我必须创建一个多线程TCP / IP服务器，该服务器包含一个变量来计算已连接的客户端（和断开连接的客户端）的数量，并在客户端连接到服务器时打印已连接的客户端的数量。
这是我的client.c文件：
#define PORT 4444
int main ()
{
int clientSocket;
struct sockaddr_in serverAddress;
char buffer[1024];
ssize_t nread;
clientSocket = socket(AF_INET, SOCK_STREAM, 0);
if (clientSocket == -1) {
perror("[-]Errore durante la creazione della socket\n");
exit(-1);
}
printf("[+]Client socket has been created\n");
memset(&serverAddress, '\0', sizeof(serverAddress));
serverAddress.sin_family = AF_INET;
serverAddress.sin_port = htons(PORT);
serverAddress.sin_addr.s_addr = INADDR_ANY;
if (connect(clientSocket, (struct sockaddr*)&serverAddress, sizeof(serverAddress)) == -1) {
perror("Errore con la connessione\n");
exit(-1);
}
while (1) {
printf("> ");
fflush(stdin);
scanf("%s", buffer);
if (nread != -1)
buffer[nread] = '\0';*/
if (send(clientSocket, buffer, strlen(buffer), 0) == -1) {
perror("Errore con l'invio");
exit(1);
}
if(strcmp(buffer, ":exit") == 0) {
close(clientSocket);
printf("[-]Disconnected from Server\n");
exit(0);
}
if ( (nread=recv(clientSocket, buffer, sizeof buffer - 1, 0)) <= 0) {
perror("[-]Error in receiving data from server\n");
}
else {
buffer[nread] = '\0';
printf("Server received: %s\n", buffer);
}
}
close(clientSocket);
return 0;
}
这是我的server.c文件：
#define PORT 4444
#define MAX_CONNESSIONI 100
typedef struct myStruct {
int clientCollegati;
int clientCheSiSonoScollegati;
pthread_mutex_t mutex; // Creazione del mutex per sincronizzare la struttura
} myStruct;
myStruct *test;
myStruct *initStruct();
void *incrementa(void*);
int main ()
{
int serverSocket, bindStatus;
struct sockaddr_in serverAddress;
int clientSocket;
struct sockaddr_in newAddress;
char buffer[1024];
pid_t child;
socklen_t addrSize;
ssize_t nread;
pthread_t tid;
test = initStruct();
if (pthread_create(&tid, NULL, incrementa, NULL) != 0) {
perror("Errore nella creazione del thread t1\n");
exit(1);
}
serverSocket = socket(AF_INET, SOCK_STREAM, 0);
if (serverSocket == -1) {
perror("[-]Errore durante la creazione della socket\n");
exit(-1);
}
memset(&serverAddress, '\0', sizeof(serverAddress));
serverAddress.sin_family = AF_INET;
serverAddress.sin_port = htons(PORT);
serverAddress.sin_addr.s_addr = INADDR_ANY;
bindStatus = bind(serverSocket, (struct sockaddr*)&serverAddress, sizeof(serverAddress));
if (bindStatus == -1) {
perror("[-]Errore durante il binding\n");
exit(1);
}
printf("[+]Bind to port %d\n", PORT);
if (listen(serverSocket, MAX_CONNESSIONI) != -1) {
printf("Listening . . .\n\n");
}
else {
perror("[-]Error during listening\n");
exit(1);
}
while (1) {
clientSocket = accept(serverSocket, (struct sockaddr*)&newAddress, &addrSize);
if (clientSocket == -1) {
exit(-1);
}
printf("%s:%d joined\n", inet_ntoa(newAddress.sin_addr), ntohs(newAddress.sin_port));
if (pthread_join(tid, NULL)) { // returns 3
perror("pthread_join error\n");
exit(1);
}
printf("There is/are %d client(s) connected\n", test->clientCollegati);
child = fork();
if (child == 0) {
close(serverSocket);
while (1) {
if ( (nread=recv(clientSocket, buffer, sizeof buffer - 1, 0)) <= 0) {
perror("[-]Error in receiving data from server\n");
}
else {
buffer[nread] = '\0';
}
if (strcmp(buffer, ":exit") == 0) {
printf("%s:%d left\n", inet_ntoa(newAddress.sin_addr), ntohs(newAddress.sin_port));
break;
}
else {
printf("%s:%d wrote: %s\n", inet_ntoa(newAddress.sin_addr), ntohs(newAddress.sin_port), buffer);
send(clientSocket, buffer, strlen(buffer), 0);
bzero(buffer, sizeof(buffer));
}
}
}
}
close(clientSocket);
return 0;
}
myStruct *initStruct()
{
struct myStruct *ptr = malloc(sizeof(myStruct));
ptr->clientCollegati = 0;
ptr->clientCheSiSonoScollegati = 0;
pthread_mutex_init(&ptr->mutex, NULL); // inizializzazione dinamica del mutex
return ptr;
}
void *incrementa(void *ptr)
{
pthread_mutex_lock(&test->mutex);
test->clientCollegati++;
pthread_mutex_unlock(&test->mutex);
pthread_exit(0);
}
不幸的是，这似乎无法正常工作，您可以在server output和此处client1和此处client2 output中看到
pthread_join的第二次调用时]您的代码逻辑是错误的。您正在执行一个pthread_create()，然后执行多个pthread_join()。如果要为每个连接的客户端增加值，则必须在每个成功的pthread_create()之后执行一个accept()，然后再执行一个pthread_join()。注意：所有这些必须在[fork()的调用之前[[之前]]发生。 哪里有错？我想问题是
tid完成并且对不存在的线程（因为有一个线程）调用了对该pthread_join的第二次调用]
这就是事实。在您当前的程序中，第一个pthread_join()成功，并且任何后续调用都因errno 3而失败（没有这样的过程），因为该线程不再存在。所以您已经知道了。如果您知道那是错误的，为什么要创建一个线程却多次加入它？
您的程序编写方式（在增量之后分叉）也意味着，根本没有任何理由使用线程来进行增量，并且甚至不需要互斥体，因为只有一个线程可以访问该线程。在任何给定时间的价值。换句话说，您的服务器根本不是多线程的。如果您只想做一个实验就可以了，但这没有多大意义。
您可能想要做的（拥有多线程服务器）是让
每个客户端一个线程
而不是每次都派生，而是使用线程函数中的客户端代码（在这种情况下，使用互斥锁是有意义的） 。请注意，这对于大量客户端来说不能很好地扩展（通常，经典的fork()方法更好，在这种情况下，您实际上不需要任何线程）。