/*                    COPYRIGHT NOTICE This material was developed by Christos Faloutsos and King-Ip Linat the University of Maryland, College Park, Department of Computer Science.Permission is granted to copy this software, to redistribute iton a nonprofit basis, and to use it for any purpose, subject tothe following restrictions and understandings. 1. Any copy made of this software must include this copyright noticein full. 2. All materials developed as a consequence of the use of thissoftware shall duly acknowledge such use, in accordance with the usualstandards of acknowledging credit in academic research. 3. The authors have made no warranty or representation that theoperation of this software will be error-free or suitable for anyapplication, and they are under under no obligation to provide anyservices, by way of maintenance, update, or otherwise.  The softwareis an experimental prototype offered on an as-is basis. 4. Redistribution for profit requires the express, written permissionof the authors. */// Author : $Author$// Date : $Date$// Id : $Id$// $Source: /afs/alm/cs/quest/subseq/src2/RCS/rplus_simbuf.c,v $// $Author: davelin $// $Date: 1995/02/25 02:33:09 $// $Revision: 9.1 $#include <stdlib.h>#include <iostream.h>#include <fstream.h>#include "TVdefine.h"// extra include file for use in subsequence matching#include "TVsimbuf.h"Storage::Storage(int ps, int buffercount) {    pagesize = ps;   nextpage = 1;     // initialize buffers   bufmaxcount = buffercount;   diskpagenumber = new PageNumber[bufmaxcount];   dirty = new int[bufmaxcount];    bufcount = 0;   int i;   for (i = 0; i < bufmaxcount; i++)      {         diskpagenumber[i] = BUFAVAILABLE;         dirty[i] = FALSE;      }   // For LRU    ptrtoqnode = new DoublyLinkedListTVNode*[bufmaxcount];   for (i = 0; i < bufmaxcount; i++)      {        ptrtoqnode[i] = new DoublyLinkedListTVNode(i);	LRUqueue.inserttail(ptrtoqnode[i]);      }    // For round robin   int nextrelease = 0;   // Initialize stats   initstats();}Storage::~Storage() {   delete [] diskpagenumber;  delete [] dirty;}Storage& Storage::initstats(){   readrequestcount = 0;   writerequestcount = 0;   diskfetchcount = 0;   pagewritecount = 0;   return *this;}void Storage::MovetoLRUtail(const BufPageNumber pn){   LRUqueue.deletenode(ptrtoqnode[pn]);   LRUqueue.inserttail(ptrtoqnode[pn]);}Storage& Storage::fetch(PageNumber pn){  readrequestcount++;  int i = SearchPage(pn);  if (i == BUFNOTFOUND)     {       // Not in buffer, fetch a buffer to store it       BufPageNumber bpn = GetFreeBufNum();       diskpagenumber[bpn] = pn;       fetchfromstorage(bpn, pn);       MovetoLRUtail(bpn);     }  else     MovetoLRUtail(i);  return *this;}Storage& Storage::writepage(PageNumber pn){  writerequestcount++;  int i = SearchPage(pn);  if (i != BUFNOTFOUND)     {        dirty[i] = TRUE;        MovetoLRUtail(i);     }  return *this;}Storage& Storage::flushbuffer(){  for (BufPageNumber i = 0; i < bufmaxcount; i++)      writetostorage(i);   return *this;}Storage& Storage::emptybuffer(){  for (BufPageNumber i = 0; i < bufmaxcount; i++)   {      writetostorage(i);       diskpagenumber[i] = BUFAVAILABLE;   }   return *this;}PageNumber Storage::newpage(){//cout << "Assign new page\n";  BufPageNumber freebufnum = GetFreeBufNum();  diskpagenumber[freebufnum] = nextpage;  dirty[freebufnum] = TRUE;  MovetoLRUtail(freebufnum);  return nextpage++;}int Storage::getpagesize() {  return pagesize;}// Make that page useable againStorage& Storage::clearpage(PageNumber pn){  int i = SearchPage(pn);  if (i != BUFNOTFOUND)     dirty[i] = FALSE;  return *this;} BufPageNumber Storage::GetFreeBufNum(){   BufPageNumber i;   for (i = 0; (i < bufmaxcount) && (diskpagenumber[i] != BUFAVAILABLE); i++)       ;   BufPageNumber res;   if (i == bufmaxcount)      {         // Find a replacement         /*         writetostorage(nextrelease);         res = nextrelease++;	 nextrelease = nextrelease % bufmaxcount;	 */         res = LRUqueue.headnum(); 	 writetostorage(res);      }    else       res = i;   return res;}// return Bufpagenumber,// return BUFNOTFOUND is NOT foundBufPageNumber Storage::SearchPage(PageNumber pn){  BufPageNumber i;  for (i = 0; (i < bufmaxcount) && (diskpagenumber[i] != pn); i++)      ;  return (i == bufmaxcount ? BUFNOTFOUND : i);} void Storage::fetchfromstorage(BufPageNumber bpn, PageNumber pn){   diskfetchcount++;   diskpagenumber[bpn] = pn;} void Storage::writetostorage(BufPageNumber bpn){    if (dirty[bpn])       {	  pagewritecount++; 	  dirty[bpn] = FALSE;       }}void Storage::printstats(ostream& os) const{   os << "Read request : " << readrequestcount << "  Write request : " << writerequestcount;   os << "  Disk fetch : " << diskfetchcount << "  Pgae writes : " << pagewritecount;}  ostream& operator<<(ostream& os, const Storage& s){   os << "Pagesize : " << s.pagesize << "   No. of buffers : " << s.bufmaxcount << endl;   os << "Total page used : " << s.nextpage - 1 << endl;   DoublyLinkedListTVNode *p = s.LRUqueue.head->next;   os << "Buffer content : {" <<  s.diskpagenumber[p->bpn] << (s.dirty[0] ? "*" : "");   p = p->next;   while (p != s.LRUqueue.head)      {        os << ", " <<  s.diskpagenumber[p->bpn] << (s.dirty[0] ? "*" : "");	p = p->next;      }   os << "}\n";   s.printstats(os);   return os;}