add a persistent cache of URL lookups, and fix up the in-memory one to work

This commit is contained in:
Matthew Hodgson 2016-04-03 00:31:57 +01:00
parent d1b154a10f
commit 7426c86eb8
4 changed files with 137 additions and 14 deletions

View File

@ -251,8 +251,8 @@ class SimpleHttpClient(object):
url (str): The URL to GET url (str): The URL to GET
output_stream (file): File to write the response body to. output_stream (file): File to write the response body to.
Returns: Returns:
A (int,dict) tuple of the file length and a dict of the response A (int,dict,string,int) tuple of the file length, dict of the response
headers. headers, absolute URI of the response and HTTP response code.
""" """
response = yield self.request( response = yield self.request(
@ -287,7 +287,7 @@ class SimpleHttpClient(object):
logger.exception("Failed to download body") logger.exception("Failed to download body")
raise raise
defer.returnValue((length, headers, response.request.absoluteURI)) defer.returnValue((length, headers, response.request.absoluteURI, response.code))
# XXX: FIXME: This is horribly copy-pasted from matrixfederationclient. # XXX: FIXME: This is horribly copy-pasted from matrixfederationclient.

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@ -37,6 +37,8 @@ class PreviewUrlResource(BaseMediaResource):
def __init__(self, hs, filepaths): def __init__(self, hs, filepaths):
BaseMediaResource.__init__(self, hs, filepaths) BaseMediaResource.__init__(self, hs, filepaths)
self.client = SpiderHttpClient(hs) self.client = SpiderHttpClient(hs)
# simple memory cache mapping urls to OG metadata
self.cache = ExpiringCache( self.cache = ExpiringCache(
cache_name = "url_previews", cache_name = "url_previews",
clock = self.clock, clock = self.clock,
@ -56,17 +58,41 @@ class PreviewUrlResource(BaseMediaResource):
# XXX: if get_user_by_req fails, what should we do in an async render? # XXX: if get_user_by_req fails, what should we do in an async render?
requester = yield self.auth.get_user_by_req(request) requester = yield self.auth.get_user_by_req(request)
url = request.args.get("url")[0] url = request.args.get("url")[0]
ts = request.args.get("ts")[0] if "ts" in request.args else self.clock.time_msec()
if self.cache:
og = self.cache.get(url)
respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
return
# TODO: keep track of whether there's an ongoing request for this preview # TODO: keep track of whether there's an ongoing request for this preview
# and block and return their details if there is one. # and block and return their details if there is one.
# first check the memory cache - good to handle all the clients on this
# HS thundering away to preview the same URL at the same time.
try:
og = self.cache[url]
respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
return
except:
pass
# then check the URL cache in the DB (which will also provide us with
# historical previews, if we have any)
cache_result = yield self.store.get_url_cache(url, ts)
if (
cache_result and
cache_result["download_ts"] + cache_result["expires"] > ts and
cache_result["response_code"] / 100 == 2
):
respond_with_json_bytes(
request, 200, cache_result["og"].encode('utf-8'),
send_cors=True
)
return
media_info = yield self._download_url(url, requester.user) media_info = yield self._download_url(url, requester.user)
# FIXME: we should probably update our cache now anyway, so that
# even if the OG calculation raises, we don't keep hammering on the
# remote server. For now, leave it uncached to aid debugging OG
# calculation problems
logger.debug("got media_info of '%s'" % media_info) logger.debug("got media_info of '%s'" % media_info)
if self._is_media(media_info['media_type']): if self._is_media(media_info['media_type']):
@ -105,10 +131,21 @@ class PreviewUrlResource(BaseMediaResource):
logger.warn("Failed to find any OG data in %s", url) logger.warn("Failed to find any OG data in %s", url)
og = {} og = {}
if self.cache: logger.debug("Calculated OG for %s as %s" % (url, og));
# store OG in ephemeral in-memory cache
self.cache[url] = og self.cache[url] = og
logger.warn(og); # store OG in history-aware DB cache
yield self.store.store_url_cache(
url,
media_info["response_code"],
media_info["etag"],
media_info["expires"],
json.dumps(og),
media_info["filesystem_id"],
media_info["created_ts"],
)
respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True) respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
except: except:
@ -187,6 +224,9 @@ class PreviewUrlResource(BaseMediaResource):
og['og:image'] = self._rebase_url(images[0].attrib['src'], media_info['uri']) og['og:image'] = self._rebase_url(images[0].attrib['src'], media_info['uri'])
# pre-cache the image for posterity # pre-cache the image for posterity
# FIXME: it might be cleaner to use the same flow as the main /preview_url request itself
# and benefit from the same caching etc. But for now we just rely on the caching
# of the master request to speed things up.
if 'og:image' in og and og['og:image']: if 'og:image' in og and og['og:image']:
image_info = yield self._download_url(og['og:image'], requester.user) image_info = yield self._download_url(og['og:image'], requester.user)
@ -226,7 +266,6 @@ class PreviewUrlResource(BaseMediaResource):
text = text.strip()[:500] text = text.strip()[:500]
og['og:description'] = text if text else None og['og:description'] = text if text else None
# TODO: persist a cache mapping { url, etag } -> { og, mxc of url (if we bother keeping it around), age }
# TODO: delete the url downloads to stop diskfilling, as we only ever cared about its OG # TODO: delete the url downloads to stop diskfilling, as we only ever cared about its OG
defer.returnValue(og); defer.returnValue(og);
@ -256,7 +295,7 @@ class PreviewUrlResource(BaseMediaResource):
try: try:
with open(fname, "wb") as f: with open(fname, "wb") as f:
logger.debug("Trying to get url '%s'" % url) logger.debug("Trying to get url '%s'" % url)
length, headers, uri = yield self.client.get_file( length, headers, uri, code = yield self.client.get_file(
url, output_stream=f, max_size=self.max_spider_size, url, output_stream=f, max_size=self.max_spider_size,
) )
# FIXME: pass through 404s and other error messages nicely # FIXME: pass through 404s and other error messages nicely
@ -311,6 +350,11 @@ class PreviewUrlResource(BaseMediaResource):
"filesystem_id": file_id, "filesystem_id": file_id,
"filename": fname, "filename": fname,
"uri": uri, "uri": uri,
"response_code": code,
# FIXME: we should calculate a proper expiration based on the
# Cache-Control and Expire headers. But for now, assume 1 hour.
"expires": 60 * 60 * 1000,
"etag": headers["ETag"] if "ETag" in headers else None,
}) })
def _is_media(self, content_type): def _is_media(self, content_type):

