Demonitor users db when reinitializing the couch_auth_cachedemonitor-in-couch-auth-cache-tests

Previously when the db was re-initialized it ended up stacking monitors. We
need to demonitor the previous instance before getting a new one.

Issue: #2493

2 files changed, 25 insertions, 5 deletions

diff --git a/src/couch/src/couch_auth_cache.erl b/src/couch/src/couch_auth_cache.erl
index 157b0902e..d93d7fc0e 100644
--- a/src/couch/src/couch_auth_cache.erl
+++ b/src/couch/src/couch_auth_cache.erl
@@ -39,7 +39,8 @@
     max_cache_size = 0,
     cache_size = 0,
     db_notifier = nil,
-    event_listener = nil
+    event_listener = nil,
+    auth_db_monitor = nil
 }).
 
 
@@ -243,7 +244,10 @@ handle_info(restart_config_listener, State) ->
 
 
 
-terminate(_Reason, #state{event_listener = Listener}) ->
+terminate(_Reason, #state{event_listener = Listener, auth_db_monitor = Mon}) ->
+    if Mon =:= nil -> ok; true ->
+        erlang:demonitor(Mon, [flush])
+    end,
     couch_event:stop_listener(Listener),
     exec_if_auth_db(fun(AuthDb) -> catch couch_db:close(AuthDb) end),
     true = ets:delete(?BY_USER),
@@ -276,13 +280,16 @@ clear_cache(State) ->
 
 
 reinit_cache(#state{} = State) ->
+    Mon = State#state.auth_db_monitor,
+    if Mon =:= nil -> ok; true ->
+        erlang:demonitor(Mon, [flush])
+    end,
     NewState = clear_cache(State),
     AuthDbName = ?l2b(config:get("couch_httpd_auth", "authentication_db")),
     true = ets:insert(?STATE, {auth_db_name, AuthDbName}),
     AuthDb = open_auth_db(),
     true = ets:insert(?STATE, {auth_db, AuthDb}),
-    couch_db:monitor(AuthDb),
-    NewState.
+    NewState#state{auth_db_monitor = couch_db:monitor(AuthDb)}.
 
 
 add_cache_entry(_, _, _, #state{max_cache_size = 0} = State) ->
diff --git a/src/couch/test/eunit/couch_auth_cache_tests.erl b/src/couch/test/eunit/couch_auth_cache_tests.erl
index 5439dd7b9..18aa943bc 100644
--- a/src/couch/test/eunit/couch_auth_cache_tests.erl
+++ b/src/couch/test/eunit/couch_auth_cache_tests.erl
@@ -53,7 +53,8 @@ couch_auth_cache_test_() ->
                     fun should_restore_cache_on_auth_db_change/1,
                     fun should_recover_cache_after_shutdown/1,
                     fun should_close_old_db_on_auth_db_change/1,
-                    fun should_get_admin_from_config/1
+                    fun should_get_admin_from_config/1,
+                    fun should_not_pile_on_monitors/1
                 ]
             }
         }
@@ -247,6 +248,18 @@ should_get_admin_from_config(_DbName) ->
         ?assertEqual([<<"_admin">>], Roles)
     end).
 
+should_not_pile_on_monitors(_DbName) ->
+    ?_test(begin
+        Pid = whereis(couch_auth_cache),
+        {monitors, Mons0} =  erlang:process_info(Pid, monitors),
+        lists:foreach(fun(_) ->
+            gen_server:call(Pid, reinit_cache)
+        end, lists:seq(1,100)),
+        {monitors, Mons1} =  erlang:process_info(Pid, monitors),
+        ?assertEqual(Mons0, Mons1)
+    end).
+
+
 update_user_doc(DbName, UserName, Password) ->
     update_user_doc(DbName, UserName, Password, nil).