《Linux應(yīng)用實例教程》課件-講義31并發(fā)程序-共享內(nèi)存通信

S10、并發(fā)程序-共享內(nèi)存通信S10、并發(fā)程序-共享內(nèi)存通信S10、并發(fā)程序-共享內(nèi)存通信1、共享內(nèi)存通信寫程序shmmutexwrite.c：#include<semaphore.h>#include<stdio.h>#include<stdlib.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/sem.h>#include<sys/shm.h>#include<sys/stat.h>S10、并發(fā)程序-共享內(nèi)存通信#include<fcntl.h>#include<string.h>#defineBUFFER_SIZE10#definesem_name"mysem"intmain(){structStu{charname[10];intscore;};intshmid; sem_t*sem; intscore=60,i=1; charbuff[BUFFER_SIZE];S10、并發(fā)程序-共享內(nèi)存通信 key_tshmkey; shmkey=ftok("shmmutexread.c",0); sem=sem_open(sem_name,O_CREAT,0644,1); if(sem==SEM_FAILED) { printf("unabletocreatsemaphore!"); sem_unlink(sem_name); //刪除有名信號量 exit(-1); } shmid=shmget(shmkey,1024,0666|IPC_CREAT); /*創(chuàng)建IPC鍵值為shmkey的共享內(nèi)存，其大小為1024字節(jié)，允許讀寫*/ if(shmid==-1) printf("creatshmisfail\n");S10、并發(fā)程序-共享內(nèi)存通信 structStu*addr; addr=(structStu*)shmat(shmid,0,0); if(addr==(structStu*)-1) printf("shmshmatisfail\n"); addr->score=0;printf("寫進(jìn)程映射的共享內(nèi)存地址=%p\n",addr); do { sem_wait(sem); memset(buff,0,BUFFER_SIZE); memset((addr+i)->name,0,BUFFER_SIZE); printf("寫進(jìn)程:輸入一些姓名（不超過10個字符）到共享內(nèi)存(輸入'quit'退出):\n");S10、并發(fā)程序-共享內(nèi)存通信 if(fgets(buff,BUFFER_SIZE,stdin)==NULL)

{ sem_post(sem); break; } strncpy((addr+i)->name,buff,strlen(buff)-1); (addr+i)->score=++score; addr->score++; i++; sem_post(sem);

sleep(1); }while(strncmp(buff,"quit",4)!=0); S10、并發(fā)程序-共享內(nèi)存通信 if(shmdt(addr)==-1) /*將共享內(nèi)存與當(dāng)前進(jìn)程斷開*/ printf("shmdtisfail\n"); sem_close(sem); //關(guān)閉有名信號量 sem_unlink(sem_name); //刪除有名信號量}S10、并發(fā)程序-共享內(nèi)存通信讀程序shmmutexread.c：#include<semaphore.h>

#include<stdio.h>

#include<stdlib.h>

#include<sys/types.h>

#include<sys/ipc.h>

#include<sys/sem.h>

#include<sys/shm.h>

#include<sys/stat.h>

#include<fcntl.h>

#include<string.h>

#definesem_name"mysem"S10、并發(fā)程序-共享內(nèi)存通信intmain()

{

intshmid; sem_t*sem; inti=1; key_tshmkey; shmkey=ftok("shmmutexread.c",0); structStu

{

charname[10];

intscore;

}; S10、并發(fā)程序-共享內(nèi)存通信 sem=sem_open(sem_name,0,0644,0); if(sem==SEM_FAILED)

{

printf("unabletoopensemaphore!");

sem_close(sem); exit(-1);

}

shmid=shmget(shmkey,0,0666);

if(shmid==-1)

{

printf("creatshmisfail\n");

exit(0);

}

S10、并發(fā)程序-共享內(nèi)存通信 structStu*addr; addr=(structStu*)shmat(shmid,0,0); if(addr==(structStu*)-1) { printf("shmshmatisfail\n"); exit(0); }printf("讀進(jìn)程映射的共享內(nèi)存地址=%p\n",addr);

do

{

sem_wait(sem); S10、并發(fā)程序-共享內(nèi)存通信 if(addr->score>0)

{

printf("\n讀進(jìn)程:綁定到共享內(nèi)存%p:姓名%d%s,分值%d\n",addr,i,(addr+i)->name,(addr+i)->score);

addr->score--; if(strncmp((addr+i)->name,"quit",4)==0)break;

i++;

} sem_post(sem); }while(1);

sem_close(sem); if(shmdt(addr)==-1)printf("shmdtisfail\n");

if(shmctl(shmid,IPC_RMID,NULL)==-1) printf("shmctldeleteerror