View File

@ -25,7 +25,7 @@ class MediaRepositoryStore(SQLBaseStore):
def get_local_media(self, media_id): def get_local_media(self, media_id):
"""Get the metadata for a local piece of media """Get the metadata for a local piece of media
Returns: Returns:
None if the meia_id doesn't exist. None if the media_id doesn't exist.
""" """
return self._simple_select_one( return self._simple_select_one(
"local_media_repository", "local_media_repository",
@ -50,6 +50,58 @@ class MediaRepositoryStore(SQLBaseStore):
desc="store_local_media", desc="store_local_media",
) )
def get_url_cache(self, url, ts):
"""Get the media_id and ts for a cached URL as of the given timestamp
Returns:
None if the URL isn't cached.
"""
def get_url_cache_txn(txn):
# get the most recently cached result (relative to the given ts)
sql = (
"SELECT response_code, etag, expires, og, media_id, max(download_ts)"
" FROM local_media_repository_url_cache"
" WHERE url = ? AND download_ts <= ?"
)
txn.execute(sql, (url, ts))
row = txn.fetchone()
if not row[3]:
# ...or if we've requested a timestamp older than the oldest
# copy in the cache, return the oldest copy (if any)
sql = (
"SELECT response_code, etag, expires, og, media_id, min(download_ts)"
" FROM local_media_repository_url_cache"
" WHERE url = ? AND download_ts > ?"
)
txn.execute(sql, (url, ts))
row = txn.fetchone()
if not row[3]:
return None
return dict(zip((
'response_code', 'etag', 'expires', 'og', 'media_id', 'download_ts'
), row))
return self.runInteraction(
"get_url_cache", get_url_cache_txn
)
def store_url_cache(self, url, response_code, etag, expires, og, media_id, download_ts):
return self._simple_insert(
"local_media_repository_url_cache",
{
"url": url,
"response_code": response_code,
"etag": etag,
"expires": expires,
"og": og,
"media_id": media_id,
"download_ts": download_ts,
},
desc="store_url_cache",
)
def get_local_media_thumbnails(self, media_id): def get_local_media_thumbnails(self, media_id):
return self._simple_select_list( return self._simple_select_list(
"local_media_repository_thumbnails", "local_media_repository_thumbnails",

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@ -0,0 +1,27 @@
/* Copyright 2016 OpenMarket 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.
*/
CREATE TABLE local_media_repository_url_cache(
url TEXT, -- the URL being cached
response_code INTEGER, -- the HTTP response code of this download attempt
etag TEXT, -- the etag header of this response
expires INTEGER, -- the number of ms this response was valid for
og TEXT, -- cache of the OG metadata of this URL as JSON
media_id TEXT, -- the media_id, if any, of the URL's content in the repo
download_ts BIGINT -- the timestamp of this download attempt
);
CREATE INDEX local_media_repository_url_cache_by_url_download_ts
ON local_media_repository_url_cache(url, download_ts);