text: /*
   *
   * 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_LINUX_EVENTFD
  
  #include <errno.h>
  #include <sys/eventfd.h>
  #include <unistd.h>
  
  #include <grpc/support/log.h>
  
  #include "src/core/lib/iomgr/wakeup_fd_posix.h"
  #include "src/core/lib/profiling/timers.h"
  
  static grpc_error* eventfd_create(grpc_wakeup_fd* fd_info) {
    int efd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
    if (efd < 0) {
      return GRPC_OS_ERROR(errno, "eventfd");
    }
    fd_info->read_fd = efd;
    fd_info->write_fd = -1;
    return GRPC_ERROR_NONE;
  }
  
  static grpc_error* 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);
    if (err < 0 && errno != EAGAIN) {
      return GRPC_OS_ERROR(errno, "eventfd_read");
    }
    return GRPC_ERROR_NONE;
  }
  
  static grpc_error* eventfd_wakeup(grpc_wakeup_fd* fd_info) {
    int err;
    GPR_TIMER_BEGIN("eventfd_wakeup", 0);
    do {
      err = eventfd_write(fd_info->read_fd, 1);
    } while (err < 0 && errno == EINTR);
    if (err < 0) {
      return GRPC_OS_ERROR(errno, "eventfd_write");
    }
    GPR_TIMER_END("eventfd_wakeup", 0);
    return GRPC_ERROR_NONE;
  }
  
  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 */
  