src/core/iomgr/pollset_windows.c

/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <grpc/support/port_platform.h>

#ifdef GPR_WINSOCK_SOCKET

#include <grpc/support/thd.h>

#include "src/core/iomgr/alarm_internal.h"
#include "src/core/iomgr/iomgr_internal.h"
#include "src/core/iomgr/pollset.h"
#include "src/core/iomgr/pollset_windows.h"

static void
remove_worker (grpc_pollset * p, grpc_pollset_worker * worker)
{
  worker->prev->next = worker->next;
  worker->next->prev = worker->prev;
}

static int
has_workers (grpc_pollset * p)
{
  return p->root_worker.next != &p->root_worker;
}

static grpc_pollset_worker *
pop_front_worker (grpc_pollset * p)
{
  if (has_workers (p))
    {
      grpc_pollset_worker *w = p->root_worker.next;
      remove_worker (p, w);
      return w;
    }
  else
    {
      return NULL;
    }
}

static void
push_back_worker (grpc_pollset * p, grpc_pollset_worker * worker)
{
  worker->next = &p->root_worker;
  worker->prev = worker->next->prev;
  worker->prev->next = worker->next->prev = worker;
}

static void
push_front_worker (grpc_pollset * p, grpc_pollset_worker * worker)
{
  worker->prev = &p->root_worker;
  worker->next = worker->prev->next;
  worker->prev->next = worker->next->prev = worker;
}

/* There isn't really any such thing as a pollset under Windows, due to the
   nature of the IO completion ports. We're still going to provide a minimal
   set of features for the sake of the rest of grpc. But grpc_pollset_work
   won't actually do any polling, and return as quickly as possible. */

void
grpc_pollset_init (grpc_pollset * pollset)
{
  memset (pollset, 0, sizeof (*pollset));
  gpr_mu_init (&pollset->mu);
  pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker;
  pollset->kicked_without_pollers = 0;
}

void
grpc_pollset_shutdown (grpc_pollset * pollset, void (*shutdown_done) (void *arg), void *shutdown_done_arg)
{
  gpr_mu_lock (&pollset->mu);
  pollset->shutting_down = 1;
  grpc_pollset_kick (pollset, GRPC_POLLSET_KICK_BROADCAST);
  gpr_mu_unlock (&pollset->mu);
  shutdown_done (shutdown_done_arg);
}

void
grpc_pollset_destroy (grpc_pollset * pollset)
{
  gpr_mu_destroy (&pollset->mu);
}

void
grpc_pollset_work (grpc_pollset * pollset, grpc_pollset_worker * worker, gpr_timespec now, gpr_timespec deadline)
{
  int added_worker = 0;
  worker->next = worker->prev = NULL;
  gpr_cv_init (&worker->cv);
  if (grpc_maybe_call_delayed_callbacks (&pollset->mu, 1 /* GPR_TRUE */ ))
    {
      goto done;
    }
  if (grpc_alarm_check (&pollset->mu, now, &deadline))
    {
      goto done;
    }
  if (!pollset->kicked_without_pollers && !pollset->shutting_down)
    {
      push_front_worker (pollset, worker);
      added_worker = 1;
      gpr_cv_wait (&worker->cv, &pollset->mu, deadline);
    }
  else
    {
      pollset->kicked_without_pollers = 0;
    }
done:
  gpr_cv_destroy (&worker->cv);
  if (added_worker)
    {
      remove_worker (pollset, worker);
    }
}

void
grpc_pollset_kick (grpc_pollset * p, grpc_pollset_worker * specific_worker)
{
  if (specific_worker != NULL)
    {
      if (specific_worker == GRPC_POLLSET_KICK_BROADCAST)
	{
	  for (specific_worker = p->root_worker.next; specific_worker != &p->root_worker; specific_worker = specific_worker->next)
	    {
	      gpr_cv_signal (&specific_worker->cv);
	    }
	  p->kicked_without_pollers = 1;
	}
      else
	{
	  gpr_cv_signal (&specific_worker->cv);
	}
    }
  else
    {
      specific_worker = pop_front_worker (p);
      if (specific_worker != NULL)
	{
	  push_back_worker (p, specific_worker);
	  gpr_cv_signal (&specific_worker->cv);
	}
      else
	{
	  p->kicked_without_pollers = 1;
	}
    }
}

#endif /* GPR_WINSOCK_SOCKET */