- allow for removal of fuses

- update fuse_eqc test with remove command
- update fuse_SUITE with common test for remove

src/fuse.erl

@@ -10,6 +10,7 @@
 	ask/2,
 	install/2,
 	melt/1,
+	remove/1,
 	reset/1,
 	run/3
 ]).
@@ -69,6 +70,14 @@ reset(Name) ->
 melt(Name) ->
 	fuse_server:melt(Name).
 
+%% @doc remove/1 removs a fuse
+%% Given `remove(N)' this removes the fuse under the name `N'. This fuse will no longer exist.
+%% @end
+-spec remove(Name) -> ok
+  when Name :: atom().
+remove(Name) ->
+    fuse_server:remove(Name).
+
 %% Internal functions
 %% -----------------------
 

src/fuse_server.erl

@@ -16,6 +16,7 @@
     ask/2,
     install/2,
     melt/1,
+    remove/1,
     reset/1,
     run/3]).
 
@@ -96,7 +97,14 @@ reset(Name) ->
     when Name :: atom().
 melt(Name) ->
 	gen_server:call(?MODULE, {melt, Name}).
-
+
+%% @doc remove/1 removes the fuse
+%% The documentation is (@see fuse:remove/1)
+%% @end
+-spec remove(atom()) -> ok | {error, not_found}.
+remove(Name) ->
+	gen_server:call(?MODULE, {remove, Name}).
+
 %% sync/0 syncs the server. For internal use only in tests
 %% @private
 sync() ->
@@ -147,6 +155,9 @@ handle_call({install, #fuse { name = Name } = Fuse}, _From, #state { fuses = Fs
 handle_call({reset, Name}, _From, State) ->
 	{Reply, State2} = handle_reset(Name, State, reset),
 	{reply, Reply, State2};
+handle_call({remove, Name}, _From, State) ->
+	{Reply, State2} = handle_remove(Name, State),
+	{reply, Reply, State2};
 handle_call({melt, Name}, _From, State) ->
 	Now = ?TIME:monotonic_time(),
 	{Res, State2} = with_fuse(Name, State, fun(F) -> add_restart(Now, F) end),
@@ -165,7 +176,7 @@ handle_call(q_melts, _From, #state { fuses = Fs } = State) ->
         {reply, [{N, Ms} || #fuse { name = N, melt_history = Ms } <- Fs], State};
 handle_call(_M, _F, State) ->
 	{reply, {error, unknown}, State}.
-	
+
 %% @private
 handle_cast(_M, State) ->
 	{noreply, State}.
@@ -206,6 +217,14 @@ handle_reset(Name, State, ResetType) ->
 	  not_found -> {{error, not_found}, State2}
 	end.
 
+handle_remove(Name, #state { fuses = Fs } = State) ->
+    case lists:keytake(Name, #fuse.name, Fs) of
+        false -> {{error, not_found}, State};
+        {value, F, OtherFs} ->
+            delete(F),
+            {ok, State#state { fuses = OtherFs }}
+    end.
+
 init_state(Name, {{standard, MaxR, MaxT}, {reset, Reset}}) ->
     NativePeriod = ?TIME:convert_time_unit(MaxT, milli_seconds, native),
     #fuse { name = Name, intensity = MaxR, period = NativePeriod, heal_time = Reset }.
@@ -237,7 +256,7 @@ add_restart_([R|Restarts], Now, Period) ->
         false -> []
     end;
 add_restart_([], _, _) -> [].
-    
+
 in_period(Time, Now, Period) when (Now - Time) > Period -> false;
 in_period(_, _, _) -> true.
 
@@ -251,6 +270,11 @@ fix(#fuse { name = Name }) ->
     fuse_event:notify({Name, ok}),
     ok.
 
+delete(#fuse { name = Name }) ->
+    ets:delete(?TAB, Name),
+    fuse_event:notify({Name, removed}),
+    ok.
+
 install_metrics(#fuse { name = N }) ->
 	StatsPlugin = application:get_env(fuse, stats_plugin, fuse_stats_ets),
 	_ = StatsPlugin:init(N),

test/fuse_SUITE.erl

@@ -12,7 +12,8 @@
 %% Tests.
 -export([
 	simple_test/1,
-	reset_test/1
+	reset_test/1,
+	remove_test/1
 ]).
 
 -ifdef(EQC_TESTING).
@@ -24,11 +25,12 @@
 %% ct.
 all() -> [
 	simple_test,
-	reset_test
+	reset_test,
+	remove_test
 ].
-	
+
 groups() -> [].
-	
+
 suite() ->
 	[{timetrap, {minutes, 2}}].
 
