我正在尝试编写一个可以处理两个不同客户端的TCP服务器。我有一个请求者和提供者客户端。提供程序是多线程的，并向服务器添加和删除新服务。每次添加或删除新服务时，都应将其发送到服务器，服务器将打印更新。请求者客户端允许用户输入服务，然后检查服务器以查看该服务是否存在。
我遇到的问题是recv()函数。我在程序中调用了两次，一次从生产者客户端读取，另一次从请求者读取。问题是服务器仅收到一条消息，然后冻结。它应该在每次线程运行时更新。由于第二个recv()调用正在等待请求者，因此阻止了它，因此似乎出现了问题。我试图通过使用非阻塞事件标志（MSG_DONTWAIT）使第二个recv()呼叫变为非阻塞，但这不能解决我的问题。
如何编写可处理两个不同客户端写请求并防止它们彼此阻塞的TCP服务器？我的代码在下面。
客户端1-提供程序
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdbool.h>
#include <pthread.h>
#define PORT 8080
int SIZE = 100;
int counter = 0;
int semaphore = 1; //set to false
struct values
{
int serviceArray[100];
int portArray[100];
}input;
void callServer()
{
struct sockaddr_in address;
int sock = 0, valread;
struct sockaddr_in serv_addr;
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("\n Socket creation error \n");
}
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(PORT);
// Convert IPv4 and IPv6 addresses from text to binary form
if(inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)<=0)
{
printf("\nInvalid address/ Address not supported \n");
}
if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
printf("\nConnection Failed \n");
}
send(sock , &input , sizeof(input) , 0 );
}
int arraySearch(int number){
int i=0;
for(i=0; i< 100; i++){
if(input.serviceArray[i] == number)
{
return 0; //is found
}
}
return 1;
}
void *createService()
{
while(counter < SIZE)
{
sleep(2);
if(semaphore ==1)
{
int randomValue = rand() % SIZE;
if(arraySearch(randomValue) == 1)
{
input.serviceArray[counter] = randomValue;
input.portArray[counter] = randomValue + PORT;
printf("Thread 1 is adding service number: %d and port number: %d\n", input.serviceArray[counter], input.portArray[counter]);
semaphore = 0;//unlock
counter = counter + 1;
callServer();
}
}
}
}
void *removeService()
{
while(counter < SIZE)
{
sleep(4);
if(semaphore ==0)
{
printf("Thread 2 is removing service number: %d and port number: %d\n", input.serviceArray[counter - 1], input.portArray[counter - 1]);
input.serviceArray[counter -1] = 0;
input.portArray[counter - 1] = 0;
semaphore = 1; //lock
callServer();
}
}
}
int main(void)
{
//create threads
pthread_t thread_id1, thread_id2;
pthread_create(&thread_id1, NULL, createService, NULL);
pthread_create(&thread_id2, NULL, removeService, NULL);
pthread_join(thread_id1, NULL);
pthread_join(thread_id2, NULL);
}
客户端2-请求者
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdbool.h>
#include <pthread.h>
#define PORT 8080
void callServer(int serviceNum)
{
struct sockaddr_in address;
int sock = 0, valread;
struct sockaddr_in serv_addr;
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("\n Socket creation error \n");
}
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(PORT);
// Convert IPv4 and IPv6 addresses from text to binary form
if(inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)<=0)
{
printf("\nInvalid address/ Address not supported \n");
}
if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
printf("\nConnection Failed \n");
}
send(sock , &serviceNum , sizeof(serviceNum) , 0 );
}
void main(){
int serviceNum;
printf("Which service would you like to run?\n");
scanf("%d",&serviceNum);
printf("You entered: %d", serviceNum);
callServer(serviceNum);
}
服务器
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdbool.h>
#include <pthread.h>
#define PORT 8080
int sockfd;
int serviceNum;
struct sockaddr_in servaddr, cliaddr;
struct values {
int serviceArray[100];
int portArray[100];
}input;
int main()
{
int server_fd, server_fd2, new_socket, valread, valread2;
struct sockaddr_in address;
int opt = 1;
int addrlen = sizeof(address);
// Creating socket file descriptor
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
// Forcefully attaching socket to the port 8080
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | 0,
