我正在尝试使用Windows文件映射创建一个简单的客户端 - 服务器程序,并使用信号量。客户端向服务器发送2个号码,服务器计算nr1 + nr2和nr1 * nr2。我尝试了一些东西,但它甚至不适用于1个客户端,我希望它能为更多客户工作。这是代码:
服务器:
#include <windows.h>
#include <stdio.h>
#include <iostream>
using namespace std;
typedef struct {
int nr1;
int nr2;
} Mesaj;
int main(int argc, char** argv) {
Mesaj* mesaj;
HANDLE createSemaphore = CreateSemaphore(NULL, 1, 1, "Semafor");
if (createSemaphore == NULL || createSemaphore == INVALID_HANDLE_VALUE) {
wcout << "Failed to create a semaphore\n";
} else {
wcout << "Created the semaphore\n";
}
HANDLE hMemory = CreateFileMapping(INVALID_HANDLE_VALUE, NULL,
PAGE_READWRITE, 0, sizeof(Mesaj), "SharedMemory");
WaitForSingleObject(createSemaphore, INFINITE);
mesaj = (Mesaj*) MapViewOfFile(hMemory, FILE_MAP_READ, 0, 0, sizeof(Mesaj));
printf("The numbers received are: %d, %d\n", mesaj->nr1, mesaj->nr2);
int produs = mesaj->nr1 * mesaj->nr2;
int suma = mesaj->nr1 + mesaj->nr2;
printf("\nSuma numerelor este: %d iar produsul lor este: %d", suma, produs);
ReleaseSemaphore(createSemaphore, 1, NULL);
Sleep(INFINITE);
return 0;
}
客户:
#include <windows.h>
#include <stdio.h>
#include <iostream>
using namespace std;
typedef struct {
int nr1;
int nr2;
} Mesaj;
int main(int argc, char** argv) {
Mesaj* mesaj, *mesaj2;
mesaj2 = (Mesaj*) malloc(sizeof(Mesaj));
HANDLE hMemory = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE,
"SharedMemory");
if (hMemory == NULL) {
wcout << "Error at OpenFileMapping\n";
}
HANDLE openSemaphore = OpenSemaphore(SEMAPHORE_ALL_ACCESS,TRUE,"Semafor");
if(openSemaphore != NULL || openSemaphore != INVALID_HANDLE_VALUE){
wcout<<"the semaphore is opened\n";
}
mesaj2 = (Mesaj*) MapViewOfFile(hMemory, FILE_MAP_WRITE, 0, 0,
sizeof(Mesaj));
int nr1 = 0, nr2 = 0;
printf("Give a number: ");
scanf("%d", &nr1);
printf("Give another number: ");
scanf("%d", &nr2);
mesaj2->nr1 = nr1;
mesaj2->nr2 = nr2;
if (mesaj2 == NULL) {
wcout << "Error\n"
} else {
wcout << "I sent " << mesaj2->nr1 << " and " << mesaj2->nr2 << endl;
}
system("pause");
return 0;
}
我究竟做错了什么?我应该如何使用信号量?
答案 0 :(得分:7)
当我打开服务器时,它不会等待客户端。
The documentation for CreateSemaphore
说
信号量对象的状态在其计数大于零时发出信号,在其计数等于零时发出信号。
lInitialCount
参数指定初始计数。
您在创建信号量时传递了lInitialCount=1
。和1 > 0
,所以信号量发出信号,WaitForSingleObject
立即返回。
您可能想要创建初始计数为0
的信号量,以便在有人呼叫ReleaseSemaphore
之前不会发出信号。