C++ pthread_barrier_wait函数代码示例

static
uintptr_t
load_ppp_module()
{
    if (module_dl_handler) {
        // already loaded
        return 0;
    }

    // allocate auxiliary instance
    if (!aux_instance) {
        aux_instance = calloc(1, sizeof(*aux_instance));
        if (!aux_instance)
            return 1;

        aux_instance->id = tables_generate_new_pp_instance_id();
        tables_add_pp_instance(aux_instance->id, aux_instance);
    }

    // allocate message loop for browser thread
    if (ppb_message_loop_get_current() == 0) {
        PP_Resource message_loop = ppb_message_loop_create(aux_instance->id);
        ppb_message_loop_attach_to_current_thread(message_loop);
        ppb_message_loop_proclaim_this_thread_browser();
    }

    // allocate message loop for plugin thread (main thread)
    if (ppb_message_loop_get_for_main_thread() == 0) {
        pthread_barrier_init(&aux_instance->main_thread_barrier, NULL, 2);
        pthread_create(&aux_instance->main_thread, NULL, fresh_wrapper_main_thread, aux_instance);
        pthread_detach(aux_instance->main_thread);
        pthread_barrier_wait(&aux_instance->main_thread_barrier);
        pthread_barrier_destroy(&aux_instance->main_thread_barrier);
    }

    fpp_config_initialize();

    if (tried_files) {
        g_list_free_full(tried_files, g_free);
        tried_files = NULL;
    }

    if (fpp_config_get_plugin_path()) {
        const char *ptr = fpp_config_get_plugin_path();
        const char *last = strchr(ptr, ':');
        uintptr_t   ret;

        // parse ':'-separated list
        while (last != NULL) {
            // try entries one by one
            char *entry = strndup(ptr, last - ptr);
            ret = do_load_ppp_module(entry);
            free(entry);
            if (ret == 0)
                return 0;

            ptr = last + 1;
            last = strchr(ptr, ':');
        }

        // and the last entry
        ret = do_load_ppp_module(ptr);
        if (ret == 0)
            return 0;

        goto failure;
    }

    // try all paths
    const char **path_list = fpp_config_get_plugin_path_list();
    while (*path_list) {
        gchar *fname = g_strdup_printf("%s/%s", *path_list, fpp_config_get_plugin_file_name());
        uintptr_t ret = do_load_ppp_module(fname);
        g_free(fname);
        if (ret == 0)
            return 0;
        path_list ++;
    }

failure:
    config.quirks.plugin_missing = 1;
    use_fallback_version_strings();
    trace_error("%s, can't find %s\n", __func__, fpp_config_get_plugin_file_name());
    return 1;
}

/* xdd_barrier() - This is the actual barrier subroutine.
 * The caller will block in this subroutine until all required threads enter
 * this subroutine <barrier> at which time they will all be released.
 *
 * The "owner" parameter indicates whether or not the calling thread is the
 * owner of this barrier. 0==NOT owner, 1==owner. If this thread owns this
 * barrier then it will be responsible for removing the "occupant" chain
 * upon being released from this barrier.
 *
 * Before entering the barrier, the occupant structure is added to the end
 * of the occupant chain. This allows the debug routine to see which threads
 * are in a barrier at any given time as well as when they entered the barrier.
 *
 * If the barrier is a Target Thread or a Worker Thread then the Target_Data pointer is
 * valid and the "current_barrier" member of that Target_Data is set to the barrier
 * pointer of the barrier that this thread is about to enter. Upon leaving the
 * barrier, this pointer is cleared.
 *
 * THIS SUBROUTINE IMPLEMENTS BARRIERS USING PTHREAD_BARRIERS
 */
int32_t
xdd_barrier(struct xdd_barrier *bp, xdd_occupant_t *occupantp, char owner) {
    int32_t 	status;  			// Status of the pthread_barrier call


    /* "threads" is the number of participating threads */
    if (bp->threads == 1) return(0); /* If there is only one thread then why bother sleeping */

