switch scylla-cql's request::Batch to use new BatchV2 version

this is the version that the top crate (scylla) will use to send batches

Author: nrxus

scylla-cql/src/frame/request/batch.rs

@@ -81,6 +81,65 @@ impl SerializableRequest for BatchV2<'_> {
     }
 }
 
+impl DeserializableRequest for BatchV2<'static> {
+    fn deserialize(buf: &mut &[u8]) -> Result<Self, RequestDeserializationError> {
+        let batch_type = buf.get_u8().try_into()?;
+        let statements_len = types::read_short(buf)?;
+
+        let statements_and_values = (0..statements_len).try_fold(
+            // technically allocating 3-13 bytes too many but that's OK
+            Vec::with_capacity(buf.len()),
+            |mut statements_and_values, _| {
+                BatchStatement::deserialize_to_buffer(buf, &mut statements_and_values)?;
+                // As stated in CQL protocol v4 specification, values names in Batch are broken and should be never used.
+                let values = SerializedValues::new_from_frame(buf)?;
+                statements_and_values.extend_from_slice(&values.element_count().to_be_bytes());
+                statements_and_values.extend_from_slice(values.get_contents());
+
+                Result::<_, RequestDeserializationError>::Ok(statements_and_values)
+            },
+        )?;
+
+        let consistency = types::read_consistency(buf)?;
+
+        let flags = buf.get_u8();
+        let unknown_flags = flags & (!ALL_FLAGS);
+        if unknown_flags != 0 {
+            return Err(RequestDeserializationError::UnknownFlags {
+                flags: unknown_flags,
+            });
+        }
+        let serial_consistency_flag = (flags & FLAG_WITH_SERIAL_CONSISTENCY) != 0;
+        let default_timestamp_flag = (flags & FLAG_WITH_DEFAULT_TIMESTAMP) != 0;
+
+        let serial_consistency = serial_consistency_flag
+            .then(|| types::read_consistency(buf))
+            .transpose()?
+            .map(
+                |consistency| match SerialConsistency::try_from(consistency) {
+                    Ok(serial_consistency) => Ok(serial_consistency),
+                    Err(_) => Err(RequestDeserializationError::ExpectedSerialConsistency(
+                        consistency,
+                    )),
+                },
+            )
+            .transpose()?;
+
+        let timestamp = default_timestamp_flag
+            .then(|| types::read_long(buf))
+            .transpose()?;
+
+        Ok(Self {
+            batch_type,
+            consistency,
+            serial_consistency,
+            timestamp,
+            statements_len,
+            statements_and_values: Cow::Owned(statements_and_values),
+        })
+    }
+}
+
 /// The type of a batch.
 #[derive(Clone, Copy)]
 #[cfg_attr(test, derive(Debug, PartialEq, Eq))]
@@ -251,6 +310,29 @@ impl BatchStatement<'_> {
             )),
         }
     }
+
+    fn deserialize_to_buffer(
+        input: &mut &[u8],
+        out: &mut Vec<u8>,
+    ) -> Result<(), RequestDeserializationError> {
+        match input.get_u8() {
+            0 => {
+                out.put_u8(0);
+                types::read_long_string_to_buff(input, out)?;
+
+                Ok(())
+            }
+            1 => {
+                out.put_u8(1);
+                types::read_short_bytes_to_buffer(input, out)?;
+
+                Ok(())
+            }
+            kind => Err(RequestDeserializationError::UnexpectedBatchStatementKind(
+                kind,
+            )),
+        }
+    }
 }
 
 impl BatchStatement<'_> {

scylla-cql/src/frame/request/mod.rs

@@ -16,6 +16,7 @@ use bytes::Bytes;
 
 pub use auth_response::AuthResponse;
 pub use batch::Batch;
+pub use batch::BatchV2;
 pub use execute::Execute;
 pub use options::Options;
 pub use prepare::Prepare;
@@ -138,6 +139,7 @@ pub enum Request<'r> {
     Query(Query<'r>),
     Execute(Execute<'r>),
     Batch(Batch<'r, BatchStatement<'r>, Vec<SerializedValues>>),
+    BatchV2(BatchV2<'r>),
 }
 
