erts,kernel: Add erts_internal:get_dflags/0

for kernel to ask erts about distribution flags
and keep this info in one place.

7 files changed, 60 insertions, 7 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 42a368cdd8..b40d9a325b 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -250,6 +250,7 @@ atom error_handler
 atom error_logger
 atom erts_code_purger
 atom erts_debug
+atom erts_dflags
 atom erts_internal
 atom ets
 atom ETS_TRANSFER='ETS-TRANSFER'
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 0d1166f6ed..be653ee2a0 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -690,6 +690,7 @@ bif erlang:iolist_to_iovec/1
 # New in 21.0
 #
 
+bif erts_internal:get_dflags/0
 bif erts_internal:new_connection/1
 bif erts_internal:abort_connection/2
 bif erts_internal:map_next/3
diff --git a/erts/emulator/beam/dist.c b/erts/emulator/beam/dist.c
index 30390cdb5e..6f122273dc 100644
--- a/erts/emulator/beam/dist.c
+++ b/erts/emulator/beam/dist.c
@@ -641,6 +641,13 @@ trap_function(Eterm func, int arity)
     return erts_export_put(am_erlang, func, arity);
 }
 
+/*
+ * Sync with dist_util.erl:
+ *
+ * -record(erts_dflags, {default, mandatory, addable, rejectable}).
+ */
+static Eterm erts_dflags_record;
+
 void init_dist(void)
 {
     init_nodes_monitors();
@@ -657,6 +664,15 @@ void init_dist(void)
     dist_ctrl_put_data_trap = erts_export_put(am_erts_internal,
                                               am_dist_ctrl_put_data,
                                               2);
+    {
+        Eterm* hp = erts_alloc(ERTS_ALC_T_LITERAL, (1+5)*sizeof(Eterm));
+        erts_dflags_record = TUPLE5(hp, am_erts_dflags,
+                                    make_small(DFLAG_DIST_DEFAULT),
+                                    make_small(DFLAG_DIST_MANDATORY),
+                                    make_small(DFLAG_DIST_ADDABLE),
+                                    make_small(DFLAG_DIST_REJECTABLE));
+        erts_set_literal_tag(&erts_dflags_record, hp, (1+5));
+    }
 }
 
 #define ErtsDistOutputBuf2Binary(OB) \
@@ -3506,6 +3522,11 @@ BIF_RETTYPE setnode_3(BIF_ALIST_3)
     goto done;
 }
 
+BIF_RETTYPE erts_internal_get_dflags_0(BIF_ALIST_0)
+{
+    return erts_dflags_record;
+}
+
 BIF_RETTYPE erts_internal_new_connection_1(BIF_ALIST_1)
 {
     DistEntry* dep;
diff --git a/erts/emulator/beam/dist.h b/erts/emulator/beam/dist.h
index ea4697815f..202457bb3b 100644
--- a/erts/emulator/beam/dist.h
+++ b/erts/emulator/beam/dist.h
@@ -40,26 +40,51 @@
 #define DFLAG_UNICODE_IO          0x1000
 #define DFLAG_DIST_HDR_ATOM_CACHE 0x2000
 #define DFLAG_SMALL_ATOM_TAGS     0x4000
-#define DFLAG_INTERNAL_TAGS       0x8000
+#define DFLAG_INTERNAL_TAGS       0x8000   /* used by ETS 'compressed' option */
 #define DFLAG_UTF8_ATOMS          0x10000
 #define DFLAG_MAP_TAG             0x20000
 #define DFLAG_BIG_CREATION        0x40000
 #define DFLAG_SEND_SENDER         0x80000
-#define DFLAG_NO_MAGIC            0x100000
+#define DFLAG_NO_MAGIC            0x100000 /* internal for pending connection */
 
-/* Mandatory flags for distribution (sync with dist_util.erl) */
+/* Mandatory flags for distribution */
 #define DFLAG_DIST_MANDATORY (DFLAG_EXTENDED_REFERENCES         \
                               | DFLAG_EXTENDED_PIDS_PORTS       \
 			      | DFLAG_UTF8_ATOMS                \
 			      | DFLAG_NEW_FUN_TAGS)
 
