add a persistent cache of URL lookups, and fix up the in-memory one to work
This commit is contained in:
Matthew Hodgson
parent
d1b154a10f
commit
7426c86eb8
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@ -251,8 +251,8 @@ class SimpleHttpClient(object):
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url (str): The URL to GET
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output_stream (file): File to write the response body to.
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Returns:
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A (int,dict) tuple of the file length and a dict of the response
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headers.
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A (int,dict,string,int) tuple of the file length, dict of the response
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headers, absolute URI of the response and HTTP response code.
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"""
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response = yield self.request(
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@ -287,7 +287,7 @@ class SimpleHttpClient(object):
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logger.exception("Failed to download body")
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raise
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defer.returnValue((length, headers, response.request.absoluteURI))
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defer.returnValue((length, headers, response.request.absoluteURI, response.code))
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# XXX: FIXME: This is horribly copy-pasted from matrixfederationclient.
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@ -37,6 +37,8 @@ class PreviewUrlResource(BaseMediaResource):
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def __init__(self, hs, filepaths):
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BaseMediaResource.__init__(self, hs, filepaths)
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self.client = SpiderHttpClient(hs)
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# simple memory cache mapping urls to OG metadata
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self.cache = ExpiringCache(
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cache_name = "url_previews",
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clock = self.clock,
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@ -56,17 +58,41 @@ class PreviewUrlResource(BaseMediaResource):
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# XXX: if get_user_by_req fails, what should we do in an async render?
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requester = yield self.auth.get_user_by_req(request)
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url = request.args.get("url")[0]
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if self.cache:
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og = self.cache.get(url)
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respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
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return
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ts = request.args.get("ts")[0] if "ts" in request.args else self.clock.time_msec()
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# TODO: keep track of whether there's an ongoing request for this preview
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# and block and return their details if there is one.
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# first check the memory cache - good to handle all the clients on this
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# HS thundering away to preview the same URL at the same time.
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try:
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og = self.cache[url]
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respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
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return
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except:
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pass
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# then check the URL cache in the DB (which will also provide us with
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# historical previews, if we have any)
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cache_result = yield self.store.get_url_cache(url, ts)
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if (
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cache_result and
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cache_result["download_ts"] + cache_result["expires"] > ts and
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cache_result["response_code"] / 100 == 2
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):
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respond_with_json_bytes(
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request, 200, cache_result["og"].encode('utf-8'),
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send_cors=True
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)
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return
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media_info = yield self._download_url(url, requester.user)
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# FIXME: we should probably update our cache now anyway, so that
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# even if the OG calculation raises, we don't keep hammering on the
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# remote server. For now, leave it uncached to aid debugging OG
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# calculation problems
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logger.debug("got media_info of '%s'" % media_info)
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if self._is_media(media_info['media_type']):
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@ -105,10 +131,21 @@ class PreviewUrlResource(BaseMediaResource):
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logger.warn("Failed to find any OG data in %s", url)
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og = {}
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if self.cache:
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self.cache[url] = og
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logger.debug("Calculated OG for %s as %s" % (url, og));
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logger.warn(og);
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# store OG in ephemeral in-memory cache
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self.cache[url] = og
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# store OG in history-aware DB cache
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yield self.store.store_url_cache(
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url,
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media_info["response_code"],
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media_info["etag"],
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media_info["expires"],
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json.dumps(og),
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media_info["filesystem_id"],
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media_info["created_ts"],
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)
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respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
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except:
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@ -187,6 +224,9 @@ class PreviewUrlResource(BaseMediaResource):
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og['og:image'] = self._rebase_url(images[0].attrib['src'], media_info['uri'])
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# pre-cache the image for posterity
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# FIXME: it might be cleaner to use the same flow as the main /preview_url request itself
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# and benefit from the same caching etc. But for now we just rely on the caching
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# of the master request to speed things up.
