Sprint 1: Implement Background Monitoring Scheduler

[CLoaKY233]

Epic: PingSpider MVP - Distributed Uptime & Latency Monitor

Sprint: 1

Story Points: 8

Description

Create a background task scheduler that periodically checks all registered endpoints and stores metrics in SurrealDB.

Acceptance Criteria

• Create src/monitoring/scheduler.rs with async task scheduler
• Load all active endpoints from database on startup
• Schedule health checks based on each endpoint's check_interval
• Execute checks concurrently (use tokio::spawn for parallelization)
• Store check results in metrics table
• Handle endpoint addition/removal dynamically
• Implement graceful shutdown on SIGTERM/SIGINT
• Add scheduler status endpoint GET /api/scheduler/status

Technical Notes

• Use tokio::time::interval for periodic execution
• Use tokio::select! for shutdown handling
• Limit concurrent checks to prevent resource exhaustion (e.g., max 100 concurrent)
• Use Arc<RwLock<HashMap>> or similar for in-memory endpoint tracking
• Consider using tokio-cron-scheduler for more complex scheduling

Scheduler Logic Flow

1. On startup: Load all endpoints from DB
2. For each endpoint: Spawn a task with its check_interval
3. On interval tick: Execute health check
4. Store result in metrics table
5. Update endpoint status if changed
6. On shutdown: Cancel all tasks gracefully

Dependencies

• tokio with signal feature for graceful shutdown
• Optional: tokio-cron-scheduler crate

Files to Create/Modify

• src/monitoring/scheduler.rs
• src/sys/init.rs (start scheduler on app init)
• src/rts/scheduler.rs (status endpoint handler)

Definition of Done

• Scheduler runs all endpoint checks on schedule
• Metrics correctly stored in SurrealDB
• No memory leaks or resource exhaustion
• Graceful shutdown works
• Load testing completed (100+ endpoints)
• Code reviewed and merged to main