[kernel] Introduce connect_all kernel parameter

Also fix the '-connect_all' command line argument.

7 files changed, 84 insertions, 23 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 340196502f..9a33daccb3 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -218,10 +218,11 @@
       </item>
       <tag><marker id="connect_all"/><c><![CDATA[-connect_all false]]></c></tag>
       <item>
-        <p>If this flag is present, <c><![CDATA[global]]></c> does not maintain
-          a fully connected network of distributed Erlang nodes, and then
-          global name registration cannot be used; see
-          <seealso marker="kernel:global"><c>global(3)</c></seealso>.</p>
+        <p>
+          This flag is deprecated and has been replaced by the <c>kernel</c>
+          application parameter
+          <seealso marker="kernel:kernel_app#connect_all"><c>connect_all</c></seealso>.
+        </p>
       </item>
       <tag><c><![CDATA[-cookie Cookie]]></c></tag>
       <item>
diff --git a/lib/kernel/doc/src/global.xml b/lib/kernel/doc/src/global.xml
index b8385436b5..afe7ea793b 100644
--- a/lib/kernel/doc/src/global.xml
+++ b/lib/kernel/doc/src/global.xml
@@ -70,6 +70,17 @@
         enabled by default.
       </p>
     </warning>
+    <note>
+      <p>
+        None of the above services will be reliably delivered unless both of
+        the kernel parameters
+        <seealso marker="kernel_app#connect_all"><c>connect_all</c></seealso>
+        and <seealso marker="kernel_app#prevent_overlapping_partitions">
+        <c>prevent_overlapping_partitions</c></seealso> are enabled. Calls to
+        the <c>global</c> API will, however, <i>not</i> fail even though one or
+        both of them are disabled. You will just get unreliable results.
+      </p>
+    </note>
     <p>These services are controlled through the process
       <c>global_name_server</c> that exists on every node. The global
       name server starts automatically when a node is started.
@@ -108,9 +119,7 @@
       example, if node <c>N1</c> connects to node <c>N2</c> (which is
       already connected to <c>N3</c>), the global name servers on the
       nodes <c>N1</c> and <c>N3</c> ensure that also <c>N1</c>
-      and <c>N3</c> are connected. If this is not desired,
-      command-line flag <c>-connect_all false</c> can be used (see also
-      <seealso marker="erts:erl#connect_all"><c>erl(1)</c></seealso>).
+      and <c>N3</c> are connected.
       In this case, the name registration service cannot be used, but the
       lock mechanism still works.</p>
     <p>If the global name server fails to connect nodes (<c>N1</c> and
diff --git a/lib/kernel/doc/src/kernel_app.xml b/lib/kernel/doc/src/kernel_app.xml
index aef5a9fbe2..d3aee7630c 100644
--- a/lib/kernel/doc/src/kernel_app.xml
+++ b/lib/kernel/doc/src/kernel_app.xml
@@ -121,6 +121,32 @@
       application. For more information about configuration parameters,
     see file <seealso marker="app"><c>app(4)</c></seealso>.</p>
     <taglist>
+      <tag><marker id="connect_all"/>
+      <c>connect_all = true | false</c></tag>
+      <item>
+        <p>
+          If enabled (<c>true</c>), which also is the default,
+          <seealso marker="global"><c>global(3)</c></seealso> will
+          actively connect to all nodes that becomes known to it. Note
+          that you also want to enable
+          <seealso marker="#prevent_overlapping_partitions">
+          <c>prevent_overlapping_partitions</c></seealso> in order for
+          <c>global</c> to ensure that a fully connected network
+          is maintained. <c>prevent_overlapping_partitions</c>
+          will also prevent inconsistencies in <c>global</c>'s
+          name registration and locking. Note that
+          <c>prevent_overlapping_partitions</c> currently is disabled
+          by default.
+        </p>
+        <p>
+          The now deprecated command line argument
+          <seealso marker="erts:erl#connect_all"><c>-connect_all
+          &lt;boolean&gt;</c></seealso> has the same effect as the
+          <c>connect_all</c> configuration parameter. If this
+          configuration parameter is defined, it will override
+          the command line argument.
+        </p>
+      </item>
       <tag><c>distributed = [Distrib]</c></tag>
       <item>
         <p>Specifies which applications that are distributed and on which
diff --git a/lib/kernel/src/global.erl b/lib/kernel/src/global.erl
index f61ccb1c56..0c100136e2 100644
--- a/lib/kernel/src/global.erl
+++ b/lib/kernel/src/global.erl
@@ -546,23 +546,35 @@ init([]) ->
                  no_trace
          end,
 
