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added error handling abillity into scheduler loop

/*************************************************************************
* (C) 2011 AITNET ltd - Sofia/Bulgaria - <misho@aitbg.com>
*  by Michael Pounov <misho@openbsd-bg.org>
*
* $Author: misho $
* $Id: hooks.c,v 1.2.2.3 2011/10/04 14:04:35 misho Exp $
*
**************************************************************************
The ELWIX and AITNET software is distributed under the following
terms:

All of the documentation and software included in the ELWIX and AITNET
Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>

Copyright 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
	by Michael Pounov <misho@elwix.org>.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. 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.
3. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
This product includes software developed by Michael Pounov <misho@elwix.org>
ELWIX - Embedded LightWeight unIX and its contributors.
4. Neither the name of AITNET 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 AITNET 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 REGENTS 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 "global.h"
#include "hooks.h"


/*
 * sched_hook_init() - Default INIT hook
 * @root = root task
 * @data = optional data if !=NULL
 * return: <0 errors and 0 ok
 */
void *
sched_hook_init(void *root, void *data)
{
	sched_root_task_t *r = root;

	if (!r || r->root_data.iov_base || r->root_data.iov_len)
		return (void*) -1;

	r->root_data.iov_base = malloc(sizeof(struct sched_IO));
	if (!r->root_data.iov_base) {
		LOGERR;
		return (void*) -1;
	} else {
		r->root_data.iov_len = sizeof(struct sched_IO);
		memset(r->root_data.iov_base, 0, r->root_data.iov_len);
	}

	r->root_kq = kqueue();
	if (r->root_kq == -1) {
		LOGERR;
		return (void*) -1;
	}

	return NULL;
}

/*
 * sched_hook_fini() - Default FINI hook
 * @root = root task
 * @arg = unused
 * return: <0 errors and 0 ok
 */
void *
sched_hook_fini(void *root, void *arg __unused)
{
	sched_root_task_t *r = root;

	if (!r)
		return (void*) -1;

	if (r->root_kq > 2) {
		close(r->root_kq);
		r->root_kq = 0;
	}

	if (r->root_data.iov_base && r->root_data.iov_len) {
		free(r->root_data.iov_base);
		r->root_data.iov_base = NULL;
		r->root_data.iov_len = 0;
	}

	return NULL;
}

/*
 * sched_hook_cancel() - Default CANCEL hook
 * @task = current task
 * @arg = unused
 * return: <0 errors and 0 ok
 */
void *
sched_hook_cancel(void *task, void *arg __unused)
{
	struct sched_IO *io;
	sched_task_t *t = task;
	struct kevent chg[1];
	struct timespec timeout = { 0, 0 };

	if (!t || !t->task_root || !ROOT_DATA(t->task_root) || !ROOT_DATLEN(t->task_root))
		return (void*) -1;
	else
		io = ROOT_DATA(t->task_root);

	switch (t->task_type) {
		case taskREAD:
#ifdef __NetBSD__
			EV_SET(&chg[0], TASK_FD(t), EVFILT_READ, EV_DELETE, 0, 0, (intptr_t) TASK_FD(t));
#else
			EV_SET(&chg[0], TASK_FD(t), EVFILT_READ, EV_DELETE, 0, 0, (void*) TASK_FD(t));
#endif
			kevent(t->task_root->root_kq, chg, 1, NULL, 0, &timeout);
			FD_CLR(TASK_FD(t), &io->rfd);
			break;
		case taskWRITE:
#ifdef __NetBSD__
			EV_SET(&chg[0], TASK_FD(t), EVFILT_WRITE, EV_DELETE, 0, 0, (intptr_t) TASK_FD(t));
#else
			EV_SET(&chg[0], TASK_FD(t), EVFILT_WRITE, EV_DELETE, 0, 0, (void*) TASK_FD(t));
#endif
			kevent(t->task_root->root_kq, chg, 1, NULL, 0, &timeout);
			FD_CLR(TASK_FD(t), &io->wfd);
			break;
		default:
			break;
	}

	return NULL;
}

/*
 * sched_hook_read() - Default READ hook
 * @task = current task
 * @arg = unused
 * return: <0 errors and 0 ok
 */
void *
sched_hook_read(void *task, void *arg __unused)
{
	struct sched_IO *io;
	sched_task_t *t = task;
	struct kevent chg[1];
	struct timespec timeout = { 0, 0 };

	if (!t || !t->task_root || !ROOT_DATA(t->task_root) || !ROOT_DATLEN(t->task_root))
		return (void*) -1;
	else
		io = ROOT_DATA(t->task_root);

	if (FD_ISSET(TASK_FD(t), &io->rfd))
		return NULL;
	else
		FD_SET(TASK_FD(t), &io->rfd);

