nickva commented on a change in pull request #1972: Introduce Shard Splitting To CouchDB URL: https://github.com/apache/couchdb/pull/1972#discussion_r270219195
########## File path: src/mem3/src/mem3_reshard_index.erl ########## @@ -0,0 +1,169 @@ +% 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(mem3_reshard_index). + + +-export([ + design_docs/1, + target_indices/2, + spawn_builders/1 +]). + + +-include_lib("mem3/include/mem3.hrl"). +-include_lib("couch/include/couch_db.hrl"). + + +%% Public API + +design_docs(DbName) -> + try + case fabric_design_docs(mem3:dbname(DbName)) of + {error, {maintenance_mode, _, _Node}} -> + {ok, []}; + {ok, DDocs} -> + JsonDocs = [couch_doc:from_json_obj(DDoc) || DDoc <- DDocs], + {ok, JsonDocs}; + Else -> + Else + end + catch error:database_does_not_exist -> + {ok, []} + end. + + +target_indices(Docs, Targets) -> + Indices = [[indices(N, D) || D <- Docs] || #shard{name = N} <- Targets], + lists:flatten(Indices). + + +spawn_builders(Indices) -> + Results = [build_index(Index) || Index <- Indices], + Oks = [{ok, Pid} || {ok, Pid} <- Results, is_pid(Pid)], + case Results -- Oks of + [] -> + {ok, [Pid || {ok, Pid} <- Results]}; + Error -> + % Do a all or nothing pattern, if some indices could not be + % spawned, kill the spawned ones and and return the error. + ErrMsg = "~p failed to spawn index builders: ~p ~p", + couch_log:error(ErrMsg, [?MODULE, Error, Indices]), + lists:foreach(fun({ok, Pid}) -> + catch unlink(Pid), + catch exit(Pid, kill) + end, Oks), + {error, Error} + end. + + +%% Private API + +fabric_design_docs(DbName) -> + case couch_util:with_proc(fabric, design_docs, [DbName], infinity) of + {ok, Resp} -> Resp; + {error, Error} -> Error + end. + + +indices(DbName, Doc) -> + mrview_indices(DbName, Doc) + ++ [dreyfus_indices(DbName, Doc) || has_app(dreyfus)] + ++ [hastings_indices(DbName, Doc) || has_app(hastings)]. + + +mrview_indices(DbName, Doc) -> + try + {ok, MRSt} = couch_mrview_util:ddoc_to_mrst(DbName, Doc), + Views = couch_mrview_index:get(views, MRSt), + case Views =/= [] of + true -> + [{mrview, DbName, MRSt}]; + false -> + [] + end + catch + Tag:Err -> + Msg = "~p couldn't get mrview index ~p ~p ~p:~p", + couch_log:error(Msg, [?MODULE, DbName, Doc, Tag, Err]), + [] + end. + + +dreyfus_indices(DbName, Doc) -> + try + Indices = dreyfus_index:design_doc_to_indexes(Doc), + [{dreyfus, DbName, Index} || Index <- Indices] + catch + Tag:Err -> + Msg = "~p couldn't get dreyfus indices ~p ~p ~p:~p", + couch_log:error(Msg, [?MODULE, DbName, Doc, Tag, Err]), + [] + end. + + +hastings_indices(DbName, Doc) -> + try + Indices = hastings_index:design_doc_to_indexes(Doc), + [{hastings, DbName, Index} || Index <- Indices] + catch + Tag:Err -> + Msg = "~p couldn't get hasting indices ~p ~p ~p:~p", + couch_log:error(Msg, [?MODULE, DbName, Doc, Tag, Err]), + [] + end. + + +build_index({mrview, DbName, MRSt}) -> + case couch_index_server:get_index(couch_mrview_index, MRSt) of + {ok, Pid} -> + Args = [Pid, get_update_seq(DbName)], + WPid = spawn_link(couch_index, get_state, Args), + {ok, WPid}; + Error -> + Error + end; + +build_index({dreyfus, DbName, Index})-> + case dreyfus_index_manager:get_index(DbName, Index) of + {ok, Pid} -> + Args = [Pid, get_update_seq(DbName)], + WPid = spawn_link(dreyfus_index, await, Args), + {ok, WPid}; + Error -> + Error + end; + +build_index({hastings, DbName, Index}) -> + case hastings_index_manager:get_index(DbName, Index) of + {ok, Pid} -> + Args = [Pid, get_update_seq(DbName)], + WPid = spawn_link(hastings_index, await, Args), + {ok, WPid}; + Error -> + Error + end. + + +has_app(App) -> + case application:get_application(App) of Review comment: I have found that we enabled saving api level features in application env: https://github.com/apache/couchdb-config/commit/c92f3ce27155ea88866a0b93d5823d6a5fe7d8b7 But we don't really enable geo or dreyfus as high level API feature. One is a config and the other doesn't bubble up through the config API. But I found we do ```HaveDreyfus = code:lib_dir(dreyfus) /= {error, bad_name}``` I'll try to copy that pattern. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
