Make Shared transparent to parent kernels

vortex-array/src/arrays/shared/vtable.rs

@@ -113,6 +113,14 @@ impl VTable for Shared {
             .get_or_compute(|source| source.clone().execute::<Canonical>(ctx))
             .map(ExecutionResult::done)
     }
+
+    fn reduce_parent(
+        array: ArrayView<'_, Self>,
+        parent: &ArrayRef,
+        child_idx: usize,
+    ) -> VortexResult<Option<ArrayRef>> {
+        array.current_array_ref().reduce_parent(parent, child_idx)
+    }
 }
 impl OperationsVTable<Shared> for Shared {
     fn scalar_at(

vortex-array/src/executor.rs

@@ -34,6 +34,8 @@ use crate::ArrayRef;
 use crate::Canonical;
 use crate::IntoArray;
 use crate::array::ArrayId;
+use crate::arrays::Shared;
+use crate::arrays::shared::SharedArrayExt;
 use crate::builders::ArrayBuilder;
 use crate::builders::builder_with_capacity_in;
 use crate::dtype::DType;
@@ -568,6 +570,35 @@ fn execute_parent_for_child(
     slot_idx: usize,
     kernels: &ParentExecutionKernels,
     ctx: &mut ExecutionCtx,
+) -> VortexResult<Option<ArrayRef>> {
+    if let Some(result) = execute_parent_for_exact_child(parent, child, slot_idx, kernels, ctx)? {
+        return Ok(Some(result));
+    }
+
+    // Shared is a transparent cache wrapper. Try kernels against the wrapped source/current array
+    // before forcing Shared to canonicalize and populate its cache.
+    let mut current = child.clone();
+    while let Some(source) = current
+        .as_opt::<Shared>()
+        .map(|shared| shared.current_array_ref().clone())
+    {
+        if let Some(result) =
+            execute_parent_for_exact_child(parent, &source, slot_idx, kernels, ctx)?
+        {
+            return Ok(Some(result));
+        }
+        current = source;
+    }
+
+    Ok(None)
+}
+
+fn execute_parent_for_exact_child(
+    parent: &ArrayRef,
+    child: &ArrayRef,
+    slot_idx: usize,
+    kernels: &ParentExecutionKernels,
+    ctx: &mut ExecutionCtx,
 ) -> VortexResult<Option<ArrayRef>> {
     let key = execute_parent_key(parent.encoding_id(), child.encoding_id());
     if let Some(plugins) = kernels.get(&key) {