erts: Add enif_consume_timeslice

5 files changed, 146 insertions, 5 deletions

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 068f904b76..d4c2b5bdcc 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -1443,6 +1443,19 @@ void* enif_dlsym(void* handle, const char* symbol,
     return ret;
 }
 
+int enif_consume_timeslice(ErlNifEnv* env, int percent)
+{
+    Sint reds;
+
+    ASSERT(is_proc_bound(env) && percent >= 1 && percent <= 100);
+    if (percent < 1) percent = 1;
+    else if (percent > 100) percent = 100;
+
+    reds = ((CONTEXT_REDS+99) / 100) * percent;
+    ASSERT(reds > 0 && reds <= CONTEXT_REDS);
+    BUMP_REDS(env->proc, reds);
+    return ERTS_BIF_REDS_LEFT(env->proc) == 0;
+}
 
 /***************************************************************************
  **                              load_nif/2                               **
diff --git a/erts/emulator/beam/erl_nif.h b/erts/emulator/beam/erl_nif.h
index 93e56332e1..62aebcab6c 100644
--- a/erts/emulator/beam/erl_nif.h
+++ b/erts/emulator/beam/erl_nif.h
@@ -32,10 +32,11 @@
 ** 2.0: R14A
 ** 2.1: R14B02 "vm_variant"
 ** 2.2: R14B03 enif_is_exception
-** 2.3: R15 enif_make_reverse_list
+** 2.3: R15 enif_make_reverse_list, enif_is_number
+** 2.4: R16 enif_consume_timeslice
 */
 #define ERL_NIF_MAJOR_VERSION 2
-#define ERL_NIF_MINOR_VERSION 3
+#define ERL_NIF_MINOR_VERSION 4
 
 #include <stdlib.h>
 
diff --git a/erts/emulator/beam/erl_nif_api_funcs.h b/erts/emulator/beam/erl_nif_api_funcs.h
index af27573433..2f841645e1 100644
--- a/erts/emulator/beam/erl_nif_api_funcs.h
+++ b/erts/emulator/beam/erl_nif_api_funcs.h
@@ -140,6 +140,7 @@ ERL_NIF_API_FUNC_DECL(int,enif_make_reverse_list,(ErlNifEnv*, ERL_NIF_TERM term,
 ERL_NIF_API_FUNC_DECL(int,enif_is_number,(ErlNifEnv*, ERL_NIF_TERM term));
 ERL_NIF_API_FUNC_DECL(void*,enif_dlopen,(const char* lib, void (*err_handler)(void*,const char*), void* err_arg));
 ERL_NIF_API_FUNC_DECL(void*,enif_dlsym,(void* handle, const char* symbol, void (*err_handler)(void*,const char*), void* err_arg));
+ERL_NIF_API_FUNC_DECL(int,enif_consume_timeslice,(ErlNifEnv*, int percent));
 
 /*
 ** Add new entries here to keep compatibility on Windows!!!
@@ -264,6 +265,7 @@ ERL_NIF_API_FUNC_DECL(void*,enif_dlsym,(void* handle, const char* symbol, void (
 #  define enif_is_number ERL_NIF_API_FUNC_MACRO(enif_is_number)
 #  define enif_dlopen ERL_NIF_API_FUNC_MACRO(enif_dlopen)
 #  define enif_dlsym ERL_NIF_API_FUNC_MACRO(enif_dlsym)
+#  define enif_consume_timeslice ERL_NIF_API_FUNC_MACRO(enif_consume_timeslice)
 
 /*
 ** Add new entries here
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 6bd7361612..0a9d997c3b 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -36,7 +36,7 @@
 	 threading/1, send/1, send2/1, send3/1, send_threaded/1, neg/1, 
 	 is_checks/1,
 	 get_length/1, make_atom/1, make_string/1, reverse_list_test/1,
-	 otp_9668/1
+	 otp_9668/1, consume_timeslice/1
 	]).
 
 -export([many_args_100/100]).
@@ -63,7 +63,7 @@ all() ->
      resource_takeover, threading, send, send2, send3,
      send_threaded, neg, is_checks, get_length, make_atom,
      make_string,reverse_list_test,
-     otp_9668
+     otp_9668, consume_timeslice
     ].
 
 groups() -> 
@@ -1259,6 +1259,108 @@ otp_9668(Config) ->
     ?line verify_tmpmem(TmpMem),
     ok.
 
