| 1 | #include "pseudo_barrier.h" |
|---|---|
| 2 | #include "thread.h" |
| 3 | #include <atomic> |
| 4 | #include <chrono> |
| 5 | #include <cinttypes> |
| 6 | #include <csignal> |
| 7 | #include <cstdio> |
| 8 | #include <cstdlib> |
| 9 | #include <cstring> |
| 10 | #include <mutex> |
| 11 | #include <thread> |
| 12 | #include <unistd.h> |
| 13 | #include <vector> |
| 14 | |
| 15 | pseudo_barrier_t barrier; |
| 16 | std::mutex print_mutex; |
| 17 | std::atomic<bool> can_work; |
| 18 | thread_local volatile sig_atomic_t can_exit_now = false; |
| 19 | |
| 20 | static void sigint_handler(int signo) {} |
| 21 | |
| 22 | static void sigusr1_handler(int signo) { |
| 23 | std::lock_guard<std::mutex> lock{print_mutex}; |
| 24 | std::printf(format: "received SIGUSR1 on thread id: %"PRIx64 "\n", get_thread_id()); |
| 25 | can_exit_now = true; |
| 26 | } |
| 27 | |
| 28 | static void thread_func() { |
| 29 | // this ensures that all threads start before we stop |
| 30 | pseudo_barrier_wait(barrier); |
| 31 | |
| 32 | // wait till the main thread indicates that we can go |
| 33 | // (note: using a mutex here causes hang on FreeBSD when another thread |
| 34 | // is suspended) |
| 35 | while (!can_work.load()) |
| 36 | std::this_thread::sleep_for(rtime: std::chrono::milliseconds(50)); |
| 37 | |
| 38 | // the mutex guarantees that two writes don't get interspersed |
| 39 | { |
| 40 | std::lock_guard<std::mutex> lock{print_mutex}; |
| 41 | std::printf(format: "thread %"PRIx64 " running\n", get_thread_id()); |
| 42 | } |
| 43 | |
| 44 | // give other threads a fair chance to run |
| 45 | for (int i = 0; i < 5; ++i) { |
| 46 | std::this_thread::yield(); |
| 47 | std::this_thread::sleep_for(rtime: std::chrono::milliseconds(200)); |
| 48 | if (can_exit_now) |
| 49 | return; |
| 50 | } |
| 51 | |
| 52 | // if we didn't get signaled, terminate the program explicitly. |
| 53 | _exit(status: 0); |
| 54 | } |
| 55 | |
| 56 | int main(int argc, char **argv) { |
| 57 | int num = atoi(nptr: argv[1]); |
| 58 | |
| 59 | pseudo_barrier_init(barrier, num + 1); |
| 60 | |
| 61 | signal(SIGINT, handler: sigint_handler); |
| 62 | signal(SIGUSR1, handler: sigusr1_handler); |
| 63 | |
| 64 | std::vector<std::thread> threads; |
| 65 | for (int i = 0; i < num; ++i) |
| 66 | threads.emplace_back(args&: thread_func); |
| 67 | |
| 68 | // use the barrier to make sure all threads start before we stop |
| 69 | pseudo_barrier_wait(barrier); |
| 70 | std::raise(SIGINT); |
| 71 | |
| 72 | // allow the threads to work |
| 73 | can_work.store(i: true); |
| 74 | |
| 75 | for (std::thread &thread : threads) |
| 76 | thread.join(); |
| 77 | return 0; |
| 78 | } |
| 79 |