Expose delete_by_rel (#515)

* expose delete_by_rel

* delete_by_rel: address pheobe's smallvec comment request

Cargo.toml

@@ -149,6 +149,7 @@ sha1 = "0.10.1"
 sha3 = "0.10.0"
 slab = "0.4.7"
 sled = "0.34.7"
+smallvec = { version = "1.11.1", features = ["union", "const_generics"] }
 sqlparser = "0.38.0"
 sqllogictest-engines = "0.17"
 sqllogictest = "0.17"

crates/bindings-sys/src/lib.rs

@@ -145,6 +145,24 @@ pub mod raw {
             out: *mut u32,
         ) -> u16;
 
+        /// Deletes those rows, in the table identified by `table_id`,
+        /// that match any row in `relation`.
+        ///
+        /// Matching is defined by first BSATN-decoding
+        /// the byte string pointed to at by `relation` to a `Vec<ProductValue>`
+        /// according to the row schema of the table
+        /// and then using `Ord for AlgebraicValue`.
+        ///
+        /// The number of rows deleted is written to the WASM pointer `out`.
+        ///
+        /// Returns an error if
+        /// - a table with the provided `table_id` doesn't exist
+        /// - `(relation, relation_len)` doesn't decode from BSATN to a `Vec<ProductValue>`
+        ///   according to the `ProductValue` that the table's schema specifies for rows.
+        /// - `relation + relation_len` overflows a 64-bit integer
+        /// - writing to `out` would overflow a 32-bit integer
+        pub fn _delete_by_rel(table_id: TableId, relation: *const u8, relation_len: usize, out: *mut u32) -> u16;
+
         /// Start iteration on each row, as bytes, of a table identified by `table_id`.
         ///
         /// The iterator is registered in the host environment
@@ -576,6 +594,24 @@ pub fn delete_by_col_eq(table_id: TableId, col_id: ColId, value: &[u8]) -> Resul
     unsafe { call(|out| raw::_delete_by_col_eq(table_id, col_id, value.as_ptr(), value.len(), out)) }
 }
 
+/// Deletes those rows, in the table identified by `table_id`,
+/// that match any row in `relation`.
+///
+/// Matching is defined by first BSATN-decoding
+/// the byte string pointed to at by `relation` to a `Vec<ProductValue>`
+/// according to the row schema of the table
+/// and then using `Ord for AlgebraicValue`.
+///
+/// Returns the number of rows deleted.
+///
+/// Returns an error if
+/// - a table with the provided `table_id` doesn't exist
+/// - `(relation, relation_len)` doesn't decode from BSATN to a `Vec<ProductValue>`
+#[inline]
+pub fn delete_by_rel(table_id: TableId, relation: &[u8]) -> Result<u32, Errno> {
+    unsafe { call(|out| raw::_delete_by_rel(table_id, relation.as_ptr(), relation.len(), out)) }
+}
+
 /// Returns an iterator for each row, as bytes, of a table identified by `table_id`.
 /// The rows can be put through an optional `filter`,
 /// which is encoded in the embedded language defined by `spacetimedb_lib::filter::Expr`.

crates/bindings/src/lib.rs

@@ -17,6 +17,7 @@ pub use spacetimedb_lib::ser::Serialize;
 use spacetimedb_lib::{bsatn, ColumnIndexAttribute, IndexType, PrimaryKey, ProductType, ProductValue};
 use std::cell::RefCell;
 use std::marker::PhantomData;
+use std::slice::from_ref;
 use std::{fmt, panic};
 
 pub use spacetimedb_bindings_macro::{duration, query, spacetimedb, TableType};
@@ -198,6 +199,33 @@ pub fn delete_by_col_eq(table_id: TableId, col_id: u8, value: &impl Serialize) -
     })
 }
 
