Merge pull request #5186 from matrix-org/erikj/simple_pagination

Add simple relations API

7 files changed, 350 insertions, 0 deletions

diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 8547a63535..30bebd749f 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -116,3 +116,11 @@ class UserTypes(object):
     """
     SUPPORT = "support"
     ALL_USER_TYPES = (SUPPORT,)
+
+
+class RelationTypes(object):
+    """The types of relations known to this server.
+    """
+    ANNOTATION = "m.annotation"
+    REPLACES = "m.replaces"
+    REFERENCES = "m.references"
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 3a24d31d1b..e6110ad9b1 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -44,6 +44,7 @@ from synapse.rest.client.v2_alpha import (
     read_marker,
     receipts,
     register,
+    relations,
     report_event,
     room_keys,
     room_upgrade_rest_servlet,
@@ -115,6 +116,7 @@ class ClientRestResource(JsonResource):
         room_upgrade_rest_servlet.register_servlets(hs, client_resource)
         capabilities.register_servlets(hs, client_resource)
         account_validity.register_servlets(hs, client_resource)
+        relations.register_servlets(hs, client_resource)
 
         # moving to /_synapse/admin
         synapse.rest.admin.register_servlets_for_client_rest_resource(
diff --git a/synapse/rest/client/v2_alpha/relations.py b/synapse/rest/client/v2_alpha/relations.py
new file mode 100644
index 0000000000..c3ac73b8c7
--- /dev/null
+++ b/synapse/rest/client/v2_alpha/relations.py
@@ -0,0 +1,167 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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.
+
+"""This class implements the proposed relation APIs from MSC 1849.
+
+Since the MSC has not been approved all APIs here are unstable and may change at
+any time to reflect changes in the MSC.
+"""
+
+import logging
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes
+from synapse.api.errors import SynapseError
+from synapse.http.servlet import (
+    RestServlet,
+    parse_integer,
+    parse_json_object_from_request,
+    parse_string,
+)
+from synapse.rest.client.transactions import HttpTransactionCache
+
+from ._base import client_v2_patterns
+
+logger = logging.getLogger(__name__)
+
+
+class RelationSendServlet(RestServlet):
+    """Helper API for sending events that have relation data.
+
+    Example API shape to send a 👍 reaction to a room:
+
+        POST /rooms/!foo/send_relation/$bar/m.annotation/m.reaction?key=%F0%9F%91%8D
+        {}
+
+        {
+            "event_id": "$foobar"
+        }
+    """
+
+    PATTERN = (
+        "/rooms/(?P<room_id>[^/]*)/send_relation"
+        "/(?P<parent_id>[^/]*)/(?P<relation_type>[^/]*)/(?P<event_type>[^/]*)"
+    )
+
+    def __init__(self, hs):
+        super(RelationSendServlet, self).__init__()
+        self.auth = hs.get_auth()
+        self.event_creation_handler = hs.get_event_creation_handler()
+        self.txns = HttpTransactionCache(hs)
+
+    def register(self, http_server):
+        http_server.register_paths(
+            "POST",
+            client_v2_patterns(self.PATTERN + "$", releases=()),
+            self.on_PUT_or_POST,
+        )
+        http_server.register_paths(
+            "PUT",
+            client_v2_patterns(self.PATTERN + "/(?P<txn_id>[^/]*)$", releases=()),
+            self.on_PUT,
+        )
+
+    def on_PUT(self, request, *args, **kwargs):
+        return self.txns.fetch_or_execute_request(
+            request, self.on_PUT_or_POST, request, *args, **kwargs
+        )
+
+    @defer.inlineCallbacks
+    def on_PUT_or_POST(
+        self, request, room_id, parent_id, relation_type, event_type, txn_id=None
+    ):
