/* io-epoll.c - epoll(7) based file descriptor monitoring
 *
 * Copyright (C) 2009 Timo Teräs <timo.teras@iki.fi>
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 or later as
 * published by the Free Software Foundation.
 *
 * See http://www.gnu.org/ for details.
 */

#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/epoll.h>

#include <libtf/io.h>
#include <libtf/fiber.h>

#define TF_FD_AUTOCLOSE			1
#define TF_FD_RESTORE_BLOCKING		2
#define TF_FD_STREAM_ORIENTED		4

static int tf_fd_init(struct tf_fd *fd, int kfd, int flags)
{
	struct tf_poll_data *pd = &tf_get_scheduler()->poll_data;
	struct epoll_event ev;
	int r;

	ev.events = EPOLLIN | EPOLLOUT | EPOLLET;
	ev.data.ptr = fd;
	r = epoll_ctl(pd->epoll_fd, EPOLL_CTL_ADD, kfd, &ev);
	if (r < 0) {
		TF_BUG_ON(errno == EEXIST);
		return -errno;
	}

	fd->fd = kfd;
	fd->flags = flags;
	fd->waiting_fiber = NULL;

	return 0;
}

static void tf_fd_wait(struct tf_fd *fd, int events)
{
	struct tf_poll_data *pd = &tf_get_scheduler()->poll_data;

	TF_BUG_ON(fd->waiting_fiber != NULL);
	fd->events = events | EPOLLERR | EPOLLHUP;
	fd->waiting_fiber = tf_get_fiber();
	pd->num_waiters++;
}

static void tf_fd_release(struct tf_fd *fd)
{
	struct tf_poll_data *pd = &tf_get_scheduler()->poll_data;

	fd->waiting_fiber = NULL;
	fd->events = 0;
	pd->num_waiters--;
}

void tf_poll_init(void)
{
	struct tf_poll_data *pd = &tf_get_scheduler()->poll_data;

	pd->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
	pd->num_waiters = 0;
	TF_BUG_ON(pd->epoll_fd < 0);
}

int tf_poll(tf_mtime_diff_t timeout)
{
	struct tf_poll_data *pd = &tf_get_scheduler()->poll_data;
	struct epoll_event events[64];
	struct tf_fd *fd;
	int ret = (timeout == 0) ? TF_WAKEUP_TIMEOUT : TF_WAKEUP_FD;
	int r, i;

	if (timeout == 0 && pd->num_waiters == 0)
		return ret;

	do {
		r = epoll_wait(pd->epoll_fd, events, array_size(events), timeout);
		for (i = 0; i < r; i++) {
			fd = (struct tf_fd *) events[i].data.ptr;
			if (likely(fd->events & events[i].events))
				tf_wakeup(fd->waiting_fiber, TF_WAKEUP_FD);
		}
		if (timeout != 0)
			ret = TF_WAKEUP_FD;
		timeout = 0;
	} while (unlikely(r == array_size(events)));

	return ret;
}

void tf_poll_close(void)
{
	struct tf_poll_data *pd = &tf_get_scheduler()->poll_data;

	close(pd->epoll_fd);
}

#include "io-unix.c"