From 5d72d3980f21ac720520e4d2450f0709b6b581ea Mon Sep 17 00:00:00 2001
From: Aspen Smith <root@gws.fyi>
Date: Sat, 10 Feb 2024 12:22:59 -0500
Subject: refactor(tvix/eval): Box the strings in CatchableErrorKind

These strings are allocated once and never changed, so they don't need
the additional overhead of a capacity given by String - instead, we can
use Box<str> and save on 16 bytes for each of these, *and* for each
Value since this is currently the largest Value variant.

Change-Id: I3e5cb070fe6c5bf82114c92d04f6bae775663a7e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10796
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
---
 tvix/eval/src/builtins/mod.rs    | 10 ++++------
 tvix/eval/src/errors.rs          |  6 +++---
 tvix/eval/src/nix_search_path.rs | 11 +++++++----
 3 files changed, 14 insertions(+), 13 deletions(-)

(limited to 'tvix/eval/src')

diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index d9f8567886e3..3048b32fb550 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -476,7 +476,7 @@ mod pure_builtins {
     async fn builtin_filterSource(_co: GenCo, #[lazy] _e: Value) -> Result<Value, ErrorKind> {
         // TODO: implement for nixpkgs compatibility
         Ok(Value::Catchable(CatchableErrorKind::UnimplementedFeature(
-            "filterSource".to_string(),
+            "filterSource".into(),
         )))
     }
 
@@ -695,7 +695,7 @@ mod pure_builtins {
     ) -> Result<Value, ErrorKind> {
         // FIXME: propagate contexts here.
         Ok(Value::Catchable(CatchableErrorKind::UnimplementedFeature(
-            "hashString".to_string(),
+            "hashString".into(),
         )))
     }
 
@@ -1392,7 +1392,7 @@ mod pure_builtins {
         // TODO(sterni): coerces to string
         // We do not care about the context here explicitly.
         Ok(Value::Catchable(CatchableErrorKind::Throw(
-            message.to_contextful_str()?.to_string(),
+            message.to_contextful_str()?.to_string().into(),
         )))
     }
 
@@ -1531,9 +1531,7 @@ pub fn pure_builtins() -> Vec<(&'static str, Value)> {
     // TODO: implement for nixpkgs compatibility
     result.push((
         "__curPos",
-        Value::Catchable(CatchableErrorKind::UnimplementedFeature(
-            "__curPos".to_string(),
-        )),
+        Value::Catchable(CatchableErrorKind::UnimplementedFeature("__curPos".into())),
     ));
 
     result
diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs
index d5cb6ef34b0d..b59ee675dda4 100644
--- a/tvix/eval/src/errors.rs
+++ b/tvix/eval/src/errors.rs
@@ -40,11 +40,11 @@ use crate::{SourceCode, Value};
 ///
 #[derive(Clone, Debug)]
 pub enum CatchableErrorKind {
-    Throw(String),
+    Throw(Box<str>),
     AssertionFailed,
-    UnimplementedFeature(String),
+    UnimplementedFeature(Box<str>),
     /// Resolving a user-supplied angle brackets path literal failed in some way.
-    NixPathResolution(String),
+    NixPathResolution(Box<str>),
 }
 
 #[derive(Clone, Debug)]
diff --git a/tvix/eval/src/nix_search_path.rs b/tvix/eval/src/nix_search_path.rs
index 2f6d444475ff..566ca122384b 100644
--- a/tvix/eval/src/nix_search_path.rs
+++ b/tvix/eval/src/nix_search_path.rs
@@ -138,10 +138,13 @@ impl NixSearchPath {
                 return Ok(Ok(p));
             }
         }
-        Ok(Err(CatchableErrorKind::NixPathResolution(format!(
-            "path '{}' was not found in the Nix search path",
-            path.display()
-        ))))
+        Ok(Err(CatchableErrorKind::NixPathResolution(
+            format!(
+                "path '{}' was not found in the Nix search path",
+                path.display()
+            )
+            .into_boxed_str(),
+        )))
     }
 }
 
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