Remove most of the fd related FHC code

Stats were not removed, including management UI stats
relating to FDs.

Web-MQTT and Web-STOMP configuration relating to FHC
were not removed.

The file_handle_cache itself must be kept until we
remove CQv1.

Author: lhoguin

deps/amqp_client/src/amqp_network_connection.erl

@@ -118,7 +118,6 @@ do_connect({Addr, Family},
                                              connection_timeout = Timeout,
                                              socket_options     = ExtraOpts},
            SIF, State) ->
-    ok = obtain(),
     case gen_tcp:connect(Addr, Port,
                          [Family | ?RABBIT_TCP_OPTS] ++ ExtraOpts,
                          Timeout) of
@@ -134,7 +133,6 @@ do_connect({Addr, Family},
            SIF, State) ->
     {ok, GlobalSslOpts} = application:get_env(amqp_client, ssl_options),
     app_utils:start_applications([asn1, crypto, public_key, ssl]),
-    ok = obtain(),
     case gen_tcp:connect(Addr, Port,
                          [Family | ?RABBIT_TCP_OPTS] ++ ExtraOpts,
                          Timeout) of
@@ -379,11 +377,5 @@ handshake_recv(Expecting) ->
         end
     end.
 
-obtain() ->
-    case code:is_loaded(file_handle_cache) of
-        false -> ok;
-        _     -> file_handle_cache:obtain()
-    end.
-
 get_reason(#'connection.close'{reply_code = ErrCode}) ->
     ?PROTOCOL:amqp_exception(ErrCode).

deps/rabbit/src/rabbit.erl

@@ -741,9 +741,6 @@ status() ->
                                         get_disk_free_limit, []}},
             {disk_free,                {rabbit_disk_monitor,
                                         get_disk_free, []}}]),
-    S3 = rabbit_misc:with_exit_handler(
-           fun () -> [] end,
-           fun () -> [{file_descriptors, file_handle_cache:info()}] end),
     S4 = [{processes,        [{limit, erlang:system_info(process_limit)},
                               {used, erlang:system_info(process_count)}]},
           {run_queue,        erlang:statistics(run_queue)},
@@ -778,7 +775,7 @@ status() ->
                (_) -> false
            end,
            maps:to_list(product_info())),
-    S1 ++ S2 ++ S3 ++ S4 ++ S5 ++ S6 ++ S7 ++ S8.
+    S1 ++ S2 ++ S4 ++ S5 ++ S6 ++ S7 ++ S8.
 
 alarms() ->
     Alarms = rabbit_misc:with_exit_handler(rabbit_misc:const([]),
@@ -1653,7 +1650,7 @@ config_files() ->
 start_fhc() ->
     ok = rabbit_sup:start_restartable_child(
       file_handle_cache,
-      [fun rabbit_alarm:set_alarm/1, fun rabbit_alarm:clear_alarm/1]),
+      [fun(_) -> ok end, fun(_) -> ok end]),
     ensure_working_fhc().
 
 ensure_working_fhc() ->

deps/rabbit/src/rabbit_amqqueue.erl

@@ -7,7 +7,6 @@
 
 -module(rabbit_amqqueue).
 
--export([warn_file_limit/0]).
 -export([recover/1, stop/1, start/1, declare/6, declare/7,
          delete_immediately/1, delete_exclusive/2, delete/4, purge/1,
          forget_all_durable/1]).
@@ -119,21 +118,6 @@
          active, activity_status, arguments]).
 -define(KILL_QUEUE_DELAY_INTERVAL, 100).
 
-warn_file_limit() ->
-    DurableQueues = find_recoverable_queues(),
-    L = length(DurableQueues),
-
-    %% if there are not enough file handles, the server might hang
-    %% when trying to recover queues, warn the user:
-    case file_handle_cache:get_limit() < L of
-        true ->
-            rabbit_log:warning(
-              "Recovering ~tp queues, available file handles: ~tp. Please increase max open file handles limit to at least ~tp!",
-              [L, file_handle_cache:get_limit(), L]);
-        false ->
-            ok
-    end.
-
 -spec recover(rabbit_types:vhost()) ->
     {Recovered :: [amqqueue:amqqueue()],
      Failed :: [amqqueue:amqqueue()]}.
@@ -183,11 +167,6 @@ find_local_durable_queues(VHostName) ->
                                                    rabbit_queue_type:is_recoverable(Q)
                                        end).
 
