diff options
Diffstat (limited to 'src/couchdb/couch_stats_collector.erl')
| -rw-r--r-- | src/couchdb/couch_stats_collector.erl | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/src/couchdb/couch_stats_collector.erl b/src/couchdb/couch_stats_collector.erl new file mode 100644 index 00000000..8d0234bb --- /dev/null +++ b/src/couchdb/couch_stats_collector.erl @@ -0,0 +1,127 @@ +% 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([init/1, handle_call/3, handle_cast/2, handle_info/2, + terminate/2, code_change/3]). + + +-export([start/0, stop/0, get/1, + increment/1, decrement/1, + record/2, clear/1, + all/0, all/1]). + +-record(state, {}). + +-define(ABSOLUTE_VALUE_COUNTER_TABLE, abs_table). +-define(HIT_COUNTER_TABLE, hit_table). + + +% PUBLIC API + +start() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + +stop() -> + gen_server:call(?MODULE, stop). + +get(Key) -> + case ets:lookup(?HIT_COUNTER_TABLE, Key) of + [] -> + case ets:lookup(?ABSOLUTE_VALUE_COUNTER_TABLE, Key) of + [] -> + 0; + Result2 -> extract_value_from_ets_result(Key, Result2) + end; + [{_,Result1}] -> Result1 + end. + +increment({Module, Key}) when is_integer(Key) -> + increment({Module, list_to_atom(integer_to_list(Key))}); +increment(Key) -> + case catch ets:update_counter(?HIT_COUNTER_TABLE, Key, 1) of + {'EXIT', {badarg, _}} -> ets:insert(?HIT_COUNTER_TABLE, {Key, 1}); + _ -> ok + end. + +decrement(Key) -> + case catch ets:update_counter(?HIT_COUNTER_TABLE, Key, -1) of + {'EXIT', {badarg, _}} -> ets:insert(?HIT_COUNTER_TABLE, {Key, -1}); + _ -> ok + end. + +record(Key, Value) -> + ets:insert(?ABSOLUTE_VALUE_COUNTER_TABLE, {Key, Value}). + +clear(Key) -> + true = ets:delete(?ABSOLUTE_VALUE_COUNTER_TABLE, Key). + +all() -> + lists:append(ets:tab2list(?HIT_COUNTER_TABLE), + ets:tab2list(?ABSOLUTE_VALUE_COUNTER_TABLE)). + +all(Type) -> + case Type of + incremental -> ets:tab2list(?HIT_COUNTER_TABLE); + absolute -> ets:tab2list(?ABSOLUTE_VALUE_COUNTER_TABLE) + end. + + +% GEN_SERVER + + +init(_) -> + ets:new(?HIT_COUNTER_TABLE, [named_table, set, public]), + ets:new(?ABSOLUTE_VALUE_COUNTER_TABLE, [named_table, duplicate_bag, public]), + {ok, #state{}}. + + +handle_call(stop, _, State) -> + {stop, normal, stopped, State}. + + +% PRIVATE API + +extract_value_from_ets_result(_Key, Result) -> + lists:map(fun({_, Value}) -> Value end, Result). + + +% Unused gen_server behaviour API functions that we need to declare. + +%% @doc Unused +handle_cast(foo, State) -> + {noreply, State}. + +handle_info(_Info, State) -> + {noreply, State}. + +%% @doc Unused +terminate(_Reason, _State) -> ok. + +%% @doc Unused +code_change(_OldVersion, State, _Extra) -> {ok, State}. + + +%% Tests + +-ifdef(TEST). +% Internal API unit tests go here + + +-endif.
\ No newline at end of file |