POSIX Threads for Windows Code

/*
 * once2.c
 *
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads4w - POSIX Threads for Windows
 *      Copyright 1998 John E. Bossom
 *      Copyright 1999-2018, Pthreads4w contributors
 *
 *      Homepage: https://sourceforge.net/projects/pthreads4w/
 *
 *      The current list of contributors is contained
 *      in the file CONTRIBUTORS included with the source
 *      code distribution. The list can also be seen at the
 *      following World Wide Web location:
 *
 *      https://sourceforge.net/p/pthreads4w/wiki/Contributors/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * --------------------------------------------------------------------------
 *
 * Create several static pthread_once objects and channel several threads
 * through each.
 *
 * Depends on API functions:
 *	pthread_once()
 *	pthread_create()
 */

#include "test.h"

#define NUM_THREADS 100 /* Targeting each once control */
#define NUM_ONCE    10

pthread_once_t o = PTHREAD_ONCE_INIT;
pthread_once_t once[NUM_ONCE];

typedef struct {
  int i;
  CRITICAL_SECTION cs;
} sharedInt_t;

static sharedInt_t numOnce;
static sharedInt_t numThreads;

void
myfunc(void)
{
  EnterCriticalSection(&numOnce.cs);
  numOnce.i++;
  LeaveCriticalSection(&numOnce.cs);
  /* Simulate slow once routine so that following threads pile up behind it */
  Sleep(100);
}

void *
mythread(void * arg)
{
   assert(pthread_once(&once[(int)(size_t)arg], myfunc) == 0);
   EnterCriticalSection(&numThreads.cs);
   numThreads.i++;   
   LeaveCriticalSection(&numThreads.cs);
   return (void*)(size_t)0;
}

int
main()
{
  pthread_t t[NUM_THREADS][NUM_ONCE];
  int i, j;
  
  memset(&numOnce, 0, sizeof(sharedInt_t));
  memset(&numThreads, 0, sizeof(sharedInt_t));

  InitializeCriticalSection(&numThreads.cs);
  InitializeCriticalSection(&numOnce.cs);

  for (j = 0; j < NUM_ONCE; j++)
    {
      once[j] = o;

      for (i = 0; i < NUM_THREADS; i++)
        {
	  /* GCC build: create was failing with EAGAIN after 790 threads */
          while (0 != pthread_create(&t[i][j], NULL, mythread, (void *)(size_t)j))
	    sched_yield();
        }
    }

  for (j = 0; j < NUM_ONCE; j++)
    for (i = 0; i < NUM_THREADS; i++)
      if (pthread_join(t[i][j], NULL) != 0)
        printf("Join failed for [thread,once] = [%d,%d]\n", i, j);

  assert(numOnce.i == NUM_ONCE);
  assert(numThreads.i == NUM_THREADS * NUM_ONCE);

  DeleteCriticalSection(&numOnce.cs);
  DeleteCriticalSection(&numThreads.cs);

  return 0;
}