EventStream does not connect during subscribe unless debugging

Please answer these questions before submitting your issue. Thanks!

What version of Python are you using (python -V)?

Python 3.6.3 :: Anaconda custom (64-bit)

What operating system and processor architecture are you using (python -c 'import platform; print(platform.uname());')?

uname_result(system=‘Darwin’, node=‘XXX’, release=‘17.3.0’, version=‘Darwin Kernel Version 17.3.0: Thu Nov 9 18:09:22 PST 2017; root:xnu-4570.31.3~1/RELEASE_X86_64’, machine=‘x86_64’, processor=‘i386’)

Which Python packages do you have installed (run the pip freeze or pip3 freeze command and paste output)?

chardet==3.0.4 click==6.7 Django==1.11.7 enum34==1.1.6 Flask==0.12.2 html5lib==0.9999999 idna==2.6 itsdangerous==0.24 Jinja2==2.10 Markdown==2.6.10 MarkupSafe==1.0 monotonic==1.4 nose==1.3.7 numpy==1.13.3 protobuf==3.5.0.post1 pytz==2017.3 requests==2.18.4 six==1.11.0 sseclient==0.0.18 tensorflow==1.4.1 tensorflow-tensorboard==0.4.0rc3 urllib3==1.22 Werkzeug==0.13

Which Arlo hardware do you have (camera types - [Arlo, Pro, Q, etc.], basestation model, etc.)?

H6

What did you do?

Sample Code

import Arlo  
  
UID='XXX'  
PWD='XXX'  
  
try:  
    arlo = Arlo.Arlo(UID,PWD)  
    print('Logged In')  
    cameras = arlo.GetDevices('camera')  
    firstCamera = cameras[0]  
    print('got camera')  
    cameraProperties = arlo.GetCameraState(firstCamera)['properties']  
    print('got properties')  
    batteryLevel = cameraProperties[0]['batteryLevel']  
    print('Battery Level: %d' % batteryLevel)  
    arlo.Logout()  
    print('Logged Out')  
except Exception as e:  
    print(e)  

What did you expect to see?

Logged In
got camera
got properties
Battery Level: 66
Logged Out

Process finished with exit code 0

What did you see instead?

without debugger, using Arlo commit aa4f976 from 9/8/17

/Users/jim/anaconda3/bin/python /Users/jim/xxx/bugdemo.py
Logged In
got camera
got properties
Battery Level: 66
Logged Out

Process finished with exit code 0

with debugger, using Arlo commit b43f191 from 12/8/17

/Users/jim/anaconda3/bin/python "/Applications/Development/PyCharm CE.app/Contents/helpers/pydev/pydevd.py" --multiproc --qt-support=auto --client 127.0.0.1 --port 58784 --file /Users/jim/xxx/bugdemo.py
pydev debugger: process 83482 is connecting

Connected to pydev debugger (build 173.4127.16)
Logged In
got camera
got properties
Battery Level: 66
Logged Out

Process finished with exit code 0

without debugger, using Arlo commit b43f191 from 12/8/17

/Users/jim/anaconda3/bin/python /Users/jim/xxx/bugdemo.py
Logged In
got camera
<program hangs>

underlying problem

at Arlo.py line 273 in Arlo.Subscribe

while not self.event_streams[basestation_id].connected:
    time.sleep(1) 

condition is never satisfied.

Does this issue reproduce with the latest release?

yes

[jimletts]

I think I see what is happening.

During the refactor process in Arlo.Subscribe, the original lines self.event_streams[basestation_id] = EventStream(QueueEvents, args=(self, event_stream,)) self.event_streams[basestation_id].Start() were combined into self.event_streams[basestation_id] = EventStream(QueueEvents, args=(self, event_stream,)).Start() The call to Start() happens before the EventStream object is put into event_streams[basestation_id]. This means when QueueEvents is trying to process the ‘connect’ message, there might be no entry for the basestation in event_streams yet, so the message would be ignored.

Race indeed!

Hope that helps.

From: jeffreydwalter [e-mail] Reply: jeffreydwalter/arlo [e-mail] Date: January 2, 2018 at 11:45:07 PM To: jeffreydwalter/arlo [e-mail] Cc: jletts [e-mail], Mention [e-mail] Subject:  Re: [jeffreydwalter/arlo] EventStream does not connect during subscribe unless debugging (#36)

@jletts I think I worked around the issue with this commit 2b65e21

Seems like after my refactor which moved the SSEClient object creation into the EventStream object there’s a race condition there. I will continue to investigate to see if I can come up with a more proper fix.

In the meantime, this change should get you going. Please let me know what your experience is.

Thanks!

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[jeffreydwalter]

Since Arlo Go has 3G and no basestation, it effectively is it’s own basestation. That’s why you only get a device back. Arlo has made kind of a mess with their device type stuff imo.

As for the race condition, You were right! Great catch and thank you for your insight!

I fixed the bug here: https://github.com/jeffreydwalter/arlo/commit/1b68464bec8fbcd593f07bb49f7cfb05281e9c51.

Let me know if you come across any more issues.

Thanks again!