// Copyright 2018 The Emscripten Authors. All rights reserved.

// Emscripten is available under two separate licenses, the MIT license and the

// University of Illinois/NCSA Open Source License. Both these licenses can be

// found in the LICENSE file.

#include <pthread.h>

#include <cassert>

#include <emscripten.h>

#include <emscripten/threading.h>

#include <math.h>

#include <stdio.h>

volatile int threadStarted = 0;

volatile int timeReceived = 0;

volatile double mainThreadTime;

void wait(volatile int *address)

{

int state = emscripten_atomic_load_u32((void*)address);

while(state == 0)

state = emscripten_atomic_load_u32((void*)address);

}

void wake(volatile int *address)

{

emscripten_atomic_store_u32((void*)address, 1);

}

void *thread_main(void *arg)

{

wake(&threadStarted);

wait(&timeReceived);

double pthreadTime = emscripten_get_now();

double timeDifference = pthreadTime - mainThreadTime;

printf("Time difference between pthread and main thread is %f msecs.\n", timeDifference);

// The time difference here should be well less than 1 msec, but test against 200msecs to be super-sure.

assert(fabs(timeDifference) < 200);

emscripten_force_exit(0);

return 0;

}

void busy_sleep(double msecs)

{

double end = emscripten_get_now() + msecs;

while(emscripten_get_now() < end)

;

}

int main()

{

// Cause a one second delay between main() and pthread start that might have a chance to drift the wallclocks on emscripten_get_now().

busy_sleep(1000);

pthread_t thread;

pthread_create(&thread, NULL, thread_main, NULL);

wait(&threadStarted);

mainThreadTime = emscripten_get_now();

wake(&timeReceived);

emscripten_exit_with_live_runtime();

}