From 6dcade97be7f1331063fd12ac85e61c6f2cf7dac Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 21 Jan 2015 16:27:04 +0000
Subject: Implement new state resolution algorithm

---
 synapse/state.py | 103 ++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 71 insertions(+), 32 deletions(-)

(limited to 'synapse')

diff --git a/synapse/state.py b/synapse/state.py
index 8144fa02b4..7d58a76ede 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -19,6 +19,7 @@ from twisted.internet import defer
 from synapse.util.logutils import log_function
 from synapse.util.async import run_on_reactor
 from synapse.api.constants import EventTypes
+from synapse.api.errors import AuthError
 from synapse.events.snapshot import EventContext
 
 from collections import namedtuple
@@ -42,6 +43,8 @@ class StateHandler(object):
 
     def __init__(self, hs):
         self.store = hs.get_datastore()
+        # self.auth = hs.get_auth()
+        self.hs = hs
 
     @defer.inlineCallbacks
     def get_current_state(self, room_id, event_type=None, state_key=""):
@@ -210,15 +213,22 @@ class StateHandler(object):
         else:
             prev_states = []
 
+        auth_events = {
+            k: e for k, e in unconflicted_state.items()
+            if k[0] in (EventTypes.Create, EventTypes.Member, EventTypes.PowerLevels,)
+        }
+
         try:
-            new_state = {}
-            new_state.update(unconflicted_state)
-            for key, events in conflicted_state.items():
-                new_state[key] = self._resolve_state_events(events)
+            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)
+
         defer.returnValue((None, new_state, prev_states))
 
     def _get_power_level_from_event_state(self, event, user_id):
@@ -238,36 +248,65 @@ class StateHandler(object):
             return 0
 
     @log_function
-    def _resolve_state_events(self, events):
-        curr_events = events
+    def _resolve_state_events(self, conflicted_state, auth_events):
+        resolved_state = {}
+        power_key = (EventTypes.PowerLevels, "")
+        if power_key in conflicted_state.items():
+            power_levels = conflicted_state[power_key]
+            resolved_state[power_key] = self._resolve_auth_events(power_levels)
+
+        auth_events.update(resolved_state)
+
+        for key, events in conflicted_state.items():
+            if key[0] == EventTypes.Member:
+                resolved_state[key] = self._resolve_auth_events(
+                    events,
+                    auth_events
+                )
 
-        new_powers = [
-            self._get_power_level_from_event_state(e, e.user_id)
-            for e in curr_events
-        ]
+        auth_events.update(resolved_state)
 
-        new_powers = [
-            int(p) if p else 0 for p in new_powers
-        ]
+        for key, events in conflicted_state.items():
+            if key not in resolved_state:
+                resolved_state[key] = self._resolve_normal_events(
+                    events, auth_events
+                )
 
-        max_power = max(new_powers)
+        return resolved_state
 
-        curr_events = [
-            z[0] for z in zip(curr_events, new_powers)
-            if z[1] == max_power
-        ]
+    def _resolve_auth_events(self, events, auth_events):
+        reverse = [i for i in reversed(self._ordered_events(events))]
 
-        if not curr_events:
-            raise RuntimeError("Max didn't get a max?")
-        elif len(curr_events) == 1:
-            return curr_events[0]
-
-        # TODO: For now, just choose the one with the largest event_id.
-        return (
-            sorted(
-                curr_events,
-                key=lambda e: hashlib.sha1(
-                    e.event_id + e.user_id + e.room_id + e.type
-                ).hexdigest()
-            )[0]
-        )
+        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.
+                self.hs.get_auth().check(event, auth_events)
+                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.
+                self.hs.get_auth().check(event, auth_events)
+                return event
+            except AuthError as e:
+                pass
+
+        # Oh dear.
+        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)
\ No newline at end of file
-- 
cgit 1.5.1


From b390bf39f280c64497da089c647402bc3287f4b0 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 21 Jan 2015 16:44:04 +0000
Subject: Remove unused function. Add comment.

