nickva commented on code in PR #4291: URL: https://github.com/apache/couchdb/pull/4291#discussion_r1170868332
########## src/nouveau/src/nouveau_index_manager.erl: ########## @@ -0,0 +1,161 @@ +%% +%% 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. + +%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*- + +%% index manager ensures only one process is updating a nouveau index at a time. +%% calling update_index will block until at least one attempt has been made to +%% make the index as current as the database at the time update_index was called. + +-module(nouveau_index_manager). +-behaviour(gen_server). +-behaviour(config_listener). +-include("nouveau.hrl"). + +%% public api +-export([ + update_index/1 +]). + +%% gen_server bits +-export([ + start_link/0, + init/1, + handle_call/3, + handle_cast/2, + handle_info/2 +]). + +% config_listener api +-export([handle_config_change/5, handle_config_terminate/3]). + +-export([handle_db_event/3]). + +-define(BY_DBSIG, nouveau_by_dbsig). +-define(BY_REF, nouveau_by_ref). + +start_link() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + +update_index(#index{} = Index) -> + case nouveau:enabled() of + true -> + gen_server:call(?MODULE, {update, Index}, infinity); + false -> + {error, nouveau_not_enabled} + end. + +init(_) -> + couch_util:set_mqd_off_heap(?MODULE), + ets:new(?BY_DBSIG, [set, named_table]), + ets:new(?BY_REF, [set, named_table]), + couch_event:link_listener(?MODULE, handle_db_event, nil, [all_dbs]), + configure_ibrowse(nouveau_util:nouveau_url()), + ok = config:listen_for_changes(?MODULE, nil), + {ok, nil}. + +handle_call({update, #index{} = Index0}, From, State) -> + DbSig = {Index0#index.dbname, Index0#index.sig}, + case ets:lookup(?BY_DBSIG, DbSig) of + [] -> + {_IndexerPid, IndexerRef} = spawn_monitor(nouveau_index_updater, update, [Index0]), + Queue = queue:in(From, queue:new()), + true = ets:insert(?BY_DBSIG, {DbSig, Index0, Queue}), + true = ets:insert(?BY_REF, {IndexerRef, DbSig}); + [{_DbSig, Index1, Queue}] -> + ets:insert(?BY_DBSIG, {DbSig, Index1, queue:in(From, Queue)}) + end, + {noreply, State}; +handle_call(_Msg, _From, State) -> + {reply, unexpected_msg, State}. + +handle_cast(_Msg, State) -> + {noreply, State}. + +handle_info({'DOWN', IndexerRef, process, _Pid, Reason}, State) -> + case ets:lookup(?BY_REF, IndexerRef) of + [] -> + % not one of ours, somehow... Review Comment: Would we ever expect it? May make sense to log an error at least. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
