diff options
Diffstat (limited to 'tvix/eval/src/vm')
| -rw-r--r-- | tvix/eval/src/vm/generators.rs | 2 | ||||
| -rw-r--r-- | tvix/eval/src/vm/mod.rs | 40 |
2 files changed, 39 insertions, 3 deletions
diff --git a/tvix/eval/src/vm/generators.rs b/tvix/eval/src/vm/generators.rs index 138600be194a..fb60a45f20cc 100644 --- a/tvix/eval/src/vm/generators.rs +++ b/tvix/eval/src/vm/generators.rs @@ -393,7 +393,7 @@ impl<'o> VM<'o> { } VMRequest::ImportCacheLookup(path) => { - if let Some(cached) = self.import_cache.get(&path) { + if let Some(cached) = self.import_cache.get(path) { message = VMResponse::Value(cached.clone()); } else { message = VMResponse::Empty; diff --git a/tvix/eval/src/vm/mod.rs b/tvix/eval/src/vm/mod.rs index d004af3c6f45..cc66ee4b6f36 100644 --- a/tvix/eval/src/vm/mod.rs +++ b/tvix/eval/src/vm/mod.rs @@ -14,7 +14,7 @@ mod macros; use codemap::Span; use serde_json::json; -use std::{cmp::Ordering, collections::HashMap, ops::DerefMut, path::PathBuf, rc::Rc}; +use std::{cmp::Ordering, collections::HashMap, ops::DerefMut, path::Path, path::PathBuf, rc::Rc}; use crate::{ arithmetic_op, @@ -218,6 +218,42 @@ impl Frame { } } +#[derive(Default)] +struct ImportCache(Box<HashMap<PathBuf, Value>>); + +/// The `ImportCache` holds the `Value` resulting from `import`ing a certain +/// file, so that the same file doesn't need to be re-evaluated multiple times. +/// Currently the real path of the imported file (determined using +/// [`std::fs::canonicalize()`], not to be confused with our +/// [`value::canon_path()`]) is used to identify the file, just like C++ Nix +/// does. +/// +/// Errors while determining the real path are currently just ignored, since we +/// pass around some fake paths like `/__corepkgs__/fetchurl.nix`. +/// +/// In the future, we could use something more sophisticated, like file hashes. +/// However, a consideration is that the eval cache is observable via impurities +/// like pointer equality and `builtins.trace`. +impl ImportCache { + fn get(&self, path: PathBuf) -> Option<&Value> { + let path = match std::fs::canonicalize(path.as_path()).map_err(ErrorKind::from) { + Ok(path) => path, + Err(_) => path, + }; + self.0.get(&path) + } + + fn insert(&mut self, path: PathBuf, value: Value) -> Option<Value> { + self.0.insert( + match std::fs::canonicalize(path.as_path()).map_err(ErrorKind::from) { + Ok(path) => path, + Err(_) => path, + }, + value, + ) + } +} + struct VM<'o> { /// VM's frame stack, representing the execution contexts the VM is working /// through. Elements are usually pushed when functions are called, or @@ -241,7 +277,7 @@ struct VM<'o> { /// Import cache, mapping absolute file paths to the value that /// they compile to. Note that this reuses thunks, too! // TODO: should probably be based on a file hash - pub import_cache: Box<HashMap<PathBuf, Value>>, + pub import_cache: ImportCache, /// Parsed Nix search path, which is used to resolve `<...>` /// references. |