Store raw size in DeserializedMetadataAndRawRows

We want to switch driver to deserialize metadata eagerly. One thing that
driver does with RawMetadataAndRawRows is logging the raw size of
metadata and raw rows. In order to keep it doing that, we need to store
the size in the deserialized metadata result.

Author: Lorak-mmk

scylla-cql/src/frame/response/result.rs

@@ -666,6 +666,7 @@ pub struct DeserializedMetadataAndRawRows {
     metadata: ResultMetadataHolder,
     rows_count: usize,
     raw_rows: Bytes,
+    raw_metadata_and_rows_bytes_size: usize,
 }
 
 impl DeserializedMetadataAndRawRows {
@@ -695,6 +696,12 @@ impl DeserializedMetadataAndRawRows {
         self.raw_rows.len()
     }
 
+    /// Returns the serialized size of the raw metadata and raw rows.
+    #[inline]
+    pub fn metadata_and_rows_bytes_size(&self) -> usize {
+        self.raw_metadata_and_rows_bytes_size
+    }
+
     /// Creates an empty [DeserializedMetadataAndRawRows].
     // Preferred to implementing Default, because users shouldn't be encouraged to create
     // empty DeserializedMetadataAndRawRows.
@@ -706,6 +713,7 @@ impl DeserializedMetadataAndRawRows {
             ),
             rows_count: 0,
             raw_rows: Bytes::new(),
+            raw_metadata_and_rows_bytes_size: 0,
         }
     }
 
@@ -1070,6 +1078,7 @@ impl RawMetadataAndRawRows {
     pub fn deserialize_metadata(
         self,
     ) -> StdResult<DeserializedMetadataAndRawRows, ResultMetadataAndRowsCountParseError> {
+        let raw_metadata_and_rows_bytes_size = self.metadata_and_rows_bytes_size();
         let (metadata_deserialized, row_count_and_raw_rows) = match self.cached_metadata {
             Some(cached) if self.no_metadata => {
                 // Server sent no metadata, but we have metadata cached. This means that we asked the server
@@ -1120,6 +1129,7 @@ impl RawMetadataAndRawRows {
             metadata: metadata_deserialized,
             rows_count,
             raw_rows: frame_slice.to_bytes(),
+            raw_metadata_and_rows_bytes_size,
         })
     }
 }
@@ -1461,6 +1471,7 @@ mod test_utils {
                 metadata: ResultMetadataHolder::SharedCached(Arc::new(metadata)),
                 rows_count,
                 raw_rows,
+                raw_metadata_and_rows_bytes_size: 0,
             }
         }
     }