Merge pull request #2697 from matrix-org/rav/fix_urlcache_index_error

Fix error on sqlite 3.7

synapse/rest/media/v1/preview_url_resource.py

@@ -352,11 +352,16 @@ class PreviewUrlResource(Resource):
     def _expire_url_cache_data(self):
         """Clean up expired url cache content, media and thumbnails.
         """
-
         # TODO: Delete from backup media store
 
         now = self.clock.time_msec()
 
+        logger.info("Running url preview cache expiry")
+
+        if not (yield self.store.has_completed_background_updates()):
+            logger.info("Still running DB updates; skipping expiry")
+            return
+
         # First we delete expired url cache entries
         media_ids = yield self.store.get_expired_url_cache(now)
 
@@ -430,8 +435,7 @@ class PreviewUrlResource(Resource):
 
         yield self.store.delete_url_cache_media(removed_media)
 
-        if removed_media:
-            logger.info("Deleted %d media from url cache", len(removed_media))
+        logger.info("Deleted %d media from url cache", len(removed_media))
 
 
 def decode_and_calc_og(body, media_uri, request_encoding=None):

synapse/storage/_base.py

@@ -607,20 +607,18 @@ class SQLBaseStore(object):
 
     @staticmethod
     def _simple_select_onecol_txn(txn, table, keyvalues, retcol):
-        if keyvalues:
-            where = "WHERE %s" % " AND ".join("%s = ?" % k for k in keyvalues.iterkeys())
-        else:
-            where = ""
-
         sql = (
-            "SELECT %(retcol)s FROM %(table)s %(where)s"
+            "SELECT %(retcol)s FROM %(table)s"
         ) % {
             "retcol": retcol,
             "table": table,
-            "where": where,
         }
 
-        txn.execute(sql, keyvalues.values())
+        if keyvalues:
+            sql += " WHERE %s" % " AND ".join("%s = ?" % k for k in keyvalues.iterkeys())
+            txn.execute(sql, keyvalues.values())
+        else:
+            txn.execute(sql)
 
         return [r[0] for r in txn]
 
@@ -631,7 +629,7 @@ class SQLBaseStore(object):
 
         Args:
             table (str): table name
-            keyvalues (dict): column names and values to select the rows with
+            keyvalues (dict|None): column names and values to select the rows with
             retcol (str): column whos value we wish to retrieve.
 
         Returns:

synapse/storage/background_updates.py

@@ -85,6 +85,7 @@ class BackgroundUpdateStore(SQLBaseStore):
         self._background_update_performance = {}
         self._background_update_queue = []
         self._background_update_handlers = {}
+        self._all_done = False
 
     @defer.inlineCallbacks
     def start_doing_background_updates(self):
@@ -106,8 +107,40 @@ class BackgroundUpdateStore(SQLBaseStore):
                         "No more background updates to do."
                         " Unscheduling background update task."
                     )
+                    self._all_done = True
                     defer.returnValue(None)
 
+    @defer.inlineCallbacks
+    def has_completed_background_updates(self):
+        """Check if all the background updates have completed
+
+        Returns:
+            Deferred[bool]: True if all background updates have completed
+        """
+        # if we've previously determined that there is nothing left to do, that
+        # is easy
+        if self._all_done:
+            defer.returnValue(True)
+
+        # obviously, if we have things in our queue, we're not done.
+        if self._background_update_queue:
+            defer.returnValue(False)
+
+        # otherwise, check if there are updates to be run. This is important,
+        # as we may be running on a worker which doesn't perform the bg updates
+        # itself, but still wants to wait for them to happen.
+        updates = yield self._simple_select_onecol(
+            "background_updates",
+            keyvalues=None,
+            retcol="1",
+            desc="check_background_updates",
+        )
+        if not updates:
+            self._all_done = True
+            defer.returnValue(True)
+
+        defer.returnValue(False)
+
     @defer.inlineCallbacks
     def do_next_background_update(self, desired_duration_ms):
         """Does some amount of work on the next queued background update
@@ -269,7 +302,7 @@ class BackgroundUpdateStore(SQLBaseStore):
             # Sqlite doesn't support concurrent creation of indexes.
             #
             # We don't use partial indices on SQLite as it wasn't introduced
-            # until 3.8, and wheezy has 3.7
+            # until 3.8, and wheezy and CentOS 7 have 3.7
             #
             # We assume that sqlite doesn't give us invalid indices; however
             # we may still end up with the index existing but the

synapse/storage/media_repository.py

@@ -12,13 +12,23 @@
 # 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 ._base import SQLBaseStore
+from synapse.storage.background_updates import BackgroundUpdateStore
 
 
-class MediaRepositoryStore(SQLBaseStore):
+class MediaRepositoryStore(BackgroundUpdateStore):
     """Persistence for attachments and avatars"""
 
+    def __init__(self, db_conn, hs):
+        super(MediaRepositoryStore, self).__init__(db_conn, hs)
+
+        self.register_background_index_update(
+            update_name='local_media_repository_url_idx',
+            index_name='local_media_repository_url_idx',
+            table='local_media_repository',
+            columns=['created_ts'],
+            where_clause='url_cache IS NOT NULL',
+        )
+
     def get_default_thumbnails(self, top_level_type, sub_type):
         return []
 

synapse/storage/schema/delta/44/expire_url_cache.sql

@@ -13,7 +13,10 @@
  * limitations under the License.
  */
 
-CREATE INDEX local_media_repository_url_idx ON local_media_repository(created_ts) WHERE url_cache IS NOT NULL;
+-- this didn't work on SQLite 3.7 (because of lack of partial indexes), so was
+-- removed and replaced with 46/local_media_repository_url_idx.sql.
+--
+-- CREATE INDEX local_media_repository_url_idx ON local_media_repository(created_ts) WHERE url_cache IS NOT NULL;
 
 -- we need to change `expires` to `expires_ts` so that we can index on it. SQLite doesn't support
 -- indices on expressions until 3.9.

synapse/storage/schema/delta/46/local_media_repository_url_idx.sql

@@ -0,0 +1,24 @@
+/* Copyright 2017 New Vector 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.
+ */
+
+-- register a background update which will recreate the
+-- local_media_repository_url_idx index.
+--
+-- We do this as a bg update not because it is a particularly onerous
+-- operation, but because we'd like it to be a partial index if possible, and
+-- the background_index_update code will understand whether we are on
+-- postgres or sqlite and behave accordingly.
+INSERT INTO background_updates (update_name, progress_json) VALUES
+    ('local_media_repository_url_idx', '{}');