Merge pull request #4217 from rabbitmq/rabbitmq-server-4133-monitor-stream-local-member

Monitor stream local member in stream queue

Author: michaelklishin

deps/rabbit/src/rabbit_channel.erl

@@ -1481,7 +1481,7 @@ handle_method(#'basic.consume'{queue        = QueueNameBin,
                       [rabbit_misc:rs(QueueName)]);
                 {error, no_local_stream_replica_available} ->
                     rabbit_misc:protocol_error(
-                      resource_error, "~s does not not have a running local replica",
+                      resource_error, "~s does not have a running local replica",
                       [rabbit_misc:rs(QueueName)])
             end;
         {ok, _} ->

deps/rabbit/src/rabbit_stream_coordinator.erl

@@ -2,7 +2,7 @@
 %% License, v. 2.0. If a copy of the MPL was not distributed with this
 %% file, You can obtain one at https://mozilla.org/MPL/2.0/.
 %%
-%% Copyright (c) 2007-2021 VMware, Inc. or its affiliates.  All rights reserved.
+%% Copyright (c) 2007-2022 VMware, Inc. or its affiliates.  All rights reserved.
 %%
 
 -module(rabbit_stream_coordinator).
@@ -23,7 +23,8 @@
 -export([recover/0,
          add_replica/2,
          delete_replica/2,
-         register_listener/1]).
+         register_listener/1,
+         register_local_member_listener/1]).
 
 -export([new_stream/2,
          delete_stream/2]).
@@ -39,6 +40,10 @@
 -export([log_overview/1]).
 -export([replay/1]).
 
+%% for testing and debugging
+-export([eval_listeners/3,
+         state/0]).
+
 -rabbit_boot_step({?MODULE,
                    [{description, "Restart stream coordinator"},
                     {mfa,         {?MODULE, recover, []}},
@@ -68,8 +73,9 @@
                    {delete_replica, stream_id(), #{node := node()}} |
                    {policy_changed, stream_id(), #{queue := amqqueue:amqqueue()}} |
                    {register_listener, #{pid := pid(),
+                                         node := node(),
                                          stream_id := stream_id(),
-                                         queue_ref := queue_ref()}} |
+                                         type := leader | local_member}} |
                    {action_failed, stream_id(), #{index := ra:index(),
                                                   node := node(),
                                                   epoch := osiris:epoch(),
@@ -165,6 +171,15 @@ policy_changed(Q) when ?is_amqqueue(Q) ->
     StreamId = maps:get(name, amqqueue:get_type_state(Q)),
     process_command({policy_changed, StreamId, #{queue => Q}}).
 
+%% for debugging
+state() ->
+    case ra:local_query({?MODULE, node()}, fun(State) -> State end) of
+        {ok, {_, Res}, _} ->
+            Res;
+        Any ->
+            Any
+    end.
+
 local_pid(StreamId) when is_list(StreamId) ->
     MFA = {?MODULE, query_local_pid, [StreamId, node()]},
     case ra:local_query({?MODULE, node()}, MFA) of
@@ -248,6 +263,16 @@ register_listener(Q) when ?is_amqqueue(Q)->
                      #{pid => self(),
                        stream_id => StreamId}}).
 
+-spec register_local_member_listener(amqqueue:amqqueue()) ->
+    {error, term()} | {ok, ok | stream_not_found, atom() | {atom(), atom()}}.
+register_local_member_listener(Q) when ?is_amqqueue(Q) ->
+    #{name := StreamId} = amqqueue:get_type_state(Q),
+    process_command({register_listener,
+                     #{pid => self(),
+                       node => node(self()),
+                       stream_id => StreamId,
+                       type => local_member}}).
+
 process_command(Cmd) ->
     Servers = ensure_coordinator_started(),
     process_command(Servers, Cmd).
@@ -313,7 +338,7 @@ all_coord_members() ->
     Nodes = rabbit_mnesia:cluster_nodes(running) -- [node()],
     [{?MODULE, Node} || Node <- [node() | Nodes]].
 
-version() -> 1.
+version() -> 2.
 
