Merge pull request #490 from cloudant/revert-Add-sys_dbs-to-LRU

Revert add sys dbs to lru

4 files changed, 88 insertions, 36 deletions

diff --git a/src/couch/src/couch_db_updater.erl b/src/couch/src/couch_db_updater.erl
index 270fffe46..78726358e 100644
--- a/src/couch/src/couch_db_updater.erl
+++ b/src/couch/src/couch_db_updater.erl
@@ -61,7 +61,12 @@ init({DbName, Filepath, Fd, Options}) ->
         end
     end,
     Db = init_db(DbName, Filepath, Fd, Header, Options),
-    couch_stats_process_tracker:track([couchdb, open_databases]),
+    case lists:member(sys_db, Options) of
+        false ->
+            couch_stats_process_tracker:track([couchdb, open_databases]);
+        true ->
+            ok
+    end,
     % we don't load validation funs here because the fabric query is liable to
     % race conditions.  Instead see couch_db:validate_doc_update, which loads
     % them lazily
diff --git a/src/couch/src/couch_file.erl b/src/couch/src/couch_file.erl
index d7b176e98..d40c525f2 100644
--- a/src/couch/src/couch_file.erl
+++ b/src/couch/src/couch_file.erl
@@ -362,7 +362,7 @@ init({Filepath, Options, ReturnPid, Ref}) ->
                     {ok, 0} = file:position(Fd, 0),
                     ok = file:truncate(Fd),
                     ok = file:sync(Fd),
-                    couch_stats_process_tracker:track([couchdb, open_os_files]),
+                    maybe_track_open_os_files(Options),
                     erlang:send_after(?INITIAL_WAIT, self(), maybe_close),
                     {ok, #file{fd=Fd, is_sys=IsSys, pread_limit=Limit}};
                 false ->
@@ -370,7 +370,7 @@ init({Filepath, Options, ReturnPid, Ref}) ->
                     init_status_error(ReturnPid, Ref, {error, eexist})
                 end;
             false ->
-                couch_stats_process_tracker:track([couchdb, open_os_files]),
+                maybe_track_open_os_files(Options),
                 erlang:send_after(?INITIAL_WAIT, self(), maybe_close),
                 {ok, #file{fd=Fd, is_sys=IsSys, pread_limit=Limit}}
             end;
@@ -385,7 +385,7 @@ init({Filepath, Options, ReturnPid, Ref}) ->
             %% Save Fd in process dictionary for debugging purposes
             put(couch_file_fd, {Fd, Filepath}),
             ok = file:close(Fd_Read),
-            couch_stats_process_tracker:track([couchdb, open_os_files]),
+            maybe_track_open_os_files(Options),
             {ok, Eof} = file:position(Fd, eof),
             erlang:send_after(?INITIAL_WAIT, self(), maybe_close),
             {ok, #file{fd=Fd, eof=Eof, is_sys=IsSys, pread_limit=Limit}};
@@ -402,6 +402,14 @@ file_open_options(Options) ->
         [append]
     end.
 
+maybe_track_open_os_files(Options) ->
+    case not lists:member(sys_db, Options) of
+        true ->
+            couch_stats_process_tracker:track([couchdb, open_os_files]);
+        false ->
+            ok
+    end.
+
 terminate(_Reason, #file{fd = nil}) ->
     ok;
 terminate(_Reason, #file{fd = Fd}) ->
@@ -668,7 +676,13 @@ split_iolist([Byte | Rest], SplitAt, BeginAcc) when is_integer(Byte) ->
     split_iolist(Rest, SplitAt - 1, [Byte | BeginAcc]).
 
 
-is_idle(#file{}) ->
+% System dbs aren't monitored by couch_stats_process_tracker
+is_idle(#file{is_sys=true}) ->
+    case process_info(self(), monitored_by) of
+        {monitored_by, []} -> true;
+        _ -> false
+    end;
+is_idle(#file{is_sys=false}) ->
     Tracker = whereis(couch_stats_process_tracker),
     case process_info(self(), monitored_by) of
         {monitored_by, []} -> true;
diff --git a/src/couch/src/couch_server.erl b/src/couch/src/couch_server.erl
index 115230029..ad2a5f0ec 100644
--- a/src/couch/src/couch_server.erl
+++ b/src/couch/src/couch_server.erl
@@ -73,8 +73,8 @@ sup_start_link() ->
 open(DbName, Options0) ->
     Ctx = couch_util:get_value(user_ctx, Options0, #user_ctx{}),
     case ets:lookup(couch_dbs, DbName) of
-    [#db{fd=Fd, fd_monitor=Lock} = Db] when Lock =/= locked ->
-        update_lru(DbName),
+    [#db{fd=Fd, fd_monitor=Lock, options=Options} = Db] when Lock =/= locked ->
+        update_lru(DbName, Options),
         {ok, Db#db{user_ctx=Ctx, fd_monitor=erlang:monitor(process,Fd)}};
     _ ->
         Options = maybe_add_sys_db_callbacks(DbName, Options0),
@@ -91,8 +91,11 @@ open(DbName, Options0) ->
         end
     end.
 