    // Put this Target_Data on the Barrier Target_Data Chain so that we can track it later if we need to
    /////// this is to keep track of which Target_Data are in a particular barrier at any given time...
    pthread_mutex_lock(&bp->mutex);
    // Add occupant structure here
    if (bp->counter == 0) { // Add first occupant to the chain
        bp->first_occupant = occupantp;
        bp->last_occupant = occupantp;
        occupantp->prev_occupant = occupantp;
        occupantp->next_occupant = occupantp;
    } else { // Add this barrier to the end of the chain
        occupantp->next_occupant = bp->first_occupant; // The last one on the chain points back to the first barrier on the chain as its "next"
        occupantp->prev_occupant = bp->last_occupant;
        bp->last_occupant->next_occupant = occupantp;
        bp->last_occupant = occupantp;
    } // Done adding this barrier to the chain
    if (occupantp->occupant_type & XDD_OCCUPANT_TYPE_TARGET ) {
        // Put the barrier pointer into this thread's Target_Data->current_barrier
        ((target_data_t *)(occupantp->occupant_data))->td_current_state |= TARGET_CURRENT_STATE_BARRIER;
        ((target_data_t *)(occupantp->occupant_data))->td_current_barrier = bp;
    } else if (occupantp->occupant_type & XDD_OCCUPANT_TYPE_WORKER_THREAD) {
        // Put the barrier pointer into this thread's Worker_Data->current_barrier
        ((worker_data_t *)(occupantp->occupant_data))->wd_current_state |= WORKER_CURRENT_STATE_BARRIER;
        ((worker_data_t *)(occupantp->occupant_data))->wd_current_barrier = bp;
    }

    bp->counter++;
    pthread_mutex_unlock(&bp->mutex);

    // Now we wait here at this barrier until all the other threads arrive...
    nclk_now(&occupantp->entry_time);

#ifdef HAVE_PTHREAD_BARRIER_T
    status = pthread_barrier_wait(&bp->pbar);
    nclk_now(&occupantp->exit_time);
    if ((status != 0) && (status != PTHREAD_BARRIER_SERIAL_THREAD)) {
        fprintf(xgp->errout,"%s: xdd_barrier<pthread_barriers>: ERROR: pthread_barrier_wait failed: Barrier %s, status is %d, errno is %d\n",
                xgp->progname, bp->name, status, errno);
        perror("Reason");
        status = -1;
    }
#else
    status = xint_barrier_wait(&bp->pbar);
    nclk_now(&occupantp->exit_time);
    if (status != 0) {
        fprintf(xgp->errout,"%s: xdd_barrier<pthread_barriers>: ERROR: xint_barrier_wait failed: Barrier %s, status is %d, errno is %d\n",
                xgp->progname, bp->name, status, errno);
        perror("Reason");
        status = -1;
    }
#endif

    if (occupantp->occupant_type & XDD_OCCUPANT_TYPE_TARGET ) {
        // Clear this thread's Target_Data->current_barrier
        ((target_data_t *)(occupantp->occupant_data))->td_current_barrier = NULL;
        ((target_data_t *)(occupantp->occupant_data))->td_current_state &= ~TARGET_CURRENT_STATE_BARRIER;
    } else if (occupantp->occupant_type & XDD_OCCUPANT_TYPE_WORKER_THREAD) {
        // Put the barrier pointer into this thread's Worker_Data->current_barrier
        ((worker_data_t *)(occupantp->occupant_data))->wd_current_barrier = NULL;
        ((worker_data_t *)(occupantp->occupant_data))->wd_current_state &= ~WORKER_CURRENT_STATE_BARRIER;
    }
    // Clear this occupant chain if we are the owner of this barrier
    if (owner) {
        pthread_mutex_lock(&bp->mutex);
        // Clear the first/last chain pointers
        bp->first_occupant = NULL;
        bp->last_occupant = NULL;
        bp->counter = 0;
        pthread_mutex_unlock(&bp->mutex);
    }
    return(status);
} // End of xdd_barrier() POSIX

//.........这里部分代码省略.........
					if (!strcmp(dev_path, path)) {
						/* Matched Paths. Open this device */

						/* OPEN HERE */
						res = libusb_open(usb_dev, &dev->device_handle);
						if (res < 0) {
							LOG("can't open device\n");
							free(dev_path);
							break;
						}
						good_open = 1;
#ifdef DETACH_KERNEL_DRIVER
						/* Detach the kernel driver, but only if the
						   device is managed by the kernel */
						if (libusb_kernel_driver_active(dev->device_handle, intf_desc->bInterfaceNumber) == 1) {
							res = libusb_detach_kernel_driver(dev->device_handle, intf_desc->bInterfaceNumber);
							if (res < 0) {
								libusb_close(dev->device_handle);
								LOG("Unable to detach Kernel Driver\n");
								free(dev_path);
								good_open = 0;
								break;
							}
						}
#endif
						res = libusb_claim_interface(dev->device_handle, intf_desc->bInterfaceNumber);
						if (res < 0) {
							LOG("can't claim interface %d: %d\n", intf_desc->bInterfaceNumber, res);
							free(dev_path);
							libusb_close(dev->device_handle);
							good_open = 0;
							break;
						}