 impl Request<'_> {
@@ -148,7 +150,7 @@ impl Request<'_> {
         match opcode {
             RequestOpcode::Query => Query::deserialize(buf).map(Self::Query),
             RequestOpcode::Execute => Execute::deserialize(buf).map(Self::Execute),
-            RequestOpcode::Batch => Batch::deserialize(buf).map(Self::Batch),
+            RequestOpcode::Batch => BatchV2::deserialize(buf).map(Self::BatchV2),
             _ => unimplemented!(
                 "Deserialization of opcode {:?} is not yet supported",
                 opcode
@@ -162,6 +164,7 @@ impl Request<'_> {
             Request::Query(q) => Some(q.parameters.consistency),
             Request::Execute(e) => Some(e.parameters.consistency),
             Request::Batch(b) => Some(b.consistency),
+            Request::BatchV2(b) => Some(b.consistency),
             #[expect(unreachable_patterns)] // until other opcodes are supported
             _ => None,
         }
@@ -173,6 +176,7 @@ impl Request<'_> {
             Request::Query(q) => Some(q.parameters.serial_consistency),
             Request::Execute(e) => Some(e.parameters.serial_consistency),
             Request::Batch(b) => Some(b.serial_consistency),
+            Request::BatchV2(b) => Some(b.serial_consistency),
             #[expect(unreachable_patterns)] // until other opcodes are supported
             _ => None,
         }
@@ -181,15 +185,15 @@ impl Request<'_> {
 
 #[cfg(test)]
 mod tests {
-    use std::{borrow::Cow, ops::Deref};
+    use std::borrow::Cow;
 
     use bytes::Bytes;
 
     use crate::serialize::row::SerializedValues;
     use crate::{
         frame::{
             request::{
-                batch::{Batch, BatchStatement, BatchType},
+                batch::{BatchStatement, BatchType, BatchV2},
                 execute::Execute,
                 query::{Query, QueryParameters},
                 DeserializableRequest, SerializableRequest,
@@ -261,32 +265,39 @@ mod tests {
         }
 
         // Batch
-        let statements = vec![
-            BatchStatement::Query {
-                text: query.contents,
-            },
-            BatchStatement::Prepared {
-                id: Cow::Borrowed(&execute.id),
-            },
-        ];
-        let batch = Batch {
-            statements: Cow::Owned(statements),
+        // Not execute's values, because named values are not supported in batches.
+        let mut statements_and_values = vec![];
+        BatchStatement::Query {
+            text: query.contents,
+        }
+        .serialize(&mut statements_and_values)
+        .unwrap();
+        statements_and_values
+            .extend_from_slice(&query.parameters.values.element_count().to_be_bytes());
+        statements_and_values.extend_from_slice(query.parameters.values.get_contents());
+
+        BatchStatement::Prepared {
+            id: Cow::Borrowed(&execute.id),
+        }
+        .serialize(&mut statements_and_values)
+        .unwrap();
+        statements_and_values
+            .extend_from_slice(&query.parameters.values.element_count().to_be_bytes());
+        statements_and_values.extend_from_slice(query.parameters.values.get_contents());
+
+        let batch = BatchV2 {
+            statements_and_values: Cow::Owned(statements_and_values),
             batch_type: BatchType::Logged,
             consistency: Consistency::EachQuorum,
             serial_consistency: Some(SerialConsistency::LocalSerial),
             timestamp: Some(32432),
-
-            // Not execute's values, because named values are not supported in batches.
-            values: vec![
-                query.parameters.values.deref().clone(),
-                query.parameters.values.deref().clone(),
-            ],
+            statements_len: 2,
         };
         {
             let mut buf = Vec::new();
             batch.serialize(&mut buf).unwrap();
 
-            let batch_deserialized = Batch::deserialize(&mut &buf[..]).unwrap();
+            let batch_deserialized = BatchV2::deserialize(&mut &buf[..]).unwrap();
             assert_eq!(&batch_deserialized, &batch);
         }
     }
@@ -341,24 +352,30 @@ mod tests {
         }
 
