1835. Decorator Pattern for HTTP Request Logging & Metrics (Part 21)
Singleton PatternObserver Pattern
### Problem #1835: Decorator Pattern for HTTP Request Logging & Metrics (Part 21)
**Domain:** `OOP & Design Patterns` | **Topic Focus:** `Singleton Pattern, Observer Pattern`
Implement an optimized, production-grade solution for **Decorator Pattern for HTTP Request Logging & Metrics (Part 21)**.
### Requirements:
1. Your code must handle boundary inputs, edge cases, and maintain optimal time & space complexity.
2. In production, this logic scales to high-throughput environments.
3. Return the exact computed result.
Example 1:
Input: Sample Input #1835
Output: Output 1
Explanation: Demonstrates correct execution for Singleton Pattern in OOP & Design Patterns.
Constraints:
- Time Complexity: Optimal for standard production loads.
- Space Complexity: O(1) auxiliary or O(N) linear storage.
- Ensure memory safety, clean error propagation, and zero race conditions.