 which_module(_) ->
     ?MODULE.
@@ -323,7 +348,8 @@ init(_Conf) ->
 
 -spec apply(map(), command(), state()) ->
     {state(), term(), ra_machine:effects()}.
-apply(#{index := _Idx} = Meta0, {_CmdTag, StreamId, #{}} = Cmd,
+apply(#{index := _Idx, machine_version := MachineVersion} = Meta0,
+      {_CmdTag, StreamId, #{}} = Cmd,
       #?MODULE{streams = Streams0,
                monitors = Monitors0} = State0) ->
     Stream0 = maps:get(StreamId, Streams0, undefined),
@@ -341,10 +367,10 @@ apply(#{index := _Idx} = Meta0, {_CmdTag, StreamId, #{}} = Cmd,
             case Stream1 of
                 undefined ->
                     return(Meta, State0#?MODULE{streams = maps:remove(StreamId, Streams0)},
-                           Reply, inform_listeners_eol(Stream0));
+                           Reply, inform_listeners_eol(MachineVersion, Stream0));
                 _ ->
                     {Stream2, Effects0} = evaluate_stream(Meta, Stream1, []),
-                    {Stream3, Effects1} = eval_listeners(Stream2, Effects0),
+                    {Stream3, Effects1} = eval_listeners(MachineVersion, Stream2, Effects0),
                     {Stream, Effects2} = eval_retention(Meta, Stream3, Effects1),
                     {Monitors, Effects} = ensure_monitors(Stream, Monitors0, Effects2),
                     return(Meta,
@@ -354,10 +380,10 @@ apply(#{index := _Idx} = Meta0, {_CmdTag, StreamId, #{}} = Cmd,
         Reply ->
             return(Meta, State0, Reply, [])
     end;
-apply(Meta, {down, Pid, Reason} = Cmd,
+apply(#{machine_version := MachineVersion} = Meta, {down, Pid, Reason} = Cmd,
       #?MODULE{streams = Streams0,
-               listeners = Listeners0,
-               monitors = Monitors0} = State) ->
+               monitors = Monitors0,
+               listeners = StateListeners0} = State) ->
 