-update_lru(DbName) ->
-    gen_server:cast(couch_server, {update_lru, DbName}).
+update_lru(DbName, Options) ->
+    case lists:member(sys_db, Options) of
+        false -> gen_server:cast(couch_server, {update_lru, DbName});
+        true -> ok
+    end.
 
 close_lru() ->
     gen_server:call(couch_server, close_lru).
@@ -268,15 +271,21 @@ all_databases(Fun, Acc0) ->
     {ok, FinalAcc}.
 
 
+make_room(Server, Options) ->
+    case lists:member(sys_db, Options) of
+        false -> maybe_close_lru_db(Server);
+        true -> {ok, Server}
+    end.
+
 maybe_close_lru_db(#server{dbs_open=NumOpen, max_dbs_open=MaxOpen}=Server)
         when NumOpen < MaxOpen ->
     {ok, Server};
 maybe_close_lru_db(#server{lru=Lru}=Server) ->
     case couch_lru:close(Lru) of
-        false ->
-            {ok, Server};
         {true, NewLru} ->
-            maybe_close_lru_db(db_closed(Server#server{lru = NewLru}))
+            {ok, db_closed(Server#server{lru = NewLru}, [])};
+        false ->
+            {error, all_dbs_active}
     end.
 
 open_async(Server, From, DbName, Filepath, Options) ->
@@ -308,14 +317,14 @@ open_async(Server, From, DbName, Filepath, Options) ->
         options = Options
     }),
     true = ets:insert(couch_dbs_pid_to_name, {Opener, DbName}),
-    db_opened(Server).
+    db_opened(Server, Options).
 
 handle_call(close_lru, _From, #server{lru=Lru} = Server) ->
     case couch_lru:close(Lru) of
-        false ->
-            {reply, ok, Server};
         {true, NewLru} ->
-            {reply, ok, db_closed(Server#server{lru = NewLru})}
+            {reply, ok, db_closed(Server#server{lru = NewLru}, [])};
+        false ->
+            {reply, {error, all_dbs_active}, Server}
     end;
 handle_call(open_dbs_count, _From, Server) ->
     {reply, Server#server.dbs_open, Server};
@@ -348,7 +357,12 @@ handle_call({open_result, T0, DbName, {ok, Db}}, {FromPid, _Tag}, Server) ->
             end,
             true = ets:insert(couch_dbs, Db),
             true = ets:insert(couch_dbs_pid_to_name, {Db#db.main_pid, DbName}),
-            Lru = couch_lru:insert(DbName, Server#server.lru),
+            Lru = case couch_db:is_system_db(Db) of
+                false ->
+                    couch_lru:insert(DbName, Server#server.lru);
+                true ->
+                    Server#server.lru
+            end,
             {reply, ok, Server#server{lru = Lru}}
     end;
 handle_call({open_result, T0, DbName, {error, eexist}}, From, Server) ->
@@ -359,7 +373,7 @@ handle_call({open_result, _T0, DbName, Error}, {FromPid, _Tag}, Server) ->
         [] ->
             % db was deleted during async open
             {reply, ok, Server};
-        [#db{fd=ReqType, compactor_pid=Froms}] ->
+        [#db{fd=ReqType, compactor_pid=Froms}=Db] ->
             [gen_server:reply(From, Error) || From <- Froms],
             couch_log:info("open_result error ~p for ~s", [Error, DbName]),
             true = ets:delete(couch_dbs, DbName),
@@ -370,7 +384,7 @@ handle_call({open_result, _T0, DbName, Error}, {FromPid, _Tag}, Server) ->
                 _ ->
                     Server
             end,
-            {reply, ok, db_closed(NewServer)}
+            {reply, ok, db_closed(NewServer, Db#db.options)}
     end;
 handle_call({open, DbName, Options}, From, Server) ->
     case ets:lookup(couch_dbs, DbName) of
@@ -378,9 +392,13 @@ handle_call({open, DbName, Options}, From, Server) ->
         DbNameList = binary_to_list(DbName),
         case check_dbname(Server, DbNameList) of
         ok ->
-            {ok, Server2} = maybe_close_lru_db(Server),
-            Filepath = get_full_filename(Server, DbNameList),
-            {noreply, open_async(Server2, From, DbName, Filepath, Options)};
+            case make_room(Server, Options) of
+            {ok, Server2} ->
+                Filepath = get_full_filename(Server, DbNameList),
+                {noreply, open_async(Server2, From, DbName, Filepath, Options)};
+            CloseError ->
+                {reply, CloseError, Server}
+            end;
         Error ->
             {reply, Error, Server}
         end;
@@ -402,9 +420,13 @@ handle_call({create, DbName, Options}, From, Server) ->
     ok ->
         case ets:lookup(couch_dbs, DbName) of
         [] ->
-            {ok, Server2} = maybe_close_lru_db(Server),
-            {noreply, open_async(Server2, From, DbName, Filepath,
-                [create | Options])};
+            case make_room(Server, Options) of
+            {ok, Server2} ->
+                {noreply, open_async(Server2, From, DbName, Filepath,
+                        [create | Options])};
+            CloseError ->
+                {reply, CloseError, Server}
+            end;
         [#db{fd=open}=Db] ->
             % We're trying to create a database while someone is in
             % the middle of trying to open it. We allow one creator
@@ -428,18 +450,18 @@ handle_call({delete, DbName, Options}, _From, Server) ->
         Server2 =
         case ets:lookup(couch_dbs, DbName) of
         [] -> Server;
-        [#db{main_pid=Pid, compactor_pid=Froms}] when is_list(Froms) ->
+        [#db{main_pid=Pid, compactor_pid=Froms} = Db] when is_list(Froms) ->
             % icky hack of field values - compactor_pid used to store clients
             true = ets:delete(couch_dbs, DbName),
             true = ets:delete(couch_dbs_pid_to_name, Pid),
             exit(Pid, kill),
             [gen_server:reply(F, not_found) || F <- Froms],
-            db_closed(Server);
-        [#db{main_pid=Pid}] ->
+            db_closed(Server, Db#db.options);
+        [#db{main_pid=Pid} = Db] ->
             true = ets:delete(couch_dbs, DbName),
             true = ets:delete(couch_dbs_pid_to_name, Pid),
             exit(Pid, kill),
-            db_closed(Server)
+            db_closed(Server, Db#db.options)
         end,
 
