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Document StateStore and use transactions
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1 changed files with 55 additions and 27 deletions
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@ -14,16 +14,38 @@
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# limitations under the License.
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from ._base import SQLBaseStore
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from twisted.internet import defer
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class StateStore(SQLBaseStore):
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""" Keeps track of the state at a given event.
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This is done by the concept of `state groups`. Every event is a assigned
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a state group (identified by an arbitrary string), which references a
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collection of state events. The current state of an event is then the
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collection of state events referenced by the event's state group.
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Hence, every change in the current state causes a new state group to be
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generated. However, if no change happens (e.g., if we get a message event
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with only one parent it inherits the state group from its parent.)
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There are three tables:
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* `state_groups`: Stores group name, first event with in the group and
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room id.
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* `event_to_state_groups`: Maps events to state groups.
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* `state_groups_state`: Maps state group to state events.
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"""
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@defer.inlineCallbacks
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def get_state_groups(self, event_ids):
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""" Get the state groups for the given list of event_ids
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The return value is a dict mapping group names to lists of events.
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"""
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def f(txn):
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groups = set()
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for event_id in event_ids:
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group = yield self._simple_select_one_onecol(
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group = self._simple_select_one_onecol_txn(
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txn,
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table="event_to_state_groups",
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keyvalues={"event_id": event_id},
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retcol="state_group",
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@ -34,23 +56,29 @@ class StateStore(SQLBaseStore):
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res = {}
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for group in groups:
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state_ids = yield self._simple_select_onecol(
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state_ids = self._simple_select_onecol_txn(
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txn,
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table="state_groups_state",
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keyvalues={"state_group": group},
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retcol="event_id",
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)
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state = []
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for state_id in state_ids:
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s = yield self.get_event(
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state_id,
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allow_none=True,
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s = self._get_events_txn(
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txn,
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[state_id],
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)
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if s:
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state.append(s)
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state.extend(s)
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res[group] = state
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defer.returnValue(res)
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return res
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return self.runInteraction(
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"get_state_groups",
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f,
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)
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def store_state_groups(self, event):
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return self.runInteraction(
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