feat: add use_process flag for @daft.func(...) (#5323)

## Changes Made

adds `use_process` to daft.func to allow same performance benefits as
`use_process` for `daft.udf`.

## Related Issues

<!-- Link to related GitHub issues, e.g., "Closes #123" -->

## Checklist

- [ ] Documented in API Docs (if applicable)
- [ ] Documented in User Guide (if applicable)
- [ ] If adding a new documentation page, doc is added to
`docs/mkdocs.yml` navigation
- [ ] Documentation builds and is formatted properly

Author: universalmind303

daft/daft/__init__.pyi

@@ -1343,6 +1343,7 @@ def row_wise_udf(
     name: str,
     inner: Callable[..., Any],
     return_dtype: PyDataType,
+    use_process: bool | None,
     original_args: tuple[tuple[Any, ...], dict[str, Any]],
     expr_args: list[PyExpr],
 ) -> PyExpr: ...

daft/udf/__init__.py

@@ -28,6 +28,7 @@ class _PartialUdf:
 
     return_dtype: DataTypeLike | None
     unnest: bool
+    use_process: bool | None
 
     @overload
     def __call__(self, fn: Callable[P, Iterator[T]]) -> GeneratorUdf[P, T]: ...  # type: ignore[overload-overlap]
@@ -36,9 +37,9 @@ def __call__(self, fn: Callable[P, T]) -> RowWiseUdf[P, T]: ...
 
     def __call__(self, fn: Callable[P, Any]) -> GeneratorUdf[P, Any] | RowWiseUdf[P, Any]:
         if isgeneratorfunction(fn):
-            return GeneratorUdf(fn, return_dtype=self.return_dtype, unnest=self.unnest)
+            return GeneratorUdf(fn, return_dtype=self.return_dtype, unnest=self.unnest, use_process=self.use_process)
         else:
-            return RowWiseUdf(fn, return_dtype=self.return_dtype, unnest=self.unnest)
+            return RowWiseUdf(fn, return_dtype=self.return_dtype, unnest=self.unnest, use_process=self.use_process)
 
 
 class _DaftFuncDecorator:
@@ -212,20 +213,41 @@ class _DaftFuncDecorator:
     """
 
     @overload
-    def __new__(cls, *, return_dtype: DataTypeLike | None = None, unnest: bool = False) -> _PartialUdf: ...  # type: ignore[misc]
+    def __new__(  # type: ignore[misc]
+        cls,
+        *,
+        return_dtype: DataTypeLike | None = None,
+        unnest: bool = False,
+        use_process: bool | None = None,
+    ) -> _PartialUdf: ...
     @overload
     def __new__(  # type: ignore[misc]
-        cls, fn: Callable[P, Iterator[T]], *, return_dtype: DataTypeLike | None = None, unnest: bool = False
+        cls,
+        fn: Callable[P, Iterator[T]],
+        *,
+        return_dtype: DataTypeLike | None = None,
+        unnest: bool = False,
+        use_process: bool | None = None,
     ) -> GeneratorUdf[P, T]: ...
     @overload
     def __new__(  # type: ignore[misc]
-        cls, fn: Callable[P, T], *, return_dtype: DataTypeLike | None = None, unnest: bool = False
+        cls,
+        fn: Callable[P, T],
+        *,
+        return_dtype: DataTypeLike | None = None,
+        unnest: bool = False,
+        use_process: bool | None = None,
     ) -> RowWiseUdf[P, T]: ...
 
     def __new__(  # type: ignore[misc]
-        cls, fn: Callable[P, Any] | None = None, *, return_dtype: DataTypeLike | None = None, unnest: bool = False
+        cls,
+        fn: Callable[P, Any] | None = None,
+        *,
+        return_dtype: DataTypeLike | None = None,
+        unnest: bool = False,
+        use_process: bool | None = None,
     ) -> _PartialUdf | GeneratorUdf[P, Any] | RowWiseUdf[P, Any]:
-        partial_udf = _PartialUdf(return_dtype=return_dtype, unnest=unnest)
+        partial_udf = _PartialUdf(return_dtype=return_dtype, unnest=unnest, use_process=use_process)
         return partial_udf if fn is None else partial_udf(fn)
 
 

daft/udf/generator.py

@@ -32,10 +32,13 @@ class GeneratorUdf(Generic[P, T]):
     If no values are yielded for an input, a null value is inserted.
     """
 
-    def __init__(self, fn: Callable[P, Iterator[T]], return_dtype: DataTypeLike | None, unnest: bool):
+    def __init__(
+        self, fn: Callable[P, Iterator[T]], return_dtype: DataTypeLike | None, unnest: bool, use_process: bool | None
+    ):
         self._inner = fn
         self.name = get_unique_function_name(fn)
         self.unnest = unnest
+        self.use_process = use_process
 
         # attempt to extract return type from an Iterator or Generator type hint
         if return_dtype is None:
@@ -85,7 +88,9 @@ def inner_rowwise(*args: P.args, **kwargs: P.kwargs) -> list[T]:
         return_dtype_rowwise = DataType.list(self.return_dtype)
 
         expr = Expression._from_pyexpr(
-            row_wise_udf(self.name, inner_rowwise, return_dtype_rowwise._dtype, (args, kwargs), expr_args)
+            row_wise_udf(
+                self.name, inner_rowwise, return_dtype_rowwise._dtype, self.use_process, (args, kwargs), expr_args
+            )
         ).explode()
 
         if self.unnest:

daft/udf/row_wise.py

@@ -33,10 +33,11 @@ class RowWiseUdf(Generic[P, T]):
     Row-wise functions are called with data from one row at a time, and map that to a single output value for that row.
     """
 
