upstream/emscripten/test/pthread/test_pthread_create.c

// Copyright 2015 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 <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <emscripten/em_asm.h>
#include <emscripten/console.h>
#include <assert.h>

#define NUM_THREADS 8

unsigned int global_shared_data[NUM_THREADS];

void *ThreadMain(void *arg) {
  long idx = (long)arg;
  unsigned int param = global_shared_data[idx];

#define N 100

  emscripten_errf("Thread idx %lu: sorting %d numbers with param %d", idx, N, param);

  unsigned int n[N];
  // Create a shifted increasing sequence of numbers [0, N-1[
  for (unsigned int i = 0; i < N; ++i) {
    n[i] = (i + param) % N;
  }

  // Sort the sequence to ordered [0, N[
  for (unsigned int i = 0; i < N; ++i) {
    for (unsigned int j = i; j < N; ++j) {
      if (n[i] > n[j]) {
        unsigned int t = n[i];
        n[i] = n[j];
        n[j] = t;
      }
    }
  }
  // Ensure all elements are in place.
  intptr_t numGood = 0;
  for (unsigned int i = 0; i < N; ++i) {
    if (n[i] == i) {
      ++numGood;
    } else {
      emscripten_errf("n[%d]=%d", i, n[i]);
    }
  }

  emscripten_outf("Thread idx %ld with param %d: all done with result %ld.", idx, param, numGood);
  pthread_exit((void*)numGood);
}

pthread_t thread[NUM_THREADS];

void CreateThread(intptr_t i) {
  static int counter = 1;
  // Arbitrary random'ish data for perturbing the sort for this thread task.
  global_shared_data[i] = (counter++ * 12141231) & 0x7FFFFFFF;
  // emscripten_outf("Main: Creating thread idx %d (param %d)", i, global_shared_data[i]);
  int rc = pthread_create(&thread[i], NULL, ThreadMain, (void*)i);
  assert(rc == 0);
}

int main() {
  // Create initial threads.
  for (int i = 0; i < NUM_THREADS; ++i)
    CreateThread(i);

  int numThreadsToCreate = 1000;

  // Join all threads and create more.
  while (numThreadsToCreate > 0) {
    for (int i = 0; i < NUM_THREADS; ++i) {
      if (thread[i]) {
        intptr_t status;
        int rc = pthread_join(thread[i], (void**)&status);
        assert(rc == 0);
        emscripten_errf("Main: Joined thread idx %d (param %d) with status %d", i, global_shared_data[i], (int)status);
        assert(status == N);
        thread[i] = 0;
        if (numThreadsToCreate > 0) {
          --numThreadsToCreate;
          CreateThread(i);
        }
      }
    }
  }

  printf("All threads joined.\n");
  return 0;
}