套接字超时并删除 O_NONBLOCK 选项
我实现了套接字超时并重试，但为了做到这一点，我必须将套接字设置为非阻塞套接字。但是，我需要阻塞套接字。这是我试图解决这两个问题的尝试。这是行不通的。随后的发送调用会阻塞，但从不发送任何数据。当我在没有选择和超时的情况下连接时，后续发送调用正常工作。
参考文献：
代码：
fd_set fdset;
struct timeval tv;
fcntl(dsock, F_SETFL, O_NONBLOCK);
tv.tv_sec = theDeviceTimeout;
tv.tv_usec = 0;
int retries=0;
logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry);
for(retries=0;retries<theDeviceRetry;retries++) {
connect(dsock, (struct sockaddr *)&daddr, sizeof daddr);
FD_ZERO(&fdset);
FD_SET(dsock, &fdset);
if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) {
int so_error;
socklen_t slen = sizeof so_error;
getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen);
if (so_error == 0) {
logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP);
break;
} else {
logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries);
logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno));
logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error));
continue;
}
}
}
int opts;
opts = fcntl(dsock,F_GETFL);
logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries);
opts ^= O_NONBLOCK;
fcntl(dsock, F_SETFL, opts);
I implemented a socket timeout and retry but in order to do it I had to set the socket as a non-blocking socket. However, I need the socket to block. This was my attempt at a solution to these two problems. This is not working. Subsequent send calls block but never send any data. When I connect without the select and the timeout, subsequent send calls work normally.
References:
- C: socket connection timeout
- How to reset a socket back to blocking mode (after I set it to nonblocking mode)?
Code:
fd_set fdset;
struct timeval tv;
fcntl(dsock, F_SETFL, O_NONBLOCK);
tv.tv_sec = theDeviceTimeout;
tv.tv_usec = 0;
int retries=0;
logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry);
for(retries=0;retries<theDeviceRetry;retries++) {
connect(dsock, (struct sockaddr *)&daddr, sizeof daddr);
FD_ZERO(&fdset);
FD_SET(dsock, &fdset);
if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) {
int so_error;
socklen_t slen = sizeof so_error;
getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen);
if (so_error == 0) {
logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP);
break;
} else {
logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries);
logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno));
logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error));
continue;
}
}
}
int opts;
opts = fcntl(dsock,F_GETFL);
logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries);
opts ^= O_NONBLOCK;
fcntl(dsock, F_SETFL, opts);
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评论（2）
获得可写事件并且没有错误后，您需要再次调用
connect()，如文档所述。这会告诉您连接是成功还是失败。After you get the writeable event and no error you then need to call
connect()again, as documented. This tells you whether the connection succeeded or failed.为什么不使用
SO_RCVTIMEO或SO_SNDTIMEO套接字选项？或者我在你的问题中遗漏了什么？Why not use
SO_RCVTIMEOorSO_SNDTIMEOsocket options? Or did I miss something in your question?