Major change to use the new config app

This replaces couch_config with the config app. The config app is mostly
a direct port of couch_config to a new namespace with the addition of a
rewritten config change notification mechanism. The new change mechanism
removes the ability to register an anonymous function that breaks code
upgrades and generally cleans up the various listening patterns using a
new behavior definition.

3 files changed, 46 insertions, 19 deletions

diff --git a/src/couch_index/src/couch_index.erl b/src/couch_index/src/couch_index.erl
index 483dc59d7..3253a32b2 100644
--- a/src/couch_index/src/couch_index.erl
+++ b/src/couch_index/src/couch_index.erl
@@ -12,18 +12,20 @@
 
 -module(couch_index).
 -behaviour(gen_server).
-
+-behaviour(config_listener).
 
 %% API
 -export([start_link/1, stop/1, get_state/2, get_info/1]).
 -export([trigger_update/2]).
 -export([compact/1, compact/2]).
--export([config_change/3]).
 
 %% gen_server callbacks
 -export([init/1, terminate/2, code_change/3]).
 -export([handle_call/3, handle_cast/2, handle_info/2]).
 
+% config_listener api
+-export([handle_config_change/5]).
+
 
 -include_lib("couch/include/couch_db.hrl").
 
@@ -72,12 +74,8 @@ compact(Pid, Options) ->
     end.
 
 
-config_change("query_server_config", "commit_freq", NewValue) ->
-    ok = gen_server:cast(?MODULE, {config_update, NewValue}).
-
-
 init({Mod, IdxState}) ->
-    ok = couch_config:register(fun ?MODULE:config_change/3),
+    ok = config:listen_for_changes(?MODULE, nil),
     DbName = Mod:get(db_name, IdxState),
     Resp = couch_util:with_db(DbName, fun(Db) ->
         case Mod:open(Db, IdxState) of
@@ -92,7 +90,7 @@ init({Mod, IdxState}) ->
         {ok, NewIdxState} ->
             {ok, UPid} = couch_index_updater:start_link(self(), Mod),
             {ok, CPid} = couch_index_compactor:start_link(self(), Mod),
-            Delay = couch_config:get("query_server_config", "commit_freq", "5"),
+            Delay = config:get("query_server_config", "commit_freq", "5"),
             MsDelay = 1000 * list_to_integer(Delay),
             State = #st{
                 mod=Mod,
@@ -288,6 +286,12 @@ handle_cast(_Mesg, State) ->
     {stop, unhandled_cast, State}.
 
 
+handle_info({gen_event_EXIT, {config_listener, ?MODULE}, _Reason}, State) ->
+    erlang:send_after(5000, self(), restart_config_listener),
+    {noreply, State};
+handle_info(restart_config_listener, State) ->
+    ok = config:listen_for_changes(?MODULE, nil),
+    {noreply, State};
 handle_info(commit, #st{committed=true}=State) ->
     {noreply, State};
 handle_info(commit, State) ->
@@ -321,6 +325,12 @@ code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
 
+handle_config_change("query_server_config", "commit_freq", Val, _, _) ->
+    {ok, gen_server:cast(?MODULE, {config_update, Val})};
+handle_config_change(_, _, _, _, _) ->
+    {ok, nil}.
+
+
 maybe_restart_updater(#st{waiters=[]}) ->
     ok;
 maybe_restart_updater(#st{mod=Mod, idx_state=IdxState}=State) ->
diff --git a/src/couch_index/src/couch_index_server.erl b/src/couch_index/src/couch_index_server.erl
index 8c76a62a2..a106f14e1 100644
--- a/src/couch_index/src/couch_index_server.erl
+++ b/src/couch_index/src/couch_index_server.erl
@@ -12,13 +12,17 @@
 
 -module(couch_index_server).
 -behaviour(gen_server).
+-behaviour(config_listener).
 
 -export([start_link/0, get_index/4, get_index/3, get_index/2]).
--export([config_change/2, update_notify/1]).
+-export([update_notify/1]).
 