						/* Store off the string descriptor indexes */
						dev->manufacturer_index = desc.iManufacturer;
						dev->product_index      = desc.iProduct;
						dev->serial_index       = desc.iSerialNumber;

						/* Store off the interface number */
						dev->interface = intf_desc->bInterfaceNumber;

						/* Find the INPUT and OUTPUT endpoints. An
						   OUTPUT endpoint is not required. */
						for (i = 0; i < intf_desc->bNumEndpoints; i++) {
							const struct libusb_endpoint_descriptor *ep
								= &intf_desc->endpoint[i];

							/* Determine the type and direction of this
							   endpoint. */
							int is_interrupt =
								(ep->bmAttributes & LIBUSB_TRANSFER_TYPE_MASK)
							      == LIBUSB_TRANSFER_TYPE_INTERRUPT;
							int is_output =
								(ep->bEndpointAddress & LIBUSB_ENDPOINT_DIR_MASK)
							      == LIBUSB_ENDPOINT_OUT;
							int is_input =
								(ep->bEndpointAddress & LIBUSB_ENDPOINT_DIR_MASK)
							      == LIBUSB_ENDPOINT_IN;

							/* Decide whether to use it for intput or output. */
							if (dev->input_endpoint == 0 &&
							    is_interrupt && is_input) {
								/* Use this endpoint for INPUT */
								dev->input_endpoint = ep->bEndpointAddress;
								dev->input_ep_max_packet_size = ep->wMaxPacketSize;
							}
							if (dev->output_endpoint == 0 &&
							    is_interrupt && is_output) {
								/* Use this endpoint for OUTPUT */
								dev->output_endpoint = ep->bEndpointAddress;
							}
						}

						pthread_create(&dev->thread, NULL, read_thread, dev);

						/* Wait here for the read thread to be initialized. */
						pthread_barrier_wait(&dev->barrier);

					}
					free(dev_path);
				}
			}
		}
		libusb_free_config_descriptor(conf_desc);

	}

	libusb_free_device_list(devs, 1);

	/* If we have a good handle, return it. */
	if (good_open) {
		return dev;
	}
	else {
		/* Unable to open any devices. */
		free_hid_device(dev);
		return NULL;
	}
}

void *MavlinkStatusTask(void *ptr) {
	MavlinkStruct		*Mavlink = (MavlinkStruct *) ptr;
	AttitudeData	*AttitudeDesire = Control.AttitudeDesire;
	AttitudeData		*AttitudeMesure = Mavlink->AttitudeMesure;
	AttData				Data, Speed;
	AttData			DataD, SpeedD;
	AttData			DataM, SpeedM;
	double			Error[4]    = {0.0, 0.0, 0.0, 0.0};
	uint32_t			TimeStamp;
	mavlink_message_t 	msg;
	uint16_t 			len;
	uint8_t 			buf[BUFFER_LENGTH];
	int 				bytes_sent;
	uint32_t 			sensor = 0xf00f;

	printf("%s : Mavlink Status démarré\n", __FUNCTION__);
	pthread_barrier_wait(&(MavlinkStartBarrier));

	while (MavlinkActivated) {
		sem_wait(&MavlinkStatusTimerSem);
		if (MavlinkActivated == 0)
			break;
		memset(buf, 0, BUFFER_LENGTH);
		pthread_spin_lock(&(AttitudeMesure->AttitudeLock));
		memcpy((void *) &Data, (void *) &(AttitudeMesure->Data), sizeof(AttData));
		memcpy((void *) &Speed, (void *) &(AttitudeMesure->Speed), sizeof(AttData));
		TimeStamp = AttitudeMesure->timestamp_s*1000 + AttitudeMesure->timestamp_n/1000000L;
		pthread_spin_unlock(&(AttitudeMesure->AttitudeLock));

		//Send Heartbeat
		mavlink_msg_heartbeat_pack(SYSTEM_ID, COMPONENT_ID, &msg, MAV_TYPE_HELICOPTER, MAV_AUTOPILOT_GENERIC, MAV_MODE_GUIDED_ARMED, 0, MAV_STATE_ACTIVE);
		len = mavlink_msg_to_send_buffer(buf, &msg);
		bytes_sent = sendto(Mavlink->sock, buf, len, 0, (struct sockaddr *)&Mavlink->gcAddr, sizeof(struct sockaddr_in));