-    Ca = case init:get_argument(connect_all) of
-             {ok, [["false"]]} ->
-                 false;
-             _ ->
-                 true
+    Ca = case application:get_env(kernel, connect_all) of
+             {ok, CaBool} when is_boolean(CaBool) ->
+                 CaBool;
+             {ok, CaInvalid} ->
+                 error({invalid_parameter_value, connect_all, CaInvalid});
+             undefined ->
+                 CaBool = case init:get_argument(connect_all) of
+                              {ok, [["false" | _] | _]} ->
+                                  false;
+                              _ ->
+                                  true
+                          end,
+                 ok = application:set_env(kernel, connect_all, CaBool,
+                                          [{timeout, infinity}]),
+                 CaBool
          end,
+
     POP = case application:get_env(kernel,
                                    prevent_overlapping_partitions) of
-              {ok, Bool} when Bool == true; Bool == false ->
-                  Bool;
-              {ok, Invalid} ->
+              {ok, PopBool} when is_boolean(PopBool) ->
+                  PopBool;
+              {ok, PopInvalid} ->
                   error({invalid_parameter_value,
                          prevent_overlapping_partitions,
-                         Invalid});
+                         PopInvalid});
               undefined ->
                   false
           end,
+
     S = #state{the_locker = start_the_locker(DoTrace),
                known = Known,
                trace = T0,
diff --git a/lib/kernel/src/global_group.erl b/lib/kernel/src/global_group.erl
index daaaff61d8..69f3f367eb 100644
--- a/lib/kernel/src/global_group.erl
+++ b/lib/kernel/src/global_group.erl
@@ -85,7 +85,6 @@
 %%%====================================================================================
 
 -record(state, {sync_state = no_conf        :: sync_state(),
-		connect_all                 :: boolean(),
 		group_name = []             :: group_name() | [],
 		nodes = #{}                 :: #{node() => node_state()},
 		other_grps = [], 
diff --git a/lib/kernel/test/erl_distribution_SUITE.erl b/lib/kernel/test/erl_distribution_SUITE.erl
index 7d7108e44b..a22635dd68 100644
--- a/lib/kernel/test/erl_distribution_SUITE.erl
+++ b/lib/kernel/test/erl_distribution_SUITE.erl
@@ -771,8 +771,14 @@ run_tick_change_test(DCfg, B, C, PrevTT, TT) ->
 hidden_node(Config) when is_list(Config) ->
     run_dist_configs(fun hidden_node/2, Config).
 
-hidden_node(DCfg, _Config) ->
-    HArgs = "-hidden",
+hidden_node(DCfg, Config) ->
+    hidden_node(DCfg, "-hidden", Config),
+    hidden_node(DCfg, "-hidden -hidden", Config),
+    hidden_node(DCfg, "-hidden true -hidden true", Config),
+    ok.
+
+hidden_node(DCfg, HArgs, _Config) ->
+    ct:pal("--- Hidden argument(s): ~s~n", [HArgs]),
     {ok, V} = start_node(DCfg, visible_node),
     VMN = start_monitor_nodes_proc(V),
     {ok, H} = start_node(DCfg, hidden_node, HArgs),
diff --git a/lib/kernel/test/global_SUITE.erl b/lib/kernel/test/global_SUITE.erl
index 1a597c2fb2..769e4ec23e 100644
--- a/lib/kernel/test/global_SUITE.erl
+++ b/lib/kernel/test/global_SUITE.erl
@@ -30,7 +30,7 @@
 	 ring/1, simple_ring/1, line/1, simple_line/1,
 	 global_lost_nodes/1, otp_1849/1,
 	 otp_3162/1, otp_5640/1, otp_5737/1,
-         otp_6931/1, 
+         connect_all_false/1, 
          simple_disconnect/1, 
          simple_resolve/1, simple_resolve2/1, simple_resolve3/1,
          leftover_name/1, re_register_name/1, name_exit/1, external_nodes/1,
@@ -77,7 +77,7 @@ all() ->
 	     advanced_partition, basic_name_partition,
 	     stress_partition, simple_ring, simple_line, ring, line,
 	     global_lost_nodes, otp_1849, otp_3162, otp_5640,
-	     otp_5737, otp_6931, simple_disconnect, simple_resolve,
+	     otp_5737, connect_all_false, simple_disconnect, simple_resolve,
 	     simple_resolve2, simple_resolve3, leftover_name,
 	     re_register_name, name_exit, external_nodes, many_nodes,
 	     sync_0, global_groups_change, register_1, both_known_1,
@@ -2067,10 +2067,18 @@ otp_5737(Config) when is_list(Config) ->
     init_condition(Config),
     ok.
 
-%% OTP-6931. Ignore nodeup when connect_all=false.
-otp_6931(Config) when is_list(Config) ->
+connect_all_false(Config) when is_list(Config) ->
+    %% OTP-6931. Ignore nodeup when connect_all=false.
+    connect_all_false_test("-connect_all false", Config),
+    %% OTP-17934: multipl -connect_all false and kernel parameter connect_all
+    connect_all_false_test("-connect_all false -connect_all false", Config),
+    connect_all_false_test("-kernel connect_all false", Config),
+    ok.
+
+connect_all_false_test(CAArg, Config) ->
     Me = self(),
     {ok, CAf} = start_non_connecting_node(ca_false, Config),
+    {ok, false} = rpc:call(CAf, application, get_env, [kernel, connect_all]),
     ok = rpc:call(CAf, error_logger, add_report_handler, [?MODULE, Me]),
     info = rpc:call(CAf, error_logger, warning_map, []),
     {global_name_server,CAf} ! {nodeup, fake_node, #{connection_id => 4711}},