Split prefixtree recalculation indicator (fixes #610)

[leopoul]

Description of PR

What component(s) does this PR affect?

• Back-End (Database, Detection/Configuration/etc. Microservices)
• Front-End (Flask, API, UI, etc)
• Monitor (RIPE RIS, BGPStream RV/RIS/CAIDA, etc.)
• Docs
• Build System

Does the PR require changes on other components? If yes, please mark the components:

• Back-End (Database, Detection/Configuration/etc. Microservices)
• Front-End (Flask, API, UI, etc)
• Monitor (RIPE RIS, BGPStream RV/RIS/CAIDA, etc.)
• Docs
• Build System

Related Issue

Resolves #610

Solution

The issue hits whenever there is a config change while Artemis is running. It does not occur if one shuts down all containers and starts again.
It looks as if prefixtree remains stale for either v4 or v6 after changes. With this in mind I did a deep dig into prefixtree module. Here is what I found:

• Upon initialization prefix_tree_recalculate is set to True https://github.com/FORTH-ICS-INSPIRE/artemis/blob/master/backend-services/prefixtree/core/prefixtree.py#L437
• Upon config changes prefix_tree_recalculate is set again to True and the first prefix that triggers this method: https://github.com/FORTH-ICS-INSPIRE/artemis/blob/master/backend-services/prefixtree/core/prefixtree.py#L659 causes a new recalculation: https://github.com/FORTH-ICS-INSPIRE/artemis/blob/master/backend-services/prefixtree/core/prefixtree.py#L668. Since the recalculation sets the prefix_tree_recalculate to False, subsequent calls to the function will not trigger recalculation. So far so good. The problem is that the first prefix that "locks" the recalculation defines which pytricia tree will be recalculated, eg. if it is a v4 then only v4 will be recalculated, if v6 only v6 respectively. What this means in practice is that using the example in the issue I had created Changes in configuration have non-deterministic effect #610 , once I correct the config, only the v4 or only the v6 tree is recalculated leading to errors.
• To solve the issue I split prefix_tree_recalculate into 2: prefix_tree_recalculate_v4 and prefix_tree_recalculate_v6 and replaced every occurrence of prefix_tree_recalculate with those 2. Upon deployment in my dev env and testing any change in the config had immediate effect on both v4 and v6 since prefixes reaching https://github.com/FORTH-ICS-INSPIRE/artemis/blob/master/backend-services/prefixtree/core/prefixtree.py#L659 will trigger recalculation for both trees and essentially the "lock" https://github.com/FORTH-ICS-INSPIRE/artemis/blob/master/backend-services/prefixtree/core/prefixtree.py#L673 will take place per ip_version.

Type

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Docs update
• None of the above

Checklist:

• I have read the contributing guide and my code conforms to the guidelines.
• This change requires a change in the documentation.
• I have updated the documentation accordingly.

[gitpod-io]

[vkotronis]

Excellent catch and fix, thanks @leopoul ! Can be merged.