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From kxe...@apache.org
Subject [3/5] config commit: updated refs/heads/master to b281825
Date Wed, 04 Feb 2015 15:49:38 GMT
Callback driven API for config_listener behaviour

This implementaion replaces a mix of message driven and callback driven
API for config_listener. In particular it replaces gen_event_EXIT
message with a call to Module:handle_config_stop(Pid, Reason, State).
This fixes the problem of using config:listen_for_changes in supervisor
context where there is no way to handle arbitrary messages.

COUCHDB-2561


Project: http://git-wip-us.apache.org/repos/asf/couchdb-config/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb-config/commit/e151ae43
Tree: http://git-wip-us.apache.org/repos/asf/couchdb-config/tree/e151ae43
Diff: http://git-wip-us.apache.org/repos/asf/couchdb-config/diff/e151ae43

Branch: refs/heads/master
Commit: e151ae430454121db74a051b61bd23f582bcc39b
Parents: ee24f3e
Author: ILYA Khlopotov <iilyak@ca.ibm.com>
Authored: Thu Jan 29 12:55:27 2015 -0800
Committer: ILYA Khlopotov <iilyak@ca.ibm.com>
Committed: Wed Feb 4 06:00:10 2015 -0800

----------------------------------------------------------------------
 src/config.erl          |  18 +++++-
 src/config_listener.erl |  15 ++---
 test/config_tests.erl   | 137 ++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 159 insertions(+), 11 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/couchdb-config/blob/e151ae43/src/config.erl
----------------------------------------------------------------------
diff --git a/src/config.erl b/src/config.erl
index d123b12..dcffe86 100644
--- a/src/config.erl
+++ b/src/config.erl
@@ -175,7 +175,7 @@ delete(Section, Key, Persist, Reason) when is_list(Section), is_list(Key)
->
 
 
 listen_for_changes(CallbackModule, InitialState) ->
-    config_listener:start(CallbackModule, InitialState).
+    gen_server:call(?MODULE, {listen_for_changes, CallbackModule, InitialState}).
 
 init(IniFiles) ->
     ets:new(?MODULE, [named_table, set, protected]),
@@ -250,14 +250,26 @@ handle_call(reload, _From, Config) ->
                 ets:delete(?MODULE, K)
         end
     end, nil, ?MODULE),
-    {reply, ok, Config}.
-
+    {reply, ok, Config};
+handle_call({listen_for_changes, CallbackModule, InitialState},
+        {Subscriber, _}, Config) ->
+    Reply = config_listener:start(CallbackModule, {Subscriber, InitialState}),
+    {reply, Reply, Config}.
 
 handle_cast(stop, State) ->
     {stop, normal, State};
 handle_cast(_Msg, State) ->
     {noreply, State}.
 
+handle_info({gen_event_EXIT, {config_listener, Module}, shutdown}, State)  ->
+    couch_log:notice("config_listener(~p) stopped with reason: shutdown~n", [Module]),
+    {noreply, State};
+handle_info({gen_event_EXIT, {config_listener, Module}, normal}, State)  ->
+    couch_log:info("config_listener(~p) stopped with reason: shutdown~n", [Module]),
+    {noreply, State};
+handle_info({gen_event_EXIT, {config_listener, Module}, Reason}, State) ->
+    couch_log:error("config_listener(~p) stopped with reason: ~p~n", [Module, Reason]),
+    {noreply, State};
 handle_info(Info, State) ->
     couch_log:error("config:handle_info Info: ~p~n", [Info]),
     {noreply, State}.

http://git-wip-us.apache.org/repos/asf/couchdb-config/blob/e151ae43/src/config_listener.erl
----------------------------------------------------------------------
diff --git a/src/config_listener.erl b/src/config_listener.erl
index 79d3806..22ce366 100644
--- a/src/config_listener.erl
+++ b/src/config_listener.erl
@@ -13,7 +13,7 @@
 -module(config_listener).
 
 -behaviour(gen_event).
--vsn(1).
+-vsn(2).
 
 %% Public interface
 -export([start/2]).
@@ -22,11 +22,12 @@
 -export([behaviour_info/1]).
 
