/*	$NetBSD: rf_cvscan.c,v 1.2 1998/11/18 15:13:51 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.
 */

/*******************************************************************************
 *
 * cvscan.c --  prioritized cvscan disk queueing code.  
 *
 * Nov 9, 1994, adapted from raidSim version (MCH)
 *
 ******************************************************************************/

/*
 * :  
 * Log: rf_cvscan.c,v 
 * Revision 1.6  1996/07/27 23:36:08  jimz
 * Solaris port of simulator
 *
 * Revision 1.5  1996/07/15  17:22:18  jimz
 * nit-pick code cleanup
 * resolve stdlib problems on DEC OSF
 *
 * Revision 1.4  1996/06/09  02:36:46  jimz
 * lots of little crufty cleanup- fixup whitespace
 * issues, comment #ifdefs, improve typing in some
 * places (esp size-related)
 *
 * Revision 1.3  1996/06/07  22:26:27  jimz
 * type-ify which_ru (RF_ReconUnitNum_t)
 *
 * Revision 1.2  1996/06/07  21:33:04  jimz
 * begin using consistent types for sector numbers,
 * stripe numbers, row+col numbers, recon unit numbers
 *
 * Revision 1.1  1996/06/05  19:17:40  jimz
 * Initial revision
 *
 */

#include "rf_types.h"
#include "rf_alloclist.h"
#include "rf_stripelocks.h"
#include "rf_layout.h"
#include "rf_diskqueue.h"
#include "rf_cvscan.h"
#include "rf_debugMem.h"
#include "rf_general.h"
#include "rf_sys.h"

#define DO_CHECK_STATE(_hdr_) CheckCvscanState((_hdr_), __FILE__, __LINE__)

#define pri_ok(p)  ( ((p) == RF_IO_NORMAL_PRIORITY) || ((p) == RF_IO_LOW_PRIORITY))

static void CheckCvscanState(RF_CvscanHeader_t *hdr, char *file, int line)
{
	long i, key;
	RF_DiskQueueData_t *tmp;

	if( hdr->left != (RF_DiskQueueData_t *) NULL )
		RF_ASSERT( hdr->left->sectorOffset < hdr->cur_block );
	for( key=hdr->cur_block, i=0, tmp=hdr->left;
		tmp != (RF_DiskQueueData_t *) NULL;
		key=tmp->sectorOffset, i++, tmp=tmp->next )
		RF_ASSERT( tmp->sectorOffset <= key
		&& tmp->priority == hdr->nxt_priority && pri_ok(tmp->priority) );
	RF_ASSERT( i == hdr->left_cnt );

	for( key=hdr->cur_block, i=0, tmp=hdr->right;
		tmp != (RF_DiskQueueData_t *) NULL;
		key=tmp->sectorOffset, i++, tmp=tmp->next )
	{
		RF_ASSERT(key <= tmp->sectorOffset);
		RF_ASSERT(tmp->priority == hdr->nxt_priority);
		RF_ASSERT(pri_ok(tmp->priority));
	}
	RF_ASSERT( i == hdr->right_cnt );

	for( key=hdr->nxt_priority-1, tmp=hdr->burner;
		tmp != (RF_DiskQueueData_t *) NULL;
		key=tmp->priority, tmp=tmp->next )
	{
		RF_ASSERT(tmp);
		RF_ASSERT(hdr);
		RF_ASSERT(pri_ok(tmp->priority));
		RF_ASSERT(key >= tmp->priority);
		RF_ASSERT(tmp->priority < hdr->nxt_priority);
	}
}



static void PriorityInsert(RF_DiskQueueData_t **list_ptr, RF_DiskQueueData_t *req )
{
	/* 
	** insert block pointed to by req in to list whose first
	** entry is pointed to by the pointer that list_ptr points to
	** ie., list_ptr is a grandparent of the first entry
	*/

	for( ; (*list_ptr)!=(RF_DiskQueueData_t *)NULL &&
		(*list_ptr)->priority > req->priority;
		list_ptr = &((*list_ptr)->next) ) {}
	req->next = (*list_ptr);
	(*list_ptr) = req;
}



static void ReqInsert(RF_DiskQueueData_t **list_ptr, RF_DiskQueueData_t *req, RF_CvscanArmDir_t order)
{
	/* 
	** insert block pointed to by req in to list whose first
	** entry is pointed to by the pointer that list_ptr points to
	** ie., list_ptr is a grandparent of the first entry
	*/

