Change the way pagination works to support out of order events.

1 files changed, 157 insertions, 29 deletions

diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index c03c983e14..87fc978813 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -16,8 +16,9 @@
 from twisted.internet import defer
 
 from ._base import SQLBaseStore
-
+from synapse.api.errors import SynapseError
 from synapse.api.constants import Membership
+from synapse.util.logutils import log_function
 
 import json
 import logging
@@ -29,9 +30,96 @@ logger = logging.getLogger(__name__)
 MAX_STREAM_SIZE = 1000
 
 
+_STREAM_TOKEN = "stream"
+_TOPOLOGICAL_TOKEN = "topological"
+
+
+def _parse_stream_token(string):
+    try:
+        if string[0] != 's':
+            raise
+        return int(string[1:])
+    except:
+        logger.debug("Not stream token: %s", string)
+        raise SynapseError(400, "Invalid token")
+
+
+def _parse_topological_token(string):
+    try:
+        if string[0] != 't':
+            raise
+        parts = string[1:].split('-', 1)
+        return (int(parts[0]), int(parts[1]))
+    except:
+        logger.debug("Not topological token: %s", string)
+        raise SynapseError(400, "Invalid token")
+
+
+def is_stream_token(string):
+    try:
+        _parse_stream_token(string)
+        return True
+    except:
+        return False
+
+
+def is_topological_token(string):
+    try:
+        _parse_topological_token(string)
+        return True
+    except:
+        return False
+
+
+def _get_token_bound(token, comparison):
+    try:
+        s = _parse_stream_token(token)
+        return "%s %s %d" % ("stream_ordering", comparison, s)
+    except:
+        pass
+
+    try:
+        top, stream = _parse_topological_token(token)
+        return "%s %s %d AND %s %s %d" % (
+            "topological_ordering", comparison, top,
+            "stream_ordering", comparison, stream,
+        )
+    except:
+        pass
+
+    raise SynapseError(400, "Invalid token")
+
+
 class StreamStore(SQLBaseStore):
+    @log_function
+    def get_room_events(self, user_id, from_key, to_key, room_id, limit=0,
+                        direction='f', with_feedback=False):
+        is_events = (
+            direction == 'f'
+            and is_stream_token(from_key)
+            and to_key and is_stream_token(to_key)
+        )
+
+        if is_events:
+            return self.get_room_events_stream(
+                user_id=user_id,
+                from_key=from_key,
+                to_key=to_key,
+                room_id=room_id,
+                limit=limit,
+                with_feedback=with_feedback,
+            )
+        else:
+            return self.paginate_room_events(
+                from_key=from_key,
+                to_key=to_key,
+                room_id=room_id,
+                limit=limit,
+                with_feedback=with_feedback,
+            )
 
     @defer.inlineCallbacks
+    @log_function
     def get_room_events_stream(self, user_id, from_key, to_key, room_id,
                                limit=0, with_feedback=False):
         # TODO (erikj): Handle compressed feedback
@@ -54,8 +142,8 @@ class StreamStore(SQLBaseStore):
             limit = MAX_STREAM_SIZE
 
         # From and to keys should be integers from ordering.
-        from_key = int(from_key)
-        to_key = int(to_key)
+        from_id = _parse_stream_token(from_key)
+        to_id = _parse_stream_token(to_key)
 
         if from_key == to_key:
             defer.returnValue(([], to_key))
@@ -65,42 +153,79 @@ class StreamStore(SQLBaseStore):
             "SELECT * FROM events as e WHERE "
             "((room_id IN (%(current)s)) OR "
             "(event_id IN (%(invites)s))) "
+            "AND e.stream_ordering > ? AND e.stream_ordering < ? "
+            "ORDER BY stream_ordering ASC LIMIT %(limit)d "
         ) % {
             "current": current_room_membership_sql,
             "invites": invites_sql,
+            "limit": limit
         }
 