@@ -45,15 +47,15 @@ init_per_suite(Config) ->
       true ->
         {skip, running_eqc}
     end.
-	
-end_per_suite(_Config) ->	
+
+end_per_suite(_Config) ->
 	application:stop(fuse),
 	application:stop(sasl),
 	ok.
-	
+
 init_per_group(_Group, Config) ->
 	Config.
-	
+
 end_per_group(_Group, _Config) ->
 	ok.
 
@@ -114,3 +116,27 @@ reset_test(_Config) ->
 	2 = proplists:get_value(ok, Stats),
 	1 = proplists:get_value(blown, Stats),
 	ok.
+
+-define(FUSE_REMOVE, remove_fuse).
+remove_test(_Config) ->
+	ct:log("Install a fuse, melt it, blow it, then remove it, then recreate it"),
+	ok = fuse:install(?FUSE_REMOVE, {{standard, 2, 60}, {reset, 5000}}),
+	ok = fuse:ask(?FUSE_REMOVE, sync),
+	ok = fuse:melt(?FUSE_REMOVE),
+	ok = fuse:melt(?FUSE_REMOVE),
+	ok = fuse:melt(?FUSE_REMOVE),
+	blown = fuse:ask(?FUSE_REMOVE, sync),
+	Stats = fuse_stats_ets:counters(?FUSE_REMOVE),
+	3 = proplists:get_value(melt, Stats),
+	1 = proplists:get_value(ok, Stats),
+	1 = proplists:get_value(blown, Stats),
+	ok = fuse:remove(?FUSE_REMOVE),
+	{error, not_found} = fuse:ask(?FUSE_REMOVE, sync),
+	{error, not_found} = fuse:remove(?FUSE_REMOVE),
+	ok = fuse:install(?FUSE_REMOVE, {{standard, 2, 60}, {reset, 5000}}),
+	ok = fuse:ask(?FUSE_REMOVE, sync),
+	Stats2 = fuse_stats_ets:counters(?FUSE_REMOVE),
+	0 = proplists:get_value(melt, Stats2),
+	1 = proplists:get_value(ok, Stats2),
+	0 = proplists:get_value(blown, Stats2),
+	ok.

test/fuse_eqc.erl

@@ -61,7 +61,7 @@ g_strategy() ->
 %% g_refresh()/0 generates a refresh setting.
 g_refresh() ->
     {reset, 60000}.
-    
+
 %% g_options() generates install options
 g_options() ->
     {g_strategy(), g_refresh()}.
@@ -80,7 +80,7 @@ initial_state() -> #state{}.
 %% at a later point than normally.
 elapse_time(N) ->
     fuse_time_mock:elapse_time(N).
-    
+
 elapse_time_args(_S) -> [g_time_inc()].
 
 elapse_time_next(#state { time = T } = State, _V, [N]) ->
@@ -202,7 +202,7 @@ reset_features(S, [Name], _V) ->
 %% Split into two variants
 ask_installed(Name) ->
     fuse:ask(Name, ?CONTEXT).
-    
+
 ask_installed_pre(S) -> has_fuses_installed(S).
 
 ask_installed_args(_S) -> [g_name()].
@@ -219,11 +219,11 @@ ask_installed_return(S, [Name]) ->
 
 ask(Name) ->
     fuse:ask(Name, ?CONTEXT).
-    
+
 ask_pre(S) -> has_fuses_installed(S).
 
 ask_args(_S) -> [g_name()].
-    
+
 ask_features(S, [Name], _V) ->
     case is_installed(Name, S) of
        true -> [{fuse_eqc, r15, ask_installed}];
@@ -245,7 +245,7 @@ ask_return(S, [Name]) ->
 %% ---------------------------------------------------------------
 run(Name, _Result, _Return, Fun) ->
     fuse:run(Name, Fun, ?CONTEXT).
-    
+
 run_pre(S) ->
     has_fuses_installed(S).
 
