Add a new module API to update user presence state. (#16544)

This adds a module API which allows a module to update a user's
presence state/status message. This is useful for controlling presence
from an external system.

To fully control presence from the module the presence.enabled config
parameter gains a new state of "untracked" which disables internal tracking
of presence changes via user actions, etc. Only updates from the module will
be persisted and sent down sync properly).

1 files changed, 47 insertions, 31 deletions

diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index dfc0b9db07..202beee738 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -192,7 +192,8 @@ class BasePresenceHandler(abc.ABC):
         self.state = hs.get_state_handler()
         self.is_mine_id = hs.is_mine_id
 
-        self._presence_enabled = hs.config.server.use_presence
+        self._presence_enabled = hs.config.server.presence_enabled
+        self._track_presence = hs.config.server.track_presence
 
         self._federation = None
         if hs.should_send_federation():
@@ -512,7 +513,7 @@ class WorkerPresenceHandler(BasePresenceHandler):
         )
 
     async def _on_shutdown(self) -> None:
-        if self._presence_enabled:
+        if self._track_presence:
             self.hs.get_replication_command_handler().send_command(
                 ClearUserSyncsCommand(self.instance_id)
             )
@@ -524,7 +525,7 @@ class WorkerPresenceHandler(BasePresenceHandler):
         is_syncing: bool,
         last_sync_ms: int,
     ) -> None:
-        if self._presence_enabled:
+        if self._track_presence:
             self.hs.get_replication_command_handler().send_user_sync(
                 self.instance_id, user_id, device_id, is_syncing, last_sync_ms
             )
@@ -571,7 +572,7 @@ class WorkerPresenceHandler(BasePresenceHandler):
         Called by the sync and events servlets to record that a user has connected to
         this worker and is waiting for some events.
         """
-        if not affect_presence or not self._presence_enabled:
+        if not affect_presence or not self._track_presence:
             return _NullContextManager()
 
         # Note that this causes last_active_ts to be incremented which is not
@@ -702,8 +703,8 @@ class WorkerPresenceHandler(BasePresenceHandler):
 
         user_id = target_user.to_string()
 
-        # If presence is disabled, no-op
-        if not self._presence_enabled:
+        # If tracking of presence is disabled, no-op
+        if not self._track_presence:
             return
 
         # Proxy request to instance that writes presence
@@ -723,7 +724,7 @@ class WorkerPresenceHandler(BasePresenceHandler):
         with the app.
         """
         # If presence is disabled, no-op
-        if not self._presence_enabled:
+        if not self._track_presence:
             return
 
         # Proxy request to instance that writes presence
@@ -760,7 +761,7 @@ class PresenceHandler(BasePresenceHandler):
         ] = {}
 
         now = self.clock.time_msec()
-        if self._presence_enabled:
+        if self._track_presence:
             for state in self.user_to_current_state.values():
                 # Create a psuedo-device to properly handle time outs. This will
                 # be overridden by any "real" devices within SYNC_ONLINE_TIMEOUT.
@@ -831,7 +832,7 @@ class PresenceHandler(BasePresenceHandler):
 
         self.external_sync_linearizer = Linearizer(name="external_sync_linearizer")
 
-        if self._presence_enabled:
+        if self._track_presence:
             # Start a LoopingCall in 30s that fires every 5s.
             # The initial delay is to allow disconnected clients a chance to
             # reconnect before we treat them as offline.
@@ -839,6 +840,9 @@ class PresenceHandler(BasePresenceHandler):
                 30, self.clock.looping_call, self._handle_timeouts, 5000
             )
 
+        # Presence information is persisted, whether or not it is being tracked
+        # internally.
+        if self._presence_enabled:
             self.clock.call_later(
                 60,
                 self.clock.looping_call,
@@ -854,7 +858,7 @@ class PresenceHandler(BasePresenceHandler):
         )
 
         # Used to handle sending of presence to newly joined users/servers
-        if self._presence_enabled:
+        if self._track_presence:
             self.notifier.add_replication_callback(self.notify_new_event)
 
         # Presence is best effort and quickly heals itself, so lets just always
@@ -905,7 +909,9 @@ class PresenceHandler(BasePresenceHandler):
             )
 
     async def _update_states(
-        self, new_states: Iterable[UserPresenceState], force_notify: bool = False
+        self,
+        new_states: Iterable[UserPresenceState],
+        force_notify: bool = False,
     ) -> None:
         """Updates presence of users. Sets the appropriate timeouts. Pokes
         the notifier and federation if and only if the changed presence state
@@ -943,7 +949,7 @@ class PresenceHandler(BasePresenceHandler):
             for new_state in new_states:
                 user_id = new_state.user_id
 
