From bf286a54bc2ac5eeb78c3d5c5ae66e9af24d74d4 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Sun, 11 Dec 2022 15:16:59 +0300 Subject: refactor(tvix/eval): add a LightSpan type for lighter span tracking This type carries the information required for calculating a span (i.e. the chunk and offset), instead of the span itself. The span is then only calculated in cases where it is required (when throwing errors). This reduces the eval time for `builtins.length (builtins.attrNames (import {}))` by *one third*! The data structure in chunks that carries span information reduces in-memory size by trading off the speed of retrieving span information. This is because the span information is only actually required when throwing errors (or emitting warnings). However, somewhere along the way we grew a dependency on carrying span information in thunks (for correctly reporting error chains). Hitting the code paths for span retrieval was expensive, and carrying the spans in a different way would still be less cache-efficient. This change is the best tradeoff I could come up with. Refs: b/229. Change-Id: I27d4c4b5c5f9be90ac47f2db61941e123a78a77b Reviewed-on: https://cl.tvl.fyi/c/depot/+/7558 Reviewed-by: grfn Tested-by: BuildkiteCI --- tvix/eval/src/builtins/impure.rs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'tvix/eval/src/builtins/impure.rs') diff --git a/tvix/eval/src/builtins/impure.rs b/tvix/eval/src/builtins/impure.rs index ee6cb2afdee4..b086df2f843d 100644 --- a/tvix/eval/src/builtins/impure.rs +++ b/tvix/eval/src/builtins/impure.rs @@ -12,6 +12,7 @@ use crate::{ compiler::GlobalsMap, errors::ErrorKind, observer::NoOpObserver, + spans::LightSpan, value::{Builtin, BuiltinArgument, NixAttrs, Thunk}, vm::VM, SourceCode, Value, @@ -176,7 +177,7 @@ pub fn builtins_import(globals: &Weak, source: SourceCode) -> Builti let res = entry .insert(Value::Thunk(Thunk::new_suspended( result.lambda, - current_span, + LightSpan::new_actual(current_span), ))) .clone(); -- cgit 1.4.1