#ifdef __NetBSD__
	EV_SET(&chg[0], TASK_FD(t), EVFILT_READ, EV_ADD, 0, 0, (intptr_t) TASK_FD(t));
#else
	EV_SET(&chg[0], TASK_FD(t), EVFILT_READ, EV_ADD, 0, 0, (void*) TASK_FD(t));
#endif
	if (kevent(t->task_root->root_kq, chg, 1, NULL, 0, &timeout) == -1) {
		if (t->task_root->root_hooks.hook_exec.exception)
			t->task_root->root_hooks.hook_exec.exception(t->task_root, NULL);
		else
			LOGERR;
		return (void*) -1;
	}

	return NULL;
}

/*
 * sched_hook_write() - Default WRITE hook
 * @task = current task
 * @arg = unused
 * return: <0 errors and 0 ok
 */
void *
sched_hook_write(void *task, void *arg __unused)
{
	struct sched_IO *io;
	sched_task_t *t = task;
	struct kevent chg[1];
	struct timespec timeout = { 0, 0 };

	if (!t || !t->task_root || !ROOT_DATA(t->task_root) || !ROOT_DATLEN(t->task_root))
		return (void*) -1;
	else
		io = ROOT_DATA(t->task_root);

	if (FD_ISSET(TASK_FD(t), &io->wfd))
		return NULL;
	else
		FD_SET(TASK_FD(t), &io->wfd);

#ifdef __NetBSD__
	EV_SET(&chg[0], TASK_FD(t), EVFILT_WRITE, EV_ADD, 0, 0, (intptr_t) TASK_FD(t));
#else
	EV_SET(&chg[0], TASK_FD(t), EVFILT_WRITE, EV_ADD, 0, 0, (void*) TASK_FD(t));
#endif
	if (kevent(t->task_root->root_kq, chg, 1, NULL, 0, &timeout) == -1) {
		if (t->task_root->root_hooks.hook_exec.exception)
			t->task_root->root_hooks.hook_exec.exception(t->task_root, NULL);
		else
			LOGERR;
		return (void*) -1;
	}

	return NULL;
}

/*
 * sched_hook_fetch() - Default FETCH hook
 * @root = root task
 * @arg = unused
 * return: NULL error or !=NULL fetched task
 */
void *
sched_hook_fetch(void *root, void *arg __unused)
{
	struct sched_IO *io;
	sched_root_task_t *r = root;
	sched_task_t *task;
	struct timeval now, m, mtmp;
	struct timespec nw, *timeout;
	struct kevent evt[1], res[KQ_EVENTS];
	register int i;
	int en;

	if (!r || !ROOT_DATA(r) || !ROOT_DATLEN(r))
		return NULL;

	/* get new task by queue priority */
retry:
	while ((task = TAILQ_FIRST(&r->root_event))) {
		TAILQ_REMOVE(&r->root_event, task, task_node);
		task->task_type = taskUNUSE;
		TAILQ_INSERT_TAIL(&r->root_unuse, task, task_node);
		return task;
	}
	while ((task = TAILQ_FIRST(&r->root_ready))) {
		TAILQ_REMOVE(&r->root_ready, task, task_node);
		task->task_type = taskUNUSE;
		TAILQ_INSERT_TAIL(&r->root_unuse, task, task_node);
		return task;
	}

#ifdef TIMER_WITHOUT_SORT
	clock_gettime(CLOCK_MONOTONIC, &nw);
	now.tv_sec = nw.tv_sec;
	now.tv_usec = nw.tv_nsec / 1000;

	timerclear(&r->root_wait);
	TAILQ_FOREACH(task, &r->root_timer, task_node) {
		if (!timerisset(&r->root_wait))
			r->root_wait = TASK_TV(task);
		else if (timercmp(&TASK_TV(task), &r->root_wait, -) < 0)
			r->root_wait = TASK_TV(task);
	}

	if (TAILQ_FIRST(&r->root_timer)) {
		m = r->root_wait;
		timersub(&m, &now, &mtmp);
		r->root_wait = mtmp;
	} else {
		/* set wait INFTIM */
		r->root_wait.tv_sec = r->root_wait.tv_usec = -1;
	}
#else
	if (!TAILQ_FIRST(&r->root_eventlo) && (task = TAILQ_FIRST(&r->root_timer))) {
		clock_gettime(CLOCK_MONOTONIC, &nw);
		now.tv_sec = nw.tv_sec;
		now.tv_usec = nw.tv_nsec / 1000;

		m = TASK_TV(task);
		timersub(&m, &now, &mtmp);
		r->root_wait = mtmp;
	} else {
		/* set wait INFTIM */
		r->root_wait.tv_sec = r->root_wait.tv_usec = -1;
	}
#endif
	/* if present member of eventLo, set NOWAIT */
	if (TAILQ_FIRST(&r->root_eventlo))
		timerclear(&r->root_wait);

	if (r->root_wait.tv_sec != -1 && r->root_wait.tv_usec != -1) {
		nw.tv_sec = r->root_wait.tv_sec;
		nw.tv_nsec = r->root_wait.tv_usec * 1000;
		timeout = &nw;
	} else	/* wait INFTIM */
		timeout = NULL;
	if ((en = kevent(r->root_kq, NULL, 0, res, KQ_EVENTS, timeout)) == -1) {
		if (r->root_hooks.hook_exec.exception) {
			if (r->root_hooks.hook_exec.exception(r, NULL))
				return NULL;
		} else
			LOGERR;
#ifdef NDEBUG
		/* kevent no exit by error, if non-debug version */
		goto retry;
#else
		/* diagnostic exit from scheduler if kevent error occur */
		return NULL;
#endif
	}

