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% Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(couch_file_stats).
-behaviour(gen_server).
-export([init/1, terminate/2, handle_call/3, handle_cast/2, code_change/3,
handle_info/2]).
-export([start_link/0,track_file/1,get_stats/0]).
-record(stats,{
opened=0,
closed=0
}).
track_file(Fd) ->
catch gen_server:cast(couch_file_stats, {track, Fd}).
get_stats() ->
#stats{opened=Opened,closed=Closed}=gen_server:call(couch_file_stats,get),
[{files_open,Opened-Closed}, {files_closed,Closed}].
start_link() ->
gen_server:start_link({local, couch_file_stats}, couch_file_stats, [], []).
init([]) ->
{ok, #stats{}}.
terminate(_Reason, _Fd) ->
ok.
handle_call(get, _From, Stats) ->
{reply, Stats, Stats}.
handle_cast({track, Fd}, #stats{opened=Opened,closed=Closed}=Stats) ->
try erlang:monitor(process, Fd) of
_Ref ->
{noreply, Stats#stats{opened=Opened+1}}
catch
_Error ->
{noreply, Stats#stats{opened=Opened+1, closed=Closed+1}}
end.
handle_info({'DOWN',_MonRef,_Type,_Pid,_Info}, #stats{closed=Closed}=Stats) ->
{noreply, Stats#stats{closed=Closed+1}}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
|
