Re: [sane-devel] Network connected scanner, i/o error if scanner is idle for longer then 40sec
On 30/12/14 17:26, Paul Newall wrote: On 30/12/14 10:18, Louis Lagendijk wrote: On Tue, 2014-12-30 at 10:09 +, Paul Newall wrote: I have been digging down into the code, and adding extra debug output. In my network read function kodakaio_net_read it seems that poll(...) is indicating that there is data to read, but sanei_ tcp_read(..) then returns zero bytes. If there was no data I'd expect poll to timeout, and if there was some data, sanei_ tcp_read should return it? But this is the only network read code I have ever written in c so I am not too confident it is correct. Paul A read returning 0 bytes when the fd is ready indicates that the other side closed the TCP-connection. you probably need to send some form of keep-alive or close/ the connection when you don't need it and re-open the connection later. Louis Thank you Louis, that was very helpful. It seems that the scanner initiates keep-alive exchanges every 3 seconds for around 27 seconds, then it closes the connection. I had assumed the normal thing would be to open the connection in sane_open, and close it in sane_close, but perhaps it's better to open the connection in sane_start, and close it in sane_cancel. Or I could leave things more or less as they are, but detect the loss of connection and reopen it if required. Paul I have now made the changes to open the connection in sane_start, and close it in sane_cancel. And that seems to have solved the problem without breaking anything else. Paul -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org
Re: [sane-devel] Network connected scanner, i/o error if scanner is idle for longer then 40sec
I have been digging down into the code, and adding extra debug output. In my network read function kodakaio_net_read it seems that poll(...) is indicating that there is data to read, but sanei_ tcp_read(..) then returns zero bytes. If there was no data I'd expect poll to timeout, and if there was some data, sanei_ tcp_read should return it? But this is the only network read code I have ever written in c so I am not too confident it is correct. Paul On 28/12/14 23:50, Paul Newall wrote: This was using xsane. If I close xsane and reopen it I can scan again. Paul On 28/12/14 20:40, m. allan noah wrote: Are you using a long-running front-end like xsane, or multiple invocations of something like scanimage? allan On Sun, Dec 28, 2014 at 3:24 PM, Paul Newall p.newa...@ntlworld.com wrote: I found, using the kodakaio backend, that leaving the scanner idle between scans for more than around 40sec gives an i/o error when I try to scan again. I can scan any number of times with gaps of less than 30 sec between scans without getting this error. Has anyone ever had a similar experience with any other backend? Does anyone have an idea what might be the cause? -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org
Re: [sane-devel] Network connected scanner, i/o error if scanner is idle for longer then 40sec
On 30/12/14 10:18, Louis Lagendijk wrote: On Tue, 2014-12-30 at 10:09 +, Paul Newall wrote: I have been digging down into the code, and adding extra debug output. In my network read function kodakaio_net_read it seems that poll(...) is indicating that there is data to read, but sanei_ tcp_read(..) then returns zero bytes. If there was no data I'd expect poll to timeout, and if there was some data, sanei_ tcp_read should return it? But this is the only network read code I have ever written in c so I am not too confident it is correct. Paul A read returning 0 bytes when the fd is ready indicates that the other side closed the TCP-connection. you probably need to send some form of keep-alive or close/ the connection when you don't need it and re-open the connection later. Louis Thank you Louis, that was very helpful. It seems that the scanner initiates keep-alive exchanges every 3 seconds for around 27 seconds, then it closes the connection. I had assumed the normal thing would be to open the connection in sane_open, and close it in sane_close, but perhaps it's better to open the connection in sane_start, and close it in sane_cancel. Or I could leave things more or less as they are, but detect the loss of connection and reopen it if required. Paul -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org
Re: [sane-devel] Network connected scanner, i/o error if scanner is idle for longer then 40sec
Are you using a long-running front-end like xsane, or multiple invocations of something like scanimage? allan On Sun, Dec 28, 2014 at 3:24 PM, Paul Newall p.newa...@ntlworld.com wrote: I found, using the kodakaio backend, that leaving the scanner idle between scans for more than around 40sec gives an i/o error when I try to scan again. I can scan any number of times with gaps of less than 30 sec between scans without getting this error. Has anyone ever had a similar experience with any other backend? Does anyone have an idea what might be the cause? -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org -- well, I stand up next to a mountain- and I chop it down with the edge of my hand -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org
Re: [sane-devel] Network connected scanner, i/o error if scanner is idle for longer then 40sec
This was using xsane. If I close xsane and reopen it I can scan again. Paul On 28/12/14 20:40, m. allan noah wrote: Are you using a long-running front-end like xsane, or multiple invocations of something like scanimage? allan On Sun, Dec 28, 2014 at 3:24 PM, Paul Newall p.newa...@ntlworld.com wrote: I found, using the kodakaio backend, that leaving the scanner idle between scans for more than around 40sec gives an i/o error when I try to scan again. I can scan any number of times with gaps of less than 30 sec between scans without getting this error. Has anyone ever had a similar experience with any other backend? Does anyone have an idea what might be the cause? -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject unsubscribe your_password to sane-devel-requ...@lists.alioth.debian.org
