Remove file_handle_cache_stats module

The stats were not removed from management agent, instead
they are hardcoded to zero in the agent itself.

Author: lhoguin

deps/rabbit/src/rabbit_classic_queue_index_v2.erl

@@ -699,7 +699,6 @@ flush_buffer(State0 = #qi { write_buffer = WriteBuffer0,
         {Fd, FoldState} = get_fd_for_segment(Segment, FoldState1),
         LocBytes = flush_buffer_consolidate(lists:sort(LocBytes0), 1),
         ok = file:pwrite(Fd, LocBytes),
-        file_handle_cache_stats:update(queue_index_write),
         FoldState
     end, State0, Writes),
     %% Update the cache. If we are flushing the entire write buffer,
@@ -961,7 +960,6 @@ read_from_disk(SeqIdsToRead0, State0 = #qi{ write_buffer = WriteBuffer }, Acc0)
     ReadSize = (LastSeqId - FirstSeqId + 1) * ?ENTRY_SIZE,
     case get_fd(FirstSeqId, State0) of
         {Fd, OffsetForSeqId, State} ->
-            file_handle_cache_stats:update(queue_index_read),
             %% When reading further than the end of a partial file,
             %% file:pread/3 will return what it could read.
             case file:pread(Fd, OffsetForSeqId, ReadSize) of

deps/rabbit/src/rabbit_mnesia.erl

@@ -817,12 +817,8 @@ execute_mnesia_transaction(TxFun) ->
                                 Res = mnesia:sync_transaction(TxFun),
                                 DiskLogAfter  = mnesia_dumper:get_log_writes(),
                                 case DiskLogAfter == DiskLogBefore of
-                                    true  -> file_handle_cache_stats:update(
-                                              mnesia_ram_tx),
-                                             Res;
-                                    false -> file_handle_cache_stats:update(
-                                              mnesia_disk_tx),
-                                             {sync, Res}
+                                    true  -> Res;
+                                    false -> {sync, Res}
                                 end;
                        true  -> mnesia:sync_transaction(TxFun)
                    end

deps/rabbit/src/rabbit_msg_store.erl

@@ -463,7 +463,6 @@ write(MsgRef, MsgId, Msg, CState) -> client_write(MsgRef, MsgId, Msg, noflow, CS
 
 read(MsgId, CState = #client_msstate { index_ets = IndexEts,
                                        cur_file_cache_ets = CurFileCacheEts }) ->
-    file_handle_cache_stats:update(msg_store_read),
     %% Check the cur file cache
     case ets:lookup(CurFileCacheEts, MsgId) of
         [] ->
@@ -480,7 +479,6 @@ read(MsgId, CState = #client_msstate { index_ets = IndexEts,
     -> {#{rabbit_types:msg_id() => msg()}, client_msstate()}.
 
 read_many(MsgIds, CState) ->
-    file_handle_cache_stats:inc(msg_store_read, length(MsgIds)),
     %% We receive MsgIds in rouhgly the younger->older order so
     %% we can look for messages in the cache directly.
     read_many_cache(MsgIds, CState, #{}).
@@ -592,7 +590,6 @@ client_write(MsgRef, MsgId, Msg, Flow,
              CState = #client_msstate { flying_ets         = FlyingEts,
                                         cur_file_cache_ets = CurFileCacheEts,
                                         client_ref         = CRef }) ->
-    file_handle_cache_stats:update(msg_store_write),
     %% We are guaranteed that the insert will succeed.
     %% This is true even for queue crashes because CRef will change.
     true = ets:insert_new(FlyingEts, {{CRef, MsgRef}, ?FLYING_WRITE}),

deps/rabbit/src/rabbit_queue_index.erl

@@ -922,8 +922,6 @@ append_journal_to_segment(#segment { journal_entries = JEntries,
     case array:sparse_size(JEntries) of
         0 -> Segment;
         _ ->
-            file_handle_cache_stats:update(queue_index_write),
-
             {ok, Hdl} = file_handle_cache:open_with_absolute_path(
                           Path, ?WRITE_MODE,
                           [{write_buffer, infinity}]),
@@ -1172,7 +1170,6 @@ load_segment(KeepAcked, #segment { path = Path }) ->
     case rabbit_file:is_file(Path) of
         false -> Empty;
         true  -> Size = rabbit_file:file_size(Path),
-                 file_handle_cache_stats:update(queue_index_read),
                  {ok, Hdl} = file_handle_cache:open_with_absolute_path(
                                Path, ?READ_MODE, []),
                  {ok, 0} = file_handle_cache:position(Hdl, bof),

