summary refs log tree commit diff
path: root/synapse/state.py
blob: 4d48cc4605bb84169862e179115826eb26f50feb (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket 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.


from twisted.internet import defer

from synapse.util.logutils import log_function
from synapse.util.caches.expiringcache import ExpiringCache
from synapse.util.metrics import Measure
from synapse.api.constants import EventTypes
from synapse.api.errors import AuthError
from synapse.api.auth import AuthEventTypes
from synapse.events.snapshot import EventContext

from collections import namedtuple

import logging
import hashlib
import os

logger = logging.getLogger(__name__)


KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))


CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.1))


SIZE_OF_CACHE = int(1000 * CACHE_SIZE_FACTOR)
EVICTION_TIMEOUT_SECONDS = 60 * 60


class _StateCacheEntry(object):
    def __init__(self, state, state_group, ts):
        self.state = state
        self.state_group = state_group


class StateHandler(object):
    """ Responsible for doing state conflict resolution.
    """

    def __init__(self, hs):
        self.clock = hs.get_clock()
        self.store = hs.get_datastore()
        self.hs = hs

        # dict of set of event_ids -> _StateCacheEntry.
        self._state_cache = None

    def start_caching(self):
        logger.debug("start_caching")

        self._state_cache = ExpiringCache(
            cache_name="state_cache",
            clock=self.clock,
            max_len=SIZE_OF_CACHE,
            expiry_ms=EVICTION_TIMEOUT_SECONDS * 1000,
            reset_expiry_on_get=True,
        )

        self._state_cache.start()

    @defer.inlineCallbacks
    def get_current_state(self, room_id, event_type=None, state_key="",
                          latest_event_ids=None):
        """ Retrieves the current state for the room. This is done by
        calling `get_latest_events_in_room` to get the leading edges of the
        event graph and then resolving any of the state conflicts.

        This is equivalent to getting the state of an event that were to send
        next before receiving any new events.

        If `event_type` is specified, then the method returns only the one
        event (or None) with that `event_type` and `state_key`.

        Returns:
            map from (type, state_key) to event
        """
        if not latest_event_ids:
            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)

        _, state = yield self.resolve_state_groups(room_id, latest_event_ids)

        if event_type:
            event_id = state.get((event_type, state_key))
            event = None
            if event_id:
                event = yield self.store.get_event(event_id, allow_none=True)
            defer.returnValue(event)
            return

        state_map = yield self.store.get_events(state.values(), get_prev_content=False)
        state = {
            key: state_map[e_id] for key, e_id in state.items() if e_id in state_map
        }

        defer.returnValue(state)

    @defer.inlineCallbacks
    def get_current_state_ids(self, room_id, event_type=None, state_key="",
                              latest_event_ids=None):
        if not latest_event_ids:
            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)

        _, state = yield self.resolve_state_groups(room_id, latest_event_ids)

        if event_type:
            defer.returnValue(state.get((event_type, state_key)))
            return

        defer.returnValue(state)

    @defer.inlineCallbacks
    def get_current_user_in_room(self, room_id):
        latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
        group, state_ids = yield self.resolve_state_groups(room_id, latest_event_ids)
        joined_users = yield self.store.get_joined_users_from_state(
            room_id, group, state_ids
        )
        defer.returnValue(joined_users)

    @defer.inlineCallbacks
    def compute_event_context(self, event, old_state=None):
        """ Fills out the context with the `current state` of the graph. The
        `current state` here is defined to be the state of the event graph
        just before the event - i.e. it never includes `event`

        If `event` has `auth_events` then this will also fill out the
        `auth_events` field on `context` from the `current_state`.