	for( ; (*list_ptr)!=(RF_DiskQueueData_t *)NULL &&

		( (order==rf_cvscan_RIGHT && (*list_ptr)->sectorOffset <= req->sectorOffset)
		|| (order==rf_cvscan_LEFT && (*list_ptr)->sectorOffset > req->sectorOffset) );
		list_ptr = &((*list_ptr)->next) ) {}
	req->next = (*list_ptr);
	(*list_ptr) = req;
}



static RF_DiskQueueData_t *ReqDequeue(RF_DiskQueueData_t **list_ptr)
{
	RF_DiskQueueData_t * ret = (*list_ptr);
	if( (*list_ptr) != (RF_DiskQueueData_t *) NULL ) {
		(*list_ptr) = (*list_ptr)->next;
	}
	return( ret );
}



static void ReBalance(RF_CvscanHeader_t *hdr)
{
	/* DO_CHECK_STATE(hdr); */
	while( hdr->right != (RF_DiskQueueData_t *) NULL
		&& hdr->right->sectorOffset < hdr->cur_block ) {
		hdr->right_cnt--;
		hdr->left_cnt++;
		ReqInsert( &hdr->left, ReqDequeue( &hdr->right ), rf_cvscan_LEFT );
	}
	/* DO_CHECK_STATE(hdr); */
}



static void Transfer(RF_DiskQueueData_t **to_list_ptr, RF_DiskQueueData_t **from_list_ptr )
{
	RF_DiskQueueData_t *gp;
	for( gp=(*from_list_ptr); gp != (RF_DiskQueueData_t *) NULL; ) {
		RF_DiskQueueData_t *p = gp->next;
		PriorityInsert( to_list_ptr, gp );
		gp = p;
	}
	(*from_list_ptr) = (RF_DiskQueueData_t *) NULL;
}



static void RealEnqueue(RF_CvscanHeader_t *hdr, RF_DiskQueueData_t *req)
{
	RF_ASSERT(req->priority == RF_IO_NORMAL_PRIORITY || req->priority == RF_IO_LOW_PRIORITY);
	
	DO_CHECK_STATE(hdr);
	if( hdr->left_cnt == 0 && hdr->right_cnt == 0 ) {
		hdr->nxt_priority = req->priority;
	}
	if( req->priority > hdr->nxt_priority ) {
		/*
		** dump all other outstanding requests on the back burner
		*/
		Transfer( &hdr->burner, &hdr->left );
		Transfer( &hdr->burner, &hdr->right );
		hdr->left_cnt = 0;
		hdr->right_cnt = 0;
		hdr->nxt_priority = req->priority;
	}
	if( req->priority < hdr->nxt_priority ) {
		/*
		** yet another low priority task!
		*/
		PriorityInsert( &hdr->burner, req );
	} else {
		if( req->sectorOffset < hdr->cur_block ) {
			/* this request is to the left of the current arms */
			ReqInsert( &hdr->left, req, rf_cvscan_LEFT );
			hdr->left_cnt++;
		} else {
			/* this request is to the right of the current arms */
			ReqInsert( &hdr->right, req, rf_cvscan_RIGHT );
			hdr->right_cnt++;
		}
	}
	DO_CHECK_STATE(hdr);
}



void rf_CvscanEnqueue(void *q_in, RF_DiskQueueData_t *elem, int priority)
{
        RF_CvscanHeader_t *hdr = (RF_CvscanHeader_t *) q_in;
	RealEnqueue( hdr, elem /*req*/ );
}



RF_DiskQueueData_t *rf_CvscanDequeue(void *q_in)
{
        RF_CvscanHeader_t *hdr = (RF_CvscanHeader_t *) q_in;
	long range, i, sum_dist_left, sum_dist_right;
	RF_DiskQueueData_t *ret;
	RF_DiskQueueData_t *tmp;

