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Diffstat (limited to 'apps/couch/src/couch_stats_collector.erl')
| -rw-r--r-- | apps/couch/src/couch_stats_collector.erl | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/apps/couch/src/couch_stats_collector.erl b/apps/couch/src/couch_stats_collector.erl new file mode 100644 index 00000000..74238fc8 --- /dev/null +++ b/apps/couch/src/couch_stats_collector.erl @@ -0,0 +1,131 @@ +% 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. + +% todo +% - remove existance check on increment(), decrement() and record(). have +% modules initialize counters on startup. + +-module(couch_stats_collector). + +-behaviour(gen_server). + +-export([start/0, stop/0]). +-export([all/0, all/1, get/1, increment/1, decrement/1, record/2, clear/1]). +-export([track_process_count/1, track_process_count/2]). + +-export([init/1, terminate/2, code_change/3]). +-export([handle_call/3, handle_cast/2, handle_info/2]). + +-define(HIT_TABLE, stats_hit_table). +-define(ABS_TABLE, stats_abs_table). + +start() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + +stop() -> + gen_server:call(?MODULE, stop). + +all() -> + ets:tab2list(?HIT_TABLE) ++ abs_to_list(). + +all(Type) -> + case Type of + incremental -> ets:tab2list(?HIT_TABLE); + absolute -> abs_to_list() + end. + +get(Key) -> + case ets:lookup(?HIT_TABLE, Key) of + [] -> + case ets:lookup(?ABS_TABLE, Key) of + [] -> + nil; + AbsVals -> + lists:map(fun({_, Value}) -> Value end, AbsVals) + end; + [{_, Counter}] -> + Counter + end. + +increment(Key) -> + Key2 = make_key(Key), + case catch ets:update_counter(?HIT_TABLE, Key2, 1) of + {'EXIT', {badarg, _}} -> + catch ets:insert(?HIT_TABLE, {Key2, 1}), + ok; + _ -> + ok + end. + +decrement(Key) -> + Key2 = make_key(Key), + case catch ets:update_counter(?HIT_TABLE, Key2, -1) of + {'EXIT', {badarg, _}} -> + catch ets:insert(?HIT_TABLE, {Key2, -1}), + ok; + _ -> ok + end. + +record(Key, Value) -> + catch ets:insert(?ABS_TABLE, {make_key(Key), Value}). + +clear(Key) -> + catch ets:delete(?ABS_TABLE, make_key(Key)). + +track_process_count(Stat) -> + track_process_count(self(), Stat). + +track_process_count(Pid, Stat) -> + gen_server:cast(?MODULE, {track_process_count, Stat, Pid}). + +init(_) -> + ets:new(?HIT_TABLE, [named_table, set, public]), + ets:new(?ABS_TABLE, [named_table, duplicate_bag, public]), + {ok, []}. + +terminate(_Reason, _State) -> + ok. + +handle_call(stop, _, State) -> + {stop, normal, stopped, State}. + +handle_cast({track_process_count, Stat, Pid}, State) -> + ok = couch_stats_collector:increment(Stat), + Ref = erlang:monitor(process, Pid), + {noreply, [{Ref,Stat} | State]}. + +handle_info({'DOWN', Ref, _, _, _}, State) -> + {Ref, Stat} = lists:keyfind(Ref, 1, State), + ok = couch_stats_collector:decrement(Stat), + {noreply, lists:keydelete(Ref, 1, State)}. + +code_change(_OldVersion, State, _Extra) -> + {ok, State}. + + +make_key({Module, Key}) when is_integer(Key) -> + {Module, list_to_atom(integer_to_list(Key))}; +make_key(Key) -> + Key. + +abs_to_list() -> + SortedKVs = lists:sort(ets:tab2list(?ABS_TABLE)), + lists:foldl(fun({Key, Val}, Acc) -> + case Acc of + [] -> + [{Key, [Val]}]; + [{Key, Prev} | Rest] -> + [{Key, [Val | Prev]} | Rest]; + Others -> + [{Key, [Val]} | Others] + end + end, [], SortedKVs).
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