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refactor(tvix/eval): Box Value::String

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NixString is *quite* large - like 80 bytes - because of the extra
capacity value for BString and because of the context. We want to keep
Value small since we're passing it around a lot, so let's box the
NixString inside Value::String to save on some memory, and make cloning
ostensibly a little cheaper

Change-Id: I343c8b4e7f61dc3dcbbaba4382efb3b3e5bbabb2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10729
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
This commit is contained in:
Aspen Smith 2024-02-01 12:28:29 -05:00 • committed by aspen
parent 4c5d9fa356
commit 5f0f4ea374
15 changed files with 69 additions and 72 deletions
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14
tvix/eval/src/value/mod.rs
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@ -47,7 +47,7 @@ pub enum Value {
Bool(bool),
Integer(i64),
Float(f64),
String(NixString),
String(Box<NixString>),
#[serde(skip)]
Path(Box<Path>),
@ -186,7 +186,7 @@ where
T: Into<NixString>,
{
fn from(t: T) -> Self {
Self::String(t.into())
Self::String(Box::new(t.into()))
}
}
@ -327,7 +327,9 @@ impl Value {
let value = if let Some(v) = vals.pop() {
v.force(co, span.clone()).await?
} else {
return Ok(Value::String(NixString::new_context_from(context, result)));
return Ok(Value::String(Box::new(NixString::new_context_from(
context, result,
))));
};
let coerced: Result<BString, _> = match (value, kind) {
// coercions that are always done
@ -335,7 +337,7 @@ impl Value {
if let Some(ctx) = s.context_mut() {
context = context.join(ctx);
}
Ok(s.into())
Ok((*s).into())
}
// TODO(sterni): Think about proper encoding handling here. This needs
@ -692,7 +694,7 @@ impl Value {
/// everytime you want a string.
pub fn to_str(&self) -> Result<NixString, ErrorKind> {
match self {
Value::String(s) if !s.has_context() => Ok(s.clone()),
Value::String(s) if !s.has_context() => Ok((**s).clone()),
Value::Thunk(thunk) => Self::to_str(&thunk.value()),
other => Err(type_error("contextless strings", other)),
}
@ -703,7 +705,7 @@ impl Value {
NixString,
"contextful string",
Value::String(s),
s.clone()
(**s).clone()
);
gen_cast!(to_path, Box<Path>, "path", Value::Path(p), p.clone());
gen_cast!(to_attrs, Box<NixAttrs>, "set", Value::Attrs(a), a.clone());