https://github.com/acoyfellow/cache-sync
Scalable caching pattern using Cloudflare Durable Objects for high-traffic applications
https://github.com/acoyfellow/cache-sync
cloudflare cloudflare-durable-objects cloudflare-workers
Last synced: about 1 month ago
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Scalable caching pattern using Cloudflare Durable Objects for high-traffic applications
- Host: GitHub
- URL: https://github.com/acoyfellow/cache-sync
- Owner: acoyfellow
- Created: 2025-02-21T14:40:39.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2025-02-23T02:06:03.000Z (over 1 year ago)
- Last Synced: 2025-06-05T21:06:49.996Z (12 months ago)
- Topics: cloudflare, cloudflare-durable-objects, cloudflare-workers
- Language: Svelte
- Homepage: http://cache-sync.coey.dev
- Size: 215 KB
- Stars: 24
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Durable Cache Sync Pattern
A production-ready pattern for high-traffic applications needing low-latency reads with eventual consistency. Perfect for:
- Session management
- User profile caching
- Real-time collaboration features
- High-velocity write buffers
## Why This Pattern?
| Traditional Database Challenges | With Cache Sync Pattern |
|------------------------------------------|----------------------------------------|
| 📉 90%+ of queries hit primary DB | 📈 90%+ cache hit rate |
| 💸 Expensive direct DB writes | 🐢 Batched async writes save costs |
| 🌍 Global latency inconsistencies | 🚀 Edge caching <5ms responses |
| 🔄 Complex cache invalidation | 🔄 Auto-sync with writeback queue |
## Architecture
**Key Components**:
- **Durable Object Cache**: Per-key cache with in-memory access
- **Write Buffer**: Batched updates every 60s
- **Auto Refresh**: Stale-while-revalidate pattern
- **Pass-through Worker**: Simple edge routing
## Napkin Math Cost Comparison (1M Requests/Month)
| Resource | Traditional DB | Cache Sync Pattern |
|-------------------|---------------------|---------------------|
| Database Reads | \$500-\$2000 | \$15-\$50 |
| Database Writes | \$300-\$1500 | \$5-\$20 |
| Cache Layer | \$0 | \$10-\$30 |
| **Total** | **\$800-\$3500** | **\$30-\$100** |
## Getting Started
1. **Clone and install**:
```bash
git clone https://github.com/acoyfellow/cache-sync.git
cd cache-sync
bun install
```
2. **Configure environment** (`wrangler.json`):
```json
{
"name": "cache-sync-pattern",
"main": "src/worker.ts",
"compatibility_date": "2024-03-01",
"durable_objects": {
"bindings": [
{
"name": "userprofile",
"class_name": "UserProfileCache"
}
]
},
"vars": {
"MAIN_DB_API": "https://your-db-api.com"
}
}
```
3. **Local development**:
```bash
bun run dev
# Interact with App.svelte at http://localhost:5173
```
4. **Deploy to Cloudflare**:
```bash
bunx wrangler deploy
```
[](https://deploy.workers.cloudflare.com/?url=https://github.com/acoyfellow/cache-sync)
## How It Works
1. **Read Path**:
```plaintext
Client → Worker → Dedicated User DO Instance (Isolated per session)
↳ (Cache Miss) → Create New DO Instance → Return Stub
```
2. **Write Path**:
```plaintext
Client → Dedicated User DO Instance → In-Memory State + Storage
↳ Alarm → Batch Sync to Main DB
```
3. **Client Sync**:
```plaintext
Offline → Local Storage → Auto Retry
```
**Features**:
- Network detection
- Local persistence
- Auto-retry on reconnect
- Accessible status
This implements a robust offline-first pattern where:
- All user interactions remain available offline
- Changes queue locally until connectivity resumes
- UI clearly indicates sync status
- Data automatically reconciles when back online
## Implementation Phases:
1. Shadow Mode: Run cache layer parallel to main API, compare results
2. Read-Only Canary: Route 5% of read traffic through cache
3. Write Queueing: Enable write buffering for canary users
4. Full Cutover: Gradually increase traffic over 1-2 weeks
This maintains security while allowing gradual rollout. The key is keeping the cache layer as a transparent proxy that enforces existing auth rules.
## Future Concerns
- [x] **Data Compression** - Store more data in Durable Object state
- [x] **TTL Expiration** - Automatically expire stale data
- [ ] **Rate Limiting** - Prevent API abuse
- [ ] **Auth Integration** - Add request validation
- [ ] **Metrics Dashboard** - Track cache performance
## License
MIT License - Free for commercial and personal use.