Stop search indexer when it is deleted.

Allow dreyfus to listen to ddoc_updated events and check if the index
is deleted as a result of update to it's design document. If the index
is deleted then it will stop the index if waitlist is empty, if the
waitlist is not empty then it will wait for a minute before shutting
down.

BugzId:85718

src/dreyfus_index.erl

@@ -40,6 +40,8 @@
     waiting_list=[]
 }).
 
+-define(INDEX_SHUTDOWN_DELAY, index_shutdown_delay()).
+
 % exported for callback.
 -export([search_int/2, group1_int/2, group2_int/2, info_int/1]).
 
@@ -157,9 +159,28 @@ handle_call(info, _From, State) -> % obsolete
     Reply = info_int(State#state.index_pid),
     {reply, Reply, State}.
 
+handle_cast({ddoc_updated, DDocResult}, State) ->
+    #state{index=#index{sig=CurrentSig}, waiting_list = WaitList} = State,
+    case check_if_index_is_deleted(DDocResult, CurrentSig) of
+        true ->
+            case WaitList of
+                [] ->
+                    self() ! index_deleted;
+                [_Index] ->
+                    erlang:send_after(?INDEX_SHUTDOWN_DELAY, self(), index_deleted)
+            end
+    end,
+    {noreply, State};
+
 handle_cast(_Msg, State) ->
     {noreply, State}.
 
+handle_info(index_deleted, State) ->
+    #state{index=Index} = State,
+    couch_log:notice("Shutting down index for ~s. It is either deleted or invalidated with the update to it's design document",
+    [index_name(Index)]),
+    {stop, normal, State};
+
 handle_info({'EXIT', FromPid, {updated, NewSeq}},
             #state{
               index=Index0,
@@ -222,6 +243,35 @@ code_change(_OldVsn, State, _Extra) ->
 
 % private functions.
 
+get_index_with_sig(#doc{body={Fields}}=Doc, Sig) ->
+    RawIndexes = couch_util:get_value(<<"indexes">>, Fields, {[]}),
+    case RawIndexes of
+        {IndexList} when is_list(IndexList) ->
+            {IndexNames, _} = lists:unzip(IndexList),
+            lists:flatmap(
+                fun(IndexName) ->
+                    case design_doc_to_index(Doc, IndexName) of
+                        {ok, #index{sig=Sig_New}} when Sig_New =/= Sig ->
+                            [];
+                        {ok, #index{sig=Sig_New}=Index} when Sig_New =:= Sig ->
+                            [Index]
+                    end
+                end, IndexNames)
+    end.
+
+check_if_index_is_deleted(DDocResult, CurrentSig) ->
+    case DDocResult of
+        {not_found, deleted} ->
+            true;
+        {ok, DDoc} ->
+            case get_index_with_sig(DDoc, CurrentSig) of
+                [] ->
+                    true;
+                [_Index] ->
+                    false
+            end
+    end.
+
 open_index(DbName, #index{analyzer=Analyzer, sig=Sig}) ->
     Path = <<DbName/binary,"/",Sig/binary>>,
     case clouseau_rpc:open_index(self(), Path, Analyzer) of
@@ -367,5 +417,8 @@ group2_int(Pid, QueryArgs0) ->
             clouseau_rpc:group2(Pid, Props)
     end.
 
+index_shutdown_delay() ->
+  config:get_integer("dreyfus", "index_shutdown_delay", 60000). % 1 minute
+
 info_int(Pid) ->
     clouseau_rpc:info(Pid).

src/dreyfus_index_manager.erl

@@ -21,6 +21,7 @@
 
 -define(BY_SIG, dreyfus_by_sig).
 -define(BY_PID, dreyfus_by_pid).
+-define(BY_DB, dreyfus_by_db).
 
