Bug#30520809: CHANGE FIELD_TYPED_ARRAY TO USE A PROPER

              RECORD BUFFER FOR DATA CONVERSION

Change Field_typed_array to use one record buffer rather
than two separate buffers for null and actual values.
This makes it easier to later convert Field to use offset
values rather than record pointers.

Refactoring only, no changes of behavior.

Change-Id: I6120dc154b94e85015fde50455346fb1eaa9fc29

Author: jhauglid

sql/field.cc

@@ -9703,17 +9703,9 @@ bool Field::is_part_of_actual_key(THD *thd, uint cur_index,
 
 Field_typed_array::Field_typed_array(const Field_typed_array &other)
     : Field_json(other),
-      m_conv_field(other.m_conv_field),
       m_elt_type(other.m_elt_type),
       m_elt_decimals(other.m_elt_decimals),
-      m_elt_charset(other.m_elt_charset) {
-  /*
-    When conv_field is null the field is cloned from share and isn't
-    attached to any table yet (this will happen later).
-  */
-  //  DBUG_ASSERT(!m_conv_field);
-  m_conv_field = nullptr;
-}
+      m_elt_charset(other.m_elt_charset) {}
 
 Field_typed_array::Field_typed_array(
     enum_field_types elt_type, bool elt_is_unsigned, size_t elt_length,
@@ -9722,7 +9714,6 @@ Field_typed_array::Field_typed_array(
     uint blob_pack_length, const CHARSET_INFO *cs)
     : Field_json(ptr_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, share, blob_pack_length),
-      m_conv_field(nullptr),
       m_elt_type(elt_type),
       m_elt_decimals(elt_decimals),
       m_elt_charset(cs) {
@@ -9892,7 +9883,6 @@ type_conversion_status Field_typed_array::store_array(const Json_wrapper *data,
 }
 
 void Field_typed_array::init(TABLE *table_arg) {
-  uint fld_length = field_length;
   Field::init(table_arg);
 
   switch (type()) {
@@ -9908,22 +9898,22 @@ void Field_typed_array::init(TABLE *table_arg) {
     default:
       // Shouldn't happen
       DBUG_ASSERT(0); /* purecov: inspected */
-
       return;
   }
+
   // Create field for data conversion
   m_conv_field = ::make_field(
       // Allocate conversion field in table's mem_root
       &table_arg->mem_root,
-      nullptr,        // TABLE_SHARE, not needed
-      nullptr,        // data buffer, isn't allocated yet
-      fld_length,     // field_length
-      &null_byte, 0,  // null_pos, nul_bit
-      real_type(),    // field_type
+      nullptr,       // TABLE_SHARE, not needed
+      nullptr,       // data buffer, isn't allocated yet
+      field_length,  // field_length
+      nullptr, 0,    // null_pos, nul_bit
+      real_type(),   // field_type
       m_elt_charset,
       Field::GEOM_GEOMETRY,  // geom type
       Field::NONE,           // auto_flags
-      nullptr,               // itervals aren't supported in array
+      nullptr,               // intervals aren't supported in array
       field_name, is_nullable(),
       false,  // zerofill is meaningless with JSON
       unsigned_flag, m_elt_decimals,
@@ -9932,27 +9922,27 @@ void Field_typed_array::init(TABLE *table_arg) {
       {},     // srid
       false   // is_array
   );
-  if (!m_conv_field ||
-      !(m_conv_buf = static_cast<uchar *>(
-            table_arg->mem_root.Alloc(m_conv_field->pack_length()))))
-    return; /* purecov: inspected */
+  if (m_conv_field == nullptr) return;
+  uchar *buf =
+      table_arg->mem_root.ArrayAlloc<uchar>(m_conv_field->pack_length() + 1);
+  if (buf == nullptr) return;
   if (type() == MYSQL_TYPE_NEWDECIMAL)
     (down_cast<Field_new_decimal *>(m_conv_field))->set_keep_precision(true);
-  m_conv_field->move_field(m_conv_buf);
+  m_conv_field->move_field(buf + 1, buf, 0);
   // Allow conv_field to use table->in_use
   m_conv_field->table = table;
   m_conv_field->field_index = field_index;
   m_conv_field->table_name = table_name;
 }
 
-const char *Field_typed_array::get_index_name() {
+const char *Field_typed_array::get_index_name() const {
   uint key = part_of_key.get_first_set();
   DBUG_ASSERT(key != MY_BIT_NONE);
   return table->s->key_info[key].name;
 }
 
 size_t Field_typed_array::make_sort_key(Json_wrapper *wr, uchar *to,
-                                        size_t length) {
+                                        size_t length) const {
 #ifndef DBUG_OFF
   switch (wr->type()) {
     case enum_json_type::J_ERROR:

sql/field.h

@@ -4239,11 +4239,7 @@ class Field_json : public Field_blob {
 
 class Field_typed_array final : public Field_json {
   /// Conversion field
-  Field *m_conv_field;
-  /// Null byte for conv_field
-  uchar null_byte;
-  /// conversion field's buffer
-  uchar *m_conv_buf;
+  Field *m_conv_field{nullptr};
   /// The array element's real type.
   enum_field_types m_elt_type;
   /// Element's decimals
@@ -4354,7 +4350,7 @@ class Field_typed_array final : public Field_json {
       false  conversion succeeded
   */
   bool coerce_json_value(const Json_wrapper *wr, bool no_error,
-                         Json_wrapper *coerced);
+                         Json_wrapper *coerced) const;
 
   /**
     Get name of the index defined over this field.
@@ -4366,8 +4362,8 @@ class Field_typed_array final : public Field_json {
     @returns
       name of the index defined over the field.
   */
-  const char *get_index_name();
-  virtual uint32 get_length_bytes() const override {
+  const char *get_index_name() const;
+  uint32 get_length_bytes() const override {
     DBUG_ASSERT(m_elt_type == MYSQL_TYPE_VARCHAR);
     return field_length > 255 ? 2 : 1;
   }
@@ -4387,7 +4383,7 @@ class Field_typed_array final : public Field_json {
     @returns
       actual sort key length
   */
-  size_t make_sort_key(Json_wrapper *wr, uchar *to, size_t length);
+  size_t make_sort_key(Json_wrapper *wr, uchar *to, size_t length) const;
   /**
      Save the field metadata for typed array fields.
 
@@ -4401,8 +4397,8 @@ class Field_typed_array final : public Field_json {
 
      @returns number of bytes written to metadata_ptr
   */
-  virtual int do_save_field_metadata(uchar *metadata_ptr) const override;
-  virtual uint pack_length_from_metadata(uint) const override {
+  int do_save_field_metadata(uchar *metadata_ptr) const override;
+  uint pack_length_from_metadata(uint) const override {
     return pack_length_no_ptr();
   }
   void sql_type(String &str) const final override;

sql/item_json_func.cc

@@ -3780,7 +3780,7 @@ Field *Item_func_array_cast::tmp_table_field(TABLE *table) {
     true  Otherwise
 */
 bool Field_typed_array::coerce_json_value(const Json_wrapper *wr, bool no_error,
-                                          Json_wrapper *coerced) {
+                                          Json_wrapper *coerced) const {
   Json_wrapper saved;
   THD *thd = table->in_use;
   // Save JSON value to the conversion field

sql/sql_bitmap.h

@@ -189,7 +189,7 @@ class Bitmap<64> {
     return buf;
   }
   ulonglong to_ulonglong() const { return map; }
-  uint get_first_set() {
+  uint get_first_set() const {
     for (uint i = 0; i < ALL_BITS; i++)
       if (map & (1ULL << i)) return i;
     return MY_BIT_NONE;