From 3f5f22656a33aec1ba4ed01249732e32d08a8c50 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Fri, 18 Aug 2017 16:56:21 +0200
Subject: erts: Async auto-connect for group_leader/2

---
 erts/emulator/beam/bif.c                  |  6 ++--
 erts/emulator/test/distribution_SUITE.erl | 50 +++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 3 deletions(-)

(limited to 'erts/emulator')

diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 34f5afae78..2583a5f8d6 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -4422,16 +4422,16 @@ BIF_RETTYPE group_leader_2(BIF_ALIST_2)
 	int code;
 	ErtsDSigData dsd;
 	dep = external_pid_dist_entry(BIF_ARG_2);
+	ERTS_ASSERT(dep);
 	if(dep == erts_this_dist_entry)
 	    BIF_ERROR(BIF_P, BADARG);
 
 	code = erts_dsig_prepare(&dsd, &dep, BIF_P, ERTS_PROC_LOCK_MAIN,
-				 ERTS_DSP_NO_LOCK, 0, 0);
+				 ERTS_DSP_NO_LOCK, 0, 1);
 	switch (code) {
 	case ERTS_DSIG_PREP_NOT_ALIVE:
-	    BIF_RET(am_true);
 	case ERTS_DSIG_PREP_NOT_CONNECTED:
-	    BIF_TRAP2(dgroup_leader_trap, BIF_P, BIF_ARG_1, BIF_ARG_2);
+	    BIF_RET(am_true);
 	case ERTS_DSIG_PREP_PENDING:
 	case ERTS_DSIG_PREP_CONNECTED:
 	    code = erts_dsig_send_group_leader(&dsd, BIF_ARG_1, BIF_ARG_2);
diff --git a/erts/emulator/test/distribution_SUITE.erl b/erts/emulator/test/distribution_SUITE.erl
index 98c39dc6dd..fa683f363f 100644
--- a/erts/emulator/test/distribution_SUITE.erl
+++ b/erts/emulator/test/distribution_SUITE.erl
@@ -35,8 +35,12 @@
 
 -include_lib("common_test/include/ct.hrl").
 
+%-define(Line, erlang:display({line,?LINE}),).
+-define(Line,).
+
 -export([all/0, suite/0, groups/0,
          ping/1, bulk_send_small/1,
+         group_leader/1,
          bulk_send_big/1, bulk_send_bigbig/1,
          local_send_small/1, local_send_big/1,
          local_send_legal/1, link_to_busy/1, exit_to_busy/1,
@@ -61,6 +65,7 @@
 
 %% Internal exports.
 -export([sender/3, receiver2/2, dummy_waiter/0, dead_process/0,
+         group_leader_1/1,
          roundtrip/1, bounce/1, do_dist_auto_connect/1, inet_rpc_server/1,
          dist_parallel_sender/3, dist_parallel_receiver/0,
          dist_evil_parallel_receiver/0]).
@@ -74,6 +79,7 @@ suite() ->
 
 all() ->
     [ping, {group, bulk_send}, {group, local_send},
+     group_leader,
      link_to_busy, exit_to_busy, lost_exit, link_to_dead,
      link_to_dead_new_node,
      ref_port_roundtrip, nil_roundtrip, stop_dist,
@@ -124,6 +130,50 @@ ping(Config) when is_list(Config) ->
 
     ok.
 
+%% Test erlang:group_leader(_, ExternalPid), i.e. DOP_GROUP_LEADER
+group_leader(Config) when is_list(Config) ->
+    ?Line Sock = start_relay_node(group_leader_1, []),
+    ?Line Sock2 = start_relay_node(group_leader_2, []),
+    try
+        ?Line Node2 = inet_rpc_nodename(Sock2),
+        ?Line {ok, ok} = do_inet_rpc(Sock, ?MODULE, group_leader_1, [Node2])
+    after
+        ?Line stop_relay_node(Sock),
+        ?Line stop_relay_node(Sock2)
+    end,
+    ok.
+
+group_leader_1(Node2) ->
+    ?Line ExtPid = spawn(Node2, fun F() ->
+                                        receive {From, group_leader} ->
+                                                From ! {self(), group_leader, group_leader()}
+                                        end,
+                                        F()
+                                end),
+    ?Line GL1 = self(),
+    ?Line group_leader(GL1, ExtPid),
+    ?Line ExtPid ! {self(), group_leader},
+    ?Line {ExtPid, group_leader, GL1} = receive_one(),
+
+    %% Kill connection and repeat test when group_leader/2 triggers auto-connect
+    ?Line net_kernel:monitor_nodes(true),
+    ?Line net_kernel:disconnect(Node2),
+    ?Line {nodedown, Node2} = receive_one(),
+    ?Line GL2 = spawn(fun() -> dummy end),
+    ?Line group_leader(GL2, ExtPid),
+    ?Line {nodeup, Node2} = receive_one(),
+    ?Line ExtPid ! {self(), group_leader},
+    ?Line {ExtPid, group_leader, GL2} = receive_one(),
+    ok.
+
+receive_one() ->
+    receive M -> M after 1000 -> timeout end.
+
+
+
+
+
+
 bulk_send_small(Config) when is_list(Config) ->
     bulk_send(64, 32).
 
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