共享内存
最后更新于：2022-04-02 04:03:22
[TOC]
## 共享内存
- 不同进程之间内存空间是独立的，也就是说进程不能访问也不会干扰其他进程的内存
- 如果两个进程希望通过共享内存的方式通信,可以通过`mmap()`系统调用实现
- 共享内存是效率最高的进程间通讯机制，因为数据不需要在内核和程序之间复制
### go 实现
#include
#include
#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
int my_shm_new(char *name) {
shm_unlink(name);
return shm_open(name, O_RDWR|O_CREAT|O_EXCL, FILE_MODE);
}
*/
import "C"
import (
"fmt"
"unsafe"
)
const SHM_NAME = "my_shm"
const SHM_SIZE = 4 * 1000 * 1000 * 1000
type MyData struct {
Col1 int
Col2 int
Col3 int
}
func main() {
fd, err := C.my_shm_new(C.CString(SHM_NAME))
if err != nil {
fmt.Println(err)
return
}
C.ftruncate(fd, SHM_SIZE)
ptr, err := C.mmap(nil, SHM_SIZE, C.PROT_READ|C.PROT_WRITE, C.MAP_SHARED, fd, 0)
if err != nil {
fmt.Println(err)
return
}
C.close(fd)
data := (*MyData)(unsafe.Pointer(ptr))
data.Col1 = 100
data.Col2 = 876
data.Col3 = 8021
}
```
#include
#include
#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
int my_shm_open(char *name) {
return shm_open(name, O_RDWR, FILE_MODE);
}
*/
import "C"
import (
"fmt"
"unsafe"
)
const SHM_NAME = "my_shm"
const SHM_SIZE = 4 * 1000 * 1000 * 1000
type MyData struct {
Col1 int
Col2 int
Col3 int
}
func main() {
fd, err := C.my_shm_open(C.CString(SHM_NAME))
if err != nil {
fmt.Println(err)
return
}
ptr, err := C.mmap(nil, SHM_SIZE, C.PROT_READ|C.PROT_WRITE, C.MAP_SHARED, fd, 0)
if err != nil {
fmt.Println(err)
return
}
C.close(fd)
data := (*MyData)(unsafe.Pointer(ptr))
fmt.Println(data)
}
```
';