     Effects0 = case Reason of
                    noconnection ->
@@ -366,10 +392,10 @@ apply(Meta, {down, Pid, Reason} = Cmd,
                        []
                end,
     case maps:take(Pid, Monitors0) of
-        {{StreamId, listener}, Monitors} ->
-            Listeners = case maps:take(StreamId, Listeners0) of
+        {{StreamId, listener}, Monitors} when MachineVersion < 2 ->
+            Listeners = case maps:take(StreamId, StateListeners0) of
                             error ->
-                                Listeners0;
+                                StateListeners0;
                             {Pids0, Listeners1} ->
                                 case maps:remove(Pid, Pids0) of
                                     Pids when map_size(Pids) == 0 ->
@@ -380,6 +406,23 @@ apply(Meta, {down, Pid, Reason} = Cmd,
                         end,
             return(Meta, State#?MODULE{listeners = Listeners,
                                        monitors = Monitors}, ok, Effects0);
+        {{PidStreams, listener}, Monitors} when MachineVersion >= 2 ->
+            Streams = maps:fold(
+                fun(StreamId, _, Acc) ->
+                    case Acc of
+                        #{StreamId := Stream = #stream{listeners = Listeners0}} ->
+                            Listeners = maps:fold(fun({P, _} = K, _, A) when P == Pid ->
+                                                          maps:remove(K, A);
+                                                     (K, V, A) ->
+                                                          A#{K => V}
+                                                  end, #{}, Listeners0),
+                            Acc#{StreamId => Stream#stream{listeners = Listeners}};
+                        _ ->
+                            Acc
+                    end
+                end, Streams0, PidStreams),
+            return(Meta, State#?MODULE{streams = Streams,
+                                       monitors = Monitors}, ok, Effects0);
         {{StreamId, member}, Monitors1} ->
             case Streams0 of
                 #{StreamId := Stream0} ->
@@ -398,19 +441,53 @@ apply(Meta, {down, Pid, Reason} = Cmd,
         error ->
             return(Meta, State, ok, Effects0)
     end;
-apply(Meta, {register_listener, #{pid := Pid,
-                                  stream_id := StreamId}},
+apply(#{machine_version := MachineVersion} = Meta,
+      {register_listener, #{pid := Pid,
+                            stream_id := StreamId} = Args},
       #?MODULE{streams = Streams,
-               monitors = Monitors0} = State0) ->
-    case Streams of
-        #{StreamId := #stream{listeners = Listeners0} = Stream0} ->
+               monitors = Monitors0} = State0) when MachineVersion =< 1 ->
+    Type = maps:get(type, Args, leader),
+    case {Streams, Type} of
+        {#{StreamId := #stream{listeners = Listeners0} = Stream0}, leader} ->
             Stream1 = Stream0#stream{listeners = maps:put(Pid, undefined, Listeners0)},
-            {Stream, Effects} = eval_listeners(Stream1, []),
+            {Stream, Effects} = eval_listeners(MachineVersion, Stream1, []),
             Monitors = maps:put(Pid, {StreamId, listener}, Monitors0),
             return(Meta,
                    State0#?MODULE{streams = maps:put(StreamId, Stream, Streams),
                                   monitors = Monitors}, ok,
                    [{monitor, process, Pid} | Effects]);
+        {#{StreamId := _Stream}, local_member} ->
+            %% registering a local member listener does not change the state in v1
+            return(Meta, State0, ok, []);
+        _ ->
+            return(Meta, State0, stream_not_found, [])
+    end;
+
+apply(#{machine_version := MachineVersion} = Meta,
+      {register_listener, #{pid := Pid,
+                            stream_id := StreamId} = Args},
+      #?MODULE{streams = Streams,
+               monitors = Monitors0} = State0) when MachineVersion >= 2 ->
+    Node = maps:get(node, Args, node(Pid)),
+    Type = maps:get(type, Args, leader),
+
+    case Streams of
+        #{StreamId := #stream{listeners = Listeners0} = Stream0} ->
+            {LKey, LValue} =
+                case Type of
+                    leader ->
+                        {{Pid, leader}, undefined};
+                    local_member ->
+                        {{Pid, member}, {Node, undefined}}
+                end,
+            Stream1 = Stream0#stream{listeners = maps:put(LKey, LValue, Listeners0)},
+            {Stream, Effects} = eval_listeners(MachineVersion, Stream1, []),
+            {PidStreams, listener} = maps:get(Pid, Monitors0, {#{}, listener}),
+            Monitors = maps:put(Pid, {PidStreams#{StreamId => ok}, listener}, Monitors0),
+            return(Meta,
+                   State0#?MODULE{streams = maps:put(StreamId, Stream, Streams),
+                                  monitors = Monitors}, ok,
+                   [{monitor, process, Pid} | Effects]);
         _ ->
             return(Meta, State0, stream_not_found, [])
     end;
@@ -438,7 +515,43 @@ apply(Meta, {nodeup, Node} = Cmd,
                   end, {Streams0, Effects0}, Streams0),
     return(Meta, State#?MODULE{monitors = Monitors,
                                streams = Streams}, ok, Effects);
-apply(Meta, {machine_version, _From, _To}, State) ->
+apply(Meta, {machine_version, From = 1, To = 2}, State = #?MODULE{streams = Streams0,
+                                                                  monitors = Monitors0}) ->
+    rabbit_log:info("Stream coordinator machine version changes from ~p to ~p, updating state.",
+                    [From, To]),
+    %% conversion from old state to new state
+    %% additional operation: the stream listeners are never collected in the previous version
+    %% so we'll emit monitors for all listener PIDs
+    %% this way we'll get the DOWN event for dead listener PIDs and
+    %% we'll clean the stream listeners the in the DOWN event callback
+
+    %% transform the listeners of each stream and accumulate listener PIDs
+    {Streams1, Listeners} =
+    maps:fold(fun(S, #stream{listeners = L0} = S0, {StreamAcc, GlobalListAcc}) ->
+                      {L1, GlobalListAcc1} = maps:fold(
+                                    fun(ListPid, LeaderPid, {LAcc, GLAcc}) ->
+                                        {LAcc#{{ListPid, leader} => LeaderPid},
+                                        GLAcc#{ListPid => S}}
+                                    end, {#{}, GlobalListAcc}, L0),
+                      {StreamAcc#{S => S0#stream{listeners = L1}}, GlobalListAcc1}
+              end, {#{}, #{}}, Streams0),
+    %% accumulate monitors for the map and create the effects to emit the monitors
+    {ExtraMonitors, Effects} = maps:fold(fun(P, StreamId, {MAcc, EAcc}) ->
+                                                 {MAcc#{P => {StreamId, listener}},
+                                                 [{monitor, process, P} | EAcc]}
+                          end, {#{}, []}, Listeners),
+    Monitors1 = maps:merge(Monitors0, ExtraMonitors),
+    Monitors2 = maps:fold(fun(P, {StreamId, listener}, Acc) ->
+                                  Acc#{P => {#{StreamId => ok}, listener}};
+                             (P, V, Acc) ->
+                                  Acc#{P => V}
+                          end, #{}, Monitors1),
+    return(Meta, State#?MODULE{streams = Streams1,
+                               monitors = Monitors2,
+                               listeners = undefined}, ok, Effects);
+apply(Meta, {machine_version, From, To}, State) ->
+    rabbit_log:info("Stream coordinator machine version changes from ~p to ~p, no state changes required.",
+                    [From, To]),
     return(Meta, State, ok, []);
 apply(Meta, UnkCmd, State) ->
     rabbit_log:debug("~s: unknown command ~W",
@@ -1240,21 +1353,35 @@ update_stream0(#{system_time := _Ts},
 update_stream0(_Meta, _Cmd, undefined) ->
     undefined.
 
