数据库

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#ifndef STRUCTURE_H_INCLUDED#define STRUCTURE_H_INCLUDED#define FRAMESIZE  4096#define MAXPAGES   100000#define DEFBUFSIZE  1024#include <string>#include <cstdio>#include "structure.h"using namespace std;struct NewPage//buffer中空闲的frame的信息    { int page_id;      int frame_id;    };struct bFrame//frame    {     char field [FRAMESIZE];    };struct BCB//每个page进入buffer，将会产生BCB，frame的相关信息存储在其相应的BCB中    {      //BCB();      int page_id;      int frame_id;      int latch;      int count;      int dirty;      BCB * next;      BCB * previous;    };struct BUFFER    {bFrame bframe[DEFBUFSIZE];     bool used[DEFBUFSIZE];     int  freeFrames;    };class DSMgr//数据存储管理控制器{public:  DSMgr();  int OpenFile(string filename);  int CloseFile();  bFrame ReadPage(int page_id);  int WritePage(int frame_id, bFrame frm);  int Seek(int offset, int pos);  FILE * GetFile();  void IncNumPages();  int GetNumPages();  void SetUse(int index, int use_bit);  int GetUse(int index);  int WriteBackPage(int page_id, bFrame frm);//自创函数,写回函数  int FileSeek(int offset);//移动文件指针private:  FILE *currFile;  int numPages;  int pages[MAXPAGES];};DSMgr::DSMgr(){int flag=OpenFile("data.dbf");if(-1==flag)    throw "没有找到数据库文件";}int DSMgr::OpenFile(string filename)//打开文件{currFile=fopen(filename.c_str(),"rb+");if(currFile==NULL)    return -1;else    return  0;}int DSMgr::CloseFile(){    return fclose(currFile);}bFrame DSMgr::ReadPage(int page_id){FileSeek((page_id+1)*FRAMESIZE);bFrame bframe;int getByteCount=fread(bframe.field,1,FRAMESIZE,currFile);if(getByteCount!=FRAMESIZE)    throw "读页面失败";return bframe;}int DSMgr::WritePage(int frame_id, bFrame frm){return 0;}int DSMgr::WriteBackPage(int page_id, bFrame frm){FileSeek((page_id+1)*FRAMESIZE); int writeSuccessCount=fwrite(frm.field,1,FRAMESIZE,currFile); fflush(currFile); if(writeSuccessCount!=FRAMESIZE)    throw "写回页面失败";return 0;}int DSMgr::Seek(int offset, int pos)//三种模式{if(1==pos)fseek(currFile,offset,SEEK_SET);if(2==pos)fseek(currFile,offset,SEEK_CUR);if(3==pos)fseek(currFile,offset,SEEK_END);return 0;}int DSMgr::FileSeek(int offset){fseek(currFile,offset,SEEK_SET);return 0;}FILE* DSMgr::GetFile(){return currFile;}void DSMgr::IncNumPages(){numPages++;}int DSMgr::GetNumPages(){return numPages;}void DSMgr::SetUse(int index, int use_bit){}int DSMgr::GetUse(int index){return 0;}#endif // STRUCTURE_H_INCLUDED

#include "structure.h"#include<fstream>#include<iostream>#include<cstring>#include<string>#include <sstream>#include <list>using namespace std;int count=0;class BMgr//buffer控制管理器    {    public:      BMgr();      // Interface functions      int FixPage(int page_id, int prot);      NewPage FixNewPage();      int UnfixPage(int page_id);      int NumFreeFrames();      // Internal Functions      int SelectVictim();      int Hash(int page_id);      void RemoveBCB(BCB * ptr, int page_id);      void UpdateLRUEle(int frid);      void SetDirty(int frame_id);      void UnsetDirty(int frame_id);      void WriteDirtys();      void  PrintFrame(int frame_id);      void  getFrameData(char storage [],int frameID)            {for(int i=0;i<FRAMESIZE;i++)                {storage[i]=buffer.bframe[frameID].field[i];                }            }      BUFFER getBuffer();      int getIdleFrame()//找到第一个空闲的frame返回id        {for(int i=0;i<DEFBUFSIZE;i++)//初始化标记frame数组            {if(!buffer.used[i])                return i;            }         return -1;        }     void decreaseLatch(int frameID)        {BCBassemble[frameID]->latch--;        }      DSMgr getDSMgr()        {return dsm;        }    private:      // Hash Table      int ftop[DEFBUFSIZE];//      BCB* ptof[DEFBUFSIZE];//      BCB * BCBassemble[DEFBUFSIZE];      BUFFER buffer;      list<int> lrulist;      DSMgr dsm;    };    BMgr::BMgr()    {    for(int i=0;i<DEFBUFSIZE;i++)//初始化标记frame数组        {buffer.used[i]=false;         ptof[i]=0;        }    buffer.freeFrames=DEFBUFSIZE;//空闲的frame的数量    }    int BMgr::FixPage(int page_id, int prot)//it returns a frame_id.    {//    for(int i=0;i<DEFBUFSIZE;i++)//初始化标记frame数组//        {if(buffer.used[i])//被使用了//            {BCB * bcb=BCBassemble[i];//获得i对应的bcb//             if(bcb->page_id==page_id)//在buffer中找到page//                {//                 UpdateLRUEle(bcb->frame_id);//命中，更新LRU表////                 bcb->latch=bcb->latch+1;//                 return bcb->frame_id;//返回//                }////            }////        }//*****************************new way******************************        BCB *tempBCBPointer=ptof[page_id%DEFBUFSIZE];        if(0!=tempBCBPointer)            {while(tempBCBPointer->page_id!=page_id)                {cout<<tempBCBPointer<<" ";                tempBCBPointer=tempBCBPointer->next;                if(0==tempBCBPointer)                    break;                }            cout<<endl;            if(0!=tempBCBPointer)                {UpdateLRUEle(tempBCBPointer->frame_id);//命中，更新LRU表                tempBCBPointer->latch=tempBCBPointer->latch+1;                return tempBCBPointer->frame_id;                }            }//*****************************new way******************************    //页面不在缓存        if(0==buffer.freeFrames)//没有空余frame,需要替换            {int victimFrameID=SelectVictim();             BCB *bcbVcitim =BCBassemble[victimFrameID];             if(1==bcbVcitim->dirty)//需要写回                {                dsm.WriteBackPage(bcbVcitim->page_id,buffer.bframe[bcbVcitim->frame_id]);                count++;                }             //hashtable更新             if(0!=bcbVcitim->previous)                {bcbVcitim->previous->next=bcbVcitim->next;                if(0!=bcbVcitim->next)                  bcbVcitim->next->previous=bcbVcitim->previous;                }             else //bcbVcitim是链上第一个元素                {ptof[(bcbVcitim->page_id)%DEFBUFSIZE]=bcbVcitim->next;                if(0!=bcbVcitim->next)                   bcbVcitim->next->previous=0;                }             buffer.used[victimFrameID]=false;             buffer.freeFrames++;            //从文件中读数据到buffer frame victimPageID            bFrame abframe=dsm.ReadPage(page_id);             for(int i=0;i<FRAMESIZE;i++)                {buffer.bframe[victimFrameID].field[i]=abframe.field[i];                 //cout<<buffer.bframe[victimFrameID].field[i]<<"****************"<<endl;                }             count++;             buffer.used[victimFrameID]=true;             buffer.freeFrames--;             delete bcbVcitim;             BCB * bcb=new BCB;             //bcb更新             bcb->dirty=0;             bcb->frame_id=victimFrameID;             bcb->page_id=page_id;             bcb->next=0;             bcb->previous=0;             BCB * tempBCBPointer=ptof[page_id%DEFBUFSIZE];             if(0==tempBCBPointer)                {ptof[page_id%DEFBUFSIZE]=bcb;                 bcb->previous=0;//第一个父指针为空                bcb->next=0;                }             else                { bcb->next=tempBCBPointer->next;                 if(0!=tempBCBPointer->next)                    tempBCBPointer->next->previous=bcb;                 tempBCBPointer->next=bcb;                 bcb->previous=tempBCBPointer;                }           UpdateLRUEle(victimFrameID);//更新LRU表           bcb->latch=bcb->latch+1;//数据即将要提交到主存，需要加锁           BCBassemble[victimFrameID]=bcb;//增加bcb             //返回ID             return  victimFrameID;            }        else            //有空闲，找到第一个一个空闲的frame读入            {            int idleFrameID=getIdleFrame();             //从文件复制数据到这个frame  idleFrameID             bFrame abframe=dsm.ReadPage(page_id);             for(int i=0;i<FRAMESIZE;i++)                buffer.bframe[idleFrameID].field[i]=abframe.field[i];             count++;             buffer.used[idleFrameID]=true;             buffer.freeFrames--;             //生成bcb;             BCB * bcb=new BCB;             bcb->dirty=0;             bcb->frame_id=idleFrameID;             bcb->page_id=page_id;             bcb->next=0;             bcb->previous=0;             UpdateLRUEle(idleFrameID);//更新LRU表             cout<<"LRU队首"<<lrulist.front()<<endl;             BCBassemble[idleFrameID]=bcb;//增加bcb             BCB * tempBCBPointer=ptof[page_id%DEFBUFSIZE];             if(0==tempBCBPointer)                {ptof[page_id%DEFBUFSIZE]=bcb;                 bcb->previous=0;//第一个父指针为空                }             else                {                 bcb->next=tempBCBPointer->next;                 if(0!