	DO_CHECK_STATE(hdr);
	
	if( hdr->left_cnt == 0 && hdr->right_cnt == 0 ) return( (RF_DiskQueueData_t *) NULL );

	range = RF_MIN( hdr->range_for_avg, RF_MIN(hdr->left_cnt,hdr->right_cnt));
	for( i=0, tmp=hdr->left, sum_dist_left=
		((hdr->direction==rf_cvscan_RIGHT)?range*hdr->change_penalty:0);
		tmp != (RF_DiskQueueData_t *) NULL && i < range;
		tmp = tmp->next, i++ ) {
		sum_dist_left += hdr->cur_block - tmp->sectorOffset;
	}
	for( i=0, tmp=hdr->right, sum_dist_right=
		((hdr->direction==rf_cvscan_LEFT)?range*hdr->change_penalty:0);
		tmp != (RF_DiskQueueData_t *) NULL && i < range;
		tmp = tmp->next, i++ ) {
		sum_dist_right += tmp->sectorOffset - hdr->cur_block;
	}

	if( hdr->right_cnt == 0 || sum_dist_left < sum_dist_right ) {
		hdr->direction = rf_cvscan_LEFT;
		hdr->cur_block = hdr->left->sectorOffset + hdr->left->numSector;
		hdr->left_cnt = RF_MAX(hdr->left_cnt-1,0);
		tmp = hdr->left;
		ret = (ReqDequeue(&hdr->left))/*->parent*/;
	} else {
		hdr->direction = rf_cvscan_RIGHT;
		hdr->cur_block = hdr->right->sectorOffset + hdr->right->numSector;
		hdr->right_cnt = RF_MAX(hdr->right_cnt-1,0);
		tmp = hdr->right;
		ret = (ReqDequeue(&hdr->right))/*->parent*/;
	}
	ReBalance( hdr );

	if( hdr->left_cnt == 0 && hdr->right_cnt == 0
		&& hdr->burner != (RF_DiskQueueData_t *) NULL ) {
		/*
		** restore low priority requests for next dequeue
		*/
		RF_DiskQueueData_t *burner = hdr->burner;
		hdr->nxt_priority = burner->priority;
		while( burner != (RF_DiskQueueData_t *) NULL
			&& burner->priority == hdr->nxt_priority ) {
			RF_DiskQueueData_t *next = burner->next;
			RealEnqueue( hdr, burner );
			burner = next;
		}
		hdr->burner = burner;
	}
	DO_CHECK_STATE(hdr);
	return( ret );
}



RF_DiskQueueData_t *rf_CvscanPeek(void *q_in)
{
  RF_CvscanHeader_t *hdr = (RF_CvscanHeader_t *) q_in;
  long range, i, sum_dist_left, sum_dist_right;
  RF_DiskQueueData_t *tmp, *headElement;

  DO_CHECK_STATE(hdr);
  
  if( hdr->left_cnt == 0 && hdr->right_cnt == 0 )
    headElement = NULL;
  else {
    range = RF_MIN( hdr->range_for_avg, RF_MIN(hdr->left_cnt,hdr->right_cnt));
    for( i=0, tmp=hdr->left, sum_dist_left=
	((hdr->direction==rf_cvscan_RIGHT)?range*hdr->change_penalty:0);
	tmp != (RF_DiskQueueData_t *) NULL && i < range;
	tmp = tmp->next, i++ ) {
      sum_dist_left += hdr->cur_block - tmp->sectorOffset;
    }
    for( i=0, tmp=hdr->right, sum_dist_right=
	((hdr->direction==rf_cvscan_LEFT)?range*hdr->change_penalty:0);
	tmp != (RF_DiskQueueData_t *) NULL && i < range;
	tmp = tmp->next, i++ ) {
      sum_dist_right += tmp->sectorOffset - hdr->cur_block;
    }
    
    if( hdr->right_cnt == 0 || sum_dist_left < sum_dist_right )
      headElement = hdr->left;
    else
      headElement = hdr->right;
  }
  return(headElement);
}



/*
** CVSCAN( 1, 0 ) is Shortest Seek Time First (SSTF)
**				lowest average response time
** CVSCAN( 1, infinity ) is SCAN
**				lowest response time standard deviation
*/


int rf_CvscanConfigure()
{
  return(0);
}



void *rf_CvscanCreate(RF_SectorCount_t sectPerDisk, 
		      RF_AllocListElem_t *clList,
		      RF_ShutdownList_t **listp)
{
	RF_CvscanHeader_t *hdr;
	long range = 2;                   /* Currently no mechanism to change these */
	long penalty = sectPerDisk / 5;