-                # Its fine to not hit the database here, as the only thing not in
+                # It's fine to not hit the database here, as the only thing not in
                 # the current state cache are OFFLINE states, where the only field
                 # of interest is last_active which is safe enough to assume is 0
                 # here.
@@ -957,6 +963,9 @@ class PresenceHandler(BasePresenceHandler):
                     is_mine=self.is_mine_id(user_id),
                     wheel_timer=self.wheel_timer,
                     now=now,
+                    # When overriding disabled presence, don't kick off all the
+                    # wheel timers.
+                    persist=not self._track_presence,
                 )
 
                 if force_notify:
@@ -1072,7 +1081,7 @@ class PresenceHandler(BasePresenceHandler):
         with the app.
         """
         # If presence is disabled, no-op
-        if not self._presence_enabled:
+        if not self._track_presence:
             return
 
         user_id = user.to_string()
@@ -1124,7 +1133,7 @@ class PresenceHandler(BasePresenceHandler):
                 client that is being used by a user.
             presence_state: The presence state indicated in the sync request
         """
-        if not affect_presence or not self._presence_enabled:
+        if not affect_presence or not self._track_presence:
             return _NullContextManager()
 
         curr_sync = self._user_device_to_num_current_syncs.get((user_id, device_id), 0)
@@ -1284,7 +1293,7 @@ class PresenceHandler(BasePresenceHandler):
 
     async def incoming_presence(self, origin: str, content: JsonDict) -> None:
         """Called when we receive a `m.presence` EDU from a remote server."""
-        if not self._presence_enabled:
+        if not self._track_presence:
             return
 
         now = self.clock.time_msec()
@@ -1359,7 +1368,7 @@ class PresenceHandler(BasePresenceHandler):
             raise SynapseError(400, "Invalid presence state")
 
         # If presence is disabled, no-op
-        if not self._presence_enabled:
+        if not self._track_presence:
             return
 
         user_id = target_user.to_string()
@@ -2118,6 +2127,7 @@ def handle_update(
     is_mine: bool,
     wheel_timer: WheelTimer,
     now: int,
+    persist: bool,
 ) -> Tuple[UserPresenceState, bool, bool]:
     """Given a presence update:
         1. Add any appropriate timers.
@@ -2129,6 +2139,8 @@ def handle_update(
         is_mine: Whether the user is ours
         wheel_timer
         now: Time now in ms
+        persist: True if this state should persist until another update occurs.
+            Skips insertion into wheel timers.
 
     Returns:
         3-tuple: `(new_state, persist_and_notify, federation_ping)` where:
@@ -2146,14 +2158,15 @@ def handle_update(
     if is_mine:
         if new_state.state == PresenceState.ONLINE:
             # Idle timer
-            wheel_timer.insert(
-                now=now, obj=user_id, then=new_state.last_active_ts + IDLE_TIMER
-            )
+            if not persist:
+                wheel_timer.insert(
+                    now=now, obj=user_id, then=new_state.last_active_ts + IDLE_TIMER
+                )
 
             active = now - new_state.last_active_ts < LAST_ACTIVE_GRANULARITY
             new_state = new_state.copy_and_replace(currently_active=active)
 
-            if active:
+            if active and not persist:
                 wheel_timer.insert(
                     now=now,
                     obj=user_id,
@@ -2162,11 +2175,12 @@ def handle_update(
 
         if new_state.state != PresenceState.OFFLINE:
             # User has stopped syncing
-            wheel_timer.insert(
-                now=now,
-                obj=user_id,
-                then=new_state.last_user_sync_ts + SYNC_ONLINE_TIMEOUT,
-            )
+            if not persist:
+                wheel_timer.insert(
+                    now=now,
+                    obj=user_id,
+                    then=new_state.last_user_sync_ts + SYNC_ONLINE_TIMEOUT,
+                )
 
             last_federate = new_state.last_federation_update_ts
             if now - last_federate > FEDERATION_PING_INTERVAL:
@@ -2174,7 +2188,7 @@ def handle_update(
                 new_state = new_state.copy_and_replace(last_federation_update_ts=now)
                 federation_ping = True
 
-        if new_state.state == PresenceState.BUSY:
+        if new_state.state == PresenceState.BUSY and not persist:
             wheel_timer.insert(
                 now=now,
                 obj=user_id,
@@ -2182,11 +2196,13 @@ def handle_update(
             )
 
     else:
-        wheel_timer.insert(
-            now=now,
-            obj=user_id,
-            then=new_state.last_federation_update_ts + FEDERATION_TIMEOUT,
-        )
+        # An update for a remote user was received.
+        if not persist:
+            wheel_timer.insert(
+                now=now,
+                obj=user_id,
+                then=new_state.last_federation_update_ts + FEDERATION_TIMEOUT,
+            )
 
     # Check whether the change was something worth notifying about
     if should_notify(prev_state, new_state, is_mine):