+consume_timeslice(Config) when is_list(Config) ->
+    CONTEXT_REDS = 2000,
+    Me = self(),
+    Go = make_ref(),
+    RedDiff = make_ref(),
+    Done = make_ref(),
+    DummyMFA = {?MODULE,dummy_call,1},
+    P = spawn(fun () ->
+		      receive Go -> ok end,
+		      {reductions, R1} = process_info(self(), reductions),
+		      1 = consume_timeslice_nif(100, false),
+		      dummy_call(111),
+		      0 = consume_timeslice_nif(90, false),
+		      dummy_call(222),
+		      1 = consume_timeslice_nif(10, false),
+		      dummy_call(333),
+		      0 = consume_timeslice_nif(25, false),
+		      0 = consume_timeslice_nif(25, false),
+		      0 = consume_timeslice_nif(25, false),
+		      1 = consume_timeslice_nif(25, false),
+		      0 = consume_timeslice_nif(25, false),
+
+		      ok = case consume_timeslice_nif(1, true) of
+			       Cnt when Cnt > 70, Cnt < 80 -> ok;
+			       Other -> Other
+			   end,
+		      dummy_call(444),
+
+		      {reductions, R2} = process_info(self(), reductions),
+		      Me ! {RedDiff, R2 - R1},
+		      exit(Done)
+	end),
+    erlang:yield(),
+
+    erlang:trace_pattern(DummyMFA, [], [local]),
+    ?line 1 = erlang:trace(P, true, [call, running, procs, {tracer, self()}]),
+
+    P ! Go,
+
+    %% receive Go -> ok end,
+    ?line {trace, P, in, _} = next_tmsg(P),
+    
+    %% consume_timeslice_nif(100),
+    %% dummy_call(111)
+    ?line {trace, P, out, _} = next_tmsg(P),
+    ?line {trace, P, in, _} = next_tmsg(P),
+    ?line {trace, P, call, {?MODULE,dummy_call,[111]}} = next_tmsg(P),
+
+    %% consume_timeslice_nif(90),
+    %% dummy_call(222)
+    ?line {trace, P, call, {?MODULE,dummy_call,[222]}} = next_tmsg(P),
+
+    %% consume_timeslice_nif(10),
+    %% dummy_call(333)
+    ?line {trace, P, out, _} = next_tmsg(P),
+    ?line {trace, P, in, _} = next_tmsg(P),
+    ?line {trace, P, call, {?MODULE,dummy_call,[333]}} = next_tmsg(P),
+
+    %% 25,25,25,25, 25
+    ?line {trace, P, out, {?MODULE,consume_timeslice_nif,2}} = next_tmsg(P),
+    ?line {trace, P, in, {?MODULE,consume_timeslice_nif,2}} = next_tmsg(P),
+
+    %% consume_timeslice(1,true)
+    %% dummy_call(444)
+    ?line {trace, P, out, DummyMFA} = next_tmsg(P),
+    ?line {trace, P, in, DummyMFA} = next_tmsg(P),
+    ?line {trace, P, call, {?MODULE,dummy_call,[444]}} = next_tmsg(P),
+
+    %% exit(Done)
+    ?line {trace, P, exit, Done} = next_tmsg(P),
+
+    ExpReds = (100 + 90 + 10 + 25*5 + 75) * CONTEXT_REDS div 100,
+    receive
+	{RedDiff, Reductions} when Reductions < (ExpReds + 10), Reductions > (ExpReds - 10) ->
+	    io:format("Reductions = ~p~n", [Reductions]),
+	    ok;
+	{RedDiff, Reductions} ->
+	    ?t:fail({unexpected_reduction_count, Reductions})
+    end,
+    
+    none = next_msg(P),
+
+    ok.
+
+next_msg(Pid) ->
+    receive
+	M -> M
+    after 100 ->
+	  none
+    end.
+
+next_tmsg(Pid) ->    
+    receive TMsg when is_tuple(TMsg),
+		      element(1, TMsg) == trace,
+		      element(2, TMsg) == Pid ->
+     	    TMsg
+     after 100 ->
+     	    none
+     end.
+
+dummy_call(_) ->    
+    ok.
 
 tmpmem() ->
     case erlang:system_info({allocator,temp_alloc}) of
@@ -1370,6 +1472,7 @@ reverse_list(_) -> ?nif_stub.
 echo_int(_) -> ?nif_stub.
 type_sizes() -> ?nif_stub.
 otp_9668_nif(_) -> ?nif_stub.
+consume_timeslice_nif(_,_) -> ?nif_stub.
 
 nif_stub_error(Line) ->
     exit({nif_not_loaded,module,?MODULE,line,Line}).
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 03092fef5e..2504d24b51 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -1456,6 +1456,27 @@ static ERL_NIF_TERM otp_9668_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM ar
     return atom_ok;
 }
 
+static ERL_NIF_TERM consume_timeslice_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    int percent;
+    char atom[10];
+    int do_repeat;
+
+    if (!enif_get_int(env, argv[0], &percent) ||
+	!enif_get_atom(env, argv[1], atom, sizeof(atom), ERL_NIF_LATIN1)) {
+	return enif_make_badarg(env);
+    }
+    if (strcmp(atom , "true") == 0) {
+	int cnt = 1;
+	while (enif_consume_timeslice(env, percent) == 0 && cnt < 200)
+	    cnt++;
+	return enif_make_int(env, cnt);
+    }
+    else {
+	return enif_make_int(env, enif_consume_timeslice(env, percent));
+    }
+}
+
 static ErlNifFunc nif_funcs[] =
 {
     {"lib_version", 0, lib_version},
@@ -1504,7 +1525,8 @@ static ErlNifFunc nif_funcs[] =
     {"reverse_list",1, reverse_list},
     {"echo_int", 1, echo_int},
     {"type_sizes", 0, type_sizes},
-    {"otp_9668_nif", 1, otp_9668_nif}
+    {"otp_9668_nif", 1, otp_9668_nif},
+    {"consume_timeslice_nif", 2, consume_timeslice_nif}
 };
 
 ERL_NIF_INIT(nif_SUITE,nif_funcs,load,reload,upgrade,unload)