/* 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>

struct tf_epoll_data {
	int			epoll_fd;
};

static void tf_epoll_main(void *ctx)
{
	struct tf_epoll_data *pd = ctx;
	struct epoll_event events[64];
	struct tf_fd *fd;
	int r, i;

	do {
		r = epoll_wait(pd->epoll_fd, events, array_size(events), 0);
		if (r == 0) {
			/* FIXME: yielding is bad */
			struct tf_fiber *self = tf_vmach_get_current_fiber();
			tf_list_add_tail(&self->queue_node, &self->wakeup_q);
			if (tf_fiber_schedule() == 0)
				continue;
		}

		for (i = 0; i < r; i++) {
			fd = (struct tf_fd *) events[i].data.ptr;
			tf_fiber_wakeup(fd->fiber);
		}
	} while (1);

	close(pd->epoll_fd);
}

static void *tf_epoll_create(void)
{
	struct tf_epoll_data *d;

	d = tf_fiber_create(tf_epoll_main, sizeof(struct tf_epoll_data));
	if (d == NULL)
		return NULL;

	d->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
	TF_BUG_ON(d->epoll_fd < 0);

	tf_fiber_run(tf_fiber_get(d));

	return d;
}

static int tf_epoll_fd_created(void *fiber, struct tf_fd *fd)
{
	struct tf_epoll_data *d = fiber;
	struct epoll_event ev;
	int r;

	ev = (struct epoll_event) {
		.events = EPOLLET,
		.data.ptr = fd,
	};
	if (fd->flags & TF_FD_READ)
		ev.events |= EPOLLIN;
	if (fd->flags & TF_FD_WRITE)
		ev.events |= EPOLLOUT;

	r = epoll_ctl(d->epoll_fd, EPOLL_CTL_ADD, fd->fd, &ev);
	if (unlikely(r < 0)) {
		TF_BUG_ON(errno == EEXIST);
		r = -errno;
		return r;
	}

	return 0;
}

static int tf_epoll_fd_destroyed(void *fiber, struct tf_fd *fd)
{
	struct tf_epoll_data *d = fiber;

	if (!(fd->flags & TF_FD_AUTOCLOSE))
		epoll_ctl(d->epoll_fd, EPOLL_CTL_DEL, fd->fd, NULL);

	return 0;
}

struct tf_poll_hooks tf_epoll_hooks = {
	.create = tf_epoll_create,
	.fd_created = tf_epoll_fd_created,
	.fd_destroyed = tf_epoll_fd_destroyed,
};