+/// Deletes those rows, in the table identified by `table_id`,
+/// that match any row in `relation`.
+///
+/// The `relation` will be BSATN encoded to `[ProductValue]`
+/// i.e., a list of product values, so each element in `relation`
+/// must serialize to what a `ProductValue` would in BSATN.
+///
+/// Matching is then defined by first BSATN-decoding
+/// the resulting bsatn to a `Vec<ProductValue>`
+/// according to the row schema of the table
+/// and then using `Ord for AlgebraicValue`.
+///
+/// Returns the number of rows deleted.
+///
+/// Returns an error if
+/// - a table with the provided `table_id` doesn't exist
+/// - `(relation, relation_len)` doesn't decode from BSATN to a `Vec<ProductValue>`
+///
+/// Panics when serialization fails.
+pub fn delete_by_rel(table_id: TableId, relation: &[impl Serialize]) -> Result<u32> {
+    with_row_buf(|bytes| {
+        // Encode `value` as BSATN into `bytes` and then use that.
+        bsatn::to_writer(bytes, relation).unwrap();
+        sys::delete_by_rel(table_id, bytes)
+    })
+}
+
 /// A table iterator which yields values of the `TableType` corresponding to the table.
 type TableTypeTableIter<T> = RawTableIter<TableTypeBufferDeserialize<T>>;
 
@@ -342,6 +370,15 @@ pub trait TableType: SpacetimeType + DeserializeOwned + Serialize {
     fn iter_filtered(filter: spacetimedb_lib::filter::Expr) -> TableIter<Self> {
         table_iter(Self::table_id(), Some(filter)).unwrap()
     }
+
+    /// Deletes this row `self` from the table.
+    ///
+    /// Returns `true` if the row was deleted.
+    fn delete(&self) -> bool {
+        let count = delete_by_rel(Self::table_id(), from_ref(self)).unwrap();
+        debug_assert!(count < 2);
+        count == 1
+    }
 }
 
 mod sealed {

crates/core/src/db/relational_db.rs

@@ -248,7 +248,7 @@ impl RelationalDB {
         bytes: &[u8],
     ) -> Result<AlgebraicValue, DBError> {
         let schema = self.schema_for_column(tx, table_id, col_id)?;
-        Ok(AlgebraicValue::decode(&schema, &mut &bytes[..])?)
+        Ok(AlgebraicValue::decode(&schema, &mut &*bytes)?)
     }
 
     /// Begin a transaction.

crates/core/src/host/instance_env.rs

@@ -144,7 +144,7 @@ impl InstanceEnv {
     /// Deletes all rows in the table identified by `table_id`
     /// where the column identified by `cols` equates to `value`.
     ///
-    /// Returns an error if no columns were deleted or if the column wasn't found.
+    /// Returns an error if no rows were deleted or if the column wasn't found.
     #[tracing::instrument(skip(self, ctx, value))]
     pub fn delete_by_col_eq(
         &self,
@@ -170,6 +170,26 @@ impl InstanceEnv {
         NonZeroU32::new(count).ok_or(NodesError::ColumnValueNotFound)
     }
 
+    /// Deletes all rows in the table identified by `table_id`
+    /// where the rows match one in `relation`
+    /// which is a bsatn encoding of `Vec<ProductValue>`.
+    ///
+    /// Returns an error if no rows were deleted.
+    #[tracing::instrument(skip(self, relation))]
+    pub fn delete_by_rel(&self, table_id: TableId, relation: &[u8]) -> Result<u32, NodesError> {
+        let stdb = &*self.dbic.relational_db;
+        let tx = &mut *self.get_tx()?;
+
+        // Find the row schema using it to decode a vector of product values.
+        let row_ty = stdb.row_schema_for_table(tx, table_id)?;
+        // `TableType::delete` cares about a single element
+        // so in that case we can avoid the allocation by using `smallvec`.
+        let relation = ProductValue::decode_smallvec(&row_ty, &mut &*relation).map_err(NodesError::DecodeRow)?;
+
+        // Delete them and return how many we deleted.
+        Ok(stdb.delete_by_rel(tx, table_id, relation))
+    }
+
     /// Returns the `table_id` associated with the given `table_name`.
     ///
     /// Errors with `TableNotFound` if the table does not exist.

