stable to default

1 files changed, 60 insertions, 0 deletions

diff --git a/src/file_handle_cache_stats.erl b/src/file_handle_cache_stats.erl
new file mode 100644
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+++ b/src/file_handle_cache_stats.erl
@@ -0,0 +1,60 @@
+%% The contents of this file are subject to the Mozilla Public License
+%% Version 1.1 (the "License"); you may not use this file except in
+%% compliance with the License. You may obtain a copy of the License
+%% at http://www.mozilla.org/MPL/
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and
+%% limitations under the License.
+%%
+%% The Original Code is RabbitMQ.
+%%
+%% The Initial Developer of the Original Code is GoPivotal, Inc.
+%% Copyright (c) 2007-2014 GoPivotal, Inc.  All rights reserved.
+%%
+
+-module(file_handle_cache_stats).
+
+%% stats about read / write operations that go through the fhc.
+
+-export([init/0, update/3, update/2, update/1, get/0]).
+
+-define(TABLE, ?MODULE).
+
+init() ->
+    ets:new(?TABLE, [public, named_table]),
+    [ets:insert(?TABLE, {{Op, Counter}, 0}) || Op      <- [read, write],
+                                               Counter <- [count, bytes, time]],
+    [ets:insert(?TABLE, {{Op, Counter}, 0}) || Op      <- [sync, seek],
+                                               Counter <- [count, time]],
+    [ets:insert(?TABLE, {{Op, Counter}, 0}) || Op      <- [reopen],
+                                               Counter <- [count]].
+
+update(Op, Bytes, Thunk) ->
+    {Time, Res} = timer_tc(Thunk),
+    ets:update_counter(?TABLE, {Op, count}, 1),
+    ets:update_counter(?TABLE, {Op, bytes}, Bytes),
+    ets:update_counter(?TABLE, {Op, time}, Time),
+    Res.
+
+update(Op, Thunk) ->
+    {Time, Res} = timer_tc(Thunk),
+    ets:update_counter(?TABLE, {Op, count}, 1),
+    ets:update_counter(?TABLE, {Op, time}, Time),
+    Res.
+
+update(Op) ->
+    ets:update_counter(?TABLE, {Op, count}, 1),
+    ok.
+
+get() ->
+    lists:sort(ets:tab2list(?TABLE)).
+
+%% TODO timer:tc/1 was introduced in R14B03; use that function once we
+%% require that version.
+timer_tc(Thunk) ->
+    T1 = os:timestamp(),
+    Res = Thunk(),
+    T2 = os:timestamp(),
+    {timer:now_diff(T2, T1), Res}.