deps/rabbit_common/app.bzl

@@ -29,7 +29,6 @@ def all_beam_files(name = "all_beam_files"):
             "src/delegate.erl",
             "src/delegate_sup.erl",
             "src/file_handle_cache.erl",
-            "src/file_handle_cache_stats.erl",
             "src/mirrored_supervisor_locks.erl",
             "src/mnesia_sync.erl",
             "src/pmon.erl",
@@ -124,7 +123,6 @@ def all_test_beam_files(name = "all_test_beam_files"):
             "src/delegate.erl",
             "src/delegate_sup.erl",
             "src/file_handle_cache.erl",
-            "src/file_handle_cache_stats.erl",
             "src/mirrored_supervisor_locks.erl",
             "src/mnesia_sync.erl",
             "src/pmon.erl",
@@ -211,7 +209,6 @@ def all_srcs(name = "all_srcs"):
             "src/delegate.erl",
             "src/delegate_sup.erl",
             "src/file_handle_cache.erl",
-            "src/file_handle_cache_stats.erl",
             "src/gen_server2.erl",
             "src/mirrored_supervisor_locks.erl",
             "src/mnesia_sync.erl",

deps/rabbit_common/src/file_handle_cache.erl

@@ -660,19 +660,16 @@ get_client_state(Pid) ->
 %%----------------------------------------------------------------------------
 
 prim_file_read(Hdl, Size) ->
-    file_handle_cache_stats:update(
-      io_read, Size, fun() -> prim_file:read(Hdl, Size) end).
+    prim_file:read(Hdl, Size).
 
 prim_file_write(Hdl, Bytes) ->
-    file_handle_cache_stats:update(
-      io_write, iolist_size(Bytes), fun() -> prim_file:write(Hdl, Bytes) end).
+    prim_file:write(Hdl, Bytes).
 
 prim_file_sync(Hdl) ->
-    file_handle_cache_stats:update(io_sync, fun() -> prim_file:sync(Hdl) end).
+    prim_file:sync(Hdl).
 
 prim_file_position(Hdl, NewOffset) ->
-    file_handle_cache_stats:update(
-      io_seek, fun() -> prim_file:position(Hdl, NewOffset) end).
+    prim_file:position(Hdl, NewOffset).
 
 is_reader(Mode) -> lists:member(read, Mode).
 
@@ -766,8 +763,7 @@ reopen([{Ref, NewOrReopen, Handle = #handle { hdl          = closed,
         RefNewOrReopenHdls] = ToOpen, Tree, RefHdls) ->
     Mode = case NewOrReopen of
                new    -> Mode0;
-               reopen -> file_handle_cache_stats:update(io_reopen),
-                         [read | Mode0]
+               reopen -> [read | Mode0]
            end,
     case prim_file:open(Path, Mode) of
         {ok, Hdl} ->
@@ -1103,7 +1099,6 @@ used(#fhc_state{open_count          = C1,
 %%----------------------------------------------------------------------------
 
 init([AlarmSet, AlarmClear]) ->
-    _ = file_handle_cache_stats:init(),
     Limit = case application:get_env(file_handles_high_watermark) of
                 {ok, Watermark} when (is_integer(Watermark) andalso
                                       Watermark > 0) ->

deps/rabbit_common/src/file_handle_cache_stats.erl

@@ -414,10 +414,23 @@ update_state(State0) ->
     FHC = get_fhc_stats(),
     State0#state{fhc_stats = FHC}.
 
+%% @todo All these stats are zeroes. Remove eventually.
 get_fhc_stats() ->
     dict:to_list(dict:merge(fun(_, V1, V2) -> V1 + V2 end,
-                            dict:from_list(file_handle_cache_stats:get()),
+                            dict:from_list(zero_fhc_stats()),
                             dict:from_list(get_ra_io_metrics()))).
 
+zero_fhc_stats() ->
+    [{{Op, Counter}, 0} || Op <- [io_read, io_write],
+                           Counter <- [count, bytes, time]]
+    ++
+    [{{Op, Counter}, 0} || Op <- [io_sync, io_seek],
+                           Counter <- [count, time]]
+    ++
+    [{{Op, Counter}, 0} || Op <- [io_reopen, mnesia_ram_tx, mnesia_disk_tx,
+                                  msg_store_read, msg_store_write,
+                                  queue_index_write, queue_index_read],
+                           Counter <- [count]].
+
 get_ra_io_metrics() ->
     lists:sort(ets:tab2list(ra_io_metrics)).

deps/rabbitmq_management_agent/src/rabbit_mgmt_external_stats.erl

@@ -768,7 +768,6 @@ rabbit_common:
 - delegate
 - delegate_sup
 - file_handle_cache
-- file_handle_cache_stats
 - gen_server2
 - mirrored_supervisor_locks
 - mnesia_sync