feat(queue): kick agents that do not return to the replaying state for long

apps/emqx_ds_shared_sub/src/emqx_ds_shared_sub_leader.erl

@@ -38,7 +38,7 @@
 -define(updating, updating).
 
 -type agent_state() :: #{
-    %% Our view of group gm's status
+    %% Our view of group sm's status
     %% it lags the actual state
     state := ?waiting_replaying | ?replaying | ?waiting_updating | ?updating,
     prev_version := emqx_maybe:t(emqx_ds_shared_sub_proto:version()),
@@ -109,6 +109,7 @@
 -define(DROP_TIMEOUT_INTERVAL, 1000).
 
 -define(AGENT_TIMEOUT, 5000).
+-define(MAX_NOT_REPLAYING, 5000).
 
 -define(START_TIME_THRESHOLD, 5000).
 
@@ -535,13 +536,24 @@ disconnect_agent(Data0, Agent, AgentStreamProgresses, Version) ->
 %% Drop agents that stopped reporting progress
 
 drop_timeout_agents(#{agents := Agents} = Data) ->
-    Now = now_ms(),
+    Now = now_ms_monotonic(),
     lists:foldl(
-        fun({Agent, #{update_deadline := Deadline} = _AgentState}, DataAcc) ->
-            case Deadline < Now of
+        fun(
+            {Agent,
+                #{update_deadline := UpdateDeadline, not_replaying_deadline := NoReplayingDeadline} =
+                    _AgentState},
+            DataAcc
+        ) ->
+            case
+                (UpdateDeadline < Now) orelse
+                    (is_integer(NoReplayingDeadline) andalso NoReplayingDeadline < Now)
+            of
                 true ->
                     ?SLOG(info, #{
                         msg => leader_agent_timeout,
+                        now => Now,
+                        update_deadline => UpdateDeadline,
+                        not_replaying_deadline => NoReplayingDeadline,
                         agent => Agent
                     }),
                     drop_invalidate_agent(DataAcc, Agent);
@@ -805,11 +817,12 @@ agent_transition_to_waiting_updating(
         prev_version => Version,
         version => NewVersion
     },
+    AgentState2 = renew_no_replaying_deadline(AgentState1),
     StreamProgresses = stream_progresses(Data, Streams),
     ok = emqx_ds_shared_sub_proto:leader_update_streams(
         Agent, Group, Version, NewVersion, StreamProgresses
     ),
-    AgentState1.
+    AgentState2.
 
 agent_transition_to_waiting_replaying(
     #{group := Group} = _Data, Agent, #{state := OldState, version := Version} = AgentState0
@@ -820,10 +833,11 @@ agent_transition_to_waiting_replaying(
         new_state => ?waiting_replaying
     }),
     ok = emqx_ds_shared_sub_proto:leader_renew_stream_lease(Agent, Group, Version),
-    AgentState0#{
+    AgentState1 = AgentState0#{
         state => ?waiting_replaying,
         revoked_streams => []
-    }.
+    },
+    renew_no_replaying_deadline(AgentState1).
 
 agent_transition_to_initial_waiting_replaying(
     #{group := Group} = Data, Agent, AgentMetadata, InitialStreams
@@ -839,15 +853,16 @@ agent_transition_to_initial_waiting_replaying(
     ok = emqx_ds_shared_sub_proto:leader_lease_streams(
         Agent, Group, Leader, StreamProgresses, Version
     ),
-    #{
+    AgentState = #{
         metadata => AgentMetadata,
         state => ?waiting_replaying,
         version => Version,
         prev_version => undefined,
         streams => InitialStreams,
         revoked_streams => [],
-        update_deadline => now_ms() + ?AGENT_TIMEOUT
-    }.
+        update_deadline => now_ms_monotonic() + ?AGENT_TIMEOUT
+    },
+    renew_no_replaying_deadline(AgentState).
 
 agent_transition_to_replaying(Agent, #{state := ?waiting_replaying} = AgentState) ->
     ?tp(warning, shared_sub_leader_agent_state_transition, #{
@@ -857,16 +872,18 @@ agent_transition_to_replaying(Agent, #{state := ?waiting_replaying} = AgentState
     }),
     AgentState#{
         state => ?replaying,
-        prev_version => undefined
+        prev_version => undefined,
+        not_replaying_deadline => undefined
     }.
 
-agent_transition_to_updating(Agent, #{state := ?waiting_updating} = AgentState) ->
+agent_transition_to_updating(Agent, #{state := ?waiting_updating} = AgentState0) ->
     ?tp(warning, shared_sub_leader_agent_state_transition, #{
         agent => Agent,
         old_state => ?waiting_updating,
         new_state => ?updating
     }),
-    AgentState#{state => ?updating}.
+    AgentState1 = AgentState0#{state => ?updating},
+    renew_no_replaying_deadline(AgentState1).
 
 %%--------------------------------------------------------------------
 %% Helper functions
@@ -878,6 +895,20 @@ gen_router_id() ->
 now_ms() ->
     erlang:system_time(millisecond).
 
+now_ms_monotonic() ->
+    erlang:monotonic_time(millisecond).
+
+renew_no_replaying_deadline(#{not_replaying_deadline := undefined} = AgentState) ->
+    AgentState#{
+        not_replaying_deadline => now_ms_monotonic() + ?MAX_NOT_REPLAYING
+    };
+renew_no_replaying_deadline(#{not_replaying_deadline := _Deadline} = AgentState) ->
+    AgentState;
+renew_no_replaying_deadline(#{} = AgentState) ->
+    AgentState#{
+        not_replaying_deadline => now_ms_monotonic() + ?MAX_NOT_REPLAYING
+    }.
+
 unassigned_streams(#{stream_states := StreamStates, stream_owners := StreamOwners}) ->
     Streams = maps:keys(StreamStates),
     AssignedStreams = maps:keys(StreamOwners),
@@ -960,7 +991,7 @@ set_agent_state(#{agents := Agents} = Data, Agent, AgentState) ->
 
 update_agent_timeout(AgentState) ->
     AgentState#{
-        update_deadline => now_ms() + ?AGENT_TIMEOUT
+        update_deadline => now_ms_monotonic() + ?AGENT_TIMEOUT
     }.
 
 get_agent_state(#{agents := Agents} = _Data, Agent) ->