Module HotReload 

Configuration Hot-Reload System

This module provides live configuration reloading capabilities with comprehensive error handling, validation, atomic updates, and rollback support for the Air daemon.

Features

• File System Monitoring: Real-time detection of configuration file changes
• Signal Handling: SIGHUP support for manual configuration reload triggers
• Atomic Swaps: Thread-safe configuration updates without service interruption
• Automatic Rollback: Revert to previous configuration on validation failure
• Change Tracking: Detailed audit trail of all configuration changes
• Validation Pipeline: Multi-stage validation with custom validators
• Retry Logic: Automatic retry with exponential backoff on transient failures
• Notification System: Callback system for configuration change events
• Graceful Degradation: System continues operating even if hot-reload fails

Integration with Configuration System

The hot-reload system works in tandem with the main configuration module:

• Uses same validation logic from Configuration module
• Shares configuration schema and structure
• Provides runtime updates without requiring service restart
• Scales horizontally across multiple Air instances

Connection to Mountain and Wind Services

Configuration changes detected by hot-reload are propagated to:

• Mountain: User settings synchronized in real-time
• Wind: All background services notified of configuration updates
• VSCode: Frontend receives configuration change events

Signal Handling

Supports the following Unix signals for manual control:

• SIGHUP: Force configuration reload from disk
• SIGUSR1: Hot-reload status information
• SIGUSR2: Disable/enable hot-reload monitoring

Notification Flow

Config file changed → File watcher detected → Load & Validate
       ↓                                               ↓
  Atomic swap ←- Validation passed ←-- Migration applied
       ↓
  Notify subscribers → Wind services update → Mountain sync
       ↓
  Change history logged → Rollback state updated

Error Recovery

The system implements a robust error recovery strategy:

• Validation failures: Automatic rollback to previous valid configuration
• Parse errors: Keep existing configuration, log error, continue monitoring
• File system errors: Temporary pause in monitoring, retry with backoff
• Concurrent modifications: Use atomic file operations, retry on conflict

Performance Considerations

• Debouncing: Multiple rapid changes trigger single reload after cooldown
• Async operations: Non-blocking file I/O and validation
• Lock-free reads: Configuration reads don’t block other operations
• Efficient diffing: Only process changed configuration sections

TODO: Add distributed configuration synchronization across multiple Air instances TODO: Implement configuration change broadcasting to connected Wind services TODO: Add configuration version conflict resolution (multi-master scenarios)

Structs

AuthConfigValidator

Validator for authentication configuration

ConfigChange

Individual configuration change

ConfigChangeEvent

Configuration change event for subscribers

ConfigChangeRecord

Configuration change record

ConfigHotReload

Configuration hot-reload manager with file watching and validation

DownloadConfigValidator

Validator for downloader configuration

GrpcConfigValidator

Validator for GRPC configuration

IndexingConfigValidator

Validator for indexing configuration

LoggingConfigValidator

Validator for logging configuration

PerformanceConfigValidator

Validator for performance configuration

UpdateConfigValidator

Validator for update configuration

Enums

ReloadRequest

Reload request from external sources

Traits

ConfigValidator

Configuration validation trait