-    def __init__(self, fn: Callable[P, T], return_dtype: DataTypeLike | None, unnest: bool):
+    def __init__(self, fn: Callable[P, T], return_dtype: DataTypeLike | None, unnest: bool, use_process: bool | None):
         self._inner = fn
         self.name = get_unique_function_name(fn)
         self.unnest = unnest
+        self.use_process = use_process
 
         if return_dtype is None:
             type_hints = get_type_hints(fn)
@@ -69,7 +70,7 @@ def __call__(self, *args: Any, **kwargs: Any) -> Expression | T:
             return self._inner(*args, **kwargs)
 
         expr = Expression._from_pyexpr(
-            row_wise_udf(self.name, self._inner, self.return_dtype._dtype, (args, kwargs), expr_args)
+            row_wise_udf(self.name, self._inner, self.return_dtype._dtype, self.use_process, (args, kwargs), expr_args)
         )
 
         if self.unnest:

src/daft-dsl/src/expr/mod.rs

@@ -1478,6 +1478,7 @@ impl Expr {
                 return_dtype,
                 original_args,
                 args: old_children,
+                use_process,
             }))) => {
                 assert!(
                     children.len() == old_children.len(),
@@ -1490,6 +1491,7 @@ impl Expr {
                     return_dtype: return_dtype.clone(),
                     original_args: original_args.clone(),
                     args: children,
+                    use_process: *use_process,
                 })))
             }
         }

src/daft-dsl/src/functions/python/mod.rs

@@ -19,7 +19,7 @@ use serde::{Deserialize, Serialize};
 use super::FunctionExpr;
 #[cfg(feature = "python")]
 use crate::python::PyExpr;
-use crate::{Expr, ExprRef, functions::scalar::ScalarFn};
+use crate::{Expr, ExprRef, functions::scalar::ScalarFn, python_udf::PyScalarFn};
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
 pub enum MaybeInitializedUDF {
@@ -375,13 +375,13 @@ pub fn get_udf_properties(expr: &ExprRef) -> UDFProperties {
                 concurrency: *concurrency,
                 use_process: *use_process,
             });
-        } else if let Expr::ScalarFn(ScalarFn::Python(py)) = e.as_ref() {
+        } else if let Expr::ScalarFn(ScalarFn::Python(PyScalarFn::RowWise(pyfn))) = e.as_ref() {
             udf_properties = Some(UDFProperties {
-                name: py.name().to_string(),
+                name: pyfn.function_name.to_string(),
                 resource_request: None,
                 batch_size: None,
                 concurrency: None,
-                use_process: None,
+                use_process: pyfn.use_process,
             });
         }
         Ok(TreeNodeRecursion::Continue)

src/daft-dsl/src/python.rs

@@ -238,6 +238,7 @@ pub fn row_wise_udf(
     name: &str,
     inner: PyObject,
     return_dtype: PyDataType,
+    use_process: Option<bool>,
     original_args: PyObject,
     expr_args: Vec<PyExpr>,
 ) -> PyExpr {
@@ -250,6 +251,7 @@ pub fn row_wise_udf(
             name,
             inner.into(),
             return_dtype.into(),
+            use_process,
             original_args.into(),
             args,
         )

src/daft-dsl/src/python_udf.rs

@@ -58,6 +58,7 @@ pub fn row_wise_udf(
     name: &str,
     inner: RuntimePyObject,
     return_dtype: DataType,
+    use_process: Option<bool>,
     original_args: RuntimePyObject,
     args: Vec<ExprRef>,
 ) -> Expr {
@@ -67,6 +68,7 @@ pub fn row_wise_udf(
         return_dtype,
         original_args,
         args,
+        use_process,
     })))
 }
 
@@ -77,6 +79,7 @@ pub struct RowWisePyFn {
     pub return_dtype: DataType,
     pub original_args: RuntimePyObject,
     pub args: Vec<ExprRef>,
+    pub use_process: Option<bool>,
 }
 
 impl Display for RowWisePyFn {
@@ -101,6 +104,7 @@ impl RowWisePyFn {
             return_dtype: self.return_dtype.clone(),
             original_args: self.original_args.clone(),
             args: children,
+            use_process: self.use_process,
         }
     }
 

src/daft-ir/src/proto/functions.rs

@@ -40,6 +40,7 @@ pub fn from_proto_function(message: proto::ScalarFn) -> ProtoResult<ir::Expr> {
                     return_dtype: from_proto(row_wise_fn.return_dtype)?,
                     original_args: from_proto(row_wise_fn.original_args)?,
                     args: args.into_inner(),
+                    use_process: row_wise_fn.use_process,
                 };
                 ir::rex::from_py_rowwise_func(func)
             }
@@ -100,6 +101,7 @@ pub fn scalar_fn_to_proto(sf: &ir::functions::scalar::ScalarFn) -> ProtoResult<p
                             return_dtype: Some(row_wise_fn.return_dtype.to_proto()?),
                             inner: Some(row_wise_fn.inner.to_proto()?),
                             original_args: Some(row_wise_fn.original_args.to_proto()?),
+                            use_process: row_wise_fn.use_process,
                         },
                     )),
                 })),

src/daft-logical-plan/src/ops/project.rs

@@ -486,6 +486,7 @@ fn replace_column_with_semantic_id(
                 return_dtype,
                 original_args,
                 args: children,
+                use_process,
             }))) => {
                 let transforms = children
                     .iter()
@@ -508,6 +509,7 @@ fn replace_column_with_semantic_id(
                             return_dtype: return_dtype.clone(),
                             original_args: original_args.clone(),
                             args: new_children,
+                            use_process: *use_process,
                         }),
                     ))))
                 }