         // Batch
-        let statements = vec![BatchStatement::Query {
+        let mut statements_and_values = vec![];
+        BatchStatement::Query {
             text: query.contents,
-        }];
-        let batch = Batch {
-            statements: Cow::Owned(statements),
+        }
+        .serialize(&mut statements_and_values)
+        .unwrap();
+        statements_and_values
+            .extend_from_slice(&query.parameters.values.element_count().to_be_bytes());
+        statements_and_values.extend_from_slice(query.parameters.values.get_contents());
+
+        let batch = BatchV2 {
             batch_type: BatchType::Logged,
             consistency: Consistency::EachQuorum,
             serial_consistency: None,
             timestamp: None,
-
-            values: vec![query.parameters.values.deref().clone()],
+            statements_and_values: Cow::Owned(statements_and_values),
+            statements_len: 1,
         };
         {
             let mut buf = Vec::new();
             batch.serialize(&mut buf).unwrap();
 
             // Sanity check: batch deserializes to the equivalent.
-            let batch_deserialized = Batch::deserialize(&mut &buf[..]).unwrap();
+            let batch_deserialized = BatchV2::deserialize(&mut &buf[..]).unwrap();
             assert_eq!(batch, batch_deserialized);
 
             // Now modify flags by adding an unknown one.
@@ -370,7 +387,7 @@ mod tests {
 
             // Unknown flag should lead to frame rejection, as unknown flags can be new protocol extensions
             // leading to different semantics.
-            let _parse_error = Batch::deserialize(&mut &buf[..]).unwrap_err();
+            let _parse_error = BatchV2::deserialize(&mut &buf[..]).unwrap_err();
         }
     }
 }

scylla-cql/src/frame/types.rs

@@ -288,6 +288,17 @@ pub fn read_short_bytes<'a>(buf: &mut &'a [u8]) -> Result<&'a [u8], LowLevelDese
     Ok(v)
 }
 
+pub fn read_short_bytes_to_buffer(
+    input: &mut &[u8],
+    out: &mut impl BufMut,
+) -> Result<(), LowLevelDeserializationError> {
+    let len = read_short(input)?;
+    let v = read_raw_bytes(len.into(), input)?;
+    write_short(len, out);
+    out.put_slice(v);
+    Ok(())
+}
+
 pub fn write_bytes(v: &[u8], buf: &mut impl BufMut) -> Result<(), std::num::TryFromIntError> {
     write_int_length(v.len(), buf)?;
     buf.put_slice(v);
@@ -394,6 +405,23 @@ pub fn write_long_string(v: &str, buf: &mut impl BufMut) -> Result<(), std::num:
     Ok(())
 }
 
+pub(crate) fn read_long_string_to_buff(
+    input: &mut &[u8],
+    out: &mut impl BufMut,
+) -> Result<(), LowLevelDeserializationError> {
+    let len = read_int(input)?;
+    let raw = read_raw_bytes(len.try_into()?, input)?;
+
+    // verify it is a valid string but ignore the out string; we already have the raw bytes
+    let _ = str::from_utf8(raw)?;
+
+    // now write it out
+    write_int(len, out);
+    out.put_slice(raw);
+
+    Ok(())
+}
+
 #[test]
 fn type_long_string() {
     let vals = [String::from(""), String::from("hello, world!")];

scylla/src/statement/prepared.rs

@@ -448,14 +448,20 @@ impl PreparedStatement {
         self.config.execution_profile_handle.as_ref()
     }
 
-    pub(crate) fn bind(
+    /// Binds values with a reference to a prepared statement
+    ///
+    /// This method will serialize the values and thus type erase them on return
+    pub fn bind(
         &self,
         values: &impl SerializeRow,
     ) -> Result<BoundStatement<'_>, SerializationError> {
         BoundStatement::new(Cow::Borrowed(self), values)
     }
 
-    pub(crate) fn into_bind(
+    /// Binds values with an owned prepared statement
+    ///
+    /// This method will serialize the values and thus type erase them on return
+    pub fn into_bind(
         self,
         values: &impl SerializeRow,
     ) -> Result<BoundStatement<'static>, SerializationError> {