-find_recoverable_queues() ->
-    rabbit_db_queue:filter_all_durable(fun(Q) ->
-                                               rabbit_queue_type:is_recoverable(Q)
-                                       end).
-
 -spec declare(name(),
               boolean(),
               boolean(),

deps/rabbit/src/rabbit_amqqueue_process.erl

@@ -210,8 +210,6 @@ init_it2(Recover, From, State = #q{q                   = Q,
                (Res == created orelse Res == existing) ->
             case matches(Recover, Q, Q1) of
                 true ->
-                    ok = file_handle_cache:register_callback(
-                           rabbit_amqqueue, set_maximum_since_use, [self()]),
                     ok = rabbit_memory_monitor:register(
                            self(), {rabbit_amqqueue,
                                     set_ram_duration_target, [self()]}),
@@ -1194,7 +1192,6 @@ prioritise_cast(Msg, _Len, State) ->
         delete_immediately                   -> 8;
         {delete_exclusive, _Pid}             -> 8;
         {set_ram_duration_target, _Duration} -> 8;
-        {set_maximum_since_use, _Age}        -> 8;
         {run_backing_queue, _Mod, _Fun}      -> 6;
         {ack, _AckTags, _ChPid}              -> 4; %% [1]
         {resume, _ChPid}                     -> 3;
@@ -1510,10 +1507,6 @@ handle_cast({set_ram_duration_target, Duration},
     BQS1 = BQ:set_ram_duration_target(Duration, BQS),
     noreply(State#q{backing_queue_state = BQS1});
 
-handle_cast({set_maximum_since_use, Age}, State) ->
-    ok = file_handle_cache:set_maximum_since_use(Age),
-    noreply(State);
-
 handle_cast({credit, SessionPid, CTag, Credit, Drain},
             #q{q = Q,
                backing_queue = BQ,

deps/rabbit/src/rabbit_classic_queue_index_v2.erl

@@ -41,15 +41,6 @@
 -define(HEADER_SIZE, 64). %% bytes
 -define(ENTRY_SIZE,  32). %% bytes
 
-%% The file_handle_cache module tracks reservations at
-%% the level of the process. This means we cannot
-%% handle them independently in the store and index.
-%% Because the index may reserve more FDs than the
-%% store the index becomes responsible for this and
-%% will always reserve at least 2 FDs, and release
-%% everything when terminating.
--define(STORE_FD_RESERVATIONS, 2).
-
 -include_lib("rabbit_common/include/rabbit.hrl").
 %% Set to true to get an awful lot of debug logs.
 -if(false).
@@ -538,7 +529,6 @@ terminate(VHost, Terms, State0 = #qi { dir = Dir,
         ok = file:sync(Fd),
         ok = file:close(Fd)
     end, OpenFds),
-    file_handle_cache:release_reservation(),
     %% Write recovery terms for faster recovery.
     _ = rabbit_recovery_terms:store(VHost,
                                 filename:basename(rabbit_file:binary_to_filename(Dir)),
@@ -555,7 +545,6 @@ delete_and_terminate(State = #qi { dir = Dir,
     _ = maps:map(fun(_, Fd) ->
         ok = file:close(Fd)
     end, OpenFds),
-    file_handle_cache:release_reservation(),
     %% Erase the data on disk.
     ok = erase_index_dir(rabbit_file:binary_to_filename(Dir)),
     State#qi{ segments = #{},
@@ -626,18 +615,9 @@ new_segment_file(Segment, SegmentEntryCount, State = #qi{ segments = Segments })
 %% using too many FDs when the consumer lags a lot. We
 %% limit at 4 because we try to keep up to 2 for reading
 %% and 2 for writing.
-reduce_fd_usage(SegmentToOpen, State = #qi{ fds = OpenFds })
+reduce_fd_usage(_SegmentToOpen, State = #qi{ fds = OpenFds })
         when map_size(OpenFds) < 4 ->
-    %% The only case where we need to update reservations is
-    %% when we are opening a segment that wasn't already open,
-    %% and we are not closing another segment at the same time.
-    case OpenFds of
-        #{SegmentToOpen := _} ->
-            State;
-        _ ->
-            file_handle_cache:set_reservation(?STORE_FD_RESERVATIONS + map_size(OpenFds) + 1),
-            State
-    end;
+    State;
 reduce_fd_usage(SegmentToOpen, State = #qi{ fds = OpenFds0 }) ->
     case OpenFds0 of
         #{SegmentToOpen := _} ->
@@ -868,7 +848,6 @@ delete_segment(Segment, State0 = #qi{ fds = OpenFds0 }) ->
     State = case maps:take(Segment, OpenFds0) of
         {Fd, OpenFds} ->
             ok = file:close(Fd),
-            file_handle_cache:set_reservation(?STORE_FD_RESERVATIONS + map_size(OpenFds)),
             State0#qi{ fds = OpenFds };
         error ->
             State0

deps/rabbit/src/rabbit_classic_queue_store_v2.erl

@@ -41,11 +41,6 @@
 %% need to look into the store to discard them. Messages on disk
 %% will be dropped at the same time as the index deletes the
 %% corresponding segment file.
-%%
-%% The file_handle_cache reservations are done by the v2 index
-%% because they are handled at a pid level. Since we are using
-%% up to 2 FDs in this module we make the index reserve 2 extra
-%% FDs.
 