---
 synapse/state.py | 28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

(limited to 'synapse')

diff --git a/synapse/state.py b/synapse/state.py
index 7d58a76ede..5b622ad3b1 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -231,24 +231,20 @@ class StateHandler(object):
 
         defer.returnValue((None, new_state, prev_states))
 
-    def _get_power_level_from_event_state(self, event, user_id):
-        if hasattr(event, "old_state_events") and event.old_state_events:
-            key = (EventTypes.PowerLevels, "", )
-            power_level_event = event.old_state_events.get(key)
-            level = None
-            if power_level_event:
-                level = power_level_event.content.get("users", {}).get(
-                    user_id
-                )
-                if not level:
-                    level = power_level_event.content.get("users_default", 0)
-
-            return level
-        else:
-            return 0
-
     @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. memberships
+            3. other events.
+
+        :param conflicted_state:
+        :param auth_events:
+        :return:
+        """
         resolved_state = {}
         power_key = (EventTypes.PowerLevels, "")
         if power_key in conflicted_state.items():
-- 
cgit 1.5.1


From 73dd81ca62885110f7fe0e51e7f4e0183b495d17 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 22 Jan 2015 15:57:08 +0000
Subject: fix pyflakes

---
 synapse/state.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'synapse')

diff --git a/synapse/state.py b/synapse/state.py
index 5b622ad3b1..d9fdfb34be 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -295,7 +295,7 @@ class StateHandler(object):
                 # get around circular deps.
                 self.hs.get_auth().check(event, auth_events)
                 return event
-            except AuthError as e:
+            except AuthError:
                 pass
 
         # Oh dear.
-- 
cgit 1.5.1


From 76d7fd39cd44393a5c712930e77c64e202df17cc Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 30 Jan 2015 13:52:02 +0000
Subject: Style changes.

---
 synapse/state.py | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

(limited to 'synapse')

diff --git a/synapse/state.py b/synapse/state.py
index d9fdfb34be..43bda35253 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -37,6 +37,9 @@ def _get_state_key_from_event(event):
 KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
 
 
+AuthEventTypes = (EventTypes.Create, EventTypes.Member, EventTypes.PowerLevels,)
+
+
 class StateHandler(object):
     """ Responsible for doing state conflict resolution.
     """
@@ -215,7 +218,7 @@ class StateHandler(object):
 
         auth_events = {
             k: e for k, e in unconflicted_state.items()
-            if k[0] in (EventTypes.Create, EventTypes.Member, EventTypes.PowerLevels,)
+            if k[0] in AuthEventTypes
         }
 
         try:
@@ -240,10 +243,6 @@ class StateHandler(object):
             1. power levels
             2. memberships
             3. other events.
-
-        :param conflicted_state:
-        :param auth_events:
-        :return:
         """
         resolved_state = {}
         power_key = (EventTypes.PowerLevels, "")
@@ -305,4 +304,4 @@ class StateHandler(object):
         def key_func(e):
             return -int(e.depth), hashlib.sha1(e.event_id).hexdigest()
 
-        return sorted(events, key=key_func)
\ No newline at end of file
+        return sorted(events, key=key_func)
-- 
cgit 1.5.1


From 7a9f6f083e0998893eb9d837512009509d81c998 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 30 Jan 2015 13:55:46 +0000
Subject: Remove commented line

---
 synapse/state.py | 1 -
 1 file changed, 1 deletion(-)

(limited to 'synapse')

diff --git a/synapse/state.py b/synapse/state.py
index 43bda35253..dff11711a6 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -46,7 +46,6 @@ class StateHandler(object):
 
     def __init__(self, hs):
         self.store = hs.get_datastore()
-        # self.auth = hs.get_auth()
         self.hs = hs
 
     @defer.inlineCallbacks
-- 
cgit 1.5.1


From 3d7026e709b145378a6b8a37404910951ef682b3 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 30 Jan 2015 14:37:19 +0000
Subject: Add a slightly more helpful comment

---
 synapse/state.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'synapse')

diff --git a/synapse/state.py b/synapse/state.py
index dff11711a6..081bc31bb5 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -296,7 +296,8 @@ class StateHandler(object):
             except AuthError:
                 pass
 
-        # Oh dear.
+        # Use the last event (the one with the least depth) if they all fail
+        # the auth check.
         return event
 
     def _ordered_events(self, events):
-- 
cgit 1.5.1