[casper] 回复: Programming a ROACH2

[lij...@xao.ac.cn]

mybe your katcp is too new(0.6?),try to install 0.5.5
if you use pip,just run : sudo pip install katcp==0.5.5

发自我的华为手机

-------- 原始邮件 --------
主题：Re: [casper] Programming a ROACH2
发件人：David MacMahon
收件人：Jason Manley
抄送：Casper Lists ,Ryan Monroe

I think the intent of exit_fail() is to try to close the connection, ignore any exceptions raised while trying to close the connection, and then re-raise the original exception that happened before exit_fail was called, but I think the implementation is flawed. Here’s the definition of exit_fail() as it appears on GitHub:

def exit_fail():
print 'FAILURE DETECTED. Log entries:\n',lh.printMessages()
try:
fpga.stop()
except: pass
raise
exit()

I think this try/except block (with "pass" in the except part) followed by "raise" is completely superfluous. I think it means try to do something and if an exception is raised while trying, ignore it but then re-raise it, which seems exactly the same as not having the try/except block there at all! Not to mention that the exit() call will never be reached. I’m also not a fan of functions that can only be called while an exception is being handled (otherwise the no-arg form of "raise" will bomb out I think).

It would probably be preferable to pass the original exception to exit_fail() as an argument so that the original exception can be re-raised. I can make that change when I get back to Berkeley next week (unless someone beats me to it).

Sorry for veering so far off topic,
Dave


> On Oct 11, 2016, at 10:16, Jason Manley wrote:
>
> Some of the earlier scripts had bad error handling. If anything fails before the host object was successfully created, then you get this error because it tries to close the connection before exiting.
>
> Jason
>
> On 11 Oct 2016, at 16:09, David MacMahon wrote:
>
>>
>>> On Oct 11, 2016, at 06:46, Heystek Grobler wrote:
>>>
>>> Connecting to server 192.168.33.7 on port 7147... FAILURE DETECTED
>>
>> Editorial comments on error handling in tut3.py aside, I think the fact that "FAILURE DETECTED" follows "Connecting to server…" on the same line (i.e. no newline character inbetween) means that something went wrong when constructing the FpgaClient object which connects to TCP port 7147 of the ROACH2 with IP address 192.168.33.7. This is expecting the ROACH2 to have a tcpborphserver process listening on that port.
>>
>> What happens when you run:
>>
>> telnet 198.168.33.7 7147
>>
>> HTH,
>> Dave
>>
>