From 5e18e917f29ed46caffa1211eb52ade01d24366a Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Thu, 9 Mar 2017 16:23:04 +0100
Subject: erts: Optimize ets:select_replace to not use heap

for temporary matchspec results.

ToDo: Would be even nicer if PAM could allocate and build
the ETS objects without extra copy_struct needed.
---
 erts/emulator/beam/erl_db_hash.c |  3 ++-
 erts/emulator/beam/erl_db_tree.c | 11 +++++++++--
 erts/emulator/beam/erl_db_util.c |  7 ++++++-
 3 files changed, 17 insertions(+), 4 deletions(-)

(limited to 'erts/emulator')

diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index 569419265b..92b833468d 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -2144,9 +2144,10 @@ static int mtraversal_select_replace_on_match_res(void* context_ptr, Sint slot_i
 #endif
         next = (**current_ptr_ptr)->next;
         hval = (**current_ptr_ptr)->hvalue;
-        new = replace_dbterm(tb, **current_ptr_ptr, match_res);
+        new = new_dbterm(tb, match_res);
         new->next = next;
         new->hvalue = hval;
+        free_term(tb, **current_ptr_ptr);
         **current_ptr_ptr = new; /* replace 'next' pointer in previous object */
         *current_ptr_ptr = &((**current_ptr_ptr)->next); /* advance to next object */
         return 1;
diff --git a/erts/emulator/beam/erl_db_tree.c b/erts/emulator/beam/erl_db_tree.c
index fadd63be34..60bf7fc979 100644
--- a/erts/emulator/beam/erl_db_tree.c
+++ b/erts/emulator/beam/erl_db_tree.c
@@ -3473,13 +3473,20 @@ static int doit_select_replace(DbTableTree *tb, TreeDbTerm **this, void *ptr,
 			  &(*this)->dbterm, NULL, 0);
 
     if (is_value(ret)) {
+        TreeDbTerm* new;
+        TreeDbTerm* old = *this;
 #ifdef DEBUG
         Eterm key = db_getkey(tb->common.keypos, ret);
         ASSERT(is_value(key));
         ASSERT(cmp_key(tb, key, old) == 0);
 #endif
-        *this = replace_dbterm(tb, *this, ret);
-        sc->lastobj = (*this)->dbterm.tpl;
+        new = new_dbterm(tb, ret);
+        new->left = old->left;
+        new->right = old->right;
+        new->balance = old->balance;
+        sc->lastobj = new->dbterm.tpl;
+        *this = new;
+        free_term(tb, old);
         ++(sc->replaced);
     }
     if (--(sc->max) <= 0) {
diff --git a/erts/emulator/beam/erl_db_util.c b/erts/emulator/beam/erl_db_util.c
index d4dbe3d434..03cc11bdc4 100644
--- a/erts/emulator/beam/erl_db_util.c
+++ b/erts/emulator/beam/erl_db_util.c
@@ -5332,6 +5332,7 @@ void db_free_tmp_uncompressed(DbTerm* obj)
 Eterm db_match_dbterm(DbTableCommon* tb, Process* c_p, Binary* bprog,
 			     int all, DbTerm* obj, Eterm** hpp, Uint extra)
 {
+    enum erts_pam_run_flags flags;
     Uint32 dummy;
     Eterm res;
 
@@ -5339,9 +5340,13 @@ Eterm db_match_dbterm(DbTableCommon* tb, Process* c_p, Binary* bprog,
 	obj = db_alloc_tmp_uncompressed(tb, obj);
     }
 
+    flags = (hpp ?
+             ERTS_PAM_COPY_RESULT | ERTS_PAM_CONTIGUOUS_TUPLE :
+             ERTS_PAM_TMP_RESULT  | ERTS_PAM_CONTIGUOUS_TUPLE);
+
     res = db_prog_match(c_p, c_p,
                         bprog, make_tuple(obj->tpl), NULL, 0,
-			ERTS_PAM_COPY_RESULT|ERTS_PAM_CONTIGUOUS_TUPLE, &dummy);
+			flags, &dummy);
 
     if (is_value(res) && hpp!=NULL) {
 	*hpp = HAlloc(c_p, extra);
-- 
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