	nw.tv_sec = nw.tv_nsec = 0;
	/* Go and catch the cat into pipes ... */
	for (i = 0; i < en; i++) {
		memcpy(evt, &res[i], sizeof evt);
		evt->flags = EV_DELETE;
		/* Put read/write task to ready queue */
		switch (res[i].filter) {
			case EVFILT_READ:
				TAILQ_FOREACH(task, &r->root_read, task_node) {
					if (TASK_FD(task) != ((int) res[i].udata))
						continue;
					/* remove read handle */
					io = ROOT_DATA(task->task_root);
					FD_CLR(TASK_FD(task), &io->rfd);

					TAILQ_REMOVE(&r->root_read, task, task_node);
					if (r->root_hooks.hook_exec.exception && res[i].flags & EV_EOF) {
 						if (r->root_hooks.hook_exec.exception(r, (void*) EV_EOF)) {
							task->task_type = taskUNUSE;
							TAILQ_INSERT_TAIL(&r->root_unuse, task, task_node);
						} else {
							task->task_type = taskREADY;
							TAILQ_INSERT_TAIL(&r->root_ready, task, task_node);
						}
					} else {
						task->task_type = taskREADY;
						TAILQ_INSERT_TAIL(&r->root_ready, task, task_node);
					}
					break;
				}
				break;
			case EVFILT_WRITE:
				TAILQ_FOREACH(task, &r->root_write, task_node) {
					if (TASK_FD(task) != ((int) res[i].udata))
						continue;
					/* remove write handle */
					io = ROOT_DATA(task->task_root);
					FD_CLR(TASK_FD(task), &io->wfd);

					TAILQ_REMOVE(&r->root_write, task, task_node);
					if (r->root_hooks.hook_exec.exception && res[i].flags & EV_EOF) {
 						if (r->root_hooks.hook_exec.exception(r, (void*) EV_EOF)) {
							task->task_type = taskUNUSE;
							TAILQ_INSERT_TAIL(&r->root_unuse, task, task_node);
						} else {
							task->task_type = taskREADY;
							TAILQ_INSERT_TAIL(&r->root_ready, task, task_node);
						}
					} else {
						task->task_type = taskREADY;
						TAILQ_INSERT_TAIL(&r->root_ready, task, task_node);
					}
					break;
				}
				break;
		}
		if (kevent(r->root_kq, evt, 1, NULL, 0, &nw) == -1) {
			if (r->root_hooks.hook_exec.exception) {
				if (r->root_hooks.hook_exec.exception(r, NULL))
					return NULL;
			} else
				LOGERR;
		}
	}

	/* timer update & put in ready queue */
	clock_gettime(CLOCK_MONOTONIC, &nw);
	now.tv_sec = nw.tv_sec;
	now.tv_usec = nw.tv_nsec / 1000;

	TAILQ_FOREACH(task, &r->root_timer, task_node)
		if (timercmp(&now, &TASK_TV(task), -) >= 0) {
			TAILQ_REMOVE(&r->root_timer, task, task_node);
			task->task_type = taskREADY;
			TAILQ_INSERT_TAIL(&r->root_ready, task, task_node);
		}

	/* put eventlo priority task to ready queue, if there is no ready task or 
	   	reach max missed fetch-rotate */
	if ((task = TAILQ_FIRST(&r->root_eventlo))) {
		if (!TAILQ_FIRST(&r->root_ready) || r->root_eventlo_miss > MAX_EVENTLO_MISS) {
			r->root_eventlo_miss = 0;

			TAILQ_REMOVE(&r->root_eventlo, task, task_node);
			task->task_type = taskREADY;
			TAILQ_INSERT_TAIL(&r->root_ready, task, task_node);
		} else
			r->root_eventlo_miss++;
	} else
		r->root_eventlo_miss = 0;

	/* OK, lets get ready task !!! */
	if (!(task = TAILQ_FIRST(&r->root_ready)))
		goto retry;
	TAILQ_REMOVE(&r->root_ready, task, task_node);
	task->task_type = taskUNUSE;
	TAILQ_INSERT_TAIL(&r->root_unuse, task, task_node);
	return task;
}

/*
 * sched_hook_exception() - Default EXCEPTION hook
 * @root = root task
 * @arg = custom handling: if arg == EV_EOF or other value; default: arg == NULL log errno
 * return: <0 errors and 0 ok
 */
void *
sched_hook_exception(void *root, void *arg)
{
	sched_root_task_t *r = root;

	if (!r || !ROOT_DATA(r) || !ROOT_DATLEN(r))
		return NULL;

	/* custom exception handling ... */
	if (arg) {
		if (arg == (void*) EV_EOF)
			return NULL;
		return (void*) -1;	/* raise scheduler error!!! */
	}

	/* if error hook exists */
	if (r->root_hooks.hook_root.error)
		return (r->root_hooks.hook_root.error(root, (void*) errno));

	/* default case! */
	LOGERR;
	return NULL;
}