Cached Generation

generator/engraving/cache.py

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+from __future__ import annotations
+
+import hashlib
+import importlib.metadata
+import json
+from pathlib import Path
+import shutil
+import sys
+import tempfile
+
+from PIL import features
+
+def renderer_fingerprint(fonts, style) -> str:
+  root = Path(__file__).resolve().parents[1]
+  versions = {name: importlib.metadata.version(name) for name in ('Pillow', 'fonttools', 'aggdraw')}
+  versions.update({name: features.version(name) for name in features.get_supported()})
+  digest = hashlib.sha256(json.dumps([fonts.fingerprint(style), sys.version, versions], sort_keys=True).encode())
+  for path in sorted([*root.joinpath('engraving').glob('*.py'), root / 'model.py', root / 'harmony.py', root / 'requirements.txt']):
+    digest.update(path.relative_to(root).as_posix().encode())
+    digest.update(path.read_bytes())
+  return digest.hexdigest()
+
+def score_fingerprint(document: dict, renderer: str) -> str:
+  music = {key: value for key, value in document.items() if key != 'playback'}
+  return hashlib.sha256(json.dumps([renderer, music], sort_keys=True, ensure_ascii=False).encode()).hexdigest()
+
+def restore_pages(entry: Path, destination: Path) -> list[dict] | None:
+  from generator.engraving import check_page
+  try:
+    if entry.is_symlink():
+      return None
+    manifest = entry / 'pages.json'
+    if manifest.is_symlink():
+      return None
+    pages = json.loads(manifest.read_text(encoding='utf-8'))
+    if not isinstance(pages, list) or not 0 < len(pages) <= 10000:
+      return None
+    destination.mkdir(parents=True, exist_ok=True)
+    for index, page in enumerate(pages, 1):
+      if not isinstance(page, dict) or set(page) != {'path', 'sha256'} or page['path'] != f'{index:04}.png':
+        return None
+      path = entry / page['path']
+      if path.is_symlink():
+        return None
+      target = destination / page['path']
+      shutil.copyfile(path, target)
+      if hashlib.sha256(target.read_bytes()).hexdigest() != page['sha256']:
+        return None
+      check_page(target)
+    return pages
+  except (OSError, ValueError, TypeError):
+    return None
+
+def store_pages(entry: Path, destination: Path, pages: list[dict]) -> None:
+  entry.parent.mkdir(parents=True, exist_ok=True)
+  if entry.is_symlink() or entry.is_file():
+    entry.unlink(missing_ok=True)
+  entry.mkdir(exist_ok=True)
+  with tempfile.TemporaryDirectory(prefix='.engraving-', dir=entry.parent) as temporary:
+    staged = Path(temporary)
+    for page in pages:
+      shutil.copyfile(destination / page['path'], staged / page['path'])
+    (staged / 'pages.json').write_text(json.dumps(pages), encoding='utf-8')
+    # Identical keys have identical pages; publish complete files, then the manifest.
+    for name in [page['path'] for page in pages] + ['pages.json']:
+      target = entry / name
+      if target.is_dir() and not target.is_symlink():
+        shutil.rmtree(target, ignore_errors=True)
+      (staged / name).replace(target)