[_sonic_yang_ext.py]: Using python mixin to extend sonic_yang class i…

[praveen-li]

…nto 2 files and resolving Other LGTM issues.

Changes:
1.) Moved al functions of _sonic_yang_ext.py file in sonic_yang_ext_mixin class.
2.) Use this class in sonic_yang to extend funtionality.
3.) Solve Other LGTM issues from
https://lgtm.com/projects/g/Azure/sonic-buildimage/rev/pr-0f82616403c02577e1155347eb5b693a51c76a9e

Note: Code shows big diff due to TAB, otherwise I am just moving all functions inside a class which does not have init.

Note: Python mixin are different from parent class since it can access all variables

of the class which is using it.

Signed-off-by: Praveen Chaudhary pchaudhary@linkedin.com

- What I did
Using Python Mixine to extend the capability of sonic Yang class.

This is done to avoid below error. This was a warning in PY2 but in PY3, it is treated as high level error. So to convert the package into a PY3 in future, we need to resolve this problem sooner or later.

import * only allowed at module level

due to below line:

import all function from extension file
-    """
-    from _sonic_yang_ext import *

Other minor LGTM issues.

- How I did it

PY mixin is a way, which looks similar to inheritance, but the class which seems like a parent class can access all the variable of child class. So PY mixin in actually extend the functionality of another class. Also it is the recommended way to write a single class into multiple files.

- How to verify it
Mixin testing:
UnInstall previous package and install new package:

admin@lnos-x1-a-fab01:~/test_pc_load_yang$ sudo pip uninstall sonic_yang_mgmt
DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. A future version of pip will drop support for Python 2.7. More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
Found existing installation: sonic-yang-mgmt 1.0
Uninstalling sonic-yang-mgmt-1.0:
  Would remove:
    /usr/local/lib/python2.7/dist-packages/_sonic_yang_ext.py
    /usr/local/lib/python2.7/dist-packages/sonic_yang.py
    /usr/local/lib/python2.7/dist-packages/sonic_yang_mgmt-1.0.dist-info/*
    /usr/local/lib/python2.7/dist-packages/tests/*
Proceed (y/n)? y
  Successfully uninstalled sonic-yang-mgmt-1.0
admin@lnos-x1-a-fab01:~/test_pc_load_yang$ ls
new_port_config.json  _sonic_yang_ext.py_orig  sonic_yang_mgmt-1.0-py2-none-any.whl
admin@lnos-x1-a-fab01:~/test_pc_load_yang$ sudo pip install sonic_yang_mgmt-1.0-py2-none-any.whl
DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. A future version of pip will drop support for Python 2.7. More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
Processing ./sonic_yang_mgmt-1.0-py2-none-any.whl
Installing collected packages: sonic-yang-mgmt
Successfully installed sonic-yang-mgmt-1.0

Check that files are updated and has new code:

admin@lnos-x1-a-fab01:~/test_pc_load_yang$ head -10 /usr/local/lib/python2.7/dist-packages/sonic_yang.py
import yang as ly
import syslog

from json import dump
from glob import glob
from _sonic_yang_ext import sonic_yang_ext_mixin

"""
Yang schema and data tree python APIs based on libyang python
Here, sonic_yang_ext_mixin extends funtionality of sonic_yang,

Running Breakout

Running Breakout Mode : 2x50G 
Target Breakout Mode : 4x25G

Ports to be deleted : 
 {
    "Ethernet6": "50000", 
    "Ethernet4": "50000"
}
Ports to be added : 
 {
    "Ethernet6": "25000", 
    "Ethernet7": "25000", 
    "Ethernet4": "25000", 
    "Ethernet5": "25000"
}

After running Logic to limit the impact

Final list of ports to be deleted : 
 {
    "Ethernet6": "50000", 
    "Ethernet4": "50000"
} 
Final list of ports to be added :  
 {
    "Ethernet6": "25000", 
    "Ethernet7": "25000", 
    "Ethernet7": "25000", 
    "Ethernet4": "25000", 
    "Ethernet5": "25000"
}


Loaded below Yang Models
['sonic-acl', 'sonic-extension', 'sonic-head', 'sonic-interface', 'sonic-loopback-interface', 'sonic-port', 
'sonic-portchannel', 'sonic-vlan']
Reading data from Redis configDb

Start Port Deletion
Find dependecies for port Ethernet6
Find dependecies for port Ethernet4
Deleting Port: Ethernet6
Deleting Port: Ethernet4
Data Validation successful
Generate Final Config to write in DB

Start Port Addition
Data Validation successful
Generate Final Config to write in DB
Writing in Config DB
Verify Port Deletion from Asic DB, Wait...
sudo redis-cli -n 1 hgetall "ASIC_STATE:SAI_OBJECT_TYPE_PORT:oid:0x1000000000815"
sudo redis-cli -n 1 hgetall "ASIC_STATE:SAI_OBJECT_TYPE_PORT:oid:0x10000000007ec"
Writing in Config DB
Breakout process got successfully completed.

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)

[zhenggen-xu]

@praveen-li Can you resolve the conflicts?