 % public api.
 -export([start_link/0, get_index/2, get_disk_size/2]).
@@ -44,8 +45,9 @@ get_disk_size(DbName, Index) ->
 % gen_server functions.
 
 init([]) ->
-    ets:new(?BY_SIG, [set, private, named_table]),
+    ets:new(?BY_SIG, [set, protected, named_table]),
     ets:new(?BY_PID, [set, private, named_table]),
+    ets:new(?BY_DB, [bag, protected, named_table]),
     couch_event:link_listener(?MODULE, handle_db_event, nil, [all_dbs]),
     process_flag(trap_exit, true),
     {ok, nil}.
@@ -69,12 +71,12 @@ handle_call({get_disk_size, DbName, #index{sig=Sig}=Index}, From, State) ->
     Reply = clouseau_rpc:disk_size(Path),
     {reply, Reply, State};
 
-handle_call({open_ok, DbName, Sig, NewPid}, {OpenerPid, _}, State) ->
+handle_call({open_ok, DbName, DDocId, Sig, NewPid}, {OpenerPid, _}, State) ->
     link(NewPid),
     [{_, WaitList}] = ets:lookup(?BY_SIG, {DbName, Sig}),
     [gen_server:reply(From, {ok, NewPid}) || From <- WaitList],
     ets:delete(?BY_PID, OpenerPid),
-    add_to_ets(NewPid, DbName, Sig),
+    add_to_ets(NewPid, DbName, DDocId, Sig),
     {reply, ok, State};
 
 handle_call({open_error, DbName, Sig, Error}, {OpenerPid, _}, State) ->
@@ -121,25 +123,49 @@ handle_db_event(DbName, created, _St) ->
 handle_db_event(DbName, deleted, _St) ->
     gen_server:cast(?MODULE, {cleanup, DbName}),
     {ok, nil};
+handle_db_event(<<"shards/", _/binary>> = DbName, {ddoc_updated, DDocId}, _St) ->
+    DDocResult = couch_util:with_db(DbName, fun(Db) ->
+        couch_db:open_doc(Db, DDocId, [ejson_body, ?ADMIN_CTX])
+    end),
+    couch_log:info("Received ddoc_updated event for ~s",[DDocId]),
+    DbShards = [mem3:name(Sh) || Sh <- mem3:local_shards(mem3:dbname(DbName))],
+    lists:foreach(fun(DbShard) ->
+        lists:foreach(fun({_DbShard, {_DDocId, Sig}}) ->
+            case ets:lookup(?BY_SIG, {DbShard, Sig}) of
+                [{_, IndexPid}] ->
+                    gen_server:cast(IndexPid, {ddoc_updated, DDocResult});
+                [] ->
+                    ok
+            end
+        end, ets:match_object(?BY_DB, {DbShard, {DDocId, '$1'}}))
+    end, DbShards),
+    {ok, nil};
 handle_db_event(_DbName, _Event, _St) ->
     {ok, nil}.
 
-new_index(DbName, #index{sig=Sig}=Index) ->
+new_index(DbName, #index{ddoc_id=DDocId, sig=Sig}=Index) ->
     case (catch dreyfus_index:start_link(DbName, Index)) of
     {ok, NewPid} ->
-        Msg = {open_ok, DbName, Sig, NewPid},
+        Msg = {open_ok, DbName, DDocId, Sig, NewPid},
         ok = gen_server:call(?MODULE, Msg, infinity),
         unlink(NewPid);
     Error ->
         Msg = {open_error, DbName, Sig, Error},
         ok = gen_server:call(?MODULE, Msg, infinity)
     end.
 
-add_to_ets(Pid, DbName, Sig) ->
+add_to_ets(Pid, DbName, DDocId, Sig) ->
     true = ets:insert(?BY_PID, {Pid, {DbName, Sig}}),
-    true = ets:insert(?BY_SIG, {{DbName, Sig}, Pid}).
+    true = ets:insert(?BY_SIG, {{DbName, Sig}, Pid}),
+    true = ets:insert(?BY_DB, {DbName, {DDocId, Sig}}).
 
 delete_from_ets(Pid, DbName, Sig) ->
+    case ets:match_object(?BY_DB, {DbName, {'$1', Sig}}) of
+        [{DbName, {DDocId, Sig}}] ->
+            true = ets:delete_object(?BY_DB, {DbName, {DDocId, Sig}});
+        _Else ->
+            true
+    end,
     true = ets:delete(?BY_PID, Pid),
     true = ets:delete(?BY_SIG, {DbName, Sig}).