Improve documentation for EventContext fields (#6319)

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Richard van der Hoff 2019-11-05 13:23:25 +00:00 committed by GitHub
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3 changed files with 66 additions and 23 deletions

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changelog.d/6319.misc Normal file
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Improve documentation for EventContext fields.

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@ -12,6 +12,8 @@
# 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 typing import Dict, Optional, Tuple, Union
from six import iteritems
import attr
@ -19,45 +21,82 @@ from frozendict import frozendict
from twisted.internet import defer
from synapse.appservice import ApplicationService
from synapse.logging.context import make_deferred_yieldable, run_in_background
@attr.s(slots=True)
class EventContext:
"""
Holds information relevant to persisting an event
Attributes:
state_group (int|None): state group id, if the state has been stored
as a state group. This is usually only None if e.g. the event is
an outlier.
rejected (bool|str): A rejection reason if the event was rejected, else
False
rejected: A rejection reason if the event was rejected, else False
prev_group (int): Previously persisted state group. ``None`` for an
outlier.
delta_ids (dict[(str, str), str]): Delta from ``prev_group``.
(type, state_key) -> event_id. ``None`` for an outlier.
state_group: The ID of the state group for this event. Note that state events
are persisted with a state group which includes the new event, so this is
effectively the state *after* the event in question.
app_service: FIXME
For a *rejected* state event, where the state of the rejected event is
ignored, this state_group should never make it into the
event_to_state_groups table. Indeed, inspecting this value for a rejected
state event is almost certainly incorrect.
For an outlier, where we don't have the state at the event, this will be
None.
prev_group: If it is known, ``state_group``'s prev_group. Note that this being
None does not necessarily mean that ``state_group`` does not have
a prev_group!
If ``state_group`` is None (ie, the event is an outlier), ``prev_group``
will always also be ``None``.
Note that this *not* (necessarily) the state group associated with
``_prev_state_ids``.
delta_ids: If ``prev_group`` is not None, the state delta between ``prev_group``
and ``state_group``.
app_service: If this event is being sent by a (local) application service, that
app service.
_current_state_ids: The room state map, including this event - ie, the state
in ``state_group``.
_current_state_ids (dict[(str, str), str]|None):
The current state map including the current event. None if outlier
or we haven't fetched the state from DB yet.
(type, state_key) -> event_id
_prev_state_ids (dict[(str, str), str]|None):
The current state map excluding the current event. None if outlier
or we haven't fetched the state from DB yet.
FIXME: what is this for an outlier? it seems ill-defined. It seems like
it could be either {}, or the state we were given by the remote
server, depending on $THINGS
Note that this is a private attribute: it should be accessed via
``get_current_state_ids``. _AsyncEventContext impl calculates this
on-demand: it will be None until that happens.
_prev_state_ids: The room state map, excluding this event. For a non-state
event, this will be the same as _current_state_events.
Note that it is a completely different thing to prev_group!
(type, state_key) -> event_id
FIXME: again, what is this for an outlier?
As with _current_state_ids, this is a private attribute. It should be
accessed via get_prev_state_ids.
"""
state_group = attr.ib(default=None)
rejected = attr.ib(default=False)
prev_group = attr.ib(default=None)
delta_ids = attr.ib(default=None)
app_service = attr.ib(default=None)
rejected = attr.ib(default=False, type=Union[bool, str])
state_group = attr.ib(default=None, type=Optional[int])
prev_group = attr.ib(default=None, type=Optional[int])
delta_ids = attr.ib(default=None, type=Optional[Dict[Tuple[str, str], str]])
app_service = attr.ib(default=None, type=Optional[ApplicationService])
_prev_state_ids = attr.ib(default=None)
_current_state_ids = attr.ib(default=None)
_current_state_ids = attr.ib(
default=None, type=Optional[Dict[Tuple[str, str], str]]
)
_prev_state_ids = attr.ib(default=None, type=Optional[Dict[Tuple[str, str], str]])
@staticmethod
def with_state(

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@ -232,6 +232,9 @@ class StateHandler(object):
# If this is an outlier, then we know it shouldn't have any current
# state. Certainly store.get_current_state won't return any, and
# persisting the event won't store the state group.
# FIXME: why do we populate current_state_ids? I thought the point was
# that we weren't supposed to have any state for outliers?
if old_state:
prev_state_ids = {(s.type, s.state_key): s.event_id for s in old_state}
if event.is_state():