"""
.. image::
../_static/mongodb.png
`GridFS <https://docs.mongodb.com/manual/core/gridfs/>`_ is a specification for storing large files
(>16 MB) in MongoDB. See :py:mod:`~requests_cache.backends.mongodb` for more general info on MongoDB.
API Reference
^^^^^^^^^^^^^
.. automodsumm:: requests_cache.backends.gridfs
:classes-only:
:nosignatures:
"""
from logging import getLogger
from threading import RLock
from gridfs import GridFS
from gridfs.errors import CorruptGridFile, FileExists
from pymongo import MongoClient
from .._utils import get_valid_kwargs
from .base import BaseCache, BaseStorage
from .mongodb import MongoDict
logger = getLogger(__name__)
[docs]class GridFSCache(BaseCache):
"""GridFS cache backend.
Example:
>>> session = CachedSession('http_cache', backend='gridfs')
Args:
db_name: Database name
connection: :py:class:`pymongo.MongoClient` object to reuse instead of creating a new one
kwargs: Additional keyword arguments for :py:class:`pymongo.MongoClient`
"""
def __init__(self, db_name: str, **kwargs):
super().__init__(**kwargs)
self.responses = GridFSPickleDict(db_name, **kwargs)
self.redirects = MongoDict(
db_name, collection_name='redirects', connection=self.responses.connection, **kwargs
)
[docs] def remove_expired_responses(self, *args, **kwargs):
with self.responses._lock:
return super().remove_expired_responses(*args, **kwargs)
[docs]class GridFSPickleDict(BaseStorage):
"""A dictionary-like interface for a GridFS database
Args:
db_name: Database name
collection_name: Ignored; GridFS internally uses collections 'fs.files' and 'fs.chunks'
connection: :py:class:`pymongo.MongoClient` object to reuse instead of creating a new one
kwargs: Additional keyword arguments for :py:class:`pymongo.MongoClient`
"""
def __init__(self, db_name, collection_name=None, connection=None, **kwargs):
super().__init__(**kwargs)
connection_kwargs = get_valid_kwargs(MongoClient, kwargs)
self.connection = connection or MongoClient(**connection_kwargs)
self.db = self.connection[db_name]
self.fs = GridFS(self.db)
self._lock = RLock()
def __getitem__(self, key):
try:
with self._lock:
result = self.fs.find_one({'_id': key})
if result is None:
raise KeyError
return self.serializer.loads(result.read())
except CorruptGridFile as e:
logger.warning(e, exc_info=True)
raise KeyError
def __setitem__(self, key, item):
value = self.serializer.dumps(item)
encoding = None if isinstance(value, bytes) else 'utf-8'
with self._lock:
try:
self.fs.delete(key)
self.fs.put(value, encoding=encoding, **{'_id': key})
# This can happen because GridFS is not thread-safe for concurrent writes
except FileExists as e:
logger.warning(e, exc_info=True)
def __delitem__(self, key):
with self._lock:
res = self.fs.find_one({'_id': key})
if res is None:
raise KeyError
self.fs.delete(res._id)
def __len__(self):
return self.db['fs.files'].estimated_document_count()
def __iter__(self):
for d in self.fs.find():
yield d._id
[docs] def clear(self):
self.db['fs.files'].drop()
self.db['fs.chunks'].drop()