Replace BFS traversal that issued 2 SQL queries per folder (list_files +
list_folders) with 2 total queries using PostgreSQL ltree <@ operator:
1. list_subtree_folders: single GiST-indexed scan for all folders
2. list_files_in_subtree: single GiST-indexed join for all files
Files are grouped by folder_id in a HashMap, then iterated in directory
order (folders pre-sorted by path from SQL).
Changes across 4 architecture layers:
- Domain: FolderRepository::list_subtree_folders (default impl)
- Application ports: FolderUseCase, FileRetrievalUseCase, FileReadPort
- Application services: FolderService, FileRetrievalService passthroughs
- Infrastructure: PG implementations + ZipService rewrite
Query count: O(N) → O(1). Latency for 100-folder tree: ~200 round-trips → 3.
ZipWriter<std::fs::File> performed every write_all() as a blocking
write(2) syscall on the Tokio worker thread, sequestering it for
10-100ms per file (0.8-12s for a 100-file ZIP).
Replace with async_zip::ZipFileWriter backed by a buffered
tokio::fs::File:
- All I/O (headers, deflate chunks, central directory) is fully async
- 256 KB BufWriter minimises syscall count
- Zero Tokio worker blocking during ZIP creation
- Streaming per-chunk writes keep RAM O(1) regardless of archive size
- Removed dead From<zip::result::ZipError> for DomainError impl
- zip crate retained for batch_operations.rs (separate concern)
Solution C - Hybrid temp-file streaming:
- ZipPort trait now returns NamedTempFile instead of Vec<u8>
- ZipService writes to a temp file via ZipWriter<std::fs::File> (O(1) RAM)
- Files are read in 64KB stream chunks via get_file_stream() instead of get_file_content()
- HTTP response streams the temp file via ReaderStream (never loads full ZIP in memory)
- Temp file auto-deleted on drop after response completes
- Removed dead imports (HeaderName, HeaderValue, Cursor, Read)
Standardize code formatting across all 173 Rust source files
using rustfmt. No functional changes - purely cosmetic.
This establishes a consistent code style baseline for the
project going forward.
Dionisio