Setting socket Timeout on Instrument Class #21

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1. alexforencich commented on Jan 23, 2017

   

   alexforencich

   on Jan 23, 2017

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   What leads you to believe that the timeout is not set on the socket?

   In [1]: import vxi11
   
   In [2]: vxi11.list_devices()
   Out[2]: ['192.168.1.108']
   
   In [3]: instr = vxi11.Instrument('192.168.1.108')
   
   In [4]: instr.client
   
   In [5]: instr.open()
   
   In [6]: instr.client
   Out[6]: <vxi11.vxi11.CoreClient at 0x7ff6cb26aa58>
   
   In [7]: instr.client.sock.timeout
   Out[7]: 11.0
   
   In [8]: instr.timeout
   Out[8]: 10
   
   In [9]: instr.timeout = 30
   
   In [10]: instr.client.sock.timeout
   Out[10]: 31.0
   
2. kchau101 commented on Jan 23, 2017

   

   kchau101

   on Jan 23, 2017

   Last edited by kchau101

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   I am using your library to search for instruments at predetermined IP addresses and rely on quick timeouts on addresses to make my search reasonably quick. Admittedly, this is a pretty dumb way to do this, but it's what I have to work with. I was using this method, and changing the timeout parameter in the instrument class did not seem to have an effect.

   Looking through your code some more, it seems on first connection, the first socket opened on line 260,

   self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

   as part of TCPClient does not have a timeout set explicitly. Only after a valid connection is established is the timeout set to the socket. I don't believe this is a bug in your implementation, just a weird use case I have.

   I managed to set a timeout for initial connections by calling socket.setdefaulttimeout(val) before attempting to communicate with an instrument. This solved my particular issue. After seeing your list_devices() command, I may be abandoning this method sometime in the future.

   I'm closing this as I don't think that the average user will need to set this parameter for initial socket connections. I have no idea how VXI-11 is laid out, so I have no idea how useful this info will be to others. Thanks for an amazing library.
3. kchau101

   closed this as completedon Jan 23, 2017
4. alexforencich commented on Jan 23, 2017

   

   alexforencich

   on Jan 23, 2017

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   Aha, I see. You're talking about the timeout for the portmapper call. I will take a look at implementing a good way of setting that. It may also be a good idea to roll a similar function into the list_devices call. Right now it uses UDP broadcast, which is not completely reliable. Having the option to attempt TCP connections to an explicit list could be a useful feature.
5. alexforencich

   reopened this on Jan 23, 2017