双向Unix域套接字锁
我正在写两个程序,一个用C++,另一个用Python,目的是让它们通过Unix域套接字互相通信。我想让C++代码发送一个数字给Python代码,然后Python代码再把另一个数字发回给C++。这个过程会一直进行,直到C++代码没有数字可以发送为止,然后执行就结束了。下面是我的代码。我发现它们在循环的第一次迭代后就无法继续运行了。
我先运行Python程序:
python code.py /tmp/1 /tmp/2
然后我运行C++代码:
./code /tmp/1 /tmp/2
这是输出结果:
C++ 输出:
发送了 0
正在监听
连接成功
接收到 5
发送了 1
正在监听
Python 输出:
正在监听 ...
接收到 (0,)
>5
发送了 5
正在监听 ...
C++ 代码:
static int connFd;
int main(int argc, char* argv[])
{
int recv_sock,
send_sock;
struct sockaddr_un server, client;
///////////////////////////////////////////
//
// setup send
//
///////////////////////////////////////////
/* Create socket on which to send. */
send_sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (send_sock < 0)
{
perror("opening unix socket");
exit(1);
}
/* Construct name of socket to send to. */
client.sun_family = AF_UNIX;
strcpy(client.sun_path, argv[1]);
if (connect(send_sock, (struct sockaddr *) &client, sizeof(struct sockaddr_un)) < 0)
{
close(send_sock);
perror("connecting stream socket");
exit(1);
}
///////////////////////////////////////////
//
// setup recv
//
///////////////////////////////////////////
recv_sock = socket(AF_UNIX, SOCK_STREAM, 0);
if(recv_sock< 0)
{
cerr << "Cannot open socket" << endl;
return 0;
}
bzero((char*) &server, sizeof(server));
server.sun_family = AF_UNIX;
strcpy(server.sun_path, argv[2]);
//bind socket
if(bind(recv_sock, (struct sockaddr *)&server, sizeof(server)) < 0)
{
cerr << "Cannot bind" << endl;
return 0;
}
listen(recv_sock, 10);
int X;
for (int i = 0; i < 10; i++)
{
write(send_sock, &i, sizeof(i));
cout << "sent " << i << endl;
cout << "Listening" << endl;
connFd = accept(recv_sock, 0, 0);
if (connFd < 0)
{
cerr << "Cannot accept connection" << endl;
return 0;
}
else
{
cout << "Connection successful" << endl;
read(connFd, &X, sizeof(X));
cout << "received " << X << endl;
}
usleep(2000000);
}
close(send_sock);
close(recv_sock);
unlink(argv[2]);
unlink(argv[1]);
return 0;
}
Python 代码:
import socket,os,struct, glob, sys
import random
send_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
recv_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
try:
os.remove(sys.argv[1])
except OSError:
pass
recv_socket.bind(sys.argv[1])
recv_socket.listen(10)
while 1:
print "listening ..."
conn, addr = recv_socket.accept()
data = conn.recv(4)
p = struct.unpack('i',data)
print 'received ', p
if p is '9':
break
l = int(raw_input(">"))
a = struct.pack('i', l)
send_socket.connect(sys.argv[2])
send_socket.sendall(a)
print 'sent ', l
send_socket.close()
conn.close()
recv_socket.close()
我在这个方法上哪里做错了?我需要使用线程吗?
谢谢
1 个回答
1
在你的C++代码中,发送和接收的套接字处理方式是不同的:发送套接字在程序开始时只绑定一次,而接收套接字在每次循环时都会接受一个新的连接。
你现在的Python实现是在每次循环中都接受一个新的连接在recv_socket
上,并且每次都连接send_socket
,这就是你遇到问题的原因。
最有效的解决办法是在循环开始之前只连接每个套接字一次,除非你有很好的理由在每次循环时都打开一个新的连接。下面是相应的代码示例:
C++
static int connFd;
int main(int argc, char *argv[]) {
int recv_sock, send_sock;
struct sockaddr_un server, client;
///////////////////////////////////////////
//
// setup send
//
///////////////////////////////////////////
/* Create socket on which to send. */
send_sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (send_sock < 0) {
perror("opening unix socket");
exit(1);
}
/* Construct name of socket to send to. */
client.sun_family = AF_UNIX;
strcpy(client.sun_path, argv[1]);
if (connect(send_sock, (struct sockaddr *)&client,
sizeof(struct sockaddr_un)) < 0) {
close(send_sock);
perror("connecting stream socket");
exit(1);
}
///////////////////////////////////////////
//
// setup recv
//
///////////////////////////////////////////
recv_sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (recv_sock < 0) {
cerr << "Cannot open socket" << endl;
return 0;
}
bzero((char *)&server, sizeof(server));
server.sun_family = AF_UNIX;
strcpy(server.sun_path, argv[2]);
// bind socket
if (::bind(recv_sock, (struct sockaddr *)&server, sizeof(server)) < 0) {
cerr << "Cannot bind" << endl;
return 0;
}
listen(recv_sock, 10);
connFd = accept(recv_sock, 0, 0);
if (connFd < 0) {
cerr << "Cannot accept connection" << endl;
return 0;
} else {
cout << "Connection successful" << endl;
}
int X;
for (int i = 0; i < 10; i++) {
write(send_sock, &i, sizeof(i));
cout << "sent " << i << endl;
cout << "Listening" << endl;
read(connFd, &X, sizeof(X));
cout << "received " << X << endl;
usleep(2000000);
}
close(send_sock);
close(recv_sock);
unlink(argv[2]);
unlink(argv[1]);
return 0;
}
Python
recv_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
send_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
try:
os.remove(sys.argv[1])
except OSError:
pass
recv_socket.bind(sys.argv[1])
recv_socket.listen(10)
conn, addr = recv_socket.accept()
send_socket.connect(sys.argv[2])
while 1:
print "listening ..."
data = conn.recv(4)
p = struct.unpack('i',data)
print 'received ', p
if p is '9':
break
l = int(raw_input(">"))
a = struct.pack('i', l)
send_socket.sendall(a)
print 'sent ', l
send_socket.close()
conn.close()
recv_socket.close()