[IGNITE-17199] Improve the usability of the abstract configuration interface

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Labels: iep-55 ignite-3
• Epic Link: Configuration
• Assignee: Unassigned
• Reporter: Kirill Tkalenko
• Created: 20/Jun/22 19:42
• Updated: 31/Oct/22 12:35
• Resolved: 21/Jun/22 08:46

Description

Problem
Consider an example of generating configuration interfaces (*Configuration) for an abstract configuration.

Configuration schemas:

@AbstractConfiguration
public class BaseConfigurationSchema {
    @Value
    public int size;
}

@Config
public class VolatileConfigurationSchema extends BaseConfigurationSchema {
    @Value
    public double evictionThreshold;
}

Configuration interfaces:

public interface BaseConfiguration<VIEWT extends BaseView, CHANGET extends BaseChange> extends ConfigurationTree<VIEWT, CHANGET> {
    ConfigurationValue<Integer> size();
}

public interface VolatileConfiguration extends BaseConfiguration<VolatileView, VolatileChange> {
    ConfigurationValue<Integer> size();
}

This implementation allows us to work with the inheritors of the abstract configuration as with a regular configuration (as if VolatileConfigurationSchema did not extend BaseConfigurationSchema), but when working with the abstract configuration itself, it creates inconvenience.

For example, to get a view of the abstract configuration, we will need to write the following code:

BaseConfiguration baseConfig0 = ...;
BaseConfiguration<?, ?> baseConfig1 = ...;
        
BaseView baseView0 = (BasePageMemoryDataRegionView) baseConfig0.value();
BaseView baseView1 = baseConfig1.value();

Which is not convenient and I would like us to be able to work in the same way as with the VolatileConfiguration.

Possible implementations

• Simplest is to leave it as is;
• Creates an additional configuration interface that will be similar to BaseConfiguration, for example BaseConfigurationTree, but it will be extended by BaseConfiguration and all its inheritors like VolatileConfiguration, then there may be confusion about whether to use BaseConfiguration or BaseConfigurationTree in the end, so we need to decide how to create a name for such an interface;
  • BaseConfigurationTree;
  • AbstractBaseConfigurationTree;
  • other.