共享内存进程线程混合通信

多线程共享内存混合编程

1. /*threadWrite线程向共享内存写数据，threadRead线程从共享内存读数据*/
2. /*读线程必须等待写线程执行完才开始*/
3. #include <stdio.h>
4. #include <stdlib.h>
5. #include <sys/types.h>
6. #include <sys/unistd.h>
7. #include <sys/ipc.h>
8. #include <sys/shm.h>
9. #include <pthread.h>
10. #include <errno.h>
12. static pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
13. static pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
14. int g_Flag=0;
15. void* threadRead(void*);
16. void* threadWrite(void*);
18. int shmid;
19. char *buf[4092];
21. int main(int argc,char** argv)
22. {
23.     printf("Enter main\n");
24.     
25.     printf("Create shared memory id\n");
26.     shmid=shmget(IPC_PRIVATE,sizeof(char)*4092,IPC_CREAT|0666);
27.     printf("shmid:%d\n",shmid);
28.     
29.     int rt=0,wt=0;
30.     pthread_t rtid,wtid;
31.     wt=pthread_create(&wtid,NULL,threadWrite,NULL);
32.     if(wt!=0)
33.     {
34.         printf("create Write Thread error:%s,errno:%d\n",strerror(errno),errno);
35.         exit(0);
36.     }
37.     rt=pthread_create(&rtid,threadRead,&wtid);
38.     if(rt!=0)
39.     {
40.         printf("create Read Thread error:%s,errno);
41.         exit(0);
42.     }
43.     pthread_cond_wait(&cond,&mutex);
44.     printf("Leave main\n");
45.     exit(0);
46. }
48. void* threadRead(void* arg)
49. {
50.     printf("Enter Read thread,start reading after Write thread finished!\n");
51.     
52.     char *shmptr;
53.     int i=0;
54.     char word;
55.     if((int)(shmptr=shmat(shmid,0))==-1)
56.     {
57.         printf("The Read thread attach the shared memory failed!\n");
58.         exit(0);
59.     }
60.     printf("Attached successfully!\n");
61.     
62.     pthread_join(*(pthread_t*)arg,NULL);
63.     printf("this is Read thread,thread id is %u,g_Flag:%d\n",(unsigned int)pthread_self(),g_Flag);
64.     pthread_mutex_lock(&mutex);
65.     g_Flag=1;
66.     printf("Reading shared memory...\n");
67.     printf("Content:%s\n",shmptr);
68.     shmdt(shmptr);
69.     pthread_mutex_unlock(&mutex);
70.     printf("Read over,g_Flag);
71.     printf("Leave Read thread!\n");
72.     pthread_cond_signal(&cond);
73.     pthread_exit(0);
74. }
76. void* threadWrite(void* arg)
77. {
78.     printf("Enter Write thread,we'll write something\n");
80.     
81.     char *shmptr;
82.     int i=0;
83.     char word;
84.     if((int)(shmptr=shmat(shmid,0))==-1)
85.     {
86.         printf("The Write thread attach the shared memory failed!\n");
87.         exit(0);
88.     }
89.     printf("Attached successfully!\n");
90.     
91.     printf("this is Write thread,g_Flag); 
92.     pthread_mutex_lock(&mutex);
93.     g_Flag=2;
94.     
95.     printf("write a string into shared memory\n");
96.     while((word=getchar())!='\n')
97.         shmptr[i++]=word;
98.     pthread_mutex_unlock(&mutex);
99.     printf("Write over,g_Flag);
100.     printf("Leave Write thread!\n");
101.     pthread_exit(0);
102. }

两进程通信

service

#include <stdio.h>   
#include <sys/types.h>   
#include <sys/ipc.h>   
#include <sys/shm.h>   
  
#define BUF_SIZE 1024   
#define MYKEY 25   
int  main()  
{  
    int shmid;  
    char * shmptr;  
  
    if((shmid = shmget(MYKEY,BUF_SIZE,IPC_CREAT)) ==-1)  
    {  
        printf("shmget error!\n");  
        exit(1);  
    }  
  
    if((shmptr = shmat(shmid,0)) == (void *)-1)  
    {  
        printf("shmat error!\n");  
        exit(1);  
    }  
  
    while(1)  
    {  
        printf("string :%s\n",shmptr);  
        sleep(3);  
    }  
  
    exit(0);  
}  

client

#include <sys/types.h>   
#include <sys/ipc.h>   
#include <sys/shm.h>   
#include <stdio.h>   
  
#define BUF_SIZE 1024   
#define MYKEY 25   
int main()  
{  
    int shmid;  
    char *shmptr;  
  
    if((shmid = shmget(MYKEY,IPC_CREAT)) ==-1)  
    {  
        printf("shmget error \n");  
        exit(1);  
    }  
  
    if((shmptr =shmat(shmid,0))==(void *)-1)  
    {  
        printf("shmat error!\n");  
        exit(1);  
    }  
  
    while(1)  
    {  
        printf("input:");  
        scanf("%s",shmptr);  
    }  
  
    exit(0);  
}