1 files changed, 45 insertions, 0 deletions
diff --git a/deps/rabbit/src/rabbit_fhc_helpers.erl b/deps/rabbit/src/rabbit_fhc_helpers.erl
new file mode 100644
index 0000000000..d310e84008
--- /dev/null
+++ b/deps/rabbit/src/rabbit_fhc_helpers.erl
@@ -0,0 +1,45 @@
+%% This Source Code Form is subject to the terms of the Mozilla Public
+%% 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) 2007-2020 VMware, Inc. or its affiliates.  All rights reserved.
+%%
+
+-module(rabbit_fhc_helpers).
+
+-export([clear_read_cache/0]).
+
+-include("amqqueue.hrl").
+
+clear_read_cache() ->
+    case application:get_env(rabbit, fhc_read_buffering) of
+        {ok, true} ->
+            file_handle_cache:clear_read_cache(),
+            clear_vhost_read_cache(rabbit_vhost:list_names());
+        _ -> %% undefined or {ok, false}
+            ok
+    end.
+
+clear_vhost_read_cache([]) ->
+    ok;
+clear_vhost_read_cache([VHost | Rest]) ->
+    clear_queue_read_cache(rabbit_amqqueue:list(VHost)),
+    clear_vhost_read_cache(Rest).
+
+clear_queue_read_cache([]) ->
+    ok;
+clear_queue_read_cache([Q | Rest]) when ?is_amqqueue(Q) ->
+    MPid = amqqueue:get_pid(Q),
+    SPids = amqqueue:get_slave_pids(Q),
+    %% Limit the action to the current node.
+    Pids = [P || P <- [MPid | SPids], node(P) =:= node()],
+    %% This function is executed in the context of the backing queue
+    %% process because the read buffer is stored in the process
+    %% dictionary.
+    Fun = fun(_, State) ->
+                  _ = file_handle_cache:clear_process_read_cache(),
+                  State
+          end,
+    [rabbit_amqqueue:run_backing_queue(Pid, rabbit_variable_queue, Fun)
+     || Pid <- Pids],
+    clear_queue_read_cache(Rest).