| """SHA256 helpers for canonical-indices cache invalidation + result-record |
| provenance. Computing the digest of every upstream parquet a loader reads, |
| embedded into ``meta.attrs["data_sha256"]``, makes silent dataset drift |
| detectable: if a panel parquet mutates, the canonical-indices cache key |
| changes and any downstream ``RunRecord`` carries a different hash. |
| """ |
|
|
| from __future__ import annotations |
|
|
| import hashlib |
| from pathlib import Path |
|
|
|
|
| _BUF_SIZE = 1 << 20 |
|
|
|
|
| def sha256_file(path: str | Path) -> str: |
| """Return the hex SHA-256 of ``path`` (full file).""" |
| p = Path(path) |
| if not p.exists(): |
| raise FileNotFoundError(f"sha256_file: {p} does not exist") |
| h = hashlib.sha256() |
| with p.open("rb") as fh: |
| while chunk := fh.read(_BUF_SIZE): |
| h.update(chunk) |
| return h.hexdigest() |
|
|
|
|
| def sha256_dataset(paths: list[str | Path]) -> dict[str, str]: |
| """Return ``{path_str: sha256}`` for every existing path in ``paths``.""" |
| return {str(Path(p)): sha256_file(p) for p in paths} |
|
|
|
|
| def sha256_combined(paths: list[str | Path]) -> str: |
| """Return a single hex digest combining every file in ``paths``. |
| |
| Used as a cache-key suffix for canonical-indices: if ANY upstream |
| parquet mutates, the suffix changes and the cache regenerates. |
| """ |
| h = hashlib.sha256() |
| for p in sorted(str(Path(x)) for x in paths): |
| sub = sha256_file(p).encode() |
| h.update(p.encode() + b":" + sub + b"\n") |
| return h.hexdigest()[:16] |
|
|