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if 'og:image' in og and og['og:image']:
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image_info = yield self._download_url(og['og:image'], requester.user)
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@ -226,7 +266,6 @@ class PreviewUrlResource(BaseMediaResource):
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text = text.strip()[:500]
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og['og:description'] = text if text else None
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# TODO: persist a cache mapping { url, etag } -> { og, mxc of url (if we bother keeping it around), age }
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# TODO: delete the url downloads to stop diskfilling, as we only ever cared about its OG
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defer.returnValue(og);
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@ -256,7 +295,7 @@ class PreviewUrlResource(BaseMediaResource):
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try:
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with open(fname, "wb") as f:
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logger.debug("Trying to get url '%s'" % url)
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length, headers, uri = yield self.client.get_file(
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length, headers, uri, code = yield self.client.get_file(
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url, output_stream=f, max_size=self.max_spider_size,
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)
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# FIXME: pass through 404s and other error messages nicely
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@ -311,6 +350,11 @@ class PreviewUrlResource(BaseMediaResource):
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"filesystem_id": file_id,
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"filename": fname,
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"uri": uri,
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"response_code": code,
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# FIXME: we should calculate a proper expiration based on the
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# Cache-Control and Expire headers. But for now, assume 1 hour.
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"expires": 60 * 60 * 1000,
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"etag": headers["ETag"] if "ETag" in headers else None,
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})
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def _is_media(self, content_type):
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@ -25,7 +25,7 @@ class MediaRepositoryStore(SQLBaseStore):
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def get_local_media(self, media_id):
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"""Get the metadata for a local piece of media
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Returns:
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None if the meia_id doesn't exist.
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None if the media_id doesn't exist.
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"""
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return self._simple_select_one(
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"local_media_repository",
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@ -50,6 +50,58 @@ class MediaRepositoryStore(SQLBaseStore):
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desc="store_local_media",
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)
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def get_url_cache(self, url, ts):
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"""Get the media_id and ts for a cached URL as of the given timestamp
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Returns:
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None if the URL isn't cached.
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"""
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def get_url_cache_txn(txn):
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# get the most recently cached result (relative to the given ts)
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sql = (
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"SELECT response_code, etag, expires, og, media_id, max(download_ts)"
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" FROM local_media_repository_url_cache"
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" WHERE url = ? AND download_ts <= ?"
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)
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txn.execute(sql, (url, ts))
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row = txn.fetchone()
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if not row[3]:
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# ...or if we've requested a timestamp older than the oldest
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# copy in the cache, return the oldest copy (if any)
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sql = (
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"SELECT response_code, etag, expires, og, media_id, min(download_ts)"
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" FROM local_media_repository_url_cache"
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" WHERE url = ? AND download_ts > ?"
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)
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txn.execute(sql, (url, ts))
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row = txn.fetchone()
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if not row[3]:
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return None
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return dict(zip((
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'response_code', 'etag', 'expires', 'og', 'media_id', 'download_ts'
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), row))
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return self.runInteraction(
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"get_url_cache", get_url_cache_txn
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)
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def store_url_cache(self, url, response_code, etag, expires, og, media_id, download_ts):
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return self._simple_insert(
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"local_media_repository_url_cache",
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{
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"url": url,
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"response_code": response_code,
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"etag": etag,
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"expires": expires,
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"og": og,
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"media_id": media_id,
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"download_ts": download_ts,
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},
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desc="store_url_cache",
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)
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def get_local_media_thumbnails(self, media_id):
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return self._simple_select_list(
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"local_media_repository_thumbnails",
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@ -0,0 +1,27 @@
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/* Copyright 2016 OpenMarket Ltd
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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CREATE TABLE local_media_repository_url_cache(
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url TEXT, -- the URL being cached
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response_code INTEGER, -- the HTTP response code of this download attempt
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etag TEXT, -- the etag header of this response
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expires INTEGER, -- the number of ms this response was valid for
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og TEXT, -- cache of the OG metadata of this URL as JSON
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media_id TEXT, -- the media_id, if any, of the URL's content in the repo
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download_ts BIGINT -- the timestamp of this download attempt
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);
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CREATE INDEX local_media_repository_url_cache_by_url_download_ts
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ON local_media_repository_url_cache(url, download_ts);
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