preemption signal blocking [WIP]

package main

/*
#include <pthread.h>
#include <signal.h>

static int ignore_sigurg()
{
    sigset_t set;
    sigemptyset(&set);
    sigaddset(&set, SIGURG);
    return pthread_sigmask(SIG_BLOCK, &set, NULL);
}

static int handleURG_alt() {
    struct sigaction sigact;
    sigact.sa_handler = SIG_BLOCK;
    sigemptyset(&sigact.sa_mask);
    sigact.sa_flags = 0;
    sigaction(SIGURG, &sigact, NULL);
    return 0;
}
*/
import "C"

import (
    "flag"
    "fmt"
    "os"
    "os/signal"
    "runtime"
    "sync"
    "syscall"
)

var ignorePreemption = flag.Bool("ignore", false, "Specify true to block SIGURG")

func main() {
    flag.Parse()

    // tight loop
    go func() {
        for {
        }
    }()

    var wg sync.WaitGroup

    for i := 0; i < 2; i++ {
        wg.Add(1)
        go func(n int) {
            defer wg.Done()
            runtime.LockOSThread()

            if n == 0 && *ignorePreemption {
                if rc := C.ignore_sigurg(); rc != 0 {
                    panic(rc)
                }
                fmt.Println("blocked SIGURG on goroutine", n)
            }

            ch := make(chan os.Signal, 1)
            signal.Notify(ch, syscall.SIGURG, os.Interrupt)

            for sig := range ch {
                fmt.Printf("got signal in goroutine %d: %v\n", n, sig)

                if sig == os.Interrupt {
                    break
                }
            }
        }(i)
    }

    wg.Wait()
}