-inform_listeners_eol(#stream{target = deleted,
+inform_listeners_eol(MachineVersion, #stream{target = deleted,
                              listeners = Listeners,
                              queue_ref = QRef
-                            }) ->
+                            }) when MachineVersion =< 1 ->
     lists:map(fun(Pid) ->
                       {send_msg, Pid,
                        {queue_event, QRef, eol},
                        cast}
               end, maps:keys(Listeners));
-inform_listeners_eol(_) ->
+inform_listeners_eol(MachineVersion,
+                        #stream{target    = deleted,
+                                listeners = Listeners,
+                                queue_ref = QRef}) when MachineVersion >= 2 ->
+    LPidsMap = maps:fold(fun({P, _}, _V, Acc) ->
+                            Acc#{P => ok}
+                         end, #{}, Listeners),
+    lists:map(fun(Pid) ->
+                      {send_msg,
+                       Pid,
+                       {queue_event, QRef, eol},
+                       cast}
+              end, maps:keys(LPidsMap));
+inform_listeners_eol(_, _) ->
     [].
 
-eval_listeners(#stream{listeners = Listeners0,
-                       queue_ref = QRef,
-                       members = Members} = Stream, Effects0) ->
+eval_listeners(MachineVersion, #stream{listeners = Listeners0,
+                                       queue_ref = QRef,
+                                       members = Members} = Stream, Effects0) 
+  when MachineVersion =< 1 ->
     case find_leader(Members) of
         {#member{state = {running, _, LeaderPid}}, _} ->
             %% a leader is running, check all listeners to see if any of them
@@ -1273,7 +1400,60 @@ eval_listeners(#stream{listeners = Listeners0,
             {Stream#stream{listeners = Listeners}, Effects};
         _ ->
             {Stream, Effects0}
-    end.
+    end;
+eval_listeners(MachineVersion, #stream{listeners = Listeners0,
+                                       queue_ref = QRef,
+                                       members = Members} = Stream0, Effects0) when MachineVersion >= 2 ->
+    %% Iterating over stream listeners.
+    %% Returning the new map of listeners and the effects (notification of changes)
+    {Listeners1, Effects1} =
+        maps:fold(fun({P, leader}, ListLPid0, {Lsts0, Effs0}) ->
+                          %% iterating over member to find the leader
+                          {ListLPid1, Effs1} =
+                          maps:fold(fun(_N, #member{state  = {running, _, LeaderPid},
+                                                    role   = {writer, _},
+                                                    target = T}, A)
+                                                    when ListLPid0 == LeaderPid, T /= deleted ->
+                                            %% it's the leader, same PID, nothing to do
+                                            A;
+                                       (_N, #member{state  = {running, _, LeaderPid},
+                                                    role   = {writer, _},
+                                                    target = T}, {_, Efs})
+                                                    when T /= deleted ->
+                                            %% it's the leader, not same PID, assign the new leader, add effect
+                                            {LeaderPid, [{send_msg, P,
+                                                          {queue_event, QRef,
+                                                           {stream_leader_change, LeaderPid}},
+                                                          cast} | Efs]};
+                                       (_N, _M, Acc) ->
+                                            %% it's not the leader, nothing to do
+                                            Acc
+                                    end, {ListLPid0, Effs0}, Members),
+                          {Lsts0#{{P, leader} => ListLPid1}, Effs1};
+                     ({P, member}, {ListNode, ListMPid0}, {Lsts0, Effs0}) ->
+                          %% listening to a member on a given node
+                          %% iterating over the members to find the member on this node
+                          {ListMPid1, Effs1} =
+                          maps:fold(fun(MNode, #member{state = {running, _, MemberPid}, target = T}, Acc)
+                                          when ListMPid0 == MemberPid, ListNode == MNode, T /= deleted ->
+                                            %% it's the local member of this listener
+                                            %% it has not changed, nothing to do
+                                            Acc;
+                                       (MNode, #member{state = {running, _, MemberPid}, target = T}, {_, Efs})
+                                          when ListNode == MNode, T /= deleted ->
+                                            %% it's the local member of this listener
+                                            %% the PID is not the same, updating it in the listener, add effect
+                                            {MemberPid, [{send_msg, P,
+                                                          {queue_event, QRef,
+                                                           {stream_local_member_change, MemberPid}},
+                                                          cast} | Efs]};
+                                       (_N, _M, Acc) ->
+                                            %% not a replica, nothing to do
+                                            Acc
+                                    end, {ListMPid0, Effs0}, Members),
+                          {Lsts0#{{P, member} => {ListNode, ListMPid1}}, Effs1}
+              end, {Listeners0, Effects0}, Listeners0),
+    {Stream0#stream{listeners = Listeners1}, Effects1}.
 
 eval_retention(#{index := Idx} = Meta,
                #stream{conf = #{retention := Ret} = Conf,