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Design and Architecture

Leo Galambos edited this page 2025-07-08 21:27:22 +02:00

Table of Contents

• Design and Architecture
• Motivation
• Why Enum Singleton
• Multi-Context Extension
• Why Weak References for Listeners
• Thread Safety
• Trade-offs

Design and Architecture

Motivation

• Provide an application-wide, strongly typed key-value store
• Avoid tight coupling of modules
• Allow subscribing to value changes without risking memory leaks
• Support multiple independent named contexts for better modularity and isolation

Why Enum Singleton

• Simple
• Thread-safe by Java specification
• Cannot be duplicated through serialization

Multi-Context Extension

• Ctx manages multiple named contexts identified by strings
• Each named context is an independent key-value store with its own listeners
• Enables modular, isolated state management within the same application
• Backwards compatible: default context operations still available via Ctx.INSTANCE

Why Weak References for Listeners

• Listeners should not prevent garbage collection
• Weak references automatically clean up when listener objects are unreachable

Thread Safety

• Uses ConcurrentHashMap for concurrent access
• Listeners stored in CopyOnWriteArrayList for safe iteration

Trade-offs

• Slightly higher cost for weak-reference listener lookups
• Enum cannot be extended (intentional for safe singleton)
• Multi-context adds minimal complexity but greatly improves flexibility

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