多線程共享內存混合編程

/*threadWrite線程向共享內存寫數據，threadRead線程從共享內存讀數據*/

/*讀線程必須等待寫線程執行完才開始*/

#include?<stdio.h>

#include?<stdlib.h>

#include?<sys/types.h>

#include?<sys/unistd.h>

#include?<sys/ipc.h>

#include?<sys/shm.h>

#include?<pthread.h>

#include?<errno.h>

?

static pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;

static pthread_cond_t cond=PTHREAD_COND_INITIALIZER;

int?g_Flag=0;

void*?threadRead(void*);

void*?threadWrite(void*);

?

int?shmid;

char?*buf[4092];

?

int?main(int?argc,char**?argv)

{

????printf("Enter main\n");

????

????printf("Create shared memory id\n");

????shmid=shmget(IPC_PRIVATE,sizeof(char)*4092,IPC_CREAT|0666);

????printf("shmid:%d\n",shmid);

????

????int?rt=0,wt=0;

????pthread_t rtid,wtid;

????wt=pthread_create(&wtid,NULL,threadWrite,NULL);

????if(wt!=0)

????{

????????printf("create Write Thread error:%s,errno:%d\n",strerror(errno),errno);

????????exit(0);

????}

????rt=pthread_create(&rtid,NULL,threadRead,&wtid);

????if(rt!=0)

????{

????????printf("create Read Thread error:%s,errno:%d\n",strerror(errno),errno);

????????exit(0);

????}

????pthread_cond_wait(&cond,&mutex);

????printf("Leave main\n");

????exit(0);

}

?

void*?threadRead(void*?arg)

{

????printf("Enter Read thread,start reading after Write thread finished!\n");

????

????char?*shmptr;

????int?i=0;

????char word;

????if((int)(shmptr=shmat(shmid,NULL,0))==-1)

????{

????????printf("The Read thread attach the shared memory failed!\n");

????????exit(0);

????}

????printf("Attached successfully!\n");

????

????pthread_join(*(pthread_t*)arg,NULL);

????printf("this is Read thread,thread id is %u,g_Flag:%d\n",(unsigned?int)pthread_self(),g_Flag);

????pthread_mutex_lock(&mutex);

????g_Flag=1;

????printf("Reading shared memory...\n");

????printf("Content:%s\n",shmptr);

????shmdt(shmptr);

????pthread_mutex_unlock(&mutex);

????printf("Read over,thread id is %u,g_Flag:%d\n",(unsigned?int)pthread_self(),g_Flag);

????printf("Leave Read thread!\n");

????pthread_cond_signal(&cond);

????pthread_exit(0);

}

?

void*?threadWrite(void*?arg)

{

????printf("Enter Write thread,we'll write something\n");

?

????

????char?*shmptr;

????int?i=0;

????char word;

????if((int)(shmptr=shmat(shmid,NULL,0))==-1)

????{

????????printf("The Write thread attach the shared memory failed!\n");

????????exit(0);

????}

????printf("Attached successfully!\n");

????

????printf("this is Write thread,thread id is %u,g_Flag:%d\n",(unsigned?int)pthread_self(),g_Flag);?

????pthread_mutex_lock(&mutex);

????g_Flag=2;

????

????printf("write a string into shared memory\n");

????while((word=getchar())!='\n')

????????shmptr[i++]=word;

????pthread_mutex_unlock(&mutex);

????printf("Write over,thread id is %u,g_Flag:%d\n",(unsigned?int)pthread_self(),g_Flag);

????printf("Leave Write thread!\n");

????pthread_exit(0);

}

?

兩進程通信

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,0,0)) == (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,BUF_SIZE,IPC_CREAT)) ==-1) ?
? ? { ?
?? ??? ?printf("shmget error \n"); ?
?? ??? ?exit(1); ?
? ? } ?
??
? ? if((shmptr =shmat(shmid,0,0))==(void *)-1) ?
? ? { ?
?? ??? ?printf("shmat error!\n"); ?
?? ??? ?exit(1); ?
? ? } ?
??
? ? while(1) ?
? ? { ?
?? ??? ?printf("input:"); ?
?? ??? ?scanf("%s",shmptr); ?
? ? } ?
??
? ? exit(0); ?
}?

?

?

?

?

總結

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