        Args:
            event (EventBase)
        Returns:
            an EventContext
        """
        context = EventContext()

        if event.internal_metadata.is_outlier():
            # 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.
            if old_state:
                context.prev_state_ids = {
                    (s.type, s.state_key): s.event_id for s in old_state
                }
                if event.is_state():
                    context.current_state_events = dict(context.prev_state_ids)
                    key = (event.type, event.state_key)
                    context.current_state_events[key] = event.event_id
                else:
                    context.current_state_events = context.prev_state_ids
            else:
                context.current_state_ids = {}
                context.prev_state_ids = {}
            context.prev_state_events = []
            context.state_group = self.store.get_next_state_group()
            defer.returnValue(context)

        if old_state:
            context.prev_state_ids = {
                (s.type, s.state_key): s.event_id for s in old_state
            }
            context.state_group = self.store.get_next_state_group()

            if event.is_state():
                key = (event.type, event.state_key)
                if key in context.prev_state_ids:
                    replaces = context.prev_state_ids[key]
                    if replaces != event.event_id:  # Paranoia check
                        event.unsigned["replaces_state"] = replaces
                context.current_state_ids = dict(context.prev_state_ids)
                context.current_state_ids[key] = event.event_id
            else:
                context.current_state_ids = context.prev_state_ids

            context.prev_state_events = []
            defer.returnValue(context)

        if event.is_state():
            ret = yield self.resolve_state_groups(
                event.room_id, [e for e, _ in event.prev_events],
                event_type=event.type,
                state_key=event.state_key,
            )
        else:
            ret = yield self.resolve_state_groups(
                event.room_id, [e for e, _ in event.prev_events],
            )

        group, curr_state = ret

        context.prev_state_ids = curr_state
        if event.is_state() or group is None:
            context.state_group = self.store.get_next_state_group()
        else:
            context.state_group = group

        if event.is_state():
            key = (event.type, event.state_key)
            if key in context.prev_state_ids:
                replaces = context.prev_state_ids[key]
                event.unsigned["replaces_state"] = replaces
            context.current_state_ids = dict(context.prev_state_ids)
            context.current_state_ids[key] = event.event_id
        else:
            context.current_state_ids = context.prev_state_ids

        context.prev_state_events = []
        defer.returnValue(context)

    @defer.inlineCallbacks
    @log_function
    def resolve_state_groups(self, room_id, event_ids, event_type=None, state_key=""):
        """ Given a list of event_ids this method fetches the state at each
        event, resolves conflicts between them and returns them.

        Returns:
            a Deferred tuple of (`state_group`, `state`, `prev_state`).
            `state_group` is the name of a state group if one and only one is
            involved. `state` is a map from (type, state_key) to event, and
            `prev_state` is a list of event ids.
        """
        logger.debug("resolve_state_groups event_ids %s", event_ids)

        state_groups_ids = yield self.store.get_state_groups_ids(
            room_id, event_ids
        )

        logger.debug(
            "resolve_state_groups state_groups %s",
            state_groups_ids.keys()
        )

        group_names = frozenset(state_groups_ids.keys())
        if len(group_names) == 1:
            name, state_list = state_groups_ids.items().pop()

            defer.returnValue((name, state_list,))

        if self._state_cache is not None:
            cache = self._state_cache.get(group_names, None)
            if cache:
                cache.ts = self.clock.time_msec()

                defer.returnValue(
                    (cache.state_group, cache.state,)
                )

        logger.info(
            "Resolving state for %s with %d groups", room_id, len(state_groups_ids)
        )

        state = {}
        for st in state_groups_ids.values():
            for key, e_id in st.items():
                state.setdefault(key, set()).add(e_id)

        conflicted_state = {
            k: list(v)
            for k, v in state.items()
            if len(v) > 1
        }

        if conflicted_state:
            logger.info("Resolving conflicted state for %r", room_id)
            state_map = yield self.store.get_events(
                [e_id for st in state_groups_ids.values() for e_id in st.values()],
                get_prev_content=False
            )
            state_sets = [
                [state_map[e_id] for key, e_id in st.items() if e_id in state_map]
                for st in state_groups_ids.values()
            ]
            new_state, _ = self._resolve_events(
                state_sets, event_type, state_key
            )
            new_state = {
                key: e.event_id for key, e in new_state.items()
            }
        else:
            new_state = {
                key: e_ids.pop() for key, e_ids in state.items()
            }

        state_group = None
        new_state_event_ids = frozenset(new_state.values())
        for sg, events in state_groups_ids.items():
            if new_state_event_ids == frozenset(e_id for e_id in events):
                state_group = sg
                break
        if not state_group:
            state_group = self.store.get_next_state_group()

        if self._state_cache is not None:
            cache = _StateCacheEntry(
                state=new_state,
                state_group=state_group,
                ts=self.clock.time_msec()
            )

