# Refactoring History—MediaManager Core

This document records the refactorings applied during development.

## Refactoring #1: Connection Pool Implementation

**Date**: 2025-11-13 
**Commits**: ```22476abb27d95e88ae0439d97ef97467b6a4f985```

### Problem Identified
- Database connections were created multiple times
- No centralized control
- Possible resource leaks

### Technique Applied
- **Pattern**: Singleton Pattern
- **Refactoring**: Extract Class + Introduce Singleton

### Solution
Created `DatabaseManager` class that:
- Maintains single instance (Singleton)
- Manages connection pool
- Provides centralized `getConnection()` method

### Result
- ✅ Single reusable connection
- ✅ Code centralized in one class
- ✅ Thread-safe
- ✅ Easier to test

### Extracted Component
`DatabaseManager` - available in `mediamanager-components`

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## Refactoring #2: Thread Pool for IPC

**Date**: 2025-11-14  
**Commits**: ```f1071dca03da33f7355a6927497509b5aedaa4a2```

### Problem Identified
- New thread created for each IPC client
- Doesn't scale well
- Thread creation overhead

### Technique Applied
- **Pattern**: Thread Pool Pattern
- **Refactoring**: Replace Thread Creation with Thread Pool

### Solution
Implemented `ExecutorService` with:
- Fixed thread pool
- Thread reuse
- Ordered shutdown

### Result
- ✅ Better performance
- ✅ Controlled resource usage
- ✅ Scalability

### Extracted Component
`IPCServer` - available in `mediamanager-components`

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## Refactoring #3: Graceful Shutdown

**Date**: 2025-11-13  
**Commits**: ```65e14930076db71a312feae373d6c5daee3c4d29```,```b7ff9d1e16c85bf986a770676827bee390f0d53c``` 

### Problem Identified
- Resources weren't released on exit
- Database connections remained open
- Thread pool didn't terminate correctly

### Technique Applied
- **Pattern**: Shutdown Hook Pattern
- **Refactoring**: Introduce Shutdown Protocol

### Solution
Implemented shutdown hooks that:
- Close database connections
- Terminate thread pools
- Release sockets
- In specific order with timeouts

### Result
- ✅ Ordered cleanup
- ✅ No resource leaks
- ✅ Shutdown logging
- ✅ Timeout to prevent hanging

### Extracted Component
Logic incorporated in `DatabaseManager` and `IPCServer`

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## Applied Principles

- **DRY** (Don't Repeat Yourself): Elimination of duplicated code
- **SOLID**: Especially Single Responsibility Principle
- **Design Patterns**: Singleton, Thread Pool, Shutdown Hook
- **Clean Code**: Clear names, small methods, well-defined responsibilities