 -export([init/1, terminate/2, code_change/3]).
 -export([handle_call/3, handle_cast/2, handle_info/2]).
 
+% config_listener api
+-export([handle_config_change/5]).
+
 -include_lib("couch/include/couch_db.hrl").
 
 -define(BY_SIG, couchdb_indexes_by_sig).
@@ -81,14 +85,14 @@ get_index(Module, IdxState) ->
 
 init([]) ->
     process_flag(trap_exit, true),
-    couch_config:register(fun ?MODULE:config_change/2),
+    ok = config:listen_for_changes(?MODULE, nil),
     ets:new(?BY_SIG, [protected, set, named_table]),
     ets:new(?BY_PID, [private, set, named_table]),
     ets:new(?BY_DB, [protected, bag, named_table]),
     couch_db_update_notifier:start_link(fun ?MODULE:update_notify/1),
     RootDir = couch_index_util:root_dir(),
     % Deprecation warning if it wasn't index_dir
-    case couch_config:get("couchdb", "index_dir") of
+    case config:get("couchdb", "index_dir") of
         undefined ->
             Msg = "Deprecation warning: 'view_index_dir' is now 'index_dir'",
             ?LOG_ERROR(Msg, []);
@@ -137,6 +141,12 @@ handle_cast({reset_indexes, DbName}, State) ->
     {noreply, State}.
 
 
+handle_info({gen_event_EXIT, {config_listener, ?MODULE}, _Reason}, State) ->
+    erlang:send_after(5000, self(), restart_config_listener),
+    {noreply, State};
+handle_info(restart_config_listener, State) ->
+    ok = config:listen_for_changes(?MODULE, State#st.root_dir),
+    {noreply, State};
 handle_info({'EXIT', Pid, Reason}, Server) ->
     case ets:lookup(?BY_PID, Pid) of
         [{Pid, {DbName, Sig}}] ->
@@ -158,6 +168,19 @@ code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
 
+handle_config_change("couchdb", "index_dir", RootDir, _, RootDir) ->
+    {ok, RootDir};
+handle_config_change("couchdb", "view_index_dir", RootDir, _, RootDir) ->
+    {ok, RootDir};
+handle_config_change("couchdb", "index_dir", _, _, _) ->
+    exit(whereis(couch_index_server), config_change),
+    remove_handler;
+handle_config_change("couchdb", "view_index_dir", _, _, _) ->
+    exit(whereis(couch_index_server), config_change),
+    remove_handler;
+handle_config_change(_, _, _, _, RootDir) ->
+    {ok, RootDir}.
+
 new_index({Mod, IdxState, DbName, Sig}) ->
     DDocId = Mod:get(idx_name, IdxState),
     case couch_index:start_link({Mod, IdxState}) of
@@ -197,12 +220,6 @@ rem_from_ets(DbName, Sig, DDocId, Pid) ->
     ets:delete_object(?BY_DB, {DbName, {DDocId, Sig}}).
 
 
-config_change("couchdb", "view_index_dir") ->
-    exit(whereis(?MODULE), config_change);
-config_change("couchdb", "index_dir") ->
-    exit(whereis(?MODULE), config_change).
-
-
 update_notify({deleted, DbName}) ->
     gen_server:cast(?MODULE, {reset_indexes, DbName});
 update_notify({created, DbName}) ->
diff --git a/src/couch_index/src/couch_index_util.erl b/src/couch_index/src/couch_index_util.erl
index cef05f5c1..cf1ff7561 100644
--- a/src/couch_index/src/couch_index_util.erl
+++ b/src/couch_index/src/couch_index_util.erl
@@ -19,8 +19,8 @@
 
 
 root_dir() ->
-    case couch_config:get("couchdb", "index_dir") of
-        undefined -> couch_config:get("couchdb", "view_index_dir");
+    case config:get("couchdb", "index_dir") of
+        undefined -> config:get("couchdb", "view_index_dir");
         Value -> Value
     end.