Merge pull request #869 from Lorak-mmk/serialize_row_is_empty

SerializeRow: Add is_empty method
scylladb · Dec 6, 2023 · b158aca · b158aca
2 parents bdcf349 + eb10f3b
commit b158aca
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Showing 2 changed files with 45 additions and 0 deletions.
diff --git a/scylla-cql/src/frame/value_tests.rs b/scylla-cql/src/frame/value_tests.rs
@@ -1000,11 +1000,14 @@ fn serialize_values<T: ValueList + SerializeRow>(
     let mut writer = BufBackedRowWriter::new(&mut new_serialized);
     <T as SerializeRow>::serialize(&vl, &ctx, &mut writer).unwrap();
     let value_count: u16 = writer.value_count().try_into().unwrap();
+    let is_empty = writer.value_count() == 0;
 
     // Prepend with value count, like `ValueList` does
     new_serialized[0..2].copy_from_slice(&value_count.to_be_bytes());
 
     assert_eq!(old_serialized, new_serialized);
+    assert_eq!(<T as SerializeRow>::is_empty(&vl), is_empty);
+    assert_eq!(serialized.is_empty(), is_empty);
 
     serialized
 }
@@ -1016,10 +1019,13 @@ fn serialize_values_only_new<T: SerializeRow>(vl: T, columns: &[ColumnSpec]) ->
     let mut writer = BufBackedRowWriter::new(&mut serialized);
     <T as SerializeRow>::serialize(&vl, &ctx, &mut writer).unwrap();
     let value_count: u16 = writer.value_count().try_into().unwrap();
+    let is_empty = writer.value_count() == 0;
 
     // Prepend with value count, like `ValueList` does
     serialized[0..2].copy_from_slice(&value_count.to_be_bytes());
 
+    assert_eq!(<T as SerializeRow>::is_empty(&vl), is_empty);
+
     serialized
 }
 

diff --git a/scylla-cql/src/types/serialize/row.rs b/scylla-cql/src/types/serialize/row.rs
@@ -53,6 +53,8 @@ pub trait SerializeRow {
         ctx: &RowSerializationContext<'_>,
         writer: &mut W,
     ) -> Result<(), SerializationError>;
+
+    fn is_empty(&self) -> bool;
 }
 
 macro_rules! fallback_impl_contents {
@@ -69,6 +71,10 @@ macro_rules! fallback_impl_contents {
         ) -> Result<(), SerializationError> {
             serialize_legacy_row(self, ctx, writer)
         }
+        #[inline]
+        fn is_empty(&self) -> bool {
+            SerializedValues::is_empty(self)
+        }
     };
 }
 
@@ -96,6 +102,11 @@ macro_rules! impl_serialize_row_for_unit {
             // Row is empty - do nothing
             Ok(())
         }
+
+        #[inline]
+        fn is_empty(&self) -> bool {
+            true
+        }
     };
 }
 
@@ -152,6 +163,11 @@ macro_rules! impl_serialize_row_for_slice {
             }
             Ok(())
         }
+
+        #[inline]
+        fn is_empty(&self) -> bool {
+            <[T]>::is_empty(self.as_ref())
+        }
     };
 }
 
@@ -227,6 +243,11 @@ macro_rules! impl_serialize_row_for_map {
 
             Ok(())
         }
+
+        #[inline]
+        fn is_empty(&self) -> bool {
+            Self::is_empty(self)
+        }
     };
 }
 
@@ -258,6 +279,11 @@ impl<T: SerializeRow> SerializeRow for &T {
     ) -> Result<(), SerializationError> {
         <T as SerializeRow>::serialize(self, ctx, writer)
     }
+
+    #[inline]
+    fn is_empty(&self) -> bool {
+        <T as SerializeRow>::is_empty(self)
+    }
 }
 
 impl SerializeRow for SerializedValues {
@@ -325,6 +351,11 @@ macro_rules! impl_tuple {
                 )*
                 Ok(())
             }
+
+            #[inline]
+            fn is_empty(&self) -> bool {
+                $length == 0
+            }
         }
     };
 }
@@ -428,6 +459,14 @@ macro_rules! impl_serialize_row_via_value_list {
             ) -> ::std::result::Result<(), $crate::types::serialize::SerializationError> {
                 $crate::types::serialize::row::serialize_legacy_row(self, ctx, writer)
             }
+
+            #[inline]
+            fn is_empty(&self) -> bool {
+                match $crate::frame::value::ValueList::serialized(self) {
+                    Ok(s) => s.is_empty(),
+                    Err(e) => false
+                }
+            }
         }
     };
 }