		// Send Status
		mavlink_msg_sys_status_pack(SYSTEM_ID, COMPONENT_ID, &msg, sensor, sensor, 0, 500, 11000, -1, -1, 0, 0, 0, 0, 0, 0);
		len = mavlink_msg_to_send_buffer(buf, &msg);
		bytes_sent = sendto(Mavlink->sock, buf, len, 0, (struct sockaddr *)&Mavlink->gcAddr, sizeof (struct sockaddr_in));

		// Send Local Position
		mavlink_msg_local_position_ned_pack(SYSTEM_ID, COMPONENT_ID, &msg, TimeStamp, 0, 0, (float) Data.Elevation, 0, 0, (float) Speed.Elevation);
		len = mavlink_msg_to_send_buffer(buf, &msg);
		bytes_sent = sendto(Mavlink->sock, buf, len, 0, (struct sockaddr *)&Mavlink->gcAddr, sizeof(struct sockaddr_in));

		pthread_spin_lock(&(AttitudeDesire->AttitudeLock));
		memcpy((void *) &DataD, (void *) &(AttitudeDesire->Data), sizeof(AttData));
		memcpy((void *) &SpeedD, (void *) &(AttitudeDesire->Speed), sizeof(AttData));
		pthread_spin_unlock(&(AttitudeDesire->AttitudeLock));

		pthread_spin_lock(&(AttitudeMesure->AttitudeLock));
		memcpy((void *) &DataM, (void *) &(AttitudeMesure->Data), sizeof(AttData));
		memcpy((void *) &SpeedM, (void *) &(AttitudeMesure->Speed), sizeof(AttData));
		pthread_spin_unlock(&(AttitudeMesure->AttitudeLock));
		Error[HEIGHT]    = DataD.Elevation - DataM.Elevation;
		Error[ROLL]      = DataD.Roll - DataM.Roll;
		Error[PITCH]     = DataD.Pitch - DataM.Pitch;
		Error[YAW]       = DataD.Yaw - DataM.Yaw;
		// Send Attitude
		mavlink_msg_attitude_pack(SYSTEM_ID, COMPONENT_ID, &msg, TimeStamp, (float) Data.Roll, (float) Data.Pitch, (float) Data.Yaw, (float) Speed.Roll, (float) Speed.Pitch, (float) Speed.Yaw);
		len = mavlink_msg_to_send_buffer(buf, &msg);
		bytes_sent = sendto(Mavlink->sock, buf, len, 0, (struct sockaddr *)&Mavlink->gcAddr, sizeof(struct sockaddr_in));

	}
	printf("%s : Mavlink Status Arrêté\n", __FUNCTION__);
	pthread_exit(NULL);
}

static int
do_test (void)
{
  pthread_mutexattr_t a;
  if (pthread_mutexattr_init (&a) != 0)
    {
      puts ("mutexattr_init failed");
      return 1;
    }

  if (pthread_mutexattr_setrobust (&a, PTHREAD_MUTEX_ROBUST) != 0)
    {
      puts ("mutexattr_setrobust failed");
      return 1;
    }

#ifdef ENABLE_PI
  if (pthread_mutexattr_setprotocol (&a, PTHREAD_PRIO_INHERIT) != 0)
    {
      puts ("pthread_mutexattr_setprotocol failed");
      return 1;
    }
#endif

  int e;
  e = pthread_mutex_init (&m, &a);
  if (e != 0)
    {
#ifdef ENABLE_PI
      if (e == ENOTSUP)
	{
	  puts ("PI robust mutexes not supported");
	  return 0;
	}
#endif
      puts ("mutex_init failed");
      return 1;
    }

  if (pthread_mutexattr_destroy (&a) != 0)
    {
      puts ("mutexattr_destroy failed");
      return 1;
    }

  if (pthread_barrier_init (&b, NULL, 2) != 0)
    {
      puts ("barrier_init failed");
      return 1;
    }

