137 lines
4.9 KiB
Python
137 lines
4.9 KiB
Python
from __future__ import annotations
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import shutil
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import uuid
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from collections.abc import Iterable
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from contextlib import contextmanager
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from pathlib import Path
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def _remove_path(path: Path) -> None:
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if path.is_symlink() or path.is_file():
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path.unlink()
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elif path.exists():
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shutil.rmtree(path)
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@contextmanager
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def staged_directory(destination: str | Path):
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"""Build a directory beside its destination and replace on success."""
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target = Path(destination)
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target.parent.mkdir(parents=True, exist_ok=True)
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token = uuid.uuid4().hex
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staging = target.with_name(f".{target.name}.{token}.tmp")
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backup = target.with_name(f".{target.name}.{token}.backup")
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staging.mkdir()
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committed = False
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try:
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yield staging
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if target.exists():
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target.replace(backup)
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try:
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staging.replace(target)
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committed = True
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except Exception:
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if backup.exists() and not target.exists():
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backup.replace(target)
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raise
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if backup.exists():
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_remove_path(backup)
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finally:
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if staging.exists():
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_remove_path(staging)
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if not committed and backup.exists() and not target.exists():
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backup.replace(target)
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@contextmanager
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def staged_files(
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destination: str | Path,
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*,
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remove: Iterable[str] = (),
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):
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"""Stage a set of files and merge them into a directory with rollback."""
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target = Path(destination)
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target.parent.mkdir(parents=True, exist_ok=True)
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token = uuid.uuid4().hex
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staging = target.parent / f".{target.name}.{token}.files.tmp"
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backup = target.parent / f".{target.name}.{token}.files.backup"
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staging.mkdir()
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committed: list[Path] = []
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try:
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yield staging
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staged = sorted(path for path in staging.iterdir() if path.is_file())
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staged_names = {path.name for path in staged}
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removed_names = set(remove) - staged_names
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target.mkdir(parents=True, exist_ok=True)
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backup.mkdir()
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try:
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for name in sorted(removed_names):
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destination_path = target / name
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if destination_path.is_file() or destination_path.is_symlink():
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destination_path.replace(backup / name)
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for source in staged:
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destination_path = target / source.name
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if destination_path.exists() or destination_path.is_symlink():
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destination_path.replace(backup / source.name)
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source.replace(destination_path)
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committed.append(destination_path)
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except Exception:
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for destination_path in reversed(committed):
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_remove_path(destination_path)
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for saved in backup.iterdir():
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saved.replace(target / saved.name)
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raise
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_remove_path(backup)
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finally:
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if staging.exists():
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_remove_path(staging)
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if backup.exists():
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for saved in backup.iterdir():
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destination_path = target / saved.name
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if not destination_path.exists():
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saved.replace(destination_path)
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_remove_path(backup)
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def publish_file_sets(file_sets: dict[Path, tuple[Path, Iterable[str]]]) -> None:
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"""Commit several staged file sets together, rolling every set back on error.
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Staging and destination directories must be on the same filesystem. Unlike
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nesting staged_files, failure in a later directory restores earlier ones too.
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"""
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token = uuid.uuid4().hex
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backups: list[tuple[Path, Path]] = []
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committed: list[Path] = []
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try:
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for target, (staging, remove) in file_sets.items():
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target.mkdir(parents=True, exist_ok=True)
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backup = target / f".publish-{token}.backup"
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backup.mkdir()
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backups.append((target, backup))
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staged = sorted(path for path in staging.iterdir() if path.is_file())
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names = {path.name for path in staged} | set(remove)
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for name in sorted(names):
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if Path(name).name != name:
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raise ValueError(f"Invalid output filename: {name}")
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destination = target / name
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if destination.exists() or destination.is_symlink():
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destination.replace(backup / name)
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for source in staged:
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destination = target / source.name
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source.replace(destination)
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committed.append(destination)
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except Exception:
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for destination in reversed(committed):
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_remove_path(destination)
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for target, backup in reversed(backups):
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for saved in backup.iterdir():
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saved.replace(target / saved.name)
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raise
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finally:
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for _, backup in backups:
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if backup.exists() and not any(backup.iterdir()):
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backup.rmdir()
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for _, backup in backups:
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_remove_path(backup)
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