[FSSDK-11158] update: add remove method in LRU Cache for CMAB service

[FarhanAnjum-opti]

Summary

Added remove method in LRU cache class

Test plan

Added remove method in LRU cache class

Issues

FSSDK-11158

[Copilot]

Pull Request Overview

This PR adds a remove method to the LRUCache class and includes corresponding tests to ensure it works under various conditions.

• Implement remove in lib/optimizely/odp/lru_cache.rb
• Add specs covering removal of existing keys, non-existent keys, zero-sized caches, re-adding keys, and thread safety in spec/odp/lru_cache_spec.rb

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
lib/optimizely/odp/lru_cache.rb	Added remove method to delete cache entries
spec/odp/lru_cache_spec.rb	New tests for remove behavior under multiple scenarios

[Copilot]

The remove method deletes the entry from the map but does not unlink the corresponding node from the internal doubly linked list, which can lead to stale nodes and incorrect eviction behavior. Consider retrieving the node before deletion and performing proper list unlinking (updating prev and next pointers) within the synchronized block.

Suggested change

	@map.delete(key)
	element = @map.delete(key)
	return nil unless element
	# Unlink the node from the doubly linked list
	if element.prev
	element.prev.next = element.next
	end
	if element.next
	element.next.prev = element.prev
	end

[Copilot]

[nitpick] The test inspects the private @map instance variable directly. It’s more maintainable to expose a public method (e.g., size or count) on LRUCache for checking the number of entries, rather than relying on internal state.

Suggested change

	expect(cache.instance_variable_get('@map').size).to eq(max_size / 2)
	expect(cache.size).to eq(max_size / 2)