Add MediaStorage class

This commit is contained in:
Erik Johnston 2018-01-08 17:07:30 +00:00
parent 1ee787912b
commit ada470bccb

View file

@ -0,0 +1,198 @@
# -*- coding: utf-8 -*-
# Copyright 2018 New Vecotr Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from twisted.internet import defer, threads
from twisted.protocols.basic import FileSender
from ._base import Responder
from synapse.util.logcontext import make_deferred_yieldable
import contextlib
import os
import logging
import shutil
logger = logging.getLogger(__name__)
class MediaStorage(object):
"""Responsible for storing/fetching files from local sources.
"""
def __init__(self, local_media_directory, filepaths):
self.local_media_directory = local_media_directory
self.filepaths = filepaths
@defer.inlineCallbacks
def store_file(self, source, file_info):
"""Write `source` to the on disk media store, and also any other
configured storage providers
Args:
source: A file like object that should be written
file_info (FileInfo): Info about the file to store
Returns:
Deferred[str]: the file path written to in the primary media store
"""
path = self._file_info_to_path(file_info)
fname = os.path.join(self.local_media_directory, path)
dirname = os.path.dirname(fname)
if not os.path.exists(dirname):
os.makedirs(dirname)
# Write to the main repository
yield make_deferred_yieldable(threads.deferToThread(
_write_file_synchronously, source, fname,
))
defer.returnValue(fname)
@contextlib.contextmanager
def store_into_file(self, file_info):
"""Context manager used to get a file like object to write into, as
described by file_info.
Actually yields a 3-tuple (file, fname, finish_cb), where finish_cb is a
function that returns a Deferred that must be waited on after the file
has been successfully written to.
Args:
file_info (FileInfo): Info about the file to store
Example:
with media_storage.store_into_file(info) as (f, fname, finish_cb):
# .. write into f ...
yield finish_cb()
"""
path = self._file_info_to_path(file_info)
fname = os.path.join(self.local_media_directory, path)
dirname = os.path.dirname(fname)
if not os.path.exists(dirname):
os.makedirs(dirname)
finished_called = [False]
def finish():
# This will be used later when we want to hit out to other storage
# places
finished_called[0] = True
return defer.succeed(None)
try:
with open(fname, "wb") as f:
yield f, fname, finish
except Exception as e:
try:
os.remove(fname)
except Exception:
pass
raise e
if not finished_called:
raise Exception("Fnished callback not called")
@defer.inlineCallbacks
def fetch_media(self, file_info):
"""Attempts to fetch media described by file_info from the local cache
and configured storage providers.
Args:
file_info (FileInfo)
Returns:
Deferred(Responder): Returns a Responder if the file was found,
otherwise None.
"""
path = self._file_info_to_path(file_info)
local_path = os.path.join(self.local_media_directory, path)
if os.path.exists(local_path):
defer.returnValue(FileResponder(open(local_path, "rb")))
defer.returnValue(None)
def _file_info_to_path(self, file_info):
"""Converts file_info into a relative path.
"""
if file_info.url_cache:
return self.filepaths.url_cache_filepath_rel(file_info.file_id)
if file_info.server_name:
if file_info.thumbnail:
return self.filepaths.remote_media_thumbnail_rel(
server_name=file_info.server_name,
file_id=file_info.file_id,
width=file_info.thumbnail_width,
height=file_info.thumbnail_height,
content_type=file_info.thumbnail_type,
method=file_info.thumbnail_method
)
return self.filepaths.remote_media_filepath_rel(
file_info.server_name, file_info.file_id,
)
if file_info.thumbnail:
return self.filepaths.local_media_thumbnail_rel(
media_id=file_info.file_id,
width=file_info.thumbnail_width,
height=file_info.thumbnail_height,
content_type=file_info.thumbnail_type,
method=file_info.thumbnail_method
)
return self.filepaths.local_media_filepath_rel(
file_info.file_id,
)
def _write_file_synchronously(source, fname):
"""Write `source` to the path `fname` synchronously. Should be called
from a thread.
Args:
source: A file like object to be written
fname (str): Path to write to
"""
dirname = os.path.dirname(fname)
if not os.path.exists(dirname):
os.makedirs(dirname)
source.seek(0) # Ensure we read from the start of the file
with open(fname, "wb") as f:
shutil.copyfileobj(source, f)
class FileResponder(Responder):
"""Wraps an open file that can be sent to a request.
Args:
open_file (file): A file like object to be streamed ot the client,
is closed when finished streaming.
"""
def __init__(self, open_file):
self.open_file = open_file
@defer.inlineCallbacks
def write_to_consumer(self, consumer):
with self.open_file:
yield FileSender().beginFileTransfer(self.open_file, consumer)
def cancel(self):
self.open_file.close()