[IGNITE-14800] Add technical ability to differentiate between create and update in configuration

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha2
• Fix Version/s: 3.0.0-alpha3
• Labels: iep-55 ignite-3
• Assignee: Ivan Bessonov
• Reporter: Ivan Bessonov
• Reviewer: Sergey Chugunov
• Created: 31/May/21 10:57
• Updated: 28/Jun/21 11:30
• Resolved: 04/Jun/21 07:16

Description

org.apache.ignite.configuration.internal.DynamicConfiguration#change method (and its variants in other classes) has a substantial disadvantage - it doesn't allow you to read current configuration in lambdas to decide a new value for some other configurations.

Why is this the way it is? For simplicity of implementation, we immediately convert it to InnerNode and only then pass into configuration changer. This means that we will apply the same exact tree on every retry iteration.

This is bad during concurrent resources creation, if you create 2 resources with the same name, then one of changes will be create and the other one is update. There is no way to tell what will happen until it is already happened. Such behavior is not convenient if you create SQL indexes or tables, for example, CREATE should not be silently converted to ALTER.

Other reason why it's bad - it complicates concurrent array fields updates. Makes it nearly impossible.

What should we do to fix it?

• CHANGE interfaces should extend VIEW interfaces. Lambda parameters should be available for read and provide configuration snapshot that's currently being updated;
• changing lambda should be applied on every retry. Only then we could guarantee that provided configuration snapshots are valid;
• consider using the same procedure for arbitrary configuration sources. This will save us some code and will be handy in https://issues.apache.org/jira/browse/IGNITE-14645 implementation.

Issue Links

• links to: GitHub Pull Request #158