 %% Required gen_event interface
--export([init/1, handle_event/2, handle_call/2, handle_info/2, terminate/2, 
+-export([init/1, handle_event/2, handle_call/2, handle_info/2, terminate/2,
     code_change/3]).
 
 behaviour_info(callbacks) ->
-    [{handle_config_change,5}];
+    [{handle_config_change,5},
+     {handle_config_terminate, 3}];
 behaviour_info(_) ->
     undefined.
 
@@ -39,10 +40,10 @@ start(Module, Id, State) ->
 init({Module, State}) ->
     {ok, {Module, State}}.
 
-handle_event({config_change, Sec, Key, Value, Persist}, {Module, State}) ->
+handle_event({config_change, Sec, Key, Value, Persist}, {Module, {From, State}}) ->
     case Module:handle_config_change(Sec, Key, Value, Persist, State) of
         {ok, NewState} ->
-            {ok, {Module, NewState}};
+            {ok, {Module, {From, NewState}}};
         remove_handler ->
             remove_handler
     end.
@@ -53,8 +54,8 @@ handle_call(_Request, St) ->
 handle_info(_Info, St) ->
     {ok, St}.
 
-terminate(_Reason, _St) ->
-    ok.
+terminate(Reason, {Module, {Subscriber, State}}) ->
+    Module:handle_config_terminate(Subscriber, Reason, State).
 
 code_change(_OldVsn, St, _Extra) ->
     {ok, St}.

http://git-wip-us.apache.org/repos/asf/couchdb-config/blob/e151ae43/test/config_tests.erl
----------------------------------------------------------------------
diff --git a/test/config_tests.erl b/test/config_tests.erl
index dcfb071..2d3968c 100644
--- a/test/config_tests.erl
+++ b/test/config_tests.erl
@@ -12,6 +12,10 @@
 
 -module(config_tests).
 
+-beahiour(config_listener).
+
+-export([handle_config_change/5, handle_config_terminate/3]).
+
 -include_lib("couch/include/couch_eunit.hrl").
 -include_lib("couch/include/couch_db.hrl").
 
@@ -50,6 +54,12 @@ setup(Chain) ->
 setup_empty() ->
     setup([]).
 
+setup_config_listener() ->
+    setup(),
+    {ok, Pid} = spawn_listener(),
+    config:listen_for_changes(?MODULE, {Pid, self(), []}),
+    {Pid, self()}.
+
 teardown({Pid, _}) ->
     stop_listener(Pid),
     [application:stop(App) || App <- ?DEPS];
@@ -59,6 +69,25 @@ teardown(_) ->
 teardown(_, _) ->
     [application:stop(App) || App <- ?DEPS].
 
+handle_config_change("remove_handler", _Key, _Value, _Persist, _State) ->
+    remove_handler;
+handle_config_change("update_state", Key, _Value, _Persist, {Listener, Subscriber, Items})
->
+    NewState = {Listener, Subscriber, [Key|Items]},
+    ok = reply(NewState, NewState),
+    {ok, NewState};
+handle_config_change(Section, Key, Value, Persist, State) ->
+    ok = reply({{Section, Key, Value, Persist}, State}, State),
+    {ok, State}.
+handle_config_terminate(Self, Reason, State) ->
+    ok = reply({stop, Self, Reason, State}, State),
+    ok.
+
+reply(Reply, {Listener, _, _}) ->
+    call_sync(Listener, {set, Reply}).
+
+wait_reply(Listener) ->
+    call_sync(Listener, get).
+
 config_test_() ->
     {
         "CouchDB config tests",
@@ -68,7 +97,8 @@ config_test_() ->
             config_del_tests(),
             config_override_tests(),
             config_persistent_changes_tests(),
-            config_no_files_tests()
+            config_no_files_tests(),
+            config_listener_behaviour_tests()
         ]
     }.
 
@@ -170,6 +200,22 @@ config_no_files_tests() ->
         }
     }.
 
