This commit addresses race conditions in multi-step database operations by:
1. Wrap write operations in BEGIN IMMEDIATE ... COMMIT transactions:
- import_run_repo: create_pending, mark_completed, mark_failed
- geo_cache_repo: all upsert_*_and_commit functions
- geo_cache_repo: bulk_upsert_entries_and_neg_entries_and_commit
2. Handle concurrent write collisions gracefully:
- import_run_repo.create_pending can now raise IntegrityError
- blocklist_import_workflow catches IntegrityError and retries lookup
- Logs 'blocklist_import_lost_race' event when another request wins the race
3. Add comprehensive documentation:
- Backend-Development.md § 6.3 Database Transactions
- Explains when to use BEGIN IMMEDIATE
- Shows transaction pattern with try-except-rollback
- Documents race condition error handling pattern
The solution leverages SQLite's UNIQUE constraint for data integrity while
handling the concurrent case gracefully in application logic. This is more
efficient than using BEGIN EXCLUSIVE which would serialize all writers.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Lukas
f9e283541b