@@ -307,14 +307,14 @@ run_return(S, [Name, _Result, Return, _]) ->
 %% fuses which are installed, since we assume the interesting aspects affects these.
 melt_installed(Name) ->
     fuse:melt(Name).
-    
+
 melt_installed_pre(S) -> has_fuses_installed(S).
 
 melt_installed_args(_S) -> [g_name()].
 
 melt_installed_pre(S, [Name]) ->
     is_installed(Name, S).
-    
+
 melt_installed_next(#state { time = Ts } = S, _V, [Name]) ->
     M = val(record_melt(Name, Ts, S)),
     {_, NewState} =
@@ -365,9 +365,41 @@ melt_features(#state { time = Ts } = S, [Name], _V) ->
               [{fuse_eqc, r11, melt_installed_fuse}] ++ Features;
         false -> [{fuse_eqc, r12, melt_uninstalled_fuse}]
     end.
-        
+
 melt_return(_S, _) -> ok.
 
+%% remove/1 removes a fuse
+%% ---------------------------------------------------------------
+remove(Name) ->
+    fuse:remove(Name).
+
+%% Generate arguments to remove from a fuse that's actually installed vs
+%% fuses that are not.
+remove_args(#state { installed = Is } = _S) ->
+    frequency(
+      [ {20, ?LET(F, elements(Is), [element(1, F)])} || Is /= [] ] ++
+      [ {1, ?SUCHTHAT([F], [g_name()], lists:keymember(F, 1, Is) == false)} ]).
+
+remove_return(S, [Name]) ->
+    case is_installed(Name, S) of
+        true -> ok;
+        false -> {error, not_found}
+    end.
+
+%% Removing a fuse, removes it from the list of installed fuses.
+remove_next(#state{ installed = Is } = S, _V, [Name]) ->
+    case is_installed(Name, S) of
+        false -> S;
+        true ->
+            S#state { installed = lists:keydelete(Name, 1, Is) }
+     end.
+
+remove_features(S, [Name], _V) ->
+    case is_installed(Name, S) of
+        false -> [{fuse_eqc, r17, remove_uninstalled_fuse}];
+        true -> [{fuse_eqc, r18, remove_installed_fuse}]
+    end.
+
 %%% Command weight distribution
 %% ---------------------------------------------------------------
 weight(_, elapse_time) -> 5;
@@ -378,7 +410,8 @@ weight(_, melt) -> 1;
 weight(_, melt_installed) -> 40;
 weight(_, fuse_reset) -> 100;
 weight(_, ask) -> 1;
-weight(_, ask_installed) -> 30.
+weight(_, ask_installed) -> 30;
+weight(_, remove) -> 1.
 
 %%% PROPERTIES
 %% ---------------------------------------------------------------
@@ -412,7 +445,7 @@ prop_model_par() ->
                    fun() -> ok end
            end,
     fault_rate(1, 40,
-     ?LET(Shrinking, parameter(shrinking, false), 
+     ?LET(Shrinking, parameter(shrinking, false),
     ?FORALL(Cmds, more_commands(2, parallel_commands(?MODULE)),
       ?ALWAYS(if not Shrinking -> 1;
                      Shrinking -> 20
@@ -478,13 +511,13 @@ valid_opts({{standard, K, R}, {reset, T}})
     true;
 valid_opts(_) ->
     false.
-    
+
 melt_state(Name, S) ->
     count_state(fuse_intensity(Name, S) - count_melts(Name, S)).
 
 is_blown(Name, #state { blown = BlownFuses }) ->
     lists:member(Name, BlownFuses).
-    
+
 fuse_intensity(Name, #state { installed = Inst }) ->
     {Name, Count, _} = lists:keyfind(Name, 1, Inst),
     Count.
@@ -526,7 +559,7 @@ expire_melts(Period, Who, #state { time = Now, melts = Ms } = S) ->
 
 clear_blown(Name, #state { blown = Rs } = S) ->
     S#state { blown = [N || N <- Rs, N /= Name] }.
-    
+
 clear_melts(Name, #state { melts = Ms } = S) ->
     S#state { melts = [{N, Ts} || {N, Ts} <- Ms, N /= Name] }.
 
@@ -547,7 +580,7 @@ t(pulse, {T, Unit}) ->
     eqc:testing_time(eval_time(T, Unit), x_prop_model_pulse());
 t(pulse, N) when is_integer(N) ->
     eqc:numtests(N, x_prop_model_pulse()).
-    
+
 
 eval_time(N, h)   -> eval_time(N*60, min);
 eval_time(N, min) -> eval_time(N*60, sec);
@@ -562,7 +595,7 @@ rv(What, T) ->
 pulse_instrument() ->
   [ pulse_instrument(File) || File <- filelib:wildcard("../src/*.erl") ++ filelib:wildcard("../eqc_test/*.erl") ],
   load_sasl().
-  
+
 load_sasl() ->
   application:load(sasl),
   application:set_env(sasl, sasl_error_logger, false),