操作系統(tǒng)報(bào)告讀者寫者問題讀者寫者問題20032320鮑小偉

操作系統(tǒng)實(shí)驗(yàn)報(bào)告讀者寫者問題PAGEPAGE10讀者寫者問題（20032320鮑小偉）設(shè)計(jì)要求：在windows98/2000下，創(chuàng)建一個控制臺進(jìn)程，此進(jìn)程包含n個線程。用這n個線程來表示n個讀者或?qū)懻?。每個線程按相應(yīng)測試數(shù)據(jù)文件的要求進(jìn)行讀寫操作。用信號量機(jī)制實(shí)現(xiàn)讀者優(yōu)先的讀者——寫入者問題。設(shè)計(jì)分析：讀者-寫者的讀寫限制（包括讀者優(yōu)先和寫者優(yōu)先）1.寫-寫互斥，即不能有兩個寫者同時進(jìn)行寫操作2.讀-寫互斥，即不能同時有一個讀者在讀，同時卻有一個寫者在寫3.讀讀允許，即可以有2個以上的讀者同時讀讀者優(yōu)先的限制：如果一個讀者申請讀操作時，已經(jīng)有一個讀者在讀，則該讀者可以直接讀寫者優(yōu)先的限制：如果一個讀者申請讀操作時，有寫者在等待訪問共享資源時，則該讀者要等到?jīng)]有寫者處于等的狀態(tài)時才能開始讀操作測試數(shù)據(jù)的格式在文件thread.dat中1R352W453R524R655W5.13其中第一個代表線程的ID，第二個字段代表是讀操作還是寫操作，第三個字段代表操作的開始時間，第4個字段是持續(xù)時間。分析：將所有的讀者和所有的寫者分別放進(jìn)兩個等待隊(duì)列中，當(dāng)讀允許時就讓讀者隊(duì)列釋放一個或多個讀者，當(dāng)寫允許時，釋放第一個寫者操作。讀者優(yōu)先：如果沒有寫者正在操作，則讀者不需要等待，用一個整型變量readcount記錄當(dāng)前的讀者數(shù)目，用于確定是否釋放寫者線程，（當(dāng)readcout=0時，說明所有的讀者都已經(jīng)讀完，釋放一個寫者線程），每個讀者開始讀之前都要修改readcount,為了互斥的實(shí)現(xiàn)對readcount的修改，需要一個互斥對象Mutex來實(shí)現(xiàn)互斥。另外，為了實(shí)現(xiàn)寫-寫互斥，需要一個臨界區(qū)對象write,當(dāng)寫者發(fā)出寫的請求時，必須先得到臨界區(qū)對象的所有權(quán)。通過這種方法，可以實(shí)現(xiàn)讀寫互斥，當(dāng)readcount=1時，（即第一個讀者的到來時，），讀者線程也必須申請臨界區(qū)對象的所有權(quán).當(dāng)讀者擁有臨界區(qū)的所有權(quán)，寫者都阻塞在臨界區(qū)對象write上。當(dāng)寫者擁有臨界區(qū)對象所有權(quán)時，第一個判斷完readcount==1后，其余的讀者由于等待對readcount的判斷，阻塞在Mutex上！寫者優(yōu)先：寫者優(yōu)先和讀者優(yōu)先有相同之處，不同的地方在：一旦有一個寫者到來時，應(yīng)該盡快讓寫者進(jìn)行寫，如果有一個寫者在等待，則新到的讀者操作不能讀操作，為此添加一個整型變量writecount,記錄寫者的數(shù)目，當(dāng)writecount=0時才可以釋放讀者進(jìn)行讀操作！為了實(shí)現(xiàn)對全局變量writecount的互斥訪問，設(shè)置了一個互斥對象Mutex3。為了實(shí)現(xiàn)寫者優(yōu)先，設(shè)置一個臨界區(qū)對象read,當(dāng)有寫者在寫或等待時，讀者必須阻塞在臨界區(qū)對象read上。讀者除了要一個全局變量readcount實(shí)現(xiàn)操作上的互斥外，還需要一個互斥對象對阻塞在read這一個過程實(shí)現(xiàn)互斥，這兩個互斥對象分別為mutex1和mutex2。程序所用結(jié)構(gòu)類型說明:1.CreateThread()；2.ExitThread();3.Sleep();4.CreateMutex();5.ReleaseMutex();6.WaitForSingleObject();7.WaitForMutipleObjects();8.CreateSemapore();9.ReleaseSemapore();10.InitializeCriticalSection();11.EnterCriticalSection();12.LeaveCriticalSection();源代碼：#include<windows.h>#include<conio.h>#include<stdlib.h>#include"fstream.h"#include<io.h>#include<string.h>#include<stdio.h>#defineREADER'R'#defineWRITER'W'#defineINTE_PER_SEC100//每秒時鐘中斷數(shù)目#defineMAX_THREAD_NUM64//最大線程數(shù)目#defineMAX_FILE_NUM32//最大數(shù)據(jù)文件數(shù)目#defineMAX_STR_LEN32//字符串長度//全局變量intreadcount=0;//讀者數(shù)目intwritecount=0;//寫者數(shù)目CRITICAL_SECTIONRP_Write;//臨界區(qū)CRITICAL_SECTIONcs_Write;CRITICAL_SECTIONcs_Read;structThreadInfo{ intserial;//線程序號 charentity;//線程類別 doubledelay;//線程開始時間 doublepersist;//線程讀寫持續(xù)時間};//讀者優(yōu)先處理函數(shù)，已經(jīng)給出voidReaderPriority(char*file);voidRP_ReaderThread(void*p);voidRP_WriterThread(void*p);//寫者優(yōu)先處理函數(shù)，精讀"讀者優(yōu)先"程序和設(shè)計(jì)分析，自己完成voidWriterPriority(char*file);voidWP_ReaderThread(void*p);voidWP_WriterThread(void*p);//為了保證現(xiàn)在程序編譯通過，寫一個空函數(shù)，請你寫出自己的WriterPriority//voidWriterPriority(char*file){}intmain(){ charch; while(true) { printf("*********************************************************\n"); printf("1:ReaderPriority\n");printf("2:WriterPriority\n"); printf("3:ExittoWindows\n"); printf("*********************************************************\n"); printf("Enteryourchoice(1,2or3)\n"); do { ch=(char)_getch(); }while(ch!