+config_listener_behaviour_tests() ->
+    {
+        "Test config_listener behaviour",
+        {
+            foreach,
+            fun setup_config_listener/0, fun teardown/1,
+            [
+                fun should_handle_value_change/1,
+                fun should_pass_correct_state_to_handle_config_change/1,
+                fun should_pass_correct_state_to_handle_config_terminate/1,
+                fun should_pass_subscriber_pid_to_handle_config_terminate/1,
+                fun should_not_call_handle_config_after_related_process_death/1,
+                fun should_remove_handler_when_requested/1
+            ]
+        }
+    }.
 
 should_load_all_configs() ->
     ?_assert(length(config:all()) > 0).
@@ -316,3 +362,92 @@ should_create_persistent_option() ->
             ok = config:set("httpd", "bind_address", "127.0.0.1"),
             config:get("httpd", "bind_address")
         end).
+
+should_handle_value_change({Pid, _}) ->
+    ?_test(begin
+        ok = config:set("httpd", "port", "80", false),
+        ?assertMatch({{"httpd", "port", "80", false}, _}, wait_reply(Pid))
+    end).
+should_pass_correct_state_to_handle_config_change({Pid, _}) ->
+    ?_test(begin
+        ok = config:set("httpd", "port", "80", false),
+        ?assertMatch({_, {Pid, _, []}}, wait_reply(Pid)),
+        ok = config:set("update_state", "foo", "any", false),
+        ?assertMatch({Pid, _, ["foo"]}, wait_reply(Pid))
+    end).
+should_pass_correct_state_to_handle_config_terminate({Pid, _}) ->
+    ?_test(begin
+        %% prepare some state
+        ok = config:set("httpd", "port", "80", false),
+        ?assertMatch({_, {Pid, _, []}}, wait_reply(Pid)),
+        ok = config:set("update_state", "foo", "any", false),
+        ?assertMatch({Pid, _, ["foo"]}, wait_reply(Pid)),
+
+        %% remove handler
+        ok = config:set("remove_handler", "any", "any", false),
+        Reply = wait_reply(Pid),
+        ?assertMatch({stop, _, remove_handler, _}, Reply),
+
+        {stop, Subscriber, _Reason, State} = Reply,
+        ?assert(is_pid(Subscriber)),
+        ?assertMatch({Pid, Subscriber, ["foo"]}, State)
+    end).
+should_pass_subscriber_pid_to_handle_config_terminate({Pid, SubscriberPid}) ->
+    ?_test(begin
+        ok = config:set("remove_handler", "any", "any", false),
+        Reply = wait_reply(Pid),
+        ?assertMatch({stop, _, remove_handler, _}, Reply),
+
+        {stop, Subscriber, _Reason, _State} = Reply,
+        ?assertMatch(SubscriberPid, Subscriber)
+    end).
+should_not_call_handle_config_after_related_process_death({Pid, _}) ->
+    ?_test(begin
+        ok = config:set("remove_handler", "any", "any", false),
+        Reply = wait_reply(Pid),
+        ?assertMatch({stop, _, remove_handler, _}, Reply),
+
+        ok = config:set("httpd", "port", "80", false),
+        ?assertMatch(undefined, wait_reply(Pid))
+    end).
+should_remove_handler_when_requested({Pid, _}) ->
+    ?_test(begin
+        ?assertEqual(1, n_handlers()),
+
+        ok = config:set("remove_handler", "any", "any", false),
+        Reply = wait_reply(Pid),
+        ?assertMatch({stop, _, remove_handler, _}, Reply),
+
+        ?assertEqual(0, n_handlers())
+    end).
+
+call_sync(Listener, Msg) ->
+    Ref = make_ref(),
+    Listener ! {Ref, self(), Msg},
+    receive
+        {ok, Ref, Reply} -> Reply
+    after ?TIMEOUT ->
+        throw({error, {timeout, call_sync}})
+    end.
+
+spawn_listener() ->
+    {ok, spawn(fun() -> loop(undefined) end)}.
+
+stop_listener(Listener) ->
+    call_sync(Listener, stop).
+
+loop(State) ->
+    receive
+        {Ref, From, stop} ->
+            From ! {ok, Ref, ok},
+            ok;
+        {Ref, From, {set, Value}} ->
+            From ! {ok, Ref, ok},
+            loop(Value);
+        {Ref, From, get} ->
+            From ! {ok, Ref, State},
+            loop(undefined)
+    end.
+
+n_handlers() ->
+    length(gen_event:which_handlers(config_event)).


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