共享内存使用

为什么80%的码农都做不了架构师？>>>   

写内存

#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

typedef struct{
  char name[4];
  int  age;
} people;

main(int argc, char** argv)
{
	int fd,i;
	people *p_map;
	char temp;
	
	fd=open(argv[1], O_CREAT|O_RDWR|O_TRUNC, 00777);
	lseek(fd, sizeof(people)*5-1, SEEK_SET);
	write(fd,"",1);
	
	p_map = (people*) mmap( NULL,sizeof(people)*10,PROT_READ|PROT_WRITE,
        MAP_SHARED,fd,0 );
	close( fd );
	temp = 'a';
	for (i=0; i<10; i++) {
		temp += 1;
		memcpy(( *(p_map+i) ).name, &temp,2 );
		(*(p_map+i) ).age = 20+i;
	}
	printf(" initialize over \n ");
	sleep(10);
	munmap( p_map, sizeof(people)*10 );
	printf( "umap ok \n" );
}

读内存

#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

typedef struct{
  char name[4];
  int  age;
} people;

main(int argc, char** argv) 
{
	int fd,i;
	people *p_map;
	fd = open(argv[1], O_CREAT|O_RDWR, 00777);
	p_map = (people*)mmap(NULL, sizeof(people)*10, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	for (i = 0; i<10; i++)
	{
		printf( "name: %s age %d;\n",(*(p_map+i)).name, (*(p_map+i)).age );
	}
	munmap( p_map,sizeof(people)*10 );
}

转载于:https://my.oschina.net/lvyi/blog/3017839