='1'&&ch!='2'&&ch!='3'); system("cls"); if(ch=='3') return0; elseif(ch=='1') ReaderPriority("thread.txt"); else WriterPriority("thread.txt"); printf("\nPressAnykeytocontinue.\n"); _getch(); system("cls"); } return0;}//讀者優(yōu)先處理函數(shù)voidReaderPriority(char*file){ DWORDn_thread=0;//線程數(shù)目 DWORDthread_ID;//線程ID DWORDwait_for_all;//等待所有線程結(jié)束 //互斥對象 HANDLEh_Mutex; h_Mutex=CreateMutex(NULL,FALSE,"mutex_for_readcount"); //線程對象數(shù)組 HANDLEh_Thread[MAX_THREAD_NUM]; ThreadInfothread_info[MAX_THREAD_NUM]; readcount=0;//初始化readcount InitializeCriticalSection(&RP_Write);//初始化臨界區(qū) ifstreaminFile; inFile.open(file);//打開文件 printf("ReaderPriority:\n\n"); while(inFile) { //讀入每一個讀者、寫者的信息 inFile>>thread_info[n_thread].serial; inFile>>thread_info[n_thread].entity; inFile>>thread_info[n_thread].delay; inFile>>thread_info[n_thread].persist; if(-1==inFile.get()) break; n_thread++; } for(inti=0;i<(int)(n_thread);i++) { if(thread_info[i].entity==READER||thread_info[i].entity=='r') //創(chuàng)建讀者線程 h_Thread[i]=CreateThread(NULL,0,\ (LPTHREAD_START_ROUTINE)(RP_ReaderThread),\ &thread_info[i],0,&thread_ID); else //創(chuàng)建寫者線程 h_Thread[i]=CreateThread(NULL,0,\ (LPTHREAD_START_ROUTINE)(RP_WriterThread),\ &thread_info[i],0,&thread_ID); } //等待所有線程結(jié)束 wait_for_all=WaitForMultipleObjects(n_thread,h_Thread,TRUE,-1); printf("AllReaderandWriterhavefinishedoperating.\n");}//讀者優(yōu)先讀者線程voidRP_ReaderThread(void*p){ //互斥變量 HANDLEh_Mutex; h_Mutex=OpenMutex(MUTEX_ALL_ACCESS,FALSE,"mutex_for_readcount"); DWORDwait_for_mutex;//等待互斥變量所有權(quán) DWORDm_delay;//延遲時間 DWORDm_persist;//讀文件持續(xù)時間 intm_serial;//線程序號 m_serial=((ThreadInfo*)(p))->serial; m_delay=(DWORD)(((ThreadInfo*)(p))->delay*INTE_PER_SEC); m_persist=(DWORD)(((ThreadInfo*)(p))->persist*INTE_PER_SEC); Sleep(m_delay);//延遲等待 printf("Readerthread%dsentsthereadingrequire.\n",m_serial); wait_for_mutex=WaitForSingleObject(h_Mutex,-1);//等待互斥信號，保證對readcount的訪問、 //修改互斥 readcount++;//讀者數(shù)目增加 if(readcount==1) EnterCriticalSection(&RP_Write); //第一個讀者，等待資源 ReleaseMutex(h_Mutex); //讀文件 printf("Readerthread%dbeginstoreadfile.\n",m_serial); Sleep(m_persist); //退出線程 printf("Readerthread%dfinishedreadingfile.\n",m_serial); wait_for_mutex=WaitForSingleObject(h_Mutex,-1);//等待互斥信號，保證對readcount的訪問、修改互斥 readcount--;//讀者數(shù)目減少 if(readcount==0) LeaveCriticalSection(&RP_Write); //如果所有讀者讀完，喚醒寫者 ReleaseMutex(h_Mutex);}//讀者優(yōu)先寫者線程voidRP_WriterThread(void*p){ DWORDm_delay;//延遲時間 DWORDm_persist;//讀文件持續(xù)時間 intm_serial;//線程序號 //從參數(shù)中獲得信息 m_serial=((ThreadInfo*)(p))->serial; m_delay=(DWORD)(((ThreadInfo*)(p))->delay*INTE_PER_SEC); m_persist=(DWORD)(((ThreadInfo*)(p))->persist*INTE_PER_SEC); Sleep(m_delay);//延遲等待 printf("Writerthread%dsentstheWritingrequire.