Replace gen_leader with locks_leader for gproc_dist

Port distributed registry to locks_leader: optional locks application,
conditional gproc_dist start when locks_server is present, and optional
peer connect via {gproc, gproc_dist} node list.

Testing: Common Test gproc_dist_SUITE with peer nodes and per-node
disk logs; eunit keeps local coverage (dist eunit generator removed).
Drop rebar.config.script that previously gated gen_leader.

Author: uwiger

Makefile

@@ -21,7 +21,7 @@
 ## DEALINGS IN THE SOFTWARE.
 REBAR3=$(shell which rebar3 || echo ./rebar3)
 
-.PHONY: all compile clean eunit test doc check dialyzer
+.PHONY: all compile clean eunit ct test doc check dialyzer
 
 DIRS=src
 
@@ -35,10 +35,18 @@ compile:
 clean:
 	$(REBAR3) clean
 
+# Local / non-distributed eunit only. gproc_dist lives under CT
+# (see gproc_dist_SUITE); the old dist eunit generator is disabled.
 eunit:
 	$(REBAR3) eunit
 
-test: eunit
+# Distributed suite: locks_leader peers + per-node disk logs.
+ct:
+	@epmd -daemon 2>/dev/null || true
+	$(REBAR3) ct --suite test/gproc_dist_SUITE
+
+# Full local gate (matches intended CI split).
+test: eunit ct
 
 doc:
 	$(REBAR3) as edown edoc

rebar.config

@@ -2,12 +2,11 @@
 {erl_opts, [debug_info]}.
 
 {deps, [
-        {gen_leader, ".*",
-         {git, "https://github.com/garret-smith/gen_leader_revival.git", "HEAD"}}
+        {locks, {git, "https://github.com/uwiger/locks.git", {ref, "d6ef026"}}}
        ]}.
 
 {dialyzer, [{plt_apps, all_deps},
-            {plt_extra_apps, [mnesia, runtime_tools, gen_leader]},
+            {plt_extra_apps, [mnesia, runtime_tools, locks]},
             {warnings, [no_unused,
                         no_improper_lists, no_fun_app, no_match,
                         no_opaque, no_fail_call,

rebar.config.script

@@ -8,7 +8,11 @@
   {vsn, "zomp"},
   {id, "GPROC"},
   {registered, [ ] },
-  {applications, [ kernel, stdlib ] },
+  %% locks is optional: listed in both applications and optional_applications
+  %% so the app controller starts it automatically when present, but gproc
+  %% still loads if locks is absent (local-only installs).
+  {applications, [ kernel, stdlib, locks ] },
+  {optional_applications, [ locks ] },
   {mod, {gproc_app, []} },
   {licenses, ["Apache-2.0"]},
   {links, [{"Github", "https://github.com/uwiger/gproc"}]}

src/gproc.app.src

@@ -41,6 +41,13 @@
 %%   starting the `gproc' and `gproc_dist' servers. Default is `[]'. It is
 %%   likely that `{priority, high | max}' and/or increasing `min_heap_size'
 %%   will improve performance.
+%% * `{gproc_dist, all | [node()] | {[node()], list()}}' - When `locks' is
+%%   available and `gproc_dist' is started, an explicit node list causes
+%%   `net_kernel:connect_node/1' for each peer before joining the society.
+%%   `all' / `true' do not connect (already-connected nodes are discovered
+%%   via locks_pg). Under gen_leader this env also controlled whether dist
+%%   started; now dist starts whenever `locks' is running
+%%   (see optional_applications).
 %%
 %% @end
 
@@ -191,6 +198,7 @@
                 ok
         end).
 
+
 -define(PID_IS_DEAD(Pid),
 	(node(Pid) == node() andalso is_process_alive(Pid) == false)).
 
@@ -706,7 +714,6 @@ await(Node, Key, Timeout) when is_atom(Node) ->
     ?CATCH_GPROC_ERROR(await1(Node, Key, Timeout), [Node, Key, Timeout]).
 
 await1({T,g,_} = Key, Timeout) when T=:=n; T=:=a; T=:=rc ->
-    ?CHK_DIST,
     request_wait(Key, Timeout);
 await1({T,l,_} = Key, Timeout) when T=:=n; T=:=a; T=:=rc ->
     case ets:lookup(?TAB, {Key, T}) of
@@ -860,7 +867,6 @@ nb_wait(Node, Key) ->
     ?CATCH_GPROC_ERROR(nb_wait1(Node, Key), [Node, Key]).
 
 nb_wait1({T,g,_} = Key) when T=:=n; T=:=a; T=:=rc ->
-    ?CHK_DIST,
     call({await, Key, self()}, g);
 nb_wait1({T,l,_} = Key) when T=:=n; T=:=a; T=:=rc ->
     call({await, Key, self()}, l);
@@ -901,7 +907,6 @@ cancel_wait(N, Key, Ref) ->
 
 
 cancel_wait1({_,g,_} = Key, Ref) ->
-    ?CHK_DIST,
     cast({cancel_wait, self(), Key, Ref}, g),
     ok;
 cancel_wait1({_,l,_} = Key, Ref) ->
@@ -917,7 +922,6 @@ cancel_wait_or_monitor(Key) ->
     ?CATCH_GPROC_ERROR(cancel_wait_or_monitor1(Key), [Key]).
 
 cancel_wait_or_monitor1({_,g,_} = Key) ->
-    ?CHK_DIST,
     cast({cancel_wait_or_monitor, self(), Key}, g),
     ok;
 cancel_wait_or_monitor1({_,l,_} = Key) ->
@@ -2610,12 +2614,14 @@ call(Req) ->
 call(Req, l) ->
     chk_reply(gen_server:call(?MODULE, Req));
 call(Req, g) ->
+    ?CHK_DIST,
     chk_reply(gproc_dist:leader_call(Req)).
 
 call(N, Req, l) ->
     chk_reply(gen_server:call({?MODULE, N}, Req));
 call(undefined, Req, g) ->
     %% we always call the leader
+    ?CHK_DIST,
     chk_reply(gproc_dist:leader_call(Req)).
 
 
@@ -2632,6 +2638,7 @@ cast(Msg) ->
 cast(Msg, l) ->
     gen_server:cast(?MODULE, Msg);
 cast(Msg, g) ->
+    ?CHK_DIST,
     gproc_dist:leader_cast(Msg).
 
 cast(N, Msg, l) ->

src/gproc.erl

@@ -40,6 +40,11 @@ start() ->
     start(normal, []).
 
 start(_Type, StartArgs) ->
+    %% locks is optional_applications: ensure_all_started(gproc) will start it
+    %% as a dep, but ensure_started/start(gproc) will not. Pull locks in here
+    %% when it is loadable so gproc_sup can start gproc_dist; ignore failure
+    %% when locks is not present (local-only install).
+    _ = application:ensure_all_started(locks),
     case gproc_sup:start_link(StartArgs) of
         {ok, Pid} ->
             {ok, Pid};