src/core/iomgr/wakeup_fd_eventfd.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.
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 * 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,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 */

#include <grpc/support/port_platform.h>

#ifdef GPR_LINUX_EVENTFD

#include <errno.h>
#include <sys/eventfd.h>
#include <unistd.h>

#include "src/core/iomgr/wakeup_fd_posix.h"
#include <grpc/support/log.h>

static void
eventfd_create (grpc_wakeup_fd * fd_info)
{
  int efd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
  /* TODO(klempner): Handle failure more gracefully */
  GPR_ASSERT (efd >= 0);
  fd_info->read_fd = efd;
  fd_info->write_fd = -1;
}

static void
eventfd_consume (grpc_wakeup_fd * fd_info)
{
  eventfd_t value;
  int err;
  do
    {
      err = eventfd_read (fd_info->read_fd, &value);
    }
  while (err < 0 && errno == EINTR);
}

static void
eventfd_wakeup (grpc_wakeup_fd * fd_info)
{
  int err;
  do
    {
      err = eventfd_write (fd_info->read_fd, 1);
    }
  while (err < 0 && errno == EINTR);
}

static void
eventfd_destroy (grpc_wakeup_fd * fd_info)
{
  if (fd_info->read_fd != 0)
    close (fd_info->read_fd);
}

static int
eventfd_check_availability (void)
{
  /* TODO(klempner): Actually check if eventfd is available */
  return 1;
}

const grpc_wakeup_fd_vtable grpc_specialized_wakeup_fd_vtable = {
  eventfd_create, eventfd_consume, eventfd_wakeup, eventfd_destroy,
  eventfd_check_availability
};

#endif /* GPR_LINUX_EVENTFD */