- Add singleflight.Group to FilerServer to deduplicate concurrent cache operations
- Wrap CacheRemoteObjectToLocalCluster with singleflight to ensure only one
caching operation runs per object when multiple clients request the same file
- Add early-return check for already-cached objects
- S3 API calls filer gRPC with timeout and graceful fallback on error
- Clear negative bucket cache when bucket is created via weed shell
- Add integration tests for remote cache with singleflight deduplication
This benefits all clients (S3, HTTP, Hadoop) accessing remote-mounted objects
by preventing redundant cache operations and improving concurrent access performance.
Fixes: https://github.com/seaweedfs/seaweedfs/discussions/7599