=tempBCBPointer->next)                    tempBCBPointer->next->previous=bcb;                 tempBCBPointer->next=bcb;                 bcb->previous=tempBCBPointer;                }             bcb->latch=bcb->latch+1;//加锁             //返回ID             return idleFrameID;            }    }    NewPage BMgr::FixNewPage()//    {for(int i=0;i<DEFBUFSIZE;i++)        {if(!buffer.used[i])            {NewPage newpage;            newpage.frame_id=i;            newpage.page_id=ftop[i];            return newpage;            }        }        NewPage newpage;        newpage.frame_id=-1;        newpage.page_id=-1;        return newpage;    }    int BMgr::UnfixPage(int page_id)    {    }    int BMgr::NumFreeFrames()    {       return buffer.freeFrames;    }    int BMgr::SelectVictim()    {        for(list<int> ::reverse_iterator riter=lrulist.rbegin();riter!=lrulist.rend();riter++)            if(0==BCBassemble[*riter]->latch)                {return  *riter;                }        return -1;    }    int BMgr::Hash(int page_id)    {     return  (page_id)%DEFBUFSIZE;    }    void BMgr::RemoveBCB(BCB* ptr, int page_id)    {    }    void BMgr::UpdateLRUEle(int frid)    { lrulist.remove(frid);//——————————————      lrulist.push_front(frid);//放入开始头    }    void BMgr::SetDirty(int frame_id)    {        BCBassemble[frame_id]->dirty=1;    }    void BMgr::UnsetDirty(int frame_id)    {    }    void BMgr::WriteDirtys()    {    }    void BMgr::PrintFrame(int frame_id)    { for(int i=0;i<FRAMESIZE;i++)            {cout<<buffer.bframe[frame_id].field[i];            }      cout<<endl;    }    BUFFER BMgr::getBuffer()        {return buffer;        }    int main()        {int datacount=0;        ifstream infileStream;        string str;        infileStream.open("data.txt",ios::in);        char requestdata[30];        BMgr bMgr;        while(!infileStream.eof())            {datacount++;            cout<<"datacount:*************"<<datacount<<endl;            infileStream.getline(requestdata,20,'\n');//字符数组中包含"\n"                //cout<<"****"<<strlen(requestdata)<<"***"<<endl;                str=string(requestdata);                if(str[str.size()-1]=='\n')                str=str.substr(0,str.size()-1);//去掉\n，最后一列没有\n               // cout<<"**"<<str<<"**"<<endl;                int pos=str.find(',',0);                string  strRorW=str.substr(0,pos);                string strPage=str.substr(pos+1,str.length());                stringstream ss;                int flagWorR=-1;                int pageAccessID=-1;        //      cout<<"**"<<strRorW<<"****"<<endl;        //      cout<<"**"<<strPage<<"****"<<endl;                ss<<strRorW;                ss>>flagWorR;                ss.clear();                ss<<strPage;                ss>>pageAccessID;               cout<<flagWorR<<","<<pageAccessID<<endl;                int frameID=bMgr.FixPage(pageAccessID,flagWorR);//获得frameid                char contentPage[FRAMESIZE];                //strncpy(contentPage,bMgr.getBuffer().bframe[frameID].field,FRAMESIZE);//读进内存                 //bMgr.PrintFrame(frameID);                 bMgr.getFrameData(contentPage,frameID);                 cout<<"&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&"<<strlen(contentPage)<<endl;                 for(int i=0;i<FRAMESIZE;i++)                    {cout<<contentPage[i];                    }                 cout<<endl;                //数据操作处理                //×××××××××××                //如果是写操作                //设置写标志                if(flagWorR==1)                    {bMgr.SetDirty(frameID);//设置frameID对的frame写污染                    }                //读操作不管                //操作完成处理之后，然后将锁减一；                bMgr.decreaseLatch(frameID);            }         infileStream.close();         bMgr.getDSMgr().CloseFile();         cout<<"buffer和磁盘之间的IO次数是"<<count<<endl;        return 0;        }//     list<int>::iterator  contain (list<int> listTemp,int elem)//            {for(list<int>::iterator iter=listTemp.begin();iter!=listTemp.end();iter++)//                {if(*iter==elem)//                    return iter;//                }//             return listTemp.end();////////            }////       list<int> getLRUList()//            {return lrulist;//            }

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