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fix(tvix): Avoid buffering file into memory in builtins.hashFile

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Right now `builtins.hashFile` always reads the entire file into memory
before hashing, which is not ideal for large files. This replaces
`read_to_string` with `open_file` which allows calculating the hash of
the file without buffering it entirely into memory. Other callers can
continue to buffer into memory if they choose, but they still use the
`open_file` VM request and then call `read_to_string` or `read_to_end`
on the `std::io::Reader`.

Fixes b/380

Change-Id: Ifa1c8324bcee8f751604b0b449feab875c632fda
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11236
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
This commit is contained in:
Connor Brewster 2024-03-22 18:52:21 -05:00
parent 17849c5c00
commit 63116d8c21
9 changed files with 80 additions and 74 deletions
Download patch file Download diff file Expand all files Collapse all files

27
tvix/eval/src/vm/generators.rs
View file

@ -102,8 +102,8 @@ pub enum VMRequest {
/// Request that the VM imports the given path through its I/O interface.
PathImport(PathBuf),
/// Request that the VM reads the given path to a string.
ReadToString(PathBuf),
/// Request that the VM opens the specified file and provides a reader.
OpenFile(PathBuf),
/// Request that the VM checks whether the given path exists.
PathExists(PathBuf),
@ -170,8 +170,8 @@ impl Display for VMRequest {
write!(f, "import_cache_put({})", p.to_string_lossy())
}
VMRequest::PathImport(p) => write!(f, "path_import({})", p.to_string_lossy()),
VMRequest::ReadToString(p) => {
write!(f, "read_to_string({})", p.to_string_lossy())
VMRequest::OpenFile(p) => {
write!(f, "open_file({})", p.to_string_lossy())
}
VMRequest::PathExists(p) => write!(f, "path_exists({})", p.to_string_lossy()),
VMRequest::ReadDir(p) => write!(f, "read_dir({})", p.to_string_lossy()),
@ -199,6 +199,9 @@ pub enum VMResponse {
/// VM response with a span to use at the current point.
Span(LightSpan),
/// [std::io::Reader] produced by the VM in response to some IO operation.
Reader(Box<dyn std::io::Read>),
}
impl Display for VMResponse {
@ -209,6 +212,7 @@ impl Display for VMResponse {
VMResponse::Path(p) => write!(f, "path({})", p.to_string_lossy()),
VMResponse::Directory(d) => write!(f, "dir(len = {})", d.len()),
VMResponse::Span(_) => write!(f, "span"),
VMResponse::Reader(_) => write!(f, "reader"),
}
}
}
@ -425,18 +429,18 @@ where
message = VMResponse::Path(imported);
}
VMRequest::ReadToString(path) => {
let content = self
VMRequest::OpenFile(path) => {
let reader = self
.