 -module(rabbit_classic_queue_store_v2).
 

deps/rabbit/src/rabbit_fifo.erl

@@ -894,10 +894,8 @@ state_enter0(leader, #?MODULE{consumers = Cons,
     Mons = [{monitor, process, P} || P <- Pids],
     Nots = [{send_msg, P, leader_change, ra_event} || P <- Pids],
     NodeMons = lists:usort([{monitor, node, node(P)} || P <- Pids]),
-    FHReservation = [{mod_call, rabbit_quorum_queue,
-                      file_handle_leader_reservation, [Resource]}],
     NotifyDecs = notify_decorators_startup(Resource),
-    Effects = TimerEffs ++ Mons ++ Nots ++ NodeMons ++ FHReservation ++ [NotifyDecs],
+    Effects = TimerEffs ++ Mons ++ Nots ++ NodeMons ++ [NotifyDecs],
     case BLH of
         undefined ->
             Effects;
@@ -914,12 +912,7 @@ state_enter0(eol, #?MODULE{enqueuers = Enqs,
     AllConsumers = maps:merge(Custs, WaitingConsumers1),
     [{send_msg, P, eol, ra_event}
      || P <- maps:keys(maps:merge(Enqs, AllConsumers))] ++
-    [{aux, eol},
-     {mod_call, rabbit_quorum_queue, file_handle_release_reservation, []} | Effects];
-state_enter0(State, #?MODULE{cfg = #cfg{resource = _Resource}}, Effects)
-  when State =/= leader ->
-    FHReservation = {mod_call, rabbit_quorum_queue, file_handle_other_reservation, []},
-    [FHReservation | Effects];
+    [{aux, eol} | Effects];
 state_enter0(_, _, Effects) ->
     %% catch all as not handling all states
     Effects.

deps/rabbit/src/rabbit_fifo_v0.erl

@@ -548,7 +548,6 @@ state_enter(leader, #?STATE{consumers = Cons,
                              enqueuers = Enqs,
                              waiting_consumers = WaitingConsumers,
                              cfg = #cfg{name = Name,
-                                        resource = Resource,
                                         become_leader_handler = BLH},
                              prefix_msgs = {0, [], 0, []}
                             }) ->
@@ -559,8 +558,7 @@ state_enter(leader, #?STATE{consumers = Cons,
     Mons = [{monitor, process, P} || P <- Pids],
     Nots = [{send_msg, P, leader_change, ra_event} || P <- Pids],
     NodeMons = lists:usort([{monitor, node, node(P)} || P <- Pids]),
-    FHReservation = [{mod_call, rabbit_quorum_queue, file_handle_leader_reservation, [Resource]}],
-    Effects = Mons ++ Nots ++ NodeMons ++ FHReservation,
+    Effects = Mons ++ Nots ++ NodeMons,
     case BLH of
         undefined ->
             Effects;
@@ -575,11 +573,7 @@ state_enter(eol, #?STATE{enqueuers = Enqs,
                                     #{}, WaitingConsumers0),
     AllConsumers = maps:merge(Custs, WaitingConsumers1),
     [{send_msg, P, eol, ra_event}
-     || P <- maps:keys(maps:merge(Enqs, AllConsumers))] ++
-        [{mod_call, rabbit_quorum_queue, file_handle_release_reservation, []}];
-state_enter(State, #?STATE{cfg = #cfg{resource = _Resource}}) when State =/= leader ->
-    FHReservation = {mod_call, rabbit_quorum_queue, file_handle_other_reservation, []},
-    [FHReservation];
+     || P <- maps:keys(maps:merge(Enqs, AllConsumers))];
  state_enter(_, _) ->
     %% catch all as not handling all states
     [].

deps/rabbit/src/rabbit_fifo_v1.erl

@@ -676,7 +676,6 @@ state_enter(leader, #?STATE{consumers = Cons,
                              enqueuers = Enqs,
                              waiting_consumers = WaitingConsumers,
                              cfg = #cfg{name = Name,
-                                        resource = Resource,
                                         become_leader_handler = BLH},
                              prefix_msgs = {0, [], 0, []}
                             }) ->
@@ -687,8 +686,7 @@ state_enter(leader, #?STATE{consumers = Cons,
     Mons = [{monitor, process, P} || P <- Pids],
     Nots = [{send_msg, P, leader_change, ra_event} || P <- Pids],
     NodeMons = lists:usort([{monitor, node, node(P)} || P <- Pids]),
-    FHReservation = [{mod_call, rabbit_quorum_queue, file_handle_leader_reservation, [Resource]}],
-    Effects = Mons ++ Nots ++ NodeMons ++ FHReservation,
+    Effects = Mons ++ Nots ++ NodeMons,
     case BLH of
         undefined ->
             Effects;
@@ -704,11 +702,7 @@ state_enter(eol, #?STATE{enqueuers = Enqs,
     AllConsumers = maps:merge(Custs, WaitingConsumers1),
     [{send_msg, P, eol, ra_event}
      || P <- maps:keys(maps:merge(Enqs, AllConsumers))] ++
-                   [{aux, eol},
-                    {mod_call, rabbit_quorum_queue, file_handle_release_reservation, []}];
-state_enter(State, #?STATE{cfg = #cfg{resource = _Resource}}) when State =/= leader ->
-    FHReservation = {mod_call, rabbit_quorum_queue, file_handle_other_reservation, []},
-    [FHReservation];
+                   [{aux, eol}];
  state_enter(_, _) ->
     %% catch all as not handling all states
     [].