## Context
Adding a new service that provides an abstract caching system for
FlatEntityMaps.
This takes care of cache invalidation and storing local and remote cache
for the map with retrieval after a comparison with map hash between
local and remote (redis).
## Implementation
Remote (redis) keys
- Flat map data:
`engine:workspace:flat-maps:{flatMapKey}:{workspaceId}:flat-map`
- Content hash:
`engine:workspace:flat-maps:{flatMapKey}:{workspaceId}:hash`
**Local Cache Hit**: If local hash matches Redis hash, return local data
**Remote Cache Hit**: If Redis has data with different hash, update
local cache
**Remote Cache Miss**: Recompute from database, store in Remote and
locally
**Invalidation**: Remove from Remote, triggering recomputation on next
access
## Usage
```typescript
@WorkspaceFlatMapCache('view') // redis key
export class WorkspaceFlatViewMapCacheService extends WorkspaceFlatMapCacheService<FlatViewMaps> {
constructor(
@InjectCacheStorage(CacheStorageNamespace.EngineWorkspace)
cacheStorageService: CacheStorageService,
@InjectRepository(ViewEntity)
private readonly viewRepository: Repository<ViewEntity>,
) {
super(cacheStorageService);
}
// only method to implement
public async computeFlatMap(workspaceId: string): Promise<FlatViewMaps> {
const views = await this.viewRepository.find({
where: { workspaceId },
relations: ['viewFields'],
select: { viewFields: { id: true } },
});
return generateFlatViewMaps(views);
}
}
```
```typescript
// 2 public methods, getExistingOrRecomputeFlatMaps to fetch the map and invalidateCache after a mutation
await this.workspaceFlatViewMapCacheService.invalidateCache(
viewData.workspaceId,
);
const flatViewMaps =
await this.workspaceFlatViewMapCacheService.getExistingOrRecomputeFlatMaps(
workspaceId,
);
```
## Multi-Pod Synchronization
- Each pod maintains local cache for performance
- SHA256 hash of flatMap content used for version comparison
- `invalidateCache()` reset Redis data, forcing other pods to refresh
when calling getExistingOrRecomputeFlatMaps
---
<img width="1072" height="325" alt="Screenshot 2025-09-11 at 15 04 48"
src="https://github.com/user-attachments/assets/ed6ce82c-db35-4a1b-8a4e-247b694e2ddf"
/>
<img width="1030" height="328" alt="Screenshot 2025-09-11 at 15 04 40"
src="https://github.com/user-attachments/assets/43a15789-7f27-4104-a9bb-bef19908a5cd"
/>
Next step: Implement a locking mechanism by reusing existing WithLock
decorator
Paul Rastoin