| % 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(couch_replicator_db_changes). |
| |
| -behaviour(gen_server). |
| |
| -export([ |
| start_link/0 |
| ]). |
| |
| -export([ |
| init/1, |
| terminate/2, |
| handle_call/3, |
| handle_info/2, |
| handle_cast/2, |
| code_change/3 |
| ]). |
| |
| -export([ |
| notify_cluster_event/2 |
| ]). |
| |
| -record(state, { |
| event_listener :: pid(), |
| mdb_changes :: pid() | nil |
| }). |
| |
| |
| -spec notify_cluster_event(pid(), {cluster, any()}) -> ok. |
| notify_cluster_event(Server, {cluster, _} = Event) -> |
| gen_server:cast(Server, Event). |
| |
| |
| -spec start_link() -> |
| {ok, pid()} | ignore | {error, any()}. |
| start_link() -> |
| gen_server:start_link(?MODULE, [], []). |
| |
| |
| init([]) -> |
| EvtPid = couch_replicator_clustering:link_cluster_event_listener(?MODULE, |
| notify_cluster_event, [self()]), |
| State = #state{event_listener = EvtPid, mdb_changes = nil}, |
| case couch_replicator_clustering:is_stable() of |
| true -> |
| {ok, restart_mdb_changes(State)}; |
| false -> |
| {ok, State} |
| end. |
| |
| |
| terminate(_Reason, _State) -> |
| ok. |
| |
| |
| handle_call(_Msg, _From, State) -> |
| {reply, {error, invalid_call}, State}. |
| |
| |
| handle_cast({cluster, unstable}, State) -> |
| {noreply, stop_mdb_changes(State)}; |
| |
| handle_cast({cluster, stable}, State) -> |
| {noreply, restart_mdb_changes(State)}. |
| |
| |
| handle_info(_Msg, State) -> |
| {noreply, State}. |
| |
| |
| code_change(_OldVsn, State, _Extra) -> |
| {ok, State}. |
| |
| |
| -spec restart_mdb_changes(#state{}) -> #state{}. |
| restart_mdb_changes(#state{mdb_changes = nil} = State) -> |
| Suffix = <<"_replicator">>, |
| CallbackMod = couch_replicator_doc_processor, |
| Options = [skip_ddocs], |
| {ok, Pid} = couch_multidb_changes:start_link(Suffix, CallbackMod, nil, |
| Options), |
| couch_stats:increment_counter([couch_replicator, db_scans]), |
| couch_log:notice("Started replicator db changes listener ~p", [Pid]), |
| State#state{mdb_changes = Pid}; |
| |
| restart_mdb_changes(#state{mdb_changes = _Pid} = State) -> |
| restart_mdb_changes(stop_mdb_changes(State)). |
| |
| |
| -spec stop_mdb_changes(#state{}) -> #state{}. |
| stop_mdb_changes(#state{mdb_changes = nil} = State) -> |
| State; |
| stop_mdb_changes(#state{mdb_changes = Pid} = State) -> |
| couch_log:notice("Stopping replicator db changes listener ~p", [Pid]), |
| unlink(Pid), |
| exit(Pid, kill), |
| State#state{mdb_changes = nil}. |