    {
        if (is_parent()) {
            wait();
        }
    }

bool fail() const noexcept
    {
        return m_pid < 0;
    }

bool is_parent() const noexcept
    {
        return m_pid > 0;
    }

void reset() noexcept
    {
        m_pid = -1;
    }

pid_t pid() const noexcept
    {
        return m_pid;
    }

int wait() noexcept
    {
        int status = -1;
        if (is_parent()) {
            waitpid(m_pid, &status, WUNTRACED);
        }
        reset();
        return status;
    }

private:
    pid_t m_pid;
};

std::mt19937 &random_gen()
{
    static std::mt19937 gen(std::chrono::system_clock::now().time_since_epoch().count());
    return gen;
}

int main()
{
    std::vector<fork_storage> processes;
    for (unsigned i = 0; i < 10; ++i) {
        fork_storage fork_obj;        
        if (fork_obj.fail()) {
            std::cerr << "fork error\n";
        } else {
            if (fork_obj.is_parent()) {
                std::string message = "process created: " + std::to_string(fork_obj.pid()) + "\n";
                processes.emplace_back(std::move(fork_obj));
            } else {
                for (auto &process: processes) {
                    process.reset();
                }
                processes.clear();
                std::chrono::seconds sec(random_gen()() % 5 + 1);
                std::string message = "child " + std::to_string(getpid()) + " paused: " + std::to_string(sec.count()) + " sec\n";
                std::cout << message;
                std::this_thread::sleep_for(sec);
                break;
            }
        }
    }

while (!processes.empty()) {
        fork_storage &fork_obj = processes.back();
        if(fork_obj.is_parent()) {
            std::string message = "wait process: " + std::to_string(fork_obj.pid()) + "\n";
            std::cout << message;            
        }
        processes.pop_back();
    }    
}

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Compilation time: 1.14 sec, absolute running time: 5.09 sec, cpu time: 2.31 sec, memory peak: 3 Mb, absolute service time: 6,24 sec