#define N 5
  pthread_t th[N];
  for (long int n = 0; n < N; ++n)
    {
      if (pthread_create (&th[n], NULL, tf, (void *) n) != 0)
	{
	  printf ("pthread_create loop %ld failed\n", n + 1);
	  return 1;
	}

      e = pthread_barrier_wait (&b);
      if (e != 0 && e != PTHREAD_BARRIER_SERIAL_THREAD)
	{
	  printf ("parent: barrier_wait failed in round %ld\n", n + 1);
	  return 1;
	}
    }

  if (pthread_mutex_lock (&m) != 0)
    {
      puts ("parent: mutex_lock failed");
      return 1;
    }

  if (pthread_mutex_unlock (&m) != 0)
    {
      puts ("parent: mutex_unlock failed");
      return 1;
    }

  if (pthread_cond_broadcast (&c) != 0)
    {
      puts ("cond_broadcast failed");
      return 1;
    }

  for (int n = 0; n < N; ++n)
    {
      void *res;
      if (pthread_join (th[n], &res) != 0)
	{
	  printf ("join round %d failed\n", n + 1);
	  return 1;
	}
      if (res != PTHREAD_CANCELED)
	{
	  printf ("thread %d not canceled\n", n + 1);
	  return 1;
	}
//.........这里部分代码省略.........

/* A worker thread receives a number and a 4-letter name via targ */
void * tmain(void * targ)
{
   /* Local variables are not shared with other threads */
   int no, i;
   char name[5];
   pthread_t tid;
   int isBooked[t];//Tells how many times train i has been booked by this thread.
   memset(isBooked, 0, sizeof(isBooked));
   int trainsBooked[t];//Tells which all trains have been booked by this thread
   int numTrainsBooked = 0;//Count of the number of trains booked by this thread
   
   /* Retrieve my number and name from the parameter passed */
   no = ((tinfo *)targ) -> tno;
   strcpy(name,((tinfo *)targ) -> tname);

   /* Retrieve my thread id */
   tid = pthread_self();

   while (1) {
      /* Check for termination condition */

      pthread_mutex_lock(&donemutex);

      /* if the master thread is done */
      if(mdone)
      {
         pthread_mutex_unlock(&donemutex);
         pthread_barrier_wait(&barrier);         
         pthread_exit(NULL);
      }
      /* The master thread is still sleeping, so I continue to work */
      pthread_mutex_unlock(&donemutex);


      //Check if number of active queries is less than MAX
      pthread_mutex_lock(&querymutex);
      if(numActiveQueries == MAX)
      {
         printf("\nThread %d : Blocked since active queries = MAX\n", no);
         pthread_cond_wait(&querycond, &querymutex);
      }      
      numActiveQueries++;
      pthread_mutex_unlock(&querymutex);        

      int a123;
      //Start query
      int queryType = 1 + rand()%3;
      if(queryType == INQUIRE)
      {
         inquiry(no);
      }
      else if(queryType == BOOK)
      {
         booking(no, isBooked, trainsBooked, &numTrainsBooked);
      }
      else
      {
         cancellation(no, isBooked, trainsBooked, &numTrainsBooked);
      }

      pthread_mutex_lock(&querymutex);
      numActiveQueries--;
      if(numActiveQueries == (MAX-1))//wake up a waiting query
         pthread_cond_signal(&querycond);
      pthread_mutex_unlock(&querymutex);
      
      sleep(SLEEPTIME);
   }
}

static void *start_lock(void *arg)
{
	pthread_mutex_lock(arg);
	pthread_barrier_wait(&barrier2);
	return 0;
}

int uv_barrier_wait(uv_barrier_t* barrier) {
  int r = pthread_barrier_wait(barrier);
  if (r && r != PTHREAD_BARRIER_SERIAL_THREAD)
    abort();
  return r == PTHREAD_BARRIER_SERIAL_THREAD;
}

/* Do the forward Fast Fourier Transform either on two input images
   (the padded image and kernel) or on one image (the multiplication
   of the FFT of the two). In the second case, it is assumed that we
   are looking at the complex conjugate of the array so in practice
   this will be a backward transform. */
void
twodimensionfft(struct convolveparams *p, struct fftonthreadparams *fp,
                int forward1backwardn1)
{
  int err;
  pthread_t t;          /* All thread ids saved in this, not used. */
  pthread_attr_t attr;
  pthread_barrier_t b;
  size_t i, nb, *indexs, thrdcols;
  size_t nt=p->cp.numthreads, multiple=0;

  /* First we are going to get the 1D fourier transform on the rows of
     both images. */
  if(forward1backwardn1==1)       multiple=2;
  else if(forward1backwardn1==-1) multiple=1;
  else
    error(EXIT_FAILURE, 0, "%s: a bug! The value of the variable "
          "`forward1backwardn1' is %d not 1 or 2. Please contact us at %s "
          "so we can find the cause of the problem and fix it", __func__,
          forward1backwardn1, PACKAGE_BUGREPORT);


