erts: Remove hashmap probabilistic heap overestimation

by adding a dynamic heap factory.

"binary_to_term" is now a hybrid solution with both
a call to decoded_size() to calculate needed heap space
AND possible dynamic allocation of more heap space
if needed for big maps.

The heap size returned from decoded_size() is guaranteed
to be sufficient for all term heap data except for hashmap
nodes. All hashmap nodes are created at the end of dec_term()
by invoking the heap factory interface that may allocate more
heap space on process heap or in fragments.

With this commit it is no longer guaranteed that a message
is confined to only one heap fragment.

1 files changed, 2 insertions, 1 deletions

diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index a21622f424..2d4bf4240c 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -6653,8 +6653,9 @@ new_map(Process* p, Eterm* reg, BeamInstr* I)
 
 	p->htop = mhp;
 
-        factory.p = p;
+        erts_factory_proc_init(&factory, p);
         res = erts_hashmap_from_array(&factory, thp, n/2, 0);
+        erts_factory_close(&factory);
         if (p->mbuf) {
             Uint live = Arg(2);
             reg[live] = res;