	RF_MallocAndAdd(hdr, sizeof(RF_CvscanHeader_t), (RF_CvscanHeader_t *), clList);
	bzero((char *)hdr, sizeof(RF_CvscanHeader_t));
	hdr->range_for_avg = RF_MAX( range, 1 );
	hdr->change_penalty = RF_MAX( penalty, 0 );
	hdr->direction = rf_cvscan_RIGHT;
	hdr->cur_block = 0;
	hdr->left_cnt = hdr->right_cnt = 0;
	hdr->left = hdr->right = (RF_DiskQueueData_t *) NULL;
	hdr->burner = (RF_DiskQueueData_t *) NULL;
	DO_CHECK_STATE(hdr);

	return( (void *) hdr );
}


#if defined(__NetBSD__) && defined(_KERNEL)
/* PrintCvscanQueue is not used, so we ignore it... */
#else
static void PrintCvscanQueue(RF_CvscanHeader_t *hdr)
{
	RF_DiskQueueData_t *tmp;

	printf( "CVSCAN(%d,%d) at %d going %s\n", 
		(int)hdr->range_for_avg,
		(int)hdr->change_penalty, 
		(int)hdr->cur_block,
		(hdr->direction==rf_cvscan_LEFT)?"LEFT":"RIGHT" );
	printf( "\tLeft(%d): ", hdr->left_cnt );
	for( tmp = hdr->left; tmp != (RF_DiskQueueData_t *) NULL; tmp = tmp->next)
		printf( "(%d,%ld,%d) ", 
			(int) tmp->sectorOffset, 
			(long) (tmp->sectorOffset + tmp->numSector),
			tmp->priority );
	printf( "\n" );
	printf( "\tRight(%d): ", hdr->right_cnt );
	for( tmp = hdr->right; tmp != (RF_DiskQueueData_t *) NULL; tmp = tmp->next)
		printf( "(%d,%ld,%d) ",
			(int) tmp->sectorOffset, 
			(long) (tmp->sectorOffset + tmp->numSector),
			tmp->priority );
	printf( "\n" );
	printf( "\tBurner: " );
	for( tmp = hdr->burner; tmp != (RF_DiskQueueData_t *) NULL; tmp = tmp->next)
		printf( "(%d,%ld,%d) ", 
			(int) tmp->sectorOffset, 
			(long) (tmp->sectorOffset + tmp->numSector),
			tmp->priority );
	printf( "\n" );
}
#endif


/* promotes reconstruction accesses for the given stripeID to normal priority.
 * returns 1 if an access was found and zero otherwise.  Normally, we should
 * only have one or zero entries in the burner queue, so execution time should
 * be short.
 */
int rf_CvscanPromote(void *q_in, RF_StripeNum_t parityStripeID, RF_ReconUnitNum_t which_ru)
{
    RF_CvscanHeader_t *hdr = (RF_CvscanHeader_t *) q_in;
    RF_DiskQueueData_t *trailer = NULL, *tmp = hdr->burner, *tlist = NULL;
    int retval=0;

	DO_CHECK_STATE(hdr);
    while (tmp) {				/* handle entries at the front of the list */
	if (tmp->parityStripeID == parityStripeID && tmp->which_ru == which_ru) {
	    hdr->burner = tmp->next;
	    tmp->priority = RF_IO_NORMAL_PRIORITY;
	    tmp->next = tlist; tlist=tmp;
	    tmp = hdr->burner;
	} else break;
    }
    if (tmp) {trailer=tmp; tmp=tmp->next;}
    while (tmp) {				/* handle entries on the rest of the list */
	if (tmp->parityStripeID == parityStripeID && tmp->which_ru == which_ru) {
	    trailer->next = tmp->next;
	    tmp->priority = RF_IO_NORMAL_PRIORITY;
	    tmp->next = tlist; tlist=tmp;		/* insert on a temp queue */
	    tmp = trailer->next;
	} else {
            trailer=tmp; tmp=tmp->next;
	}
    }
    while (tlist) {
	retval++;
	tmp = tlist->next;
        RealEnqueue(hdr, tlist);
	tlist = tmp;
    }
    RF_ASSERT(retval==0 || retval==1);
	DO_CHECK_STATE((RF_CvscanHeader_t *)q_in);
    return(retval);
}