Summary

Implement GlobalLoggerRegistry, the core component of the runtime binding pattern.

Background

The current mutual dependency between thread_system and logger_system causes issues:

• logger_system → thread_system (for async processing)
• thread_system → defines its own logger_interface.h (to avoid circular dependency)

This structure creates maintenance and extensibility problems.

Tasks

1. Implement GlobalLoggerRegistry Class

• Create include/kcenon/common/logging/global_registry.h
• Apply singleton pattern (thread-safe)
• Implement concurrency control with std::shared_mutex
• Manage default logger and named loggers

2. Interface Definition

class GlobalLoggerRegistry final : public interfaces::ILoggerRegistry {
public:
    static GlobalLoggerRegistry& instance();

    void set_default(std::shared_ptr<ILogger> logger) override;
    std::shared_ptr<ILogger> get_default() const override;

    void register_logger(std::string_view name, std::shared_ptr<ILogger> logger) override;
    std::shared_ptr<ILogger> get_logger(std::string_view name) const override;
    void unregister_logger(std::string_view name) override;

    void register_factory(std::string_view name, LoggerFactory factory) override;
};

3. Provide Convenience Functions

• get_registry() - Return Registry instance
• get_logger() - Return default logger
• get_logger(name) - Return named logger

4. NullLogger Default Implementation

• Implement NullLogger to return when no logger is registered
• All methods operate as no-op

Test Requirements

• Single-threaded registration/retrieval tests
• Multi-threaded concurrent access tests
• Factory lazy creation tests
• NullLogger fallback tests

Impact Scope

• All subsystems will use this Registry
• Replaces existing thread_system::logger_registry

Related Milestone

• Phase 1: common_system interface extension
• Priority: Critical
• Blocks: All of Phase 2 and Phase 3