optimize hash api to allow "insert if not found"

include/open_address_hash.h

@@ -64,20 +64,32 @@ class Open_address_hash
     return Key_trait::get_hash_value(get_key(value));
   }
 
-  bool insert_into_bucket(const Value &value)
+  template <typename ElemSuitsFunc, typename GetElemFunc>
+  bool insert_into_bucket(const Key& key,
+                          const ElemSuitsFunc &elem_suits,
+                          const GetElemFunc &get_elem)
   {
-    auto hash_val= to_index(hash_from_value(value));
+    auto hash_val= to_index(Key_trait::get_hash_value(&key));
 
     while (!is_empty(hash_array[hash_val]))
     {
-      if (is_equal(hash_array[hash_val], value))
+      if (elem_suits(hash_array[hash_val]))
         return false;
       hash_val= to_index(hash_val + 1);
     }
 
-    hash_array[hash_val]= value;
-    return true;
-  };
+    Value &&value= get_elem();
+    hash_array[hash_val]= get_elem();
+    return !is_empty(value);
+  }
+
+  bool insert_into_bucket(const Value &value)
+  {
+    return insert_into_bucket(*get_key(value),
+              [&value](const Value &rhs){ return is_equal(rhs, value); },
+              [&value](){ return value; }
+    );
+  }
 
   uint rehash_subsequence(uint i)
   {
@@ -175,7 +187,7 @@ class Open_address_hash
 public:
   Value find(const Value &elem) const
   {
-    return find(*Key_trait::get_key(elem),
+    return find(*get_key(elem),
                 [&elem](const Value &rhs) { return is_equal(rhs, elem); });
   }
 
@@ -184,12 +196,9 @@ class Open_address_hash
   {
     if (likely(first.mark()))
     {
-      if (first.ptr())
-      {
-        if (elem_suits(first.ptr()))
+      if (!is_empty(first.ptr()) && elem_suits(first.ptr()))
         return first.ptr();
-      }
-      else if (!is_empty(second) && elem_suits(second))
+      if (!is_empty(second) && elem_suits(second))
         return second;
 
       return EMPTY;
@@ -203,7 +212,7 @@ class Open_address_hash
     }
 
     return EMPTY;
-  };
+  }
 
   bool erase(const Value &value)
   {
@@ -215,7 +224,7 @@ class Open_address_hash
         second= EMPTY;
         return true;
       }
-      else if (second && is_equal(second, value))
+      else if (!is_empty(second) && is_equal(second, value))
       {
         second= EMPTY;
         return true;
@@ -235,30 +244,35 @@ class Open_address_hash
     return true;
   }
 
-  bool insert(const Value &value)
+  template <typename ElemSuitsFunc, typename GetElemFunc>
+  bool insert(const Key &key,
+              const ElemSuitsFunc &elem_suits,
+              const GetElemFunc &get_elem)
   {
     if (first.mark())
     {
       if (is_empty(first.ptr()))
       {
-        if (is_equal(second, value))
-          return false;
-        first.set_ptr(value);
+        first.set_ptr(get_elem());
         return true;
       }
-      else if (is_empty(second))
+
+      if (elem_suits(first.ptr()))
+        return true;
+
+      if (is_empty(second))
       {
-        if (is_equal(first.ptr(), value))
-          return false;
-        second= value;
+        second= get_elem();
         return true;
       }
-      else
-      {
+
+      if (elem_suits(second))
+        return true;
+
       first.set_mark(false);
       if (!init_hash_array())
         return false;
-      }
+
     }
 
     if (unlikely(_size == TABLE_SIZE_MAX))
@@ -269,12 +283,19 @@ class Open_address_hash
     if (unlikely(((ulonglong)_size + 1) * MAX_LOAD_FACTOR > capacity))
       res= grow(capacity_power + 1);
 
-    res= res && insert_into_bucket(value);
+    res= res && insert_into_bucket(key, elem_suits, get_elem);
     if (res)
       _size++;
     return res;
   };
 
+  bool insert(const Value &value)
+  {
+    return insert(*get_key(value),
+                  [&value](const Value &rhs){ return is_equal(rhs, value); },
+                  [&value](){ return value; });
+  }
+
   bool clear()
   {
     if (first.mark())

sql/mdl.cc

@@ -1964,7 +1964,7 @@ MDL_context::find_ticket(MDL_request *mdl_request,
                t->m_duration == mdl_request->duration;
       };
 
-  MDL_ticket *found_ticket= ticket_hash.find(&mdl_request->key,
+  MDL_ticket *found_ticket= ticket_hash.find(mdl_request->key,
                                              ticket_identical);
   if (!found_ticket)
   {

sql/sql_base.cc

@@ -5053,27 +5053,41 @@ prepare_fk_prelocking_list(THD *thd, Query_tables_list *prelocking_ctx,
     else
       lock_type= TL_READ;
 
-    MDL_key key(MDL_key::TABLE, fk->foreign_db->str, fk->foreign_table->str);
+    const char *db= fk->foreign_db->str;
+    const char *table_name= fk->foreign_table->str;
+    MDL_key key(MDL_key::TABLE, db, table_name);
 
-    TABLE_LIST *tl= find_fk_prelocked_table(prelocking_ctx, key, lock_type);
-    if (tl == NULL)
+    TABLE_LIST *tl= NULL;
+    bool success= prelocking_ctx->fk_table_hash.insert(key,
+            [db, table_name, lock_type](const TABLE_LIST *tl)
+            {
+              return tl->lock_type >= lock_type
+                     && strcmp(tl->table_name.str, table_name) == 0
+                     && strcmp(tl->db.str, db) == 0;
+            },
+            [&tl, thd]()
             {
               tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));
-      tl->init_one_table_for_prelocking(
-          fk->foreign_db, fk->foreign_table, NULL, lock_type,
-          TABLE_LIST::PRELOCK_FK, table_list->belong_to_view, op,
-          &prelocking_ctx->query_tables_last, &key,
-          table_list->for_insert_data);
-      bool success= prelocking_ctx->fk_table_hash.insert(tl);
-      if (!success)
+              return tl;
+            }
+    );
+
+    if (unlikely(!success))
     {
       my_error(ER_OUTOFMEMORY, MYF(0));
       if (arena)
         thd->restore_active_arena(arena, &backup);
       DBUG_RETURN(TRUE);
     }
-    }
 
+    if (tl != NULL)
+    {
+      tl->init_one_table_for_prelocking(
+              fk->foreign_db, fk->foreign_table, NULL, lock_type,
+              TABLE_LIST::PRELOCK_FK, table_list->belong_to_view, op,
+              &prelocking_ctx->query_tables_last, &key,
+              table_list->for_insert_data);
+    }
   }
   if (arena)
     thd->restore_active_arena(arena, &backup);