\n",m_serial); EnterCriticalSection(&RP_Write); //寫文件 printf("Writerthread%dbeginstowritefile.\n",m_serial); Sleep(m_persist); //退出線程 printf("Writerthread%dfinishedwritingfile.\n",m_serial); LeaveCriticalSection(&RP_Write); //如果所有讀者讀完，喚醒寫者}//寫者優(yōu)先處理函數(shù)voidWriterPriority(char*file){ DWORDn_thread=0;//線程數(shù)目 DWORDthread_ID;//線程ID DWORDwait_for_all;//等待所有線程結(jié)束 //互斥對象 HANDLEh_Mutex1,h_Mutex2,h_Mutex3; h_Mutex1=CreateMutex(NULL,FALSE,"mutex_for_writecount"); h_Mutex2=CreateMutex(NULL,FALSE,"mutex_for_readcount"); h_Mutex3=CreateMutex(NULL,FALSE,"mutex_for_read"); //線程對象數(shù)組 HANDLEh_Thread[MAX_THREAD_NUM]; ThreadInfothread_info[MAX_THREAD_NUM]; readcount=0;//初始化readcount InitializeCriticalSection(&cs_Write);//初始化臨界區(qū) InitializeCriticalSection(&cs_Read); ifstreaminFile; inFile.open(file);//打開文件 printf("WriterPriority:\n\n"); while(inFile) { //讀入每一個讀者、寫者的信息 inFile>>thread_info[n_thread].serial; inFile>>thread_info[n_thread].entity; inFile>>thread_info[n_thread].delay; inFile>>thread_info[n_thread].persist; if(-1==inFile.get()) break; n_thread++; } for(inti=0;i<(int)(n_thread);i++) { if(thread_info[i].entity==READER||thread_info[i].entity=='r') //創(chuàng)建讀者線程 h_Thread[i]=CreateThread(NULL,0,\ (LPTHREAD_START_ROUTINE)(WP_ReaderThread),\ &thread_info[i],0,&thread_ID); else //創(chuàng)建寫者線程 h_Thread[i]=CreateThread(NULL,0,\ (LPTHREAD_START_ROUTINE)(WP_WriterThread),\ &thread_info[i],0,&thread_ID); } //等待所有線程結(jié)束 wait_for_all=WaitForMultipleObjects(n_thread,h_Thread,TRUE,-1); printf("AllReaderandWriterhavefinishedoperating.\n");}//寫者優(yōu)先寫者線程voidWP_WriterThread(void*p){ //互斥變量 HANDLEh_Mutex1; h_Mutex1=OpenMutex(MUTEX_ALL_ACCESS,FALSE,"mutex_for_writecount"); DWORDwait_for_mutex;//等待互斥變量所有權(quán) DWORDm_delay;//延遲時間 DWORDm_persist;//讀文件持時續(xù)間 intm_serial;//線程序號 m_serial=((ThreadInfo*)(p))->serial; m_delay=(DWORD)(((ThreadInfo*)(p))->delay*INTE_PER_SEC); m_persist=(DWORD)(((ThreadInfo*)(p))->persist*INTE_PER_SEC); Sleep(m_delay); printf("Writerthread%dsentsthewritingrequire.\n",m_serial); wait_for_mutex=WaitForSingleObject(h_Mutex1,-1); writecount++; if(writecount==1) EnterCriticalSection(&cs_Read); ReleaseMutex(h_Mutex1); EnterCriticalSection(&cs_Write); printf("Writerthread%dbeginstowritefile.\n",m_serial); Sleep(m_persist); printf("Writerthread%dfinishedwritingfile.\n",m_serial); LeaveCriticalSection(&cs_Write); wait_for_mutex=WaitForSingleObject(h_Mutex1,-1); writecount--; if(writecount==0) LeaveCriticalSection(&cs_Read); ReleaseMutex(h_Mutex1);}//寫者優(yōu)先讀者線程voidWP_ReaderThread(void*p){ HANDLEh_Mutex2,h_Mutex3; h_Mutex2=OpenMutex(MUTEX_ALL_ACCESS,FALSE,"mutex_for_readcount"); h_Mutex3=OpenMutex(MUTEX_ALL_ACCESS,FALSE,"mutex_for_read"); DWORDwait_for_mutex,wait_for_mutex1;//等待互斥變量所有權(quán) DWORDm_delay;//延遲時間 DWORDm_persist;//讀文件持續(xù)時間 intm_serial;//線程序號 m_serial=((ThreadInfo*)(p))->serial; m_delay=(DWORD)(((ThreadInfo*)(p))->delay*INTE_PER_SEC); m_persist=(DWORD)(((ThreadInfo