% Copyright 2010 Cloudant % % 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_nodes). -behaviour(gen_server). -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). -export([start_link/0, get_nodelist/0, get_node_info/2]). -include("mem3.hrl"). -include_lib("couch/include/couch_db.hrl"). -record(state, {changes_pid, update_seq, nodes}). start_link() -> gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). get_nodelist() -> gen_server:call(?MODULE, get_nodelist). get_node_info(Node, Key) -> gen_server:call(?MODULE, {get_node_info, Node, Key}). init([]) -> {Nodes, UpdateSeq} = initialize_nodelist(), {Pid, _} = spawn_monitor(fun() -> listen_for_changes(UpdateSeq) end), {ok, #state{changes_pid = Pid, update_seq = UpdateSeq, nodes = Nodes}}. handle_call(get_nodelist, _From, State) -> {reply, lists:sort(dict:fetch_keys(State#state.nodes)), State}; handle_call({get_node_info, Node, Key}, _From, State) -> case dict:find(Node, State#state.nodes) of {ok, NodeInfo} -> {reply, couch_util:get_value(Key, NodeInfo), State}; error -> {reply, error, State} end; handle_call({add_node, Node, NodeInfo}, _From, #state{nodes=Nodes} = State) -> gen_event:notify(mem3_events, {add_node, Node}), {reply, ok, State#state{nodes = dict:store(Node, NodeInfo, Nodes)}}; handle_call({remove_node, Node}, _From, #state{nodes=Nodes} = State) -> gen_event:notify(mem3_events, {remove_node, Node}), {reply, ok, State#state{nodes = dict:erase(Node, Nodes)}}; handle_call(_Call, _From, State) -> {noreply, State}. handle_cast(_Msg, State) -> {noreply, State}. handle_info({'DOWN', _, _, Pid, Reason}, #state{changes_pid=Pid} = State) -> twig:log(notice, "~p changes listener died ~p", [?MODULE, Reason]), StartSeq = State#state.update_seq, Seq = case Reason of {seq, EndSeq} -> EndSeq; _ -> StartSeq end, erlang:send_after(5000, self(), start_listener), {noreply, State#state{update_seq = Seq}}; handle_info(start_listener, #state{update_seq = Seq} = State) -> {NewPid, _} = spawn_monitor(fun() -> listen_for_changes(Seq) end), {noreply, State#state{changes_pid=NewPid}}; handle_info(_Info, State) -> {noreply, State}. terminate(_Reason, _State) -> ok. code_change(_OldVsn, State, _Extra) -> {ok, State}. %% internal functions initialize_nodelist() -> DbName = couch_config:get("mem3", "node_db", "nodes"), {ok, Db} = mem3_util:ensure_exists(DbName), {ok, _, {_, Nodes0}} = couch_btree:fold(Db#db.id_tree, fun first_fold/3, {Db, dict:new()}, []), % add self if not already present case dict:find(node(), Nodes0) of {ok, _} -> Nodes = Nodes0; error -> Doc = #doc{id = couch_util:to_binary(node())}, {ok, _} = couch_db:update_doc(Db, Doc, []), Nodes = dict:store(node(), [], Nodes0) end, couch_db:close(Db), {Nodes, Db#db.update_seq}. first_fold(#full_doc_info{id = <<"_design/", _/binary>>}, _, Acc) -> {ok, Acc}; first_fold(#full_doc_info{deleted=true}, _, Acc) -> {ok, Acc}; first_fold(#full_doc_info{id=Id}=DocInfo, _, {Db, Dict}) -> {ok, #doc{body={Props}}} = couch_db:open_doc(Db, DocInfo), {ok, {Db, dict:store(mem3_util:to_atom(Id), Props, Dict)}}. listen_for_changes(Since) -> DbName = couch_config:get("mem3", "node_db", "nodes"), {ok, Db} = mem3_util:ensure_exists(DbName), Args = #changes_args{ feed = "continuous", since = Since, heartbeat = true, include_docs = true }, ChangesFun = couch_changes:handle_changes(Args, nil, Db), ChangesFun(fun changes_callback/2). changes_callback(start, _) -> {ok, nil}; changes_callback({stop, EndSeq}, _) -> exit({seq, EndSeq}); changes_callback({change, {Change}, _}, _) -> Node = couch_util:get_value(<<"id">>, Change), case Node of <<"_design/", _/binary>> -> ok; _ -> case couch_util:get_value(<<"deleted">>, Change, false) of false -> {Props} = couch_util:get_value(doc, Change), gen_server:call(?MODULE, {add_node, mem3_util:to_atom(Node), Props}); true -> gen_server:call(?MODULE, {remove_node, mem3_util:to_atom(Node)}) end end, {ok, couch_util:get_value(<<"seq">>, Change)}; changes_callback(timeout, _) -> {ok, nil}.