-/* Additional optimistic flags when encoding toward pending connection */
-#define DFLAG_DIST_HOPEFULLY (DFLAG_NO_MAGIC                    \
-                              | DFLAG_EXPORT_PTR_TAG            \
+/*
+ * Additional optimistic flags when encoding toward pending connection.
+ * If remote node does not supporting these (erl_interface)
+ * then we will need to transcode all messages enqueued before
+ * connection setup was finished.
+ */
+#define DFLAG_DIST_HOPEFULLY (DFLAG_EXPORT_PTR_TAG              \
                               | DFLAG_BIT_BINARIES              \
                               | DFLAG_DIST_MONITOR              \
                               | DFLAG_DIST_MONITOR_NAME)
 
+/* Our preferred set of flags. Used for connection setup handshake */
+#define DFLAG_DIST_DEFAULT (DFLAG_DIST_MANDATORY | DFLAG_DIST_HOPEFULLY \
+                            | DFLAG_FUN_TAGS                  \
+                            | DFLAG_NEW_FLOATS                \
+                            | DFLAG_UNICODE_IO                \
+                            | DFLAG_DIST_HDR_ATOM_CACHE       \
+                            | DFLAG_SMALL_ATOM_TAGS           \
+                            | DFLAG_UTF8_ATOMS                \
+                            | DFLAG_MAP_TAG                   \
+                            | DFLAG_BIG_CREATION              \
+                            | DFLAG_SEND_SENDER)
+
+/* Flags addable by local distr implementations */
+#define DFLAG_DIST_ADDABLE    DFLAG_DIST_DEFAULT
+
+/* Flags rejectable by local distr implementation */
+#define DFLAG_DIST_REJECTABLE (DFLAG_DIST_HDR_ATOM_CACHE         \
+                               | DFLAG_HIDDEN_ATOM_CACHE         \
+                               | DFLAG_ATOM_CACHE)
+
+
 /* All flags that should be enabled when term_to_binary/1 is used. */
 #define TERM_TO_BINARY_DFLAGS (DFLAG_EXTENDED_REFERENCES	\
 			       | DFLAG_NEW_FUN_TAGS		\
diff --git a/erts/emulator/beam/erl_node_tables.c b/erts/emulator/beam/erl_node_tables.c
index eaf133f5c0..088b087ebb 100644
--- a/erts/emulator/beam/erl_node_tables.c
+++ b/erts/emulator/beam/erl_node_tables.c
@@ -628,7 +628,7 @@ erts_set_dist_entry_pending(DistEntry *dep)
     erts_no_of_not_connected_dist_entries--;
 
     dep->status = ERTS_DE_SFLG_PENDING;
-    dep->flags = (DFLAG_DIST_MANDATORY | DFLAG_DIST_HOPEFULLY);
+    dep->flags = (DFLAG_DIST_MANDATORY | DFLAG_DIST_HOPEFULLY | DFLAG_NO_MAGIC);
     dep->connection_id = (dep->connection_id + 1) & ERTS_DIST_CON_ID_MASK;
 
     dep->prev = NULL;
diff --git a/erts/preloaded/ebin/erts_internal.beam b/erts/preloaded/ebin/erts_internal.beam
index 7d2edd9845..7206b0415d 100644
--- a/erts/preloaded/ebin/erts_internal.beam
+++ b/erts/preloaded/ebin/erts_internal.beam
diff --git a/erts/preloaded/src/erts_internal.erl b/erts/preloaded/src/erts_internal.erl
index a083e9ac2f..291a8e8fa8 100644
--- a/erts/preloaded/src/erts_internal.erl
+++ b/erts/preloaded/src/erts_internal.erl
@@ -63,6 +63,7 @@
 
 -export([dist_ctrl_put_data/2]).
 
+-export([get_dflags/0]).
 -export([new_connection/1]).
 -export([abort_connection/2]).
 
@@ -510,6 +511,10 @@ dist_ctrl_put_data(DHandle, IoList) ->
     end.
 
 
+-spec erts_internal:get_dflags() -> {erts_dflags,integer(),integer(),integer(),integer()}.
+get_dflags() ->
+    erlang:nif_error(undefined).
+
 -spec erts_internal:new_connection(Node) -> ConnId when
       Node :: atom(),
       ConnId :: {integer(), erlang:dist_handle()}.