&opt, sizeof(opt)))
{
perror("setsockopt");
exit(EXIT_FAILURE);
}
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons( PORT );
// Forcefully attaching socket to the port 8080
if (bind(server_fd, (struct sockaddr *)&address,
sizeof(address))<0)
{
perror("bind failed");
exit(EXIT_FAILURE);
}
if (listen(server_fd, 3) < 0)
{
perror("listen");
exit(EXIT_FAILURE);
}
if ((new_socket = accept(server_fd, (struct sockaddr *)&address,
(socklen_t*)&addrlen))<0)
{
perror("accept");
exit(EXIT_FAILURE);
}
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
while(1){
valread = recv( new_socket , &input, sizeof(input), 0);
int j;
for(j = 0; j < 5; j++)
{
printf("service: %d and port: %d\n", input.serviceArray[j], input.portArray[j]);
}
recv( new_socket , &serviceNum, sizeof(serviceNum), MSG_DONTWAIT)
printf("The service number you passed is %d", serviceNum);
}
}
EDIT-这是对服务器的更新，是多线程的。我仍然遇到阻止问题。
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdbool.h>
#include <pthread.h>
#define PORT 8080
int sockfd;
int serviceNum;
struct sockaddr_in servaddr, cliaddr;
struct values {
int serviceArray[100];
int portArray[100];
}input;
int server_fd, server_fd2, new_socket, valread, valread2;
struct sockaddr_in address;
int opt = 1;
int addrlen = sizeof(address);
void *producer()
{
// Creating socket file descriptor
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
// Forcefully attaching socket to the port 8080
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | 0,
&opt, sizeof(opt)))
{
perror("setsockopt");
exit(EXIT_FAILURE);
}
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons( PORT );
// Forcefully attaching socket to the port 8080
if (bind(server_fd, (struct sockaddr *)&address,
sizeof(address))<0)
{
perror("bind failed");
exit(EXIT_FAILURE);
}
if (listen(server_fd, 3) < 0)
{
perror("listen");
exit(EXIT_FAILURE);
}
if ((new_socket = accept(server_fd, (struct sockaddr *)&address,
(socklen_t*)&addrlen))<0)
{
perror("accept");
exit(EXIT_FAILURE);
}
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
while(1)
{
valread = read( new_socket , &input, sizeof(input));
int j;
for(j = 0; j < 5; j++)
{
printf("service: %d and port: %d\n", input.serviceArray[j], input.portArray[j]);
}
}
}
void *requestor()
{
// Creating socket file descriptor
if ((server_fd2 = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
// Forcefully attaching socket to the port 8080
if (setsockopt(server_fd2, SOL_SOCKET, SO_REUSEADDR | 0,
&opt, sizeof(opt)))
{
perror("setsockopt");
exit(EXIT_FAILURE);
}
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons(8090);
if (bind(server_fd2, (struct sockaddr *)&address,
sizeof(address))<0)
{
perror("bind failed");
exit(EXIT_FAILURE);
}
if (listen(server_fd2, 3) < 0)
{
perror("listen");
exit(EXIT_FAILURE);
}
if ((new_socket = accept(server_fd2, (struct sockaddr *)&address,
(socklen_t*)&addrlen))<0)
{
perror("accept");
exit(EXIT_FAILURE);
}
if ((server_fd2 = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
while(1)
{
valread2 = read( new_socket , &serviceNum, sizeof(serviceNum));
printf("The service number you passed is %d", serviceNum);
}
}
int main()
{
//create threads
pthread_t thread_id1, thread_id2;
pthread_create(&thread_id1, NULL, producer, NULL);
pthread_create(&thread_id2, NULL, requestor, NULL);
pthread_join(thread_id1, NULL);
pthread_join(thread_id2, NULL);
}
答案 0 :(得分：3)
默认情况下，套接字在阻止模式下运行。因此，有意义的是，当您在一个套接字上调用recv()时，它将在等待数据到达时阻塞同一线程上的其他套接字。
对于您要尝试执行的操作，您需要将服务器代码更改为：
以 blocking 模式保留每个接受的套接字，并在它们各自的工作线程或分支进程中对其进行操作。
将每个接受的套接字切换到非阻塞模式（fctrl(FIONBIO)等），然后使用select()，(e)poll()或其他类似的套接字一种机制，用于在一个线程中一起监视套接字，然后在它告诉您何时各个套接字具有您需要处理的活动时做出响应（即，在实际有可读取的内容之前，不要从套接字读取信息）。
（仅Windows）通过重叠I / O操作异步使用每个接受的套接字。当每个套接字上都有活动时，让操作系统通知您。