  /* ==================== */
  /* 1D FFT on each row. */
  /* ==================== */
  gal_threads_dist_in_threads(multiple*p->ps0, nt, &indexs, &thrdcols);
  if(nt==1)
    {
      fp[0].stride=1;
      fp[0].indexs=&indexs[0];
      fp[0].forward1backwardn1=forward1backwardn1;
      onedimensionfft(&fp[0]);
    }
  else
    {
      /* Initialize the attributes. Note that this running thread
         (that spinns off the nt threads) is also a thread, so the
         number the barrier should be one more than the number of
         threads spinned off. */
      if( multiple*p->ps0 < nt ) nb=multiple*p->ps0+1;
      else nb=nt+1;
      gal_threads_attr_barrier_init(&attr, &b, nb);

      /* Spin off the threads: */
      for(i=0;i<nt;++i)
        if(indexs[i*thrdcols]!=GAL_BLANK_SIZE_T)
          {
            fp[i].id=i;
            fp[i].b=&b;
            fp[i].stride=1; /* On each row, stride=1 */
            fp[i].indexs=&indexs[i*thrdcols];
            fp[i].forward1backwardn1=forward1backwardn1;
            err=pthread_create(&t, &attr, onedimensionfft, &fp[i]);
            if(err)
              error(EXIT_FAILURE, 0, "%s: can't create thread %zu for rows",
                    __func__, i);
          }

      /* Wait for all threads to finish and free the spaces. */
      pthread_barrier_wait(&b);
      pthread_attr_destroy(&attr);
      pthread_barrier_destroy(&b);
    }
  free(indexs);



  /* ====================== */
  /* 1D FFT on each column. */
  /* ====================== */
  /* No comments, exact duplicate, except the p->ps1s! */
  gal_threads_dist_in_threads(multiple*p->ps1, nt, &indexs, &thrdcols);
  if(nt==1)
    {
      fp[0].stride=p->ps1;
      fp[0].indexs=indexs;
      fp[0].forward1backwardn1=forward1backwardn1;
      onedimensionfft(&fp[0]);
    }
  else
    {
      if( multiple*p->ps1 < nt ) nb=multiple*p->ps1+1;
      else nb=nt+1;
      gal_threads_attr_barrier_init(&attr, &b, nb);
      for(i=0;i<nt;++i)
        if(indexs[i*thrdcols]!=GAL_BLANK_SIZE_T)
          {
            fp[i].b=&b;
            fp[i].stride=p->ps1; /* On each column, stride is p->ps1 */
            fp[i].indexs=&indexs[i*thrdcols];
            fp[i].forward1backwardn1=forward1backwardn1;
            err=pthread_create(&t, &attr, onedimensionfft, &fp[i]);
            if(err)
              error(EXIT_FAILURE, 0, "%s: can't create thread %zu for columns",
                    __func__, i);
//.........这里部分代码省略.........

static int
do_one_test (void)
{
  in_sh_body = 0;
  cleanups = 0;
  if (pipe (fd) != 0 || pipe (fd + 2) != 0)
    {
      puts ("pipe failed");
      return 1;
    }

  pthread_t th;
  if (pthread_create (&th, NULL, tf, NULL) != 0)
    {
      puts ("create failed");
      return 1;
    }

  int r = pthread_barrier_wait (&b);
  if (r != 0 && r != PTHREAD_BARRIER_SERIAL_THREAD)
    {
      puts ("parent thread: barrier_wait failed");
      return 1;
    }

  sleep (1);

  r = pthread_kill (th, SIGHUP);
  if (r)
    {
      errno = r;
      printf ("pthread_kill failed %m\n");
      return 1;
    }

  while (in_sh_body == 0)
    sleep (1);

  if (pthread_cancel (th) != 0)
    {
      puts ("cancel failed");
      return 1;
    }

  /* This will cause the read in the child to return.  */
  close (fd[0]);
  close (fd[1]);
  close (fd[2]);
  close (fd[3]);

  void *ret;
  if (pthread_join (th, &ret) != 0)
    {
      puts ("join failed");
      return 1;
    }

  if (ret != PTHREAD_CANCELED)
    {
      puts ("result is wrong");
      return 1;
    }

  if (cleanups != 0x1234L)
    {
      printf ("called cleanups %lx\n", cleanups);
      return 1;
    }

  return 0;
}

static void *
tf (void *arg)
{
  pthread_t th = (pthread_t) arg;

  int r = pthread_barrier_wait (&b);
  if (r != 0 && r != PTHREAD_BARRIER_SERIAL_THREAD)
    {
      puts ("parent thread: barrier_wait failed");
      exit (1);
    }

  sleep (1);

  r = pthread_kill (th, SIGHUP);
  if (r)
    {
      errno = r;
      printf ("pthread_kill failed %m\n");
      exit (1);
    }

  while (in_sh_body == 0)
    sleep (1);

  if (pthread_cancel (th) != 0)
    {
      puts ("cancel failed");
      exit (1);
    }

