/*	$OpenBSD: rf_fifo.c,v 1.6 2002/12/16 07:01:04 tdeval Exp $	*/
/*	$NetBSD: rf_fifo.c,v 1.5 2000/03/04 03:27:13 oster Exp $	*/

/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Mark Holland
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/***************************************************
 *
 * rf_fifo.c --  prioritized fifo queue code.
 * There are only two priority levels: hi and lo.
 *
 * Aug 4, 1994, adapted from raidSim version (MCH)
 *
 ***************************************************/

#include "rf_types.h"
#include "rf_alloclist.h"
#include "rf_stripelocks.h"
#include "rf_layout.h"
#include "rf_diskqueue.h"
#include "rf_fifo.h"
#include "rf_debugMem.h"
#include "rf_general.h"
#include "rf_options.h"
#include "rf_raid.h"
#include "rf_types.h"

/* Just malloc a header, zero it (via calloc), and return it. */
/*ARGSUSED*/
void *
rf_FifoCreate(RF_SectorCount_t sectPerDisk, RF_AllocListElem_t *clList,
    RF_ShutdownList_t **listp)
{
	RF_FifoHeader_t *q;

	RF_CallocAndAdd(q, 1, sizeof(RF_FifoHeader_t), (RF_FifoHeader_t *),
	    clList);
	q->hq_count = q->lq_count = 0;
	return ((void *) q);
}

void
rf_FifoEnqueue(void *q_in, RF_DiskQueueData_t *elem, int priority)
{
	RF_FifoHeader_t *q = (RF_FifoHeader_t *) q_in;

	RF_ASSERT(priority == RF_IO_NORMAL_PRIORITY ||
	    priority == RF_IO_LOW_PRIORITY);

	elem->next = NULL;
	if (priority == RF_IO_NORMAL_PRIORITY) {
		if (!q->hq_tail) {
			RF_ASSERT(q->hq_count == 0 && q->hq_head == NULL);
			q->hq_head = q->hq_tail = elem;
		} else {
			RF_ASSERT(q->hq_count != 0 && q->hq_head != NULL);
			q->hq_tail->next = elem;
			q->hq_tail = elem;
		}
		q->hq_count++;
	} else {
		RF_ASSERT(elem->next == NULL);
		if (rf_fifoDebug) {
			printf("raid%d: fifo: ENQ lopri\n",
			    elem->raidPtr->raidid);
		}
		if (!q->lq_tail) {
			RF_ASSERT(q->lq_count == 0 && q->lq_head == NULL);
			q->lq_head = q->lq_tail = elem;
		} else {
			RF_ASSERT(q->lq_count != 0 && q->lq_head != NULL);
			q->lq_tail->next = elem;
			q->lq_tail = elem;
		}
		q->lq_count++;
	}
	if ((q->hq_count + q->lq_count) != elem->queue->queueLength) {
		printf("Queue lengths differ ! : %d %d %d\n",
		    q->hq_count, q->lq_count, (int) elem->queue->queueLength);
		printf("%d %d %d %d\n",
		    (int) elem->queue->numOutstanding,
		    (int) elem->queue->maxOutstanding,
		    (int) elem->queue->row,
		    (int) elem->queue->col);
	}
	RF_ASSERT((q->hq_count + q->lq_count) == elem->queue->queueLength);
}

RF_DiskQueueData_t *
rf_FifoDequeue(void *q_in)
{
	RF_FifoHeader_t *q = (RF_FifoHeader_t *) q_in;
	RF_DiskQueueData_t *nd;

	RF_ASSERT(q);
	if (q->hq_head) {
		RF_ASSERT(q->hq_count != 0 && q->hq_tail != NULL);
		nd = q->hq_head;
		q->hq_head = q->hq_head->next;
		if (!q->hq_head)
			q->hq_tail = NULL;
		nd->next = NULL;
		q->hq_count--;
	} else
		if (q->lq_head) {
			RF_ASSERT(q->lq_count != 0 && q->lq_tail != NULL);
			nd = q->lq_head;
			q->lq_head = q->lq_head->next;
			if (!q->lq_head)
				q->lq_tail = NULL;
			nd->next = NULL;
			q->lq_count--;
			if (rf_fifoDebug) {
				printf("raid%d: fifo: DEQ lopri %lx\n",
				    nd->raidPtr->raidid, (long) nd);
			}
		} else {
			RF_ASSERT(q->hq_count == 0 && q->lq_count == 0 &&
			    q->hq_tail == NULL && q->lq_tail == NULL);
			nd = NULL;
		}
	return (nd);
}

/*
 * Return ptr to item at head of queue. Used to examine request
 * info without actually dequeueing the request.
 */
RF_DiskQueueData_t *
rf_FifoPeek(void *q_in)
{
	RF_DiskQueueData_t *headElement = NULL;
	RF_FifoHeader_t *q = (RF_FifoHeader_t *) q_in;

	RF_ASSERT(q);
	if (q->hq_head)
		headElement = q->hq_head;
	else
		if (q->lq_head)
			headElement = q->lq_head;
	return (headElement);
}

/*
 * We sometimes need to promote a low priority access to a regular priority
 * access. Currently, this is only used when the user wants to write a stripe
 * that is currently under reconstruction.
 * This routine will promote all accesses tagged with the indicated
 * parityStripeID from the low priority queue to the end of the normal
 * priority queue.
 * We assume the queue is locked upon entry.
 */
int
rf_FifoPromote(void *q_in, RF_StripeNum_t parityStripeID,
    RF_ReconUnitNum_t which_ru)
{
	RF_FifoHeader_t *q = (RF_FifoHeader_t *) q_in;
	/* lp = lo-pri queue pointer, pt = trailer */
	RF_DiskQueueData_t *lp = q->lq_head, *pt = NULL;
	int retval = 0;

	while (lp) {

		/*
		 * Search for the indicated parity stripe in the low-pri queue.
		 */
		if (lp->parityStripeID == parityStripeID &&
		    lp->which_ru == which_ru) {
			/* printf("FifoPromote:  promoting access for psid
			 * %ld\n", parityStripeID); */
			if (pt)
				/* Delete an entry other than the first. */
				pt->next = lp->next;
			else
				/* Delete the head entry. */
				q->lq_head = lp->next;

			if (!q->lq_head)
				/* We deleted the only entry. */
				q->lq_tail = NULL;
			else
				if (lp == q->lq_tail)
					/* We deleted the tail entry. */
					q->lq_tail = pt;

			lp->next = NULL;
			q->lq_count--;

			if (q->hq_tail) {
				q->hq_tail->next = lp;
				q->hq_tail = lp;
			}
			 /* Append to hi-priority queue. */
			else {
				q->hq_head = q->hq_tail = lp;
			}
			q->hq_count++;

			/* Deal with this later, if ever. */
			/* UpdateShortestSeekFinishTimeForced(lp->requestPtr,
			 * lp->diskState); */

			/* Reset low-pri pointer and continue. */
			lp = (pt) ? pt->next : q->lq_head;
			retval++;

		} else {
			pt = lp;
			lp = lp->next;
		}
	}

	/*
	 * Sanity check. Delete this if you ever put more than one entry in
	 * the low-pri queue.
	 */
	RF_ASSERT(retval == 0 || retval == 1);
	return (retval);
}
