iilyak commented on code in PR #5491: URL: https://github.com/apache/couchdb/pull/5491#discussion_r2060555474
########## src/couch_stats/src/csrt_server.erl: ########## @@ -0,0 +1,198 @@ +% 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(csrt_server). + +-behaviour(gen_server). + +-export([ + start_link/0, + init/1, + handle_call/3, + handle_cast/2 +]). + +-export([ + create_pid_ref/0, + create_resource/1, + destroy_resource/1, + get_resource/1, + get_context_type/1, + inc/2, + inc/3, + new_context/2, + set_context_dbname/2, + set_context_username/2, + set_context_type/2, + update_counter/3 +]). + +-include_lib("stdlib/include/ms_transform.hrl"). +-include_lib("couch_stats_resource_tracker.hrl"). + + +-record(st, {}). + +%% +%% Public API +%% + +-spec create_pid_ref() -> pid_ref(). +create_pid_ref() -> + {self(), make_ref()}. + +%% +%% +%% Context lifecycle API +%% + +-spec new_context(Type :: rctx_type(), Nonce :: nonce()) -> rctx(). +new_context(Type, Nonce) -> + #rctx{ + nonce = Nonce, + pid_ref = create_pid_ref(), + type = Type + }. + +-spec set_context_dbname(DbName, PidRef) -> boolean() when + DbName :: dbname(), PidRef :: maybe_pid_ref(). +set_context_dbname(_, undefined) -> + false; +set_context_dbname(DbName, PidRef) -> + update_element(PidRef, [{#rctx.dbname, DbName}]). + +%%set_context_handler_fun(_, undefined) -> +%% ok; +%%set_context_handler_fun(Fun, PidRef) when is_function(Fun) -> +%% FProps = erlang:fun_info(Fun), +%% Mod = proplists:get_value(module, FProps), +%% Func = proplists:get_value(name, FProps), +%% #rctx{type=#coordinator{}=Coordinator} = get_resource(PidRef), +%% Update = [{#rctx.type, Coordinator#coordinator{mod=Mod, func=Func}}], +%% update_element(PidRef, Update). + +-spec set_context_username(UserName, PidRef) -> boolean() when + UserName :: username(), PidRef :: maybe_pid_ref(). +set_context_username(_, undefined) -> + ok; +set_context_username(UserName, PidRef) -> + update_element(PidRef, [{#rctx.username, UserName}]). + +-spec get_context_type(Rctx :: rctx()) -> rctx_type(). +get_context_type(#rctx{type=Type}) -> + Type. + +-spec set_context_type(Type, PidRef) -> boolean() when + Type :: rctx_type(), PidRef :: maybe_pid_ref(). +set_context_type(Type, PidRef) -> + update_element(PidRef, [{#rctx.type, Type}]). + +-spec create_resource(Rctx :: rctx()) -> true. +create_resource(#rctx{} = Rctx) -> + catch ets:insert(?MODULE, Rctx). + +-spec destroy_resource(PidRef :: maybe_pid_ref()) -> boolean(). +destroy_resource(undefined) -> + false; +destroy_resource({_,_}=PidRef) -> + catch ets:delete(?MODULE, PidRef). + +-spec get_resource(PidRef :: maybe_pid_ref()) -> maybe_rctx(). +get_resource(undefined) -> + undefined; +get_resource(PidRef) -> + catch case ets:lookup(?MODULE, PidRef) of + [#rctx{}=Rctx] -> + Rctx; + [] -> + undefined + end. + +-spec is_rctx_field(Field :: rctx_field() | atom()) -> boolean(). +is_rctx_field(Field) -> + maps:is_key(Field, ?KEYS_TO_FIELDS). + +-spec get_rctx_field(Field :: rctx_field()) -> non_neg_integer(). +get_rctx_field(Field) -> + maps:get(Field, ?KEYS_TO_FIELDS). + +-spec update_counter(PidRef, Field, Count) -> non_neg_integer() when + PidRef :: maybe_pid_ref(), + Field :: rctx_field(), + Count :: non_neg_integer(). +update_counter(undefined, _Field, _Count) -> + 0; +update_counter({_Pid,_Ref}=PidRef, Field, Count) when Count >= 0 -> + %% TODO: mem3 crashes without catch, why do we lose the stats table? + case is_rctx_field(Field) of + true -> + Update = {get_rctx_field(Field), Count}, + catch ets:update_counter(?MODULE, PidRef, Update, #rctx{pid_ref=PidRef}); + false -> + 0 + end. + +-spec inc(PidRef :: maybe_pid_ref(), Field :: rctx_field()) -> non_neg_integer(). +inc(PidRef, Field) -> + inc(PidRef, Field, 1). + +-spec inc(PidRef, Field, N) -> non_neg_integer() when + PidRef :: maybe_pid_ref(), + Field :: rctx_field(), + N :: non_neg_integer(). +inc(undefined, _Field, _) -> + 0; +inc(_PidRef, _Field, 0) -> + 0; +inc({_Pid,_Ref}=PidRef, Field, N) when is_integer(N) andalso N >= 0 -> + case is_rctx_field(Field) of + true -> + update_counter(PidRef, Field, N); + false -> + 0 + end. + +%% +%% gen_server callbacks +%% + +start_link() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + +init([]) -> + ets:new(?MODULE, [ + named_table, + public, + {decentralized_counters, true}, + {write_concurrency, true}, + {read_concurrency, true}, + {keypos, #rctx.pid_ref} + ]), + {ok, #st{}}. + +handle_call(_, _From, State) -> + {reply, ok, State}. + +handle_cast(_Msg, State) -> + {noreply, State, 0}. + +%% +%% private functions +%% + +-spec update_element(PidRef :: maybe_pid_ref(), Updates :: [tuple()]) -> boolean(). +update_element(undefined, _Update) -> + false; +update_element({_Pid,_Ref}=PidRef, Update) -> + %% TODO: should we take any action when the update fails? Review Comment: You can also have an ets receiver process which is so simple that it cannot crash. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: notifications-unsubscr...@couchdb.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
