chewbranca commented on a change in pull request #610: Optimize ddoc cache URL: https://github.com/apache/couchdb/pull/610#discussion_r125152800
########## File path: src/ddoc_cache/src/ddoc_cache_lru.erl ########## @@ -0,0 +1,293 @@ +% 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(ddoc_cache_lru). +-behaviour(gen_server). +-vsn(1). + + +-export([ + start_link/0, + open/1, + refresh/2 +]). + +-export([ + init/1, + terminate/2, + handle_call/3, + handle_cast/2, + handle_info/2, + code_change/3 +]). + +-export([ + handle_db_event/3 +]). + + +-include("ddoc_cache.hrl"). + + +-record(st, { + pids, % pid -> key + dbs, % dbname -> docid -> key -> pid + size, + evictor +}). + + +start_link() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + + +open(Key) -> + try ets:lookup(?CACHE, Key) of + [] -> + lru_start(Key); Review comment: I think it would be useful to add counters for all four clauses here rather than just the miss/hit cases. Perhaps `couch_stats:increment_counter([ddoc_cache, lru_start])` and `couch_stats:increment_counter([ddoc_cache, partial_start])` or some such for this clause and the one immediately below. That would make it nice and easy to see if we're hitting thundering herd problems. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
