PIconnect no longer automatically disconnects from the server

[Hugovdberg]

Bug report

Description

With commit fe138d9 the automatic disconnect from the server at exiting the context manager was disabled. This means connections to the database remain open until the python session ends, or the SDK's grace. This issue serves as a request for comments on how to fix this more efficiently.

To Reproduce

Running this snippet:

import PIconnect as PI

with PI.PIAFDatabase() as db:
    print(db.server.IsConnected)
print(db.server.IsConnected)

prints:

True
True

Expected behavior

The expected result would be

True
False

Possible solutions

The problem is that PIconnect.PIAF.PIAFDatabase.__exit__ no longer calls self.server.Disconnect. This was done intentionally to fix unexpected disconnects, but the current fix might not be the most efficient solution.

System

• OS: Windows
• Python version: Python 3.7
• PIconnect version: Hugovdberg/PIconnect@develop

Additional context

Add any other context about the problem here.

[Hugovdberg]

The current solution was chosen based on this post: https://pisquare.osisoft.com/thread/12398#comment-61955

[vadtam]

I guess I have a bug related to this issue. From time to time I get this System.InvalidOperationException when I access the database in a loop. And the system does not recover from it. How to fix it?

        with PI.PIAFDatabase(server="XXX", database="Production") as database:
            while(True):
                try:
                    element = database.descendant(path_to_element)
                    break
                except:
                    '''
                    System.InvalidOperationException:
                    Database 'Production' has been disconnected.
                    This is caused by using an object from a database
                    after calling PISystem.Disconnect.
                    '''
                    time.sleep(60.0)
                    continue
                 #
                 # do other stuff

[Hugovdberg]

If you do the loop within the with block, the python package should not try to disconnect. I think this fix is currently only in the development version and not yet in the Pypi version. You can work around this for now by changing your code to the following:

database = PI.PIAFDatabase(server="XXX", database="Production")

while(True):
    try:
        element = database.descendant(path_to_element)
        break
    except:
        '''
        System.InvalidOperationException:
        Database 'Production' has been disconnected.
        This is caused by using an object from a database
        after calling PISystem.Disconnect.
        '''
        time.sleep(60.0)
        continue
        #
        # do other stuff

The SDK should handle connecting and disconnecting automatically.