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feat(tvix/eval): wrap Closure in Rc<> to match cppnix semantics

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Change-Id: I595087eff943d38a9fc78a83d37e207bb2ab79bc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7443
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
This commit is contained in:
Adam Joseph 2022-11-27 00:54:39 -08:00 • committed by tazjin
parent b3c34c3c61
commit e04b1697e4
6 changed files with 34 additions and 61 deletions
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59
tvix/eval/src/value/thunk.rs
View file

@ -69,12 +69,10 @@ pub struct Thunk(Rc<RefCell<ThunkRepr>>);
impl Thunk {
pub fn new_closure(lambda: Rc<Lambda>) -> Self {
Thunk(Rc::new(RefCell::new(ThunkRepr::Evaluated(Value::Closure(
Closure {
Rc::new(Closure {
upvalues: Rc::new(Upvalues::with_capacity(lambda.upvalue_count)),
lambda: lambda.clone(),
#[cfg(debug_assertions)]
is_finalised: false,
},
}),
)))))
}
@ -124,13 +122,6 @@ impl Thunk {
pub fn finalise(&self, stack: &[Value]) {
self.upvalues_mut().resolve_deferred_upvalues(stack);
#[cfg(debug_assertions)]
{
let inner: &mut ThunkRepr = &mut self.0.as_ref().borrow_mut();
if let ThunkRepr::Evaluated(Value::Closure(c)) = inner {
c.is_finalised = true;
}
}
}
pub fn is_evaluated(&self) -> bool {
@ -145,19 +136,7 @@ impl Thunk {
// API too much.
pub fn value(&self) -> Ref<Value> {
Ref::map(self.0.borrow(), |thunk| match thunk {
ThunkRepr::Evaluated(value) => {
#[cfg(debug_assertions)]
if matches!(
value,
Value::Closure(Closure {
is_finalised: false,
..
})
) {
panic!("Thunk::value called on an unfinalised closure");
}
return value;
}
ThunkRepr::Evaluated(value) => value,
ThunkRepr::Blackhole => panic!("Thunk::value called on a black-holed thunk"),
ThunkRepr::Suspended { .. } => panic!("Thunk::value called on a suspended thunk"),
})
@ -166,7 +145,7 @@ impl Thunk {
pub fn upvalues(&self) -> Ref<'_, Upvalues> {
Ref::map(self.0.borrow(), |thunk| match thunk {
ThunkRepr::Suspended { upvalues, .. } => upvalues,
ThunkRepr::Evaluated(Value::Closure(Closure { upvalues, .. })) => upvalues,
ThunkRepr::Evaluated(Value::Closure(c)) => &c.upvalues,
_ => panic!("upvalues() on non-suspended thunk"),
})
}
@ -174,19 +153,12 @@ impl Thunk {
pub fn upvalues_mut(&self) -> RefMut<'_, Upvalues> {
RefMut::map(self.0.borrow_mut(), |thunk| match thunk {
ThunkRepr::Suspended { upvalues, .. } => upvalues,
ThunkRepr::Evaluated(Value::Closure(Closure {
upvalues,
#[cfg(debug_assertions)]
is_finalised,
..
})) => {
#[cfg(debug_assertions)]
if *is_finalised {
panic!("Thunk::upvalues_mut() called on a finalised closure");
}
Rc::get_mut(upvalues)
.expect("upvalues_mut() was called on a thunk which already had multiple references to it")
}
ThunkRepr::Evaluated(Value::Closure(c)) => Rc::get_mut(
&mut Rc::get_mut(c).unwrap().upvalues,
)
.expect(
"upvalues_mut() was called on a thunk which already had multiple references to it",
),
thunk => panic!("upvalues() on non-suspended thunk: {thunk:?}"),
})
}
@ -194,7 +166,16 @@ impl Thunk {
/// Do not use this without first reading and understanding
/// `tvix/docs/value-pointer-equality.md`.
pub(crate) fn ptr_eq(&self, other: &Self) -> bool {
Rc::ptr_eq(&self.0, &other.0)
if Rc::ptr_eq(&self.0, &other.0) {
return true;
}
match &*self.0.borrow() {
ThunkRepr::Evaluated(Value::Closure(c1)) => match &*other.0.borrow() {
ThunkRepr::Evaluated(Value::Closure(c2)) => Rc::ptr_eq(c1, c2),
_ => false,
},
_ => false,
}
}
}