Files
simple-nanoshare/my_modules/filecache/metadata.py
T
daniel156161 3db374b1ab
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feat(files): cache served files and add HTML text viewer
File cache:
- Add my_modules/filecache with metadata, blob, validator and store layers
- Cache convex.get_file via AsyncCache, TTL clamped to the file expiry
- Skip caching for missing, incomplete or already expired records
- Add a process-local, size-bounded LRU for immutable storage blobs
- Build the cache stack from FILE_CACHE_* env vars in build_file_cache
- Attach the cache to the app in my_modules/app/setup.py
- Expose app-bound helpers in filecache/access.py for routes

Serving:
- Send strong ETag, Last-Modified and Cache-Control on served files
- Answer If-None-Match and If-Modified-Since with 304 from metadata only
- Avoid pulling the blob from Convex on a revalidation hit
- Add a short Cloudflare-CDN-Cache-Control edge window for deleted files
- Record cache_status in the wide event on a 304
- Invalidate cached metadata after file update and delete in both routes

Text viewer:
- Add my_modules/textview to render text/plain and text/markdown as HTML
- Linkify http(s) URLs and trim trailing sentence punctuation
- Resolve links pointing at this instance to the referenced file
- Inline image previews, mark missing and expired targets
- Cap resolution at MAX_LOOKUPS backend lookups per document
- Serve the viewer only for real browser navigations, never for curl or CLI
- Keep raw bytes for ?raw=1, downloads and Accept headers without text/html
- Add templates/side/views/webpage/files/text_view.htm with a raw link

Other:
- Add tests for cache layers, serving, text rendering and the route
- Bump multidict to 7.2.1 in uv.lock
- Update the my_helpers submodule pointer
2026-10-25 18:54:46 +01:00

54 lines
1.7 KiB
Python

from __future__ import annotations
from collections.abc import Awaitable, Callable
from .validators import remaining_seconds
class FileMetadataCache:
"""Cache-aside layer for convex.get_file, shared across workers via AsyncCache.
Only complete, non-expired records are cached. Misses and expired markers stay
uncached so a newly uploaded or just-expired file is never masked.
"""
def __init__(self, cache, ttl: int = 60, prefix: str = 'nanoshare:filemeta:'):
self._cache = cache
self._ttl = max(1, int(ttl))
self._prefix = prefix
self.hits = 0
self.misses = 0
def _key(self, file_id: str) -> str:
return f'{self._prefix}{file_id}'
def _effective_ttl(self, file_data: dict) -> int:
"""Never hold a record past the moment it expires."""
remaining = remaining_seconds(file_data.get('expires_at'))
if remaining is None:
return self._ttl
return min(self._ttl, remaining)
def _is_cacheable(self, file_data) -> bool:
if not isinstance(file_data, dict) or not file_data:
return False
if file_data.get('expired'):
return False
return bool(file_data.get('db_image_url'))
async def get(self, file_id: str, loader: Callable[[], Awaitable[dict | None]]) -> dict | None:
cached = await self._cache.get(self._key(file_id))
if isinstance(cached, dict) and cached:
self.hits += 1
return cached
self.misses += 1
file_data = await loader()
if self._is_cacheable(file_data):
ttl = self._effective_ttl(file_data)
if ttl > 0:
await self._cache.set(self._key(file_id), file_data, ttl=ttl)
return file_data
async def invalidate(self, file_id: str) -> None:
await self._cache.delete(self._key(file_id))