56 lines
1.7 KiB
Python
56 lines
1.7 KiB
Python
 
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"""Content-addressed blob store (SPEC §4 "Blob store", §6.4).
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Layout: ``${BLOB_ROOT}/{user_id}/{sha256[:2]}/{sha256}`` (filesystem default).
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Content-addressed, so identical payloads dedupe. Postgres holds metadata only;
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deleting a user removes their blob subtree.
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"""
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from __future__ import annotations
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import hashlib
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import uuid
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from pathlib import Path
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from app.config import get_settings
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def _root() -> Path:
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return Path(get_settings().blob_root)
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def sha256_hex(data: bytes) -> str:
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"""Return the hex sha256 digest of ``data``."""
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return hashlib.sha256(data).hexdigest()
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def blob_path(user_id: uuid.UUID, sha: str) -> Path:
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"""Return the on-disk path for a user's blob (does not create it)."""
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return _root() / str(user_id) / sha[:2] / sha
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def store(user_id: uuid.UUID, data: bytes) -> str:
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"""Store ``data`` content-addressed; return its sha256. Idempotent (dedupes)."""
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sha = sha256_hex(data)
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path = blob_path(user_id, sha)
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if not path.exists():
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path.parent.mkdir(parents=True, exist_ok=True)
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tmp = path.with_suffix(".tmp")
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tmp.write_bytes(data)
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tmp.replace(path) # atomic within the same directory
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return sha
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def load(user_id: uuid.UUID, sha: str) -> bytes:
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"""Load a blob by sha256. Raises FileNotFoundError if absent."""
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return blob_path(user_id, sha).read_bytes()
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def exists(user_id: uuid.UUID, sha: str) -> bool:
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"""Return True if the blob is present."""
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return blob_path(user_id, sha).exists()
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def remove(user_id: uuid.UUID, sha: str) -> None:
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"""Delete a blob if present (used by account/user deletion). Idempotent."""
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blob_path(user_id, sha).unlink(missing_ok=True)
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