test/pthread/test_pthread_proxy_hammer.cpp

#include <errno.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <emscripten.h>
#include <stdio.h>

class random_device
{
    int __f_;
public:
    // constructors
    explicit random_device();
    ~random_device();

    // generating functions
    unsigned operator()();
};

random_device::random_device()
{
    __f_ = open("/dev/urandom", O_RDONLY);
    if (__f_ < 0) abort();
}

random_device::~random_device()
{
    close(__f_);
}

unsigned
random_device::operator()()
{
    unsigned r;
    size_t n = sizeof(r);
    char* p = reinterpret_cast<char*>(&r);
    while (n > 0)
    {
        ssize_t s = read(__f_, p, 1);
        if (s == 0) abort();
        if (s == -1)
        {
            if (errno != EINTR) abort();
            continue;
        }
        n -= static_cast<size_t>(s);
        p += static_cast<size_t>(s);
    }
    return r;
}

int main() {
  int total = 0;
  for (int i = 0; i < ITERATIONS; i++) {
    // printf causes proxying
    printf("%d %d\n", i, total);
    for (int j = 0; j < 1024; j++) {
      // allocation uses a mutex
      auto* rd = new random_device();
      // reading data causes proxying
      for (int k = 0; k < 4; k++) {
        total += (*rd)();
      }
      // make sure the optimizer doesn't remove the allocation
      EM_ASM({ out("iter") }, rd);
      delete rd;
    }
  }
  printf("done: %d", total);
  return 0;
}