-        # Constraints and ordering depend on direction.
-        if from_key < to_key:
-            sql += (
-                "AND e.token_ordering > ? AND e.token_ordering < ? "
-                "ORDER BY token_ordering ASC LIMIT %(limit)d "
-            ) % {"limit": limit}
-        else:
-            sql += (
-                "AND e.token_ordering < ? "
-                "AND e.token_ordering > ? "
-                "ORDER BY e.token_ordering DESC LIMIT %(limit)d "
-            ) % {"limit": int(limit)}
-
         rows = yield self._execute_and_decode(
             sql,
-            user_id, user_id, Membership.INVITE, from_key, to_key
+            user_id, user_id, Membership.INVITE, from_id, to_id
         )
 
         ret = [self._parse_event_from_row(r) for r in rows]
 
         if rows:
-            if from_key < to_key:
-                key = max([r["token_ordering"] for r in rows])
-            else:
-                key = min([r["token_ordering"] for r in rows])
+            key = "s%d" % max([r["stream_ordering"] for r in rows])
         else:
+            # Assume we didn't get anything because there was nothing to get.
             key = to_key
 
         defer.returnValue((ret, key))
 
     @defer.inlineCallbacks
+    @log_function
+    def paginate_room_events(self, room_id, from_key, to_key=None,
+                             direction='b', limit=-1,
+                             with_feedback=False):
+        # TODO (erikj): Handle compressed feedback
+
+        from_comp = '<' if direction =='b' else '>'
+        to_comp = '>' if direction =='b' else '<'
+        order = "DESC" if direction == 'b' else "ASC"
+
+        args = [room_id]
+
+        bounds = _get_token_bound(from_key, from_comp)
+        if to_key:
+            bounds = "%s AND %s" % (bounds, _get_token_bound(to_key, to_comp))
+
+        if int(limit) > 0:
+            args.append(int(limit))
+            limit_str = " LIMIT ?"
+        else:
+            limit_str = ""
+
+        sql = (
+            "SELECT * FROM events "
+            "WHERE room_id = ? AND %(bounds)s "
+            "ORDER BY topological_ordering %(order)s, stream_ordering %(order)s %(limit)s "
+        ) % {"bounds": bounds, "order": order, "limit": limit_str}
+
+        rows = yield self._execute_and_decode(
+            sql,
+            *args
+        )
+
+        if rows:
+            topo = rows[-1]["topological_ordering"]
+            toke = rows[-1]["stream_ordering"]
+            next_token = "t%s-%s" % (topo, toke)
+        else:
+            # TODO (erikj): We should work out what to do here instead.
+            next_token = to_key if to_key else from_key
+
+        defer.returnValue(
+            (
+                [self._parse_event_from_row(r) for r in rows],
+                next_token
+            )
+        )
+
+    @defer.inlineCallbacks
     def get_recent_events_for_room(self, room_id, limit, with_feedback=False):
         # TODO (erikj): Handle compressed feedback
 
@@ -108,8 +233,8 @@ class StreamStore(SQLBaseStore):
 
         sql = (
             "SELECT * FROM events "
-            "WHERE room_id = ? AND token_ordering <= ? "
-            "ORDER BY topological_ordering, token_ordering DESC LIMIT ? "
+            "WHERE room_id = ? AND stream_ordering <= ? "
+            "ORDER BY topological_ordering, stream_ordering DESC LIMIT ? "
         )
 
         rows = yield self._execute_and_decode(
@@ -121,12 +246,12 @@ class StreamStore(SQLBaseStore):
 
         if rows:
             topo = rows[0]["topological_ordering"]
-            toke = rows[0]["token_ordering"]
+            toke = rows[0]["stream_ordering"]
             start_token = "p%s-%s" % (topo, toke)
 
             token = (start_token, end_token)
         else:
-            token = ("START", end_token)
+            token = (end_token, end_token)
 
         defer.returnValue(
             (
@@ -138,11 +263,14 @@ class StreamStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_room_events_max_id(self):
         res = yield self._execute_and_decode(
-            "SELECT MAX(token_ordering) as m FROM events"
+            "SELECT MAX(stream_ordering) as m FROM events"
         )
 
-        if not res:
-            defer.returnValue(0)
+        logger.debug("get_room_events_max_id: %s", res)
+
+        if not res or not res[0] or not res[0]["m"]:
+            defer.returnValue("s1")
             return
 
-        defer.returnValue(res[0]["m"])
+        key = res[0]["m"] + 1
+        defer.returnValue("s%d" % (key,))