+        requester = yield self.auth.get_user_by_req(request, allow_guest=True)
+
+        if event_type == EventTypes.Member:
+            # Add relations to a membership is meaningless, so we just deny it
+            # at the CS API rather than trying to handle it correctly.
+            raise SynapseError(400, "Cannot send member events with relations")
+
+        content = parse_json_object_from_request(request)
+
+        aggregation_key = parse_string(request, "key", encoding="utf-8")
+
+        content["m.relates_to"] = {
+            "event_id": parent_id,
+            "key": aggregation_key,
+            "rel_type": relation_type,
+        }
+
+        event_dict = {
+            "type": event_type,
+            "content": content,
+            "room_id": room_id,
+            "sender": requester.user.to_string(),
+        }
+
+        event = yield self.event_creation_handler.create_and_send_nonmember_event(
+            requester, event_dict=event_dict, txn_id=txn_id
+        )
+
+        defer.returnValue((200, {"event_id": event.event_id}))
+
+
+class RelationPaginationServlet(RestServlet):
+    """API to paginate relations on an event by topological ordering, optionally
+    filtered by relation type and event type.
+    """
+
+    PATTERNS = client_v2_patterns(
+        "/rooms/(?P<room_id>[^/]*)/relations/(?P<parent_id>[^/]*)"
+        "(/(?P<relation_type>[^/]*)(/(?P<event_type>[^/]*))?)?$",
+        releases=(),
+    )
+
+    def __init__(self, hs):
+        super(RelationPaginationServlet, self).__init__()
+        self.auth = hs.get_auth()
+        self.store = hs.get_datastore()
+        self.clock = hs.get_clock()
+        self._event_serializer = hs.get_event_client_serializer()
+
+    @defer.inlineCallbacks
+    def on_GET(self, request, room_id, parent_id, relation_type=None, event_type=None):
+        requester = yield self.auth.get_user_by_req(request, allow_guest=True)
+
+        yield self.auth.check_in_room_or_world_readable(
+            room_id, requester.user.to_string()
+        )
+
+        limit = parse_integer(request, "limit", default=5)
+
+        result = yield self.store.get_relations_for_event(
+            event_id=parent_id,
+            relation_type=relation_type,
+            event_type=event_type,
+            limit=limit,
+        )
+
+        events = yield self.store.get_events_as_list(
+            [c["event_id"] for c in result.chunk]
+        )
+
+        now = self.clock.time_msec()
+        events = yield self._event_serializer.serialize_events(events, now)
+
+        return_value = result.to_dict()
+        return_value["chunk"] = events
+
+        defer.returnValue((200, return_value))
+
+
+def register_servlets(hs, http_server):
+    RelationSendServlet(hs).register(http_server)
+    RelationPaginationServlet(hs).register(http_server)
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index c432041b4e..7522d3fd57 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -49,6 +49,7 @@ from .pusher import PusherStore
 from .receipts import ReceiptsStore
 from .registration import RegistrationStore
 from .rejections import RejectionsStore
+from .relations import RelationsStore
 from .room import RoomStore
 from .roommember import RoomMemberStore
 from .search import SearchStore
@@ -99,6 +100,7 @@ class DataStore(
     GroupServerStore,
     UserErasureStore,
     MonthlyActiveUsersStore,
+    RelationsStore,
 ):
     def __init__(self, db_conn, hs):
         self.hs = hs
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 7a7f841c6c..6802bf42ce 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -1351,6 +1351,8 @@ class EventsStore(
                 # Insert into the event_search table.
                 self._store_guest_access_txn(txn, event)
 
