阻塞模式的accept线程退出

c_w_l

于 2023-05-13 16:58:51 发布

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文章标签： c语言网络

本文链接：https://blog.youkuaiyun.com/c_w_l/article/details/130659472

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该程序创建了一个服务器，监听指定端口并使用多线程处理连接请求。在accept线程中，当尝试接受新连接时，如果主程序已经调用shutdown和close关闭了服务socket，accept函数将返回-1且errno为EINVAL。这表明在服务器试图接受新连接时，socket已经被关闭或中断。

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在其他线程一次调用shutdown和close良好的关闭accept对应的sock，此时accept工作线程中accept函数会返回-1，并且errno为EINVAL, 例程如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>
#include <pthread.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/select.h>

#define BUF_SIZE 1024

int serv_sock = -1, clnt_sock = -1;
pthread_t accept_thread_id, abort_accept_thread_id;
int accept_result = 0;

void error_handling(char *message);
void *accept_thread(void *arg);
void *abort_accept_thread(void *arg);

int main(int argc, char *argv[])
{
	char message[BUF_SIZE];
	int str_len, i;

	struct sockaddr_in serv_adr;
	struct sockaddr_in clnt_adr;
	socklen_t clnt_adr_sz = sizeof(clnt_adr);
	struct timeval timeout = {.tv_sec = 15, .tv_usec = 0};

	if(argc!=2) {
		printf("Usage : %s <port>\n", argv[0]);
		exit(1);
	}

	serv_sock=socket(PF_INET, SOCK_STREAM, 0);   
	if(serv_sock==-1) {
		error_handling("socket() error");
	}
	int opt = 1;
    setsockopt(serv_sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family=AF_INET;
	serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
	serv_adr.sin_port=htons(atoi(argv[1]));

	if(bind(serv_sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr))==-1) {
		error_handling("bind() error");
	}
	
	if(listen(serv_sock, 5)==-1) {
		error_handling("listen() error");
	}
	if (pthread_create(&accept_thread_id, NULL, accept_thread, NULL) < 0) {
		error_handling("create accept_thread failed");
	}
	if (pthread_create(&abort_accept_thread_id, NULL, abort_accept_thread, NULL) < 0) {
		error_handling("create abort_accept_thread failed");
	}
	int *result = NULL;
	pthread_join(accept_thread_id, (void **)&result);
	printf("result: %d\n", (int)result);
	if (0 == result) {
		error_handling("abort accept");
	}
	while (1) {
		int len = recv(clnt_sock, message, BUF_SIZE - 1, 0);
		if (len > 0) {
			send(clnt_sock, message, len, 0);
		} else if (len <= 0) {
			break;
		}
	}
	shutdown(clnt_sock, SHUT_RD);
	close(clnt_sock);
	close(serv_sock);
	
	return 0;
}

void error_handling(char *message)
{
	fputs(message, stderr);
	fprintf(stderr, "\nerrno: %d %s\n", errno, strerror(errno));
	fputc('\n', stderr);
	exit(1);
}

void *accept_thread(void *arg)
{
	int accept_result = 0;

	while (1) {
		struct sockaddr_in clnt_adr;
		socklen_t clnt_adr_sz = sizeof(clnt_adr);
		/*能够进行accept了，直接放进来*/
		printf("waitting for accept\n");
		clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_adr, &clnt_adr_sz);
		if(clnt_sock==-1) {
			printf("accept() error, errno: %d\n", errno);
			break;
		} else {
			printf("Connected client\n");
			accept_result = 1;
			break;
		}
	}
	
	return (void *)accept_result;
}

void *abort_accept_thread(void *arg)
{
	sleep(10);
	if (serv_sock != -1) {
		shutdown(serv_sock, SHUT_RDWR);
		close(serv_sock);
	}

	return NULL;
}