Immutable session + registries

Signed-off-by: Nicholas Gates <[email protected]>

Author: gatesn

java/testfiles/src/main.rs

@@ -6,9 +6,13 @@
 use std::path::Path;
 
 use vortex::array::arrays::StructArray;
-use vortex::array::builders::{ArrayBuilder, DecimalBuilder, VarBinViewBuilder};
+use vortex::array::builders::ArrayBuilder;
+use vortex::array::builders::DecimalBuilder;
+use vortex::array::builders::VarBinViewBuilder;
 use vortex::array::validity::Validity;
-use vortex::dtype::{DType, DecimalDType, Nullability};
+use vortex::dtype::DType;
+use vortex::dtype::DecimalDType;
+use vortex::dtype::Nullability;
 use vortex::file::WriteOptionsSessionExt;
 use vortex::io::runtime::current::CurrentThreadRuntime;
 use vortex::io::runtime::BlockingRuntime;
@@ -32,7 +36,9 @@ use vortex::VortexSessionDefault;
 /// | John   | 10000  | VA    |
 fn main() {
     let runtime = CurrentThreadRuntime::new();
-    let session = VortexSession::default().with_handle(runtime.handle());
+    let session = VortexSession::new_with_defaults()
+        .with_handle(runtime.handle())
+        .freeze();
 
     let mut names = VarBinViewBuilder::with_capacity(DType::Utf8(Nullability::NonNullable), 10);
     names.append_value("Alice");

vortex-session/src/lib.rs

@@ -65,9 +65,11 @@ impl VortexSession {
     ///
     /// Note that the returned value internally holds a lock on the variable.
     pub fn get_mut<V: SessionVar + Default>(&mut self) -> &mut V {
-        self.0
+        let v = self
+            .0
             .entry(TypeId::of::<V>())
-            .or_insert_with(|| Box::new(V::default()))
+            .or_insert_with(|| Box::new(V::default()));
+        (**v)
             .as_any_mut()
             .downcast_mut::<V>()
             .vortex_expect("Type mismatch - this is a bug")

vortex/src/lib.rs

@@ -157,6 +157,7 @@ impl VortexSessionDefault for VortexSession {
         VortexSession::empty().with_defaults()
     }
 
+    #[allow(unused_mut)]
     fn with_defaults(self) -> VortexSession {
         let mut this = self
             .with::<VortexMetrics>()