erts: Add erts_debug feature 'ets_force_split'

to easier generate a routing tree for test
without having to spend cpu to provoke actual repeated lock conflicts.

6 files changed, 49 insertions, 2 deletions

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 2a8e7e8858..3b0f0d33fa 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -4669,6 +4669,14 @@ BIF_RETTYPE erts_debug_set_internal_state_2(BIF_ALIST_2)
             BIF_RET(am_notsup);
 #endif
         }
+        else if (ERTS_IS_ATOM_STR("ets_force_split", BIF_ARG_1)) {
+            if (is_tuple(BIF_ARG_2)) {
+                Eterm* tpl = tuple_val(BIF_ARG_2);
+
+                if (erts_ets_force_split(tpl[1], tpl[2] == am_true))
+                    BIF_RET(am_ok);
+            }
+        }
     }
 
     BIF_ERROR(BIF_P, BADARG);
diff --git a/erts/emulator/beam/erl_db.c b/erts/emulator/beam/erl_db.c
index 337efa94bd..df6f42edd3 100644
--- a/erts/emulator/beam/erl_db.c
+++ b/erts/emulator/beam/erl_db.c
@@ -4465,3 +4465,16 @@ void erts_lcnt_update_db_locks(int enable) {
 #ifdef ETS_DBG_FORCE_TRAP
 erts_aint_t erts_ets_dbg_force_trap = 0;
 #endif
+
+int erts_ets_force_split(Eterm tid, int on)
+{
+    DbTable* tb = tid2tab(tid);
+    if (!tb || !IS_CATREE_TABLE(tb->common.type))
+        return 0;
+
+    db_lock(tb, LCK_WRITE);
+    if (!(tb->common.status & DB_DELETE))
+        db_catree_force_split(&tb->catree, on);
+    db_unlock(tb, LCK_WRITE);
+    return 1;
+}
diff --git a/erts/emulator/beam/erl_db.h b/erts/emulator/beam/erl_db.h
index 7a915ccea2..5955d42aae 100644
--- a/erts/emulator/beam/erl_db.h
+++ b/erts/emulator/beam/erl_db.h
@@ -130,6 +130,7 @@ extern Export ets_select_continue_exp;
 extern erts_atomic_t erts_ets_misc_mem_size;
 
 Eterm erts_ets_colliding_names(Process*, Eterm name, Uint cnt);
+int erts_ets_force_split(Eterm tid, int on);
 Uint erts_db_get_max_tabs(void);
 Eterm erts_db_make_tid(Process *c_p, DbTableCommon *tb);
 
diff --git a/erts/emulator/beam/erl_db_catree.c b/erts/emulator/beam/erl_db_catree.c
index f467230ced..975e19a878 100644
--- a/erts/emulator/beam/erl_db_catree.c
+++ b/erts/emulator/beam/erl_db_catree.c
@@ -885,7 +885,8 @@ static DbTableCATreeNode *create_base_node(DbTableCATree *tb,
                         "erl_db_catree_base_node",
                         lc_key,
                         ERTS_LOCK_FLAGS_CATEGORY_DB);
-    p->u.base.lock_statistics = 0;
+    p->u.base.lock_statistics = ((tb->common.status & DB_CATREE_FORCE_SPLIT)
+                                 ? INT_MAX : 0);
     p->u.base.is_valid = 1;
     return p;
 }
@@ -1205,7 +1206,8 @@ static void split_catree(DbTableCATree *tb,
     DbTableCATreeNode* ERTS_RESTRICT new_route;
 
     if (less_than_two_elements(base->u.base.root)) {
-        base->u.base.lock_statistics = 0;
+        if (!(tb->common.status & DB_CATREE_FORCE_SPLIT))
+            base->u.base.lock_statistics = 0;
         wunlock_base_node(&base->u.base);
         return;
     } else {
@@ -2118,6 +2120,25 @@ void erts_lcnt_enable_db_catree_lock_count(DbTableCATree *tb, int enable)
 }
 #endif /* ERTS_ENABLE_LOCK_COUNT */
 
+void db_catree_force_split(DbTableCATree* tb, int on)
+{
+    CATreeRootIterator iter;
+    TreeDbTerm** root;
+
+    init_root_iterator(tb, &iter, 1);
+    root = catree_find_first_root(&iter);
+    do {
+        iter.locked_bnode->lock_statistics = (on ? INT_MAX : 0);
+        root = catree_find_next_root(&iter);
+    } while (root);
+    ASSERT(!iter.locked_bnode);
+
+    if (on)
+        tb->common.status |= DB_CATREE_FORCE_SPLIT;
+    else
+        tb->common.status &= ~DB_CATREE_FORCE_SPLIT;
+}
+
 void db_calc_stats_catree(DbTableCATree* tb, DbCATreeStats* stats)
 {
     DbTableCATreeNode* stack[ERL_DB_CATREE_MAX_ROUTE_NODE_LAYER_HEIGHT];
diff --git a/erts/emulator/beam/erl_db_catree.h b/erts/emulator/beam/erl_db_catree.h
index e3d574589c..feb6f27980 100644
--- a/erts/emulator/beam/erl_db_catree.h
+++ b/erts/emulator/beam/erl_db_catree.h
@@ -120,6 +120,8 @@ TreeDbTerm** catree_find_last_root(CATreeRootIterator*);
 void erts_lcnt_enable_db_catree_lock_count(DbTableCATree *tb, int enable);
 #endif
 
+void db_catree_force_split(DbTableCATree*, int on);
+
 typedef struct {
     Uint route_nodes;
     Uint base_nodes;
diff --git a/erts/emulator/beam/erl_db_util.h b/erts/emulator/beam/erl_db_util.h
index be74bc795c..dcffaf9718 100644
--- a/erts/emulator/beam/erl_db_util.h
+++ b/erts/emulator/beam/erl_db_util.h
@@ -290,6 +290,8 @@ typedef struct db_table_common {
 #define DB_NAMED_TABLE    (1 << 11)
 #define DB_BUSY           (1 << 12)
 
+#define DB_CATREE_FORCE_SPLIT (1 << 31)  /* erts_debug */
+
 #define IS_HASH_TABLE(Status) (!!((Status) & \
 				  (DB_BAG | DB_SET | DB_DUPLICATE_BAG)))
 #define IS_TREE_TABLE(Status) (!!((Status) & \