我正在尝试实现一个监视器类来处理多线程。我必须使用Visual Studio 2010,所以对我来说没有c ++ 11。我可以通过创建全局变量来实现这一点,每个类型的值都可以在线程中读取/写入,并且每个变量都使用一个互斥量,这将是简单但更繁琐。
所以我想花时间在一个类中实现监视器概念。 这项工作已经完成了#34;在某种程度上,因为数据类型是float或int,但我想进一步实现monitor类以支持C标准类型和c ++类,例如字符串。
我的方法是让静态成员作为跨线程的共享内存工作,这样我唯一要做的就是在两个线程中实例化类,我会正确设置IPC。
事情是......我必须初始化静态成员并且我无法使它工作,因为字符串和int-ish类型(int,float等...)没有以相同的方式初始化。 / p>
这是我试图做的事情:
Left a :: Right a :: ...
工作正常如果我只声明了template<class T>
class Monitor : protected Mutex {
public:
Monitor(bool Verbose);
~Monitor();
T read(DWORD wait_time=INFINITE);
void write(T value, DWORD wait_time=INFINITE);
//friend void operator= (Monitor& m1, Monitor& m2);
private:
static T container;
};
template<class T>
T Monitor<T>::container = (typeid(T) == typeid(string) ? "" : 0);
或Monitor<string> pMonitor2(VERB_ON);
。声明两者都会引发我Monitor<int> pMonitor1(VERB_ON);
。
此外,在类中实现这种进程间通信概念的最佳方法是什么?
到目前为止的完整代码:
monitor.cpp:
error C2440: 'initializing' : cannot convert from 'const char *' to 'int'
monitor.h:
#include "monitor.h"
using namespace std;
HANDLE Mutex::hMutex = nullptr;
unsigned int Mutex::counter = 0;
Mutex::Mutex(bool V) {
Verbose = V;
if(hMutex == nullptr) {
if(Verbose) cout << "Creating mutex\n";
hMutex = CreateMutex(
NULL,
FALSE,
(LPCWSTR) "CONTMUTEX");
counter++;
}
else{
if(Verbose) cout <<"Mutex already created\n";
counter++;
}
}
Mutex::~Mutex() {
counter--;
if(counter == 0) {
if(Verbose) cout << "Destroying mutex\n";
CloseHandle(hMutex);
}
else {
if(Verbose) cout << "Awaiting closure of all instances of Mutex\n";
}
}
/*void operator= (Monitor& m1, Monitor& m2) {
m1.write(m2.read());
}*/
main.cpp进行测试:
#ifndef MONITOR_INC
#define MONITOR_INC
//#include <vector>
#include <Windows.h>
#include <iostream>
using namespace std;
enum verb{VERB_OFF, VERB_ON};
class Mutex {
public:
Mutex(bool Verbose);
~Mutex();
protected:
bool Verbose;
static HANDLE hMutex;
static unsigned int counter;
};
template<class T>
class Monitor : protected Mutex {
public:
Monitor(bool Verbose);
~Monitor();
T read(DWORD wait_time=INFINITE);
void write(T value, DWORD wait_time=INFINITE);
//friend void operator= (Monitor& m1, Monitor& m2);
private:
static T container;
};
template<class T>
T Monitor<T>::container = (typeid(T) == typeid(string) ? "" : 0);
template<class T>
Monitor<T>::Monitor(bool Verbose) : Mutex(Verbose) {
if(Verbose) cout << "Monitor Constructor\n";
}
template<class T>
Monitor<T>::~Monitor() {
if(Verbose) cout << "Monitor Destructor\n";
}
template<class T>
T Monitor<T>::read(DWORD wait_time) {
T ret_val;
WaitForSingleObject(hMutex, wait_time);
ret_val = container;
ReleaseMutex(hMutex);
return ret_val;
}
template<class T>
void Monitor<T>::write(T value, DWORD wait_time) {
WaitForSingleObject(hMutex, wait_time);
container = value;
ReleaseMutex(hMutex);
}
//void operator= (Monitor& m1, Monitor& m2);
#endif
我必须事先为任何不良做法道歉。自从我上次用C ++编写代码以来已经过去了8个月,我借此机会从我的C ++编码技巧中汲取了一些成果。
#include "monitor.h"
#include <string>
#include <sstream>
int main() {
Mutex pMutex1(VERB_ON);
Mutex pMutex2(VERB_ON);
Mutex pMutex3(VERB_ON);
Monitor<int> pMonitor1(VERB_ON);
cout << pMonitor1.read() << "\n";
pMonitor1.write(20);
cout << pMonitor1.read() << "\n";
Monitor<string> pMonitor2(VERB_ON);
cout << pMonitor2.read() << "\n";
pMonitor2.write("TURN DOWN FOR WHAT");
cout << pMonitor2.read() << "\n";
return 0;
}
实际上并不适用于int,只有字符串。
答案 0 :(得分:1)
您可以使用专业化:
template<class T> // general case
T Monitor<T>::container = 0;
template<>
std::string Monitor<std::string>::container = "";
或使用默认值
template<class T>
T Monitor<T>::container = T();