crates/core/src/host/mod.rs

@@ -176,6 +176,7 @@ pub enum AbiCall {
     ConsoleLog,
     CreateIndex,
     DeleteByColEq,
+    DeleteByRel,
     GetTableId,
     Insert,
     IterByColEq,

crates/core/src/host/wasmer/wasm_instance_env.rs

@@ -492,6 +492,36 @@ impl WasmInstanceEnv {
         result
     }
 
+    /// Deletes those rows, in the table identified by `table_id`,
+    /// that match any row in `relation`.
+    ///
+    /// Matching is defined by first BSATN-decoding
+    /// the byte string pointed to at by `relation` to a `Vec<ProductValue>`
+    /// according to the row schema of the table
+    /// and then using `Ord for AlgebraicValue`.
+    ///
+    /// The number of rows deleted is written to the WASM pointer `out`.
+    ///
+    /// Returns an error if
+    /// - a table with the provided `table_id` doesn't exist
+    /// - `(relation, relation_len)` doesn't decode from BSATN to a `Vec<ProductValue>`
+    ///   according to the `ProductValue` that the table's schema specifies for rows.
+    /// - `relation + relation_len` overflows a 64-bit integer
+    /// - writing to `out` would overflow a 32-bit integer
+    #[tracing::instrument(skip_all)]
+    pub fn delete_by_rel(
+        caller: FunctionEnvMut<'_, Self>,
+        table_id: u32,
+        relation: WasmPtr<u8>,
+        relation_len: u32,
+        out: WasmPtr<u32>,
+    ) -> RtResult<u16> {
+        Self::cvt_ret(caller, "delete_by_rel", AbiCall::DeleteByRel, out, |caller, mem| {
+            let relation = mem.read_bytes(&caller, relation, relation_len)?;
+            Ok(caller.data().instance_env.delete_by_rel(table_id.into(), &relation)?)
+        })
+    }
+
     /// Queries the `table_id` associated with the given (table) `name`
     /// where `name` points to a UTF-8 slice in WASM memory of `name_len` bytes.
     ///

crates/core/src/host/wasmer/wasmer_module.rs

@@ -59,6 +59,11 @@ impl WasmerModule {
                     env,
                     WasmInstanceEnv::delete_by_col_eq,
                 ),
+                "_delete_by_rel" => Function::new_typed_with_env(
+                    store,
+                    env,
+                    WasmInstanceEnv::delete_by_rel,
+                ),
                 "_insert" => Function::new_typed_with_env(
                     store,
                     env,

crates/sats/Cargo.toml

@@ -22,6 +22,7 @@ hex = { workspace = true, optional = true }
 itertools.workspace = true
 nonempty.workspace = true
 serde = { workspace = true, optional = true }
+smallvec.workspace = true
 thiserror.workspace = true
 tracing.workspace = true
 

crates/sats/src/bsatn.rs

@@ -1,7 +1,8 @@
 use crate::buffer::{BufReader, BufWriter};
-use crate::de::{Deserialize, DeserializeSeed};
+use crate::de::{BasicSmallVecVisitor, Deserialize, DeserializeSeed, Deserializer as _};
 use crate::ser::Serialize;
 use crate::Typespace;
+use smallvec::SmallVec;
 
 pub mod de;
 pub mod ser;
@@ -49,12 +50,23 @@ macro_rules! codec_funcs {
     };
     (val: $ty:ty) => {
         impl $ty {
+            /// Decode a value from `bytes` typed at `ty`.
             pub fn decode<'a>(
-                algebraic_type: &<Self as crate::Value>::Type,
+                ty: &<Self as crate::Value>::Type,
                 bytes: &mut impl BufReader<'a>,
             ) -> Result<Self, DecodeError> {
-                crate::WithTypespace::new(&Typespace::new(Vec::new()), algebraic_type)
-                    .deserialize(Deserializer::new(bytes))
+                crate::WithTypespace::new(&Typespace::new(Vec::new()), ty).deserialize(Deserializer::new(bytes))
+            }
+
+            /// Decode a vector of values from `bytes` with each value typed at `ty`.
+            pub fn decode_smallvec<'a>(
+                ty: &<Self as crate::Value>::Type,
+                bytes: &mut impl BufReader<'a>,
+            ) -> Result<SmallVec<[Self; 1]>, DecodeError> {
+                Deserializer::new(bytes).deserialize_array_seed(
+                    BasicSmallVecVisitor,
+                    crate::WithTypespace::new(&Typespace::new(Vec::new()), ty),
+                )
             }
 
             pub fn encode(&self, bytes: &mut impl BufWriter) {

crates/sats/src/de.rs

@@ -7,6 +7,7 @@ pub mod serde;
 
 #[doc(hidden)]
 pub use impls::{visit_named_product, visit_seq_product};
+use smallvec::SmallVec;
 
 use std::borrow::Borrow;
 use std::collections::BTreeMap;
@@ -580,6 +581,18 @@ pub trait MapAccess<'de> {
     }
 }
 
