erts: Move reason in dist messages to payload

The dist messages EXIT, EXIT2 and MONITOR_DOWN have been
updated with new versions that send the reason term as
part of the payload of the message instead of as part
of the control message.

This allows the decode of the reason to be done by the
receiving process instead of the dist entry which in turn
makes it possible for multiple decodes to be done in
parallel.

This change is done in order to make it easier to fragment
the potentially large payload of EXIT, EXIT2 and MONITOR_DOWN
into multiple distribution messages.

OTP-15611

1 files changed, 20 insertions, 2 deletions

diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index 4b8040b356..640ca338d9 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -636,11 +636,13 @@ byte* erts_encode_ext_ets(Eterm term, byte *ep, struct erl_off_heap_header** off
 }
 
 ErtsDistExternal *
-erts_make_dist_ext_copy(ErtsDistExternal *edep, Uint xsize)
+erts_make_dist_ext_copy(ErtsDistExternal *edep, Eterm *token)
 {
     size_t align_sz;
     size_t dist_ext_sz;
     size_t ext_sz = 0;
+    size_t token_sz = 0;
+    Eterm token_size;
     byte *ep;
     ErtsDistExternal *new_edep;
 
@@ -652,8 +654,12 @@ erts_make_dist_ext_copy(ErtsDistExternal *edep, Uint xsize)
 
     align_sz = ERTS_EXTRA_DATA_ALIGN_SZ(dist_ext_sz + ext_sz);
 
+    token_size = size_object(*token);
+    if (token_size)
+        token_sz = ERTS_HEAP_FRAG_SIZE(token_size);
+
     new_edep = erts_alloc(ERTS_ALC_T_EXT_TERM_DATA,
-			  dist_ext_sz + ext_sz + align_sz + xsize);
+			  dist_ext_sz + ext_sz + align_sz + token_sz);
 
     ep = (byte *) new_edep;
     sys_memcpy((void *) ep, (void *) edep, dist_ext_sz);
@@ -669,6 +675,18 @@ erts_make_dist_ext_copy(ErtsDistExternal *edep, Uint xsize)
     } else {
         erts_refc_inc(&new_edep->binp->intern.refc, 2);
     }
+
+    /* Copy the seq_trace token */
+    if (is_not_nil(*token)) {
+        ErlHeapFragment *heap_frag;
+        ErlOffHeap *ohp;
+        Eterm *hp;
+        heap_frag = erts_dist_ext_trailer(new_edep);
+        ERTS_INIT_HEAP_FRAG(heap_frag, token_size, token_size);
+        hp = heap_frag->mem;
+        ohp = &heap_frag->off_heap;
+        *token = copy_struct(*token, token_size, &hp, ohp);
+    }
     return new_edep;
 }