1 files changed, 61 insertions, 7 deletions
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 0117fdc639..b0923a9cad 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -19,6 +19,7 @@ from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 from synapse.util.caches.dictionary_cache import DictionaryCache
 from synapse.util.caches.descriptors import Cache
 from synapse.util.caches import intern_dict
+from synapse.storage.engines import PostgresEngine
 import synapse.metrics
 
 
@@ -305,13 +306,14 @@ class SQLBaseStore(object):
                     func, *args, **kwargs
                 )
 
-        with PreserveLoggingContext():
-            result = yield self._db_pool.runWithConnection(
-                inner_func, *args, **kwargs
-            )
-
-        for after_callback, after_args in after_callbacks:
-            after_callback(*after_args)
+        try:
+            with PreserveLoggingContext():
+                result = yield self._db_pool.runWithConnection(
+                    inner_func, *args, **kwargs
+                )
+        finally:
+            for after_callback, after_args in after_callbacks:
+                after_callback(*after_args)
         defer.returnValue(result)
 
     @defer.inlineCallbacks
@@ -860,6 +862,58 @@ class SQLBaseStore(object):
 
         return cache, min_val
 
+    def _invalidate_cache_and_stream(self, txn, cache_func, keys):
+        """Invalidates the cache and adds it to the cache stream so slaves
+        will know to invalidate their caches.
+
+        This should only be used to invalidate caches where slaves won't
+        otherwise know from other replication streams that the cache should
+        be invalidated.
+        """
+        txn.call_after(cache_func.invalidate, keys)
+
+        if isinstance(self.database_engine, PostgresEngine):
+            # get_next() returns a context manager which is designed to wrap
+            # the transaction. However, we want to only get an ID when we want
+            # to use it, here, so we need to call __enter__ manually, and have
+            # __exit__ called after the transaction finishes.
+            ctx = self._cache_id_gen.get_next()
+            stream_id = ctx.__enter__()
+            txn.call_after(ctx.__exit__, None, None, None)
+
+            self._simple_insert_txn(
+                txn,
+                table="cache_invalidation_stream",
+                values={
+                    "stream_id": stream_id,
+                    "cache_func": cache_func.__name__,
+                    "keys": list(keys),
+                    "invalidation_ts": self.clock.time_msec(),
+                }
+            )
+
+    def get_all_updated_caches(self, last_id, current_id, limit):
+        def get_all_updated_caches_txn(txn):
+            # We purposefully don't bound by the current token, as we want to
+            # send across cache invalidations as quickly as possible. Cache
+            # invalidations are idempotent, so duplicates are fine.
+            sql = (
+                "SELECT stream_id, cache_func, keys, invalidation_ts"
+                " FROM cache_invalidation_stream"
+                " WHERE stream_id > ? ORDER BY stream_id ASC LIMIT ?"
+            )
+            txn.execute(sql, (last_id, limit,))
+            return txn.fetchall()
+        return self.runInteraction(
+            "get_all_updated_caches", get_all_updated_caches_txn
+        )
+
+    def get_cache_stream_token(self):
+        if self._cache_id_gen:
+            return self._cache_id_gen.get_current_token()
+        else:
+            return 0
+
 
 class _RollbackButIsFineException(Exception):
     """ This exception is used to rollback a transaction without implying