+impl<'de, A: MapAccess<'de>> ArrayAccess<'de> for A {
+    type Element = (A::Key, A::Value);
+    type Error = A::Error;
+
+    fn next_element(&mut self) -> Result<Option<Self::Element>, Self::Error> {
+        self.next_entry()
+    }
+    fn size_hint(&self) -> Option<usize> {
+        self.size_hint()
+    }
+}
+
 /// `DeserializeSeed` is the stateful form of the [`Deserialize`] trait.
 pub trait DeserializeSeed<'de> {
     /// The type produced by using this seed.
@@ -635,18 +648,61 @@ impl<'de, T: Deserialize<'de>> DeserializeSeed<'de> for PhantomData<T> {
     }
 }
 
+/// A vector with two operations: `with_capacity` and `push`.
+pub trait GrowingVec<T> {
+    /// Create the collection with the given capacity.
+    fn with_capacity(cap: usize) -> Self;
+
+    /// Push to the vector the `elem`.
+    fn push(&mut self, elem: T);
+}
+
+impl<T> GrowingVec<T> for Vec<T> {
+    fn with_capacity(cap: usize) -> Self {
+        Self::with_capacity(cap)
+    }
+    fn push(&mut self, elem: T) {
+        self.push(elem)
+    }
+}
+
+impl<T, const N: usize> GrowingVec<T> for SmallVec<[T; N]> {
+    fn with_capacity(cap: usize) -> Self {
+        Self::with_capacity(cap)
+    }
+    fn push(&mut self, elem: T) {
+        self.push(elem)
+    }
+}
+
+/// A basic implementation of `ArrayVisitor::visit` using the provided size hint.
+pub fn array_visit<'de, A: ArrayAccess<'de>, V: GrowingVec<A::Element>>(mut access: A) -> Result<V, A::Error> {
+    let mut v = V::with_capacity(access.size_hint().unwrap_or(0));
+    while let Some(x) = access.next_element()? {
+        v.push(x)
+    }
+    Ok(v)
+}
+
 /// An implementation of [`ArrayVisitor<'de, T>`] where the output is a `Vec<T>`.
 pub struct BasicVecVisitor;
 
 impl<'de, T> ArrayVisitor<'de, T> for BasicVecVisitor {
     type Output = Vec<T>;
 
-    fn visit<A: ArrayAccess<'de, Element = T>>(self, mut vec: A) -> Result<Self::Output, A::Error> {
-        let mut v = Vec::with_capacity(vec.size_hint().unwrap_or(0));
-        while let Some(el) = vec.next_element()? {
-            v.push(el)
-        }
-        Ok(v)
+    fn visit<A: ArrayAccess<'de, Element = T>>(self, vec: A) -> Result<Self::Output, A::Error> {
+        array_visit(vec)
+    }
+}
+
+/// An implementation of [`ArrayVisitor<'de, T>`] where the output is a `SmallVec<[T; N]>`.
+pub struct BasicSmallVecVisitor<const N: usize>;
+
+impl<'de, T, const N: usize> ArrayVisitor<'de, T> for BasicSmallVecVisitor<N> {
+    type Output = SmallVec<[T; N]>;
+
+    fn visit<A: ArrayAccess<'de, Element = T>>(self, vec: A) -> Result<Self::Output, A::Error> {
+        array_visit(vec)
     }
 }
 
@@ -656,12 +712,8 @@ pub struct BasicMapVisitor;
 impl<'de, K: Ord, V> MapVisitor<'de, K, V> for BasicMapVisitor {
     type Output = BTreeMap<K, V>;
 
-    fn visit<A: MapAccess<'de, Key = K, Value = V>>(self, mut map: A) -> Result<Self::Output, A::Error> {
-        let mut m = Vec::with_capacity(map.size_hint().unwrap_or(0));
-        while let Some(entry) = map.next_entry()? {
-            m.push(entry)
-        }
-        Ok(m.into_iter().collect())
+    fn visit<A: MapAccess<'de, Key = K, Value = V>>(self, map: A) -> Result<Self::Output, A::Error> {
+        Ok(array_visit::<_, Vec<_>>(map)?.into_iter().collect())
     }
 }