**- Why I did it**
If we ran the CLI commands `sudo config feature autorestart snmp disabled/enabled` or `sudo config feature autorestart swss disabled/enabled`, then SNMP container will be stopped and started. This behavior was not expected since we updated the `auto_restart` field not update `state` field in `FEATURE` table. The reason behind this issue is that either `state` field or `auto_restart` field was updated, the function `update_feature_state(...)` will be invoked which then starts snmp.timer service.
The snmp.timer service will first stop snmp.service and later start snmp.service.
In order to solve this issue, the function `update_feature_state(...)` will be only invoked if `state` field in `FEATURE` table was
updated.
**- How I did it**
When the demon `hostcfgd` was activated, all the values of `state` field in `FEATURE` table of each container will be
cached. Each time the function `feature_state_handler(...)` is invoked, it will determine whether the `state` field of a
container was changed or not. If it was changed, function `update_feature_state(...)` will be invoked and the cached
value will also be updated. Otherwise, nothing will be done.
**- How to verify it**
We can run the CLI commands `sudo config feature autorestart snmp disabled/enabled` or `sudo config feature autorestart swss disabled/enabled` to check whether SNMP container is stopped and started. We also can run the CLI commands `sudo config feature state snmp disabled/enabled` or `sudo config feature state swss disabled/enabled` to check whether the container is stopped and restarted.
Signed-off-by: Yong Zhao <yozhao@microsoft.com>
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