            self._state_cache[group_names] = cache

        defer.returnValue((state_group, new_state,))

    def resolve_events(self, state_sets, event):
        logger.info(
            "Resolving state for %s with %d groups", event.room_id, len(state_sets)
        )
        if event.is_state():
            return self._resolve_events(
                state_sets, event.type, event.state_key
            )
        else:
            return self._resolve_events(state_sets)

    def _resolve_events(self, state_sets, event_type=None, state_key=""):
        """
        Returns
            (dict[(str, str), synapse.events.FrozenEvent], list[str]): a tuple
            (new_state, prev_states). new_state is a map from (type, state_key)
            to event. prev_states is a list of event_ids.
        """
        with Measure(self.clock, "state._resolve_events"):
            state = {}
            for st in state_sets:
                for e in st:
                    state.setdefault(
                        (e.type, e.state_key),
                        {}
                    )[e.event_id] = e

            unconflicted_state = {
                k: v.values()[0] for k, v in state.items()
                if len(v.values()) == 1
            }

            conflicted_state = {
                k: v.values()
                for k, v in state.items()
                if len(v.values()) > 1
            }

            if event_type:
                prev_states_events = conflicted_state.get(
                    (event_type, state_key), []
                )
                prev_states = [s.event_id for s in prev_states_events]
            else:
                prev_states = []

            auth_events = {
                k: e for k, e in unconflicted_state.items()
                if k[0] in AuthEventTypes
            }

            try:
                resolved_state = self._resolve_state_events(
                    conflicted_state, auth_events
                )
            except:
                logger.exception("Failed to resolve state")
                raise

            new_state = unconflicted_state
            new_state.update(resolved_state)

        return new_state, prev_states

    @log_function
    def _resolve_state_events(self, conflicted_state, auth_events):
        """ This is where we actually decide which of the conflicted state to
        use.

        We resolve conflicts in the following order:
            1. power levels
            2. join rules
            3. memberships
            4. other events.
        """
        resolved_state = {}
        power_key = (EventTypes.PowerLevels, "")
        if power_key in conflicted_state:
            events = conflicted_state[power_key]
            logger.debug("Resolving conflicted power levels %r", events)
            resolved_state[power_key] = self._resolve_auth_events(
                events, auth_events)

        auth_events.update(resolved_state)

        for key, events in conflicted_state.items():
            if key[0] == EventTypes.JoinRules:
                logger.debug("Resolving conflicted join rules %r", events)
                resolved_state[key] = self._resolve_auth_events(
                    events,
                    auth_events
                )

        auth_events.update(resolved_state)

        for key, events in conflicted_state.items():
            if key[0] == EventTypes.Member:
                logger.debug("Resolving conflicted member lists %r", events)
                resolved_state[key] = self._resolve_auth_events(
                    events,
                    auth_events
                )

        auth_events.update(resolved_state)

        for key, events in conflicted_state.items():
            if key not in resolved_state:
                logger.debug("Resolving conflicted state %r:%r", key, events)
                resolved_state[key] = self._resolve_normal_events(
                    events, auth_events
                )

        return resolved_state

    def _resolve_auth_events(self, events, auth_events):
        reverse = [i for i in reversed(self._ordered_events(events))]

        auth_events = dict(auth_events)

        prev_event = reverse[0]
        for event in reverse[1:]:
            auth_events[(prev_event.type, prev_event.state_key)] = prev_event
            try:
                # FIXME: hs.get_auth() is bad style, but we need to do it to
                # get around circular deps.
                # The signatures have already been checked at this point
                self.hs.get_auth().check(event, auth_events, do_sig_check=False)
                prev_event = event
            except AuthError:
                return prev_event

        return event

    def _resolve_normal_events(self, events, auth_events):
        for event in self._ordered_events(events):
            try:
                # FIXME: hs.get_auth() is bad style, but we need to do it to
                # get around circular deps.
                # The signatures have already been checked at this point
                self.hs.get_auth().check(event, auth_events, do_sig_check=False)
                return event
            except AuthError:
                pass

        # Use the last event (the one with the least depth) if they all fail
        # the auth check.
        return event

    def _ordered_events(self, events):
        def key_func(e):
            return -int(e.depth), hashlib.sha1(e.event_id).hexdigest()

        return sorted(events, key=key_func)