  /* This will cause the read in the initial thread to return.  */
  close (fd[0]);
  close (fd[1]);
  close (fd[2]);
  close (fd[3]);

  void *ret;
  if (pthread_join (th, &ret) != 0)
    {
      puts ("join failed");
      exit (1);
    }

  if (ret != PTHREAD_CANCELED)
    {
      puts ("result is wrong");
      exit (1);
    }

  if (cleanups != 0x1234L)
    {
      printf ("called cleanups %lx\n", cleanups);
      exit (1);
    }

  if (pthread_barrier_destroy (&b))
    {
      puts ("barrier destroy failed");
      exit (1);
    }

  exit (0);
}

hid_device * HID_API_EXPORT hid_open_path(const char *path)
{
	int i;
	hid_device *dev = NULL;
	CFIndex num_devices;

	dev = new_hid_device();

	/* Set up the HID Manager if it hasn't been done */
	if (hid_init() < 0)
		return NULL;

	/* give the IOHIDManager a chance to update itself */
	process_pending_events();

	CFSetRef device_set = IOHIDManagerCopyDevices(hid_mgr);

	num_devices = CFSetGetCount(device_set);
	IOHIDDeviceRef *device_array = calloc(num_devices, sizeof(IOHIDDeviceRef));
	CFSetGetValues(device_set, (const void **) device_array);
	for (i = 0; i < num_devices; i++) {
		char cbuf[BUF_LEN];
		size_t len;
		IOHIDDeviceRef os_dev = device_array[i];

		len = make_path(os_dev, cbuf, sizeof(cbuf));
		if (!strcmp(cbuf, path)) {
			/* Matched Paths. Open this Device. */
			IOReturn ret = IOHIDDeviceOpen(os_dev, kIOHIDOptionsTypeSeizeDevice);
			if (ret == kIOReturnSuccess) {
				char str[32];

				free(device_array);
				CFRetain(os_dev);
				CFRelease(device_set);
				dev->device_handle = os_dev;

				/* Create the buffers for receiving data */
				dev->max_input_report_len = (CFIndex) get_max_report_length(os_dev);
				dev->input_report_buf = calloc(dev->max_input_report_len, sizeof(uint8_t));

				/* Create the Run Loop Mode for this device.
				   printing the reference seems to work. */
				sprintf(str, "HIDAPI_%p", os_dev);
				dev->run_loop_mode =
					CFStringCreateWithCString(NULL, str, kCFStringEncodingASCII);

				/* Attach the device to a Run Loop */
				IOHIDDeviceRegisterInputReportCallback(
					os_dev, dev->input_report_buf, dev->max_input_report_len,
					&hid_report_callback, dev);
				IOHIDDeviceRegisterRemovalCallback(dev->device_handle, hid_device_removal_callback, dev);

				/* Start the read thread */
				pthread_create(&dev->thread, NULL, read_thread, dev);

				/* Wait here for the read thread to be initialized. */
				pthread_barrier_wait(&dev->barrier);

				return dev;
			}
			else {
				goto return_error;
			}
		}
	}

return_error:
	free(device_array);
	CFRelease(device_set);
	free_hid_device(dev);
	return NULL;
}

static void *read_thread(void *param)
{
	hid_device *dev = param;
	SInt32 code;

	/* Move the device's run loop to this thread. */
	IOHIDDeviceScheduleWithRunLoop(dev->device_handle, CFRunLoopGetCurrent(), dev->run_loop_mode);

	/* Create the RunLoopSource which is used to signal the
	   event loop to stop when hid_close() is called. */
	CFRunLoopSourceContext ctx;
	memset(&ctx, 0, sizeof(ctx));
	ctx.version = 0;
	ctx.info = dev;
	ctx.perform = &perform_signal_callback;
	dev->source = CFRunLoopSourceCreate(kCFAllocatorDefault, 0/*order*/, &ctx);
	CFRunLoopAddSource(CFRunLoopGetCurrent(), dev->source, dev->run_loop_mode);

