refactor(tvix/eval): remove extra Rc<..> around Value::Attrs

The `im::OrdMap` is already small and cheap to copy while sharing
memory, so this is not required anymore.

Only the `KV` variant may have slightly larger content, but in
practice this doesn't seem to make a difference when comparing the two
variants and this one is less complicated.

Change-Id: I64a563b209a2444125653777551373cb2989ca7d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7677
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2022-12-29 17:34:08 +03:00 committed by tazjin
parent 91465dc78e
commit 86361f0f4a
5 changed files with 24 additions and 21 deletions

View file

@ -21,7 +21,7 @@ use crate::{
vm::VM,
};
use crate::{arithmetic_op, unwrap_or_clone_rc};
use crate::arithmetic_op;
use self::versions::{VersionPart, VersionPartsIter};
@ -1022,8 +1022,8 @@ fn placeholders() -> Vec<Builtin> {
// values on the fields that a real derivation would contain.
//
// Crucially this means we do not yet *validate* the values either.
let attrs = unwrap_or_clone_rc(args[0].to_attrs()?);
let attrs = attrs.update(NixAttrs::from_iter(
let input = args[0].to_attrs()?;
let attrs = input.update(NixAttrs::from_iter(
[
(
"outPath",
@ -1038,7 +1038,7 @@ fn placeholders() -> Vec<Builtin> {
.into_iter(),
));
Ok(Value::Attrs(Rc::new(attrs)))
Ok(Value::Attrs(Box::new(attrs)))
},
),
]

View file

@ -37,7 +37,6 @@ mod test_utils;
mod tests;
use std::path::PathBuf;
use std::rc::Rc;
use std::str::FromStr;
use std::sync::Arc;
@ -63,12 +62,6 @@ pub mod internal {
pub use crate::vm::VM;
}
// TODO: use Rc::unwrap_or_clone once it is stabilised.
// https://doc.rust-lang.org/std/rc/struct.Rc.html#method.unwrap_or_clone
pub(crate) fn unwrap_or_clone_rc<T: Clone>(rc: Rc<T>) -> T {
Rc::try_unwrap(rc).unwrap_or_else(|rc| (*rc).clone())
}
/// An `Evaluation` represents how a piece of Nix code is evaluated. It can be
/// instantiated and configured directly, or it can be accessed through the
/// various simplified helper methods available below.

View file

@ -173,6 +173,17 @@ impl NixAttrs {
Self(AttrsRep::Empty)
}
/// Compare two attribute sets by pointer equality. Only makes
/// sense for some attribute set reprsentations, i.e. returning
/// `false` does not mean that the two attribute sets do not have
/// equal *content*.
pub fn ptr_eq(&self, other: &Self) -> bool {
match (&self.0, &other.0) {
(AttrsRep::Im(lhs), AttrsRep::Im(rhs)) => lhs.ptr_eq(rhs),
_ => false,
}
}
/// Return an attribute set containing the merge of the two
/// provided sets. Keys from the `other` set have precedence.
pub fn update(self, other: Self) -> Self {

View file

@ -39,7 +39,7 @@ pub enum Value {
Float(f64),
String(NixString),
Path(PathBuf),
Attrs(Rc<NixAttrs>),
Attrs(Box<NixAttrs>),
List(NixList),
Closure(Rc<Closure>), // must use Rc<Closure> here in order to get proper pointer equality
Builtin(Builtin),
@ -154,7 +154,7 @@ where
impl Value {
/// Construct a [`Value::Attrs`] from a [`NixAttrs`].
pub fn attrs(attrs: NixAttrs) -> Self {
Self::Attrs(Rc::new(attrs))
Self::Attrs(Box::new(attrs))
}
}
@ -303,7 +303,7 @@ impl Value {
gen_cast!(as_int, i64, "int", Value::Integer(x), *x);
gen_cast!(as_float, f64, "float", Value::Float(x), *x);
gen_cast!(to_str, NixString, "string", Value::String(s), s.clone());
gen_cast!(to_attrs, Rc<NixAttrs>, "set", Value::Attrs(a), a.clone());
gen_cast!(to_attrs, Box<NixAttrs>, "set", Value::Attrs(a), a.clone());
gen_cast!(to_list, NixList, "list", Value::List(l), l.clone());
gen_cast!(
as_closure,

View file

@ -12,7 +12,6 @@ use crate::{
observer::RuntimeObserver,
opcode::{CodeIdx, Count, JumpOffset, OpCode, StackIdx, UpvalueIdx},
spans::LightSpan,
unwrap_or_clone_rc,
upvalues::Upvalues,
value::{Builtin, Closure, CoercionKind, Lambda, NixAttrs, NixList, Thunk, Value},
warnings::{EvalWarning, WarningKind},
@ -584,7 +583,7 @@ impl<'o> VM<'o> {
(Value::List(_), _) => break false,
(Value::Attrs(a1), Value::Attrs(a2)) => {
if allow_pointer_equality_on_functions_and_thunks && Rc::ptr_eq(&a1, &a2) {
if allow_pointer_equality_on_functions_and_thunks && a1.ptr_eq(&a2) {
continue;
}
allow_pointer_equality_on_functions_and_thunks = true;
@ -620,8 +619,8 @@ impl<'o> VM<'o> {
}
_ => {}
}
let iter1 = unwrap_or_clone_rc(a1).into_iter_sorted();
let iter2 = unwrap_or_clone_rc(a2).into_iter_sorted();
let iter1 = a1.into_iter_sorted();
let iter2 = a2.into_iter_sorted();
if iter1.len() != iter2.len() {
break false;
}
@ -745,10 +744,10 @@ impl<'o> VM<'o> {
OpCode::OpAttrs(Count(count)) => self.run_attrset(count)?,
OpCode::OpAttrsUpdate => {
let rhs = unwrap_or_clone_rc(fallible!(self, self.pop().to_attrs()));
let lhs = unwrap_or_clone_rc(fallible!(self, self.pop().to_attrs()));
let rhs = fallible!(self, self.pop().to_attrs());
let lhs = fallible!(self, self.pop().to_attrs());
self.push(Value::attrs(lhs.update(rhs)))
self.push(Value::attrs(lhs.update(*rhs)))
}
OpCode::OpAttrsSelect => {