+            self._handle_event_relations(txn, event)
+
         # Insert into the room_memberships table.
         self._store_room_members_txn(
             txn,
diff --git a/synapse/storage/relations.py b/synapse/storage/relations.py
new file mode 100644
index 0000000000..31ef6679af
--- /dev/null
+++ b/synapse/storage/relations.py
@@ -0,0 +1,142 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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.
+
+import logging
+
+import attr
+
+from synapse.api.constants import RelationTypes
+from synapse.storage._base import SQLBaseStore
+
+logger = logging.getLogger(__name__)
+
+
+@attr.s
+class PaginationChunk(object):
+    """Returned by relation pagination APIs.
+
+    Attributes:
+        chunk (list): The rows returned by pagination
+    """
+
+    chunk = attr.ib()
+
+    def to_dict(self):
+        d = {"chunk": self.chunk}
+
+        return d
+
+
+class RelationsStore(SQLBaseStore):
+    def get_relations_for_event(
+        self, event_id, relation_type=None, event_type=None, limit=5, direction="b"
+    ):
+        """Get a list of relations for an event, ordered by topological ordering.
+
+        Args:
+            event_id (str): Fetch events that relate to this event ID.
+            relation_type (str|None): Only fetch events with this relation
+                type, if given.
+            event_type (str|None): Only fetch events with this event type, if
+                given.
+            limit (int): Only fetch the most recent `limit` events.
+            direction (str): Whether to fetch the most recent first (`"b"`) or
+                the oldest first (`"f"`).
+
+        Returns:
+            Deferred[PaginationChunk]: List of event IDs that match relations
+            requested. The rows are of the form `{"event_id": "..."}`.
+        """
+
+        # TODO: Pagination tokens
+
+        where_clause = ["relates_to_id = ?"]
+        where_args = [event_id]
+
+        if relation_type is not None:
+            where_clause.append("relation_type = ?")
+            where_args.append(relation_type)
+
+        if event_type is not None:
+            where_clause.append("type = ?")
+            where_args.append(event_type)
+
+        order = "ASC"
+        if direction == "b":
+            order = "DESC"
+
+        sql = """
+            SELECT event_id FROM event_relations
+            INNER JOIN events USING (event_id)
+            WHERE %s
+            ORDER BY topological_ordering %s, stream_ordering %s
+            LIMIT ?
+        """ % (
+            " AND ".join(where_clause),
+            order,
+            order,
+        )
+
+        def _get_recent_references_for_event_txn(txn):
+            txn.execute(sql, where_args + [limit + 1])
+
+            events = [{"event_id": row[0]} for row in txn]
+
+            return PaginationChunk(
+                chunk=list(events[:limit]),
+            )
+
+        return self.runInteraction(
+            "get_recent_references_for_event", _get_recent_references_for_event_txn
+        )
+
+    def _handle_event_relations(self, txn, event):
+        """Handles inserting relation data during peristence of events
+
+        Args:
+            txn
+            event (EventBase)
+        """
+        relation = event.content.get("m.relates_to")
+        if not relation:
+            # No relations
+            return
+
+        rel_type = relation.get("rel_type")
+        if rel_type not in (
+            RelationTypes.ANNOTATION,
+            RelationTypes.REFERENCES,
+            RelationTypes.REPLACES,
+        ):
+            # Unknown relation type
+            return
+
+        parent_id = relation.get("event_id")
+        if not parent_id:
+            # Invalid relation
+            return
+
+        aggregation_key = relation.get("key")
+
+        self._simple_insert_txn(
+            txn,
+            table="event_relations",
+            values={
+                "event_id": event.event_id,
+                "relates_to_id": parent_id,
+                "relation_type": rel_type,
+                "aggregation_key": aggregation_key,
+            },
+        )
diff --git a/synapse/storage/schema/delta/54/relations.sql b/synapse/storage/schema/delta/54/relations.sql
new file mode 100644
index 0000000000..134862b870
--- /dev/null
+++ b/synapse/storage/schema/delta/54/relations.sql
@@ -0,0 +1,27 @@
+/* Copyright 2019 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.
+ */
+
+-- Tracks related events, like reactions, replies, edits, etc. Note that things
+-- in this table are not necessarily "valid", e.g. it may contain edits from
+-- people who don't have power to edit other peoples events.
+CREATE TABLE IF NOT EXISTS event_relations (
+    event_id TEXT NOT NULL,
+    relates_to_id TEXT NOT NULL,
+    relation_type TEXT NOT NULL,
+    aggregation_key TEXT
+);
+
+CREATE UNIQUE INDEX event_relations_id ON event_relations(event_id);
+CREATE INDEX event_relations_relates ON event_relations(relates_to_id, relation_type, aggregation_key);