	/* Store off the Run Loop so it can be stopped from hid_close()
	   and on device disconnection. */
	dev->run_loop = CFRunLoopGetCurrent();

	/* Notify the main thread that the read thread is up and running. */
	pthread_barrier_wait(&dev->barrier);

	/* Run the Event Loop. CFRunLoopRunInMode() will dispatch HID input
	   reports into the hid_report_callback(). */
	while (!dev->shutdown_thread && !dev->disconnected) {
		code = CFRunLoopRunInMode(dev->run_loop_mode, 1000/*sec*/, FALSE);
		/* Return if the device has been disconnected */
		if (code == kCFRunLoopRunFinished) {
			dev->disconnected = 1;
			break;
		}


		/* Break if The Run Loop returns Finished or Stopped. */
		if (code != kCFRunLoopRunTimedOut &&
		    code != kCFRunLoopRunHandledSource) {
			/* There was some kind of error. Setting
			   shutdown seems to make sense, but
			   there may be something else more appropriate */
			dev->shutdown_thread = 1;
			break;
		}
	}

	/* Now that the read thread is stopping, Wake any threads which are
	   waiting on data (in hid_read_timeout()). Do this under a mutex to
	   make sure that a thread which is about to go to sleep waiting on
	   the condition acutally will go to sleep before the condition is
	   signaled. */
	pthread_mutex_lock(&dev->mutex);
	pthread_cond_broadcast(&dev->condition);
	pthread_mutex_unlock(&dev->mutex);

	/* Wait here until hid_close() is called and makes it past
	   the call to CFRunLoopWakeUp(). This thread still needs to
	   be valid when that function is called on the other thread. */
	pthread_barrier_wait(&dev->shutdown_barrier);

	return NULL;
}

//.........这里部分代码省略.........
                surround[0].x = working_list[i].x;
                surround[0].y = working_list[i].y - 1;
            }
            //find the right position
            if(working_list[i].x + 1 < size) 
            {
                surround[1].value = matrix[position + 1];
                surround[1].x = working_list[i].x + 1;
                surround[1].y = working_list[i].y;
            }
            //find bottom position
            if(position + size < size * size)
            {
                surround[2].value = matrix[position + size];
                surround[2].x = working_list[i].x;
                surround[2].y = working_list[i].y + 1;
            }
            //find left position
            if(working_list[i].x - 1 >= 0) 
            {
                surround[3].value = matrix[position - 1];
                surround[3].x = working_list[i].x - 1;
                surround[3].y = working_list[i].y;
            }

            //find the minimum among the surrounding positions
            int j;
            for(j = 0; j < 4; j++)
            {
                //set min to the new position
                if(surround[j].value != -1 && surround[j].value < local_min.value) 
                {
                    local_min.value = surround[j].value;
                    local_min.x = surround[j].x;
                    local_min.y = surround[j].y;
                } 
            }

            //determine if the local min is smaller than the minimum found so far
            if(local_min.value < min_cells[thread_id].value)
            {
                min_cells[thread_id] = local_min;
            }

            local_min.value = INT_MAX;
            local_min.x = -1;
            local_min.y = -1;
        }

        //BARRIER: Wait for all other threads to find their minimum cell
        pthread_barrier_wait(&barrier);

        //Thread 0 manages the matrix, mask, working list, and filled cell count
        if(thread_id == 0)
        {
            
            pos global_min;
            global_min.value = INT_MAX;
            global_min.x = -1;
            global_min.y = -1;
           
            //determine minimum cell            
            int k;
            for(k = 0; k < num_threads; k++)
            {
                if(min_cells[k].value < global_min.value) //set new min
                {
                    global_min = min_cells[k];
                }
            }
            
            //determine linear position of cell
            int position = size * global_min.y + global_min.x;

            //fill the cell in the mask
            mask[position] = 1;

            //set the value in the matrix to "used"
            matrix[position] = -1; 

            //add latest cell to the working list
            working_list[filled] = global_min;

            //count one more cell filled
            filled++; 
            
            int m;
            for(m = 0; m < num_threads; m++)
            {
                min_cells[m].value = INT_MAX;
                min_cells[m].x = -1;
                min_cells[m].y = -1;
            }
        }

        //BARRIER: All other threads wait for Thread 0 to finish working
        pthread_barrier_wait(&barrier);

    }
}

static void
check_threads (pthread_barrier_t *barrier)
{
  pthread_barrier_wait (barrier);
}