         %% Delete any leftover compaction files. If we don't do this a
@@ -470,7 +492,10 @@ handle_call({db_updated, #db{}=Db}, _From, Server0) ->
     Server = try ets:lookup_element(couch_dbs, DbName, #db.instance_start_time) of
         StartTime ->
             true = ets:insert(couch_dbs, Db),
-            Lru = couch_lru:update(DbName, Server0#server.lru),
+            Lru = case couch_db:is_system_db(Db) of
+                false -> couch_lru:update(DbName, Server0#server.lru);
+                true -> Server0#server.lru
+            end,
             Server0#server{lru = Lru};
         _ ->
             Server0
@@ -494,7 +519,7 @@ handle_info({'EXIT', _Pid, config_change}, Server) ->
 handle_info({'EXIT', Pid, Reason}, Server) ->
     case ets:lookup(couch_dbs_pid_to_name, Pid) of
     [{Pid, DbName}] ->
-        [#db{compactor_pid=Froms}] = ets:lookup(couch_dbs, DbName),
+        [#db{compactor_pid=Froms}=Db] = ets:lookup(couch_dbs, DbName),
         if Reason /= snappy_nif_not_loaded -> ok; true ->
             Msg = io_lib:format("To open the database `~s`, Apache CouchDB "
                 "must be built with Erlang OTP R13B04 or higher.", [DbName]),
@@ -509,7 +534,7 @@ handle_info({'EXIT', Pid, Reason}, Server) ->
         end,
         true = ets:delete(couch_dbs, DbName),
         true = ets:delete(couch_dbs_pid_to_name, Pid),
-        {noreply, db_closed(Server)};
+        {noreply, db_closed(Server, Db#db.options)};
     [] ->
         {noreply, Server}
     end;
@@ -519,11 +544,17 @@ handle_info(restart_config_listener, State) ->
 handle_info(Info, Server) ->
     {stop, {unknown_message, Info}, Server}.
 
-db_opened(Server) ->
-    Server#server{dbs_open=Server#server.dbs_open + 1}.
+db_opened(Server, Options) ->
+    case lists:member(sys_db, Options) of
+        false -> Server#server{dbs_open=Server#server.dbs_open + 1};
+        true -> Server
+    end.
 
-db_closed(Server) ->
-    Server#server{dbs_open=Server#server.dbs_open - 1}.
+db_closed(Server, Options) ->
+    case lists:member(sys_db, Options) of
+        false -> Server#server{dbs_open=Server#server.dbs_open - 1};
+        true -> Server
+    end.
 
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
diff --git a/src/couch/test/couchdb_views_tests.erl b/src/couch/test/couchdb_views_tests.erl
index f1fddfc1b..7b04e8527 100644
--- a/src/couch/test/couchdb_views_tests.erl
+++ b/src/couch/test/couchdb_views_tests.erl
@@ -372,6 +372,7 @@ couchdb_1283() ->
         MonRef = erlang:monitor(process, CPid),
         Writer3 = spawn_writer(Db3#db.name),
         ?assert(is_process_alive(Writer3)),
+        ?assertEqual({error, all_dbs_active}, get_writer_status(Writer3)),
 
         ?assert(is_process_alive(Writer1)),
         ?assert(is_process_alive(Writer2)),
@@ -390,6 +391,7 @@ couchdb_1283() ->
                   {reason, "Failure compacting view group"}]})
         end,
 
+        ?assertEqual(ok, writer_try_again(Writer3)),
         ?assertEqual(ok, get_writer_status(Writer3)),
 
         ?assert(is_process_alive(Writer1)),