一,C++ 常用进程间通信
二,共享内存
// boosttest.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include
#include
#include
#include
using namespace std;
using namespace boost::interprocess;
int main(int argc,char *argv[])
{
cout << "argc" << argc<
//1 删除共享内存
struct shm_remove
{
shm_remove() { shared_memory_object::remove("SharedMemory"); }
~shm_remove() { shared_memory_object::remove("SharedMemory"); }
}remover;
//2 创建共享内存段
shared_memory_object shm(create_only, "SharedMemory", read_write);
//3 设置共享内存大小
shm.truncate(100);
//4 映射共享内存片段
mapped_region region(shm, read_write);
//5 初始化为1
std::memset(region.get_address(), 1, region.get_size());
//运行子进程
std::string s(argv[0]);
s += " child ";
if (0 != std::system(s.c_str()))
return 1;
}
else
{
//1 创建共享内存
shared_memory_object shm(open_only, "SharedMemory", read_only);
//2 映射共享内存
mapped_region region(shm, read_only);
//3 检查共享内存是否被初始化为1
char* mem = static_cast
for (std::size_t i = 0; i < region.get_size(); ++i) {
if (*mem++ != 1)
return 1;
else
{
printf("mem:%d ", *mem);
}
}
}
system("pause");
return 0;
}
三,消息队列
// boosttest.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include
#include
#include
#include
#include
#include
using namespace std;
using namespace boost::interprocess;
int main(int argc,char *argv[])
{
cout << "argc" << argc<
//1 删除消息队列
message_queue::remove("message_queue");
//2 创建消息队列
message_queue mq(create_only, "message_queue", 100, sizeof(int));
//3 发送100个数字
for (int i = 0; i < 100; ++i) {
mq.send(&i, sizeof(i), 0);
}
//运行子进程
std::string s(argv[0]);
s += " child ";
if (0 != std::system(s.c_str()))
return 1;
}
else
{
//1 打开消息队列
message_queue mq(open_only, "message_queue");
unsigned int priority;
message_queue::size_type recvd_size;
for (int i = 0; i < 100; i++)
{
int number;
mq.receive(&number, sizeof(number),recvd_size,priority);
if (number != i || recvd_size != sizeof(number))
return 1;
else
printf("number:%d ", number);
}
message_queue::remove("message_queue");
}
system("pause");
return 0;
}
四,信号量
// boosttest.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
// boosttest.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include
#include
#include
#include
#include
using namespace std;
using namespace boost::interprocess;
struct shared_memory_buffer
{
enum { NumItems = 100};//数组大小
shared_memory_buffer():mutex(1),nempty(NumItems),nstored(0){}
interprocess_semaphore mutex, nempty, nstored;//匿名信号量
int items[NumItems];//共享数组
};
int main(int argc, char *argv[])
{
//cout << "argc" << argc << argv[0];
if (argc == 1) {//父进程
//1 删除共享内存
struct shm_remove
{
shm_remove() { shared_memory_object::remove("SharedMemory"); }
}remover;
//2 创建共享内存段
shared_memory_object shm(create_only, "SharedMemory", read_write);
//3 设置共享内存大小
shm.truncate(sizeof(shared_memory_buffer));
//4 映射共享内存片段
mapped_region region(shm, read_write);
//5 写数据,数据满了会阻塞
void *addr = region.get_address();
shared_memory_buffer *data = new(addr)shared_memory_buffer;
const int NumMsg = 100;
for (int i = 0; i < NumMsg; ++i) {
data->nempty.wait();
data->mutex.wait();
data->items[i%shared_memory_buffer::NumItems] = i;
data->mutex.post();
data->nstored.post();
}
}
else
{
struct shm_remove
{
~shm_remove() { shared_memory_object::remove("MySharedMemory"); }
} remover;
//1 创建共享内存
shared_memory_object shm(open_only, "SharedMemory", read_write);
//2 映射共享内存
mapped_region region(shm, read_write);
//3 共享数据复制到自己的缓冲
void * addr = region.get_address();
shared_memory_buffer* data = static_cast
const int NumMsg = 100;
int extracted_data[NumMsg];
for (int i = 0; i < NumMsg; ++i) {
data->nstored.wait();
data->mutex.wait();
extracted_data[i] = data->items[i%shared_memory_buffer::NumItems];
printf("data:%d ", data->items[i%shared_memory_buffer::NumItems]);
data->mutex.post();
data->nempty.post();
}
}
system("pause");
return 0;
}
信号量与互斥锁的区别:
1,作用域
信号量: 进程间或线程间(linux仅线程间)
互斥锁: 线程间
2,上锁时
信号量: 只要信号量的value大于0,其他线程就可以wait成功,成功后信号量的value减一。若value值不大于0,则wait阻塞,直到post释放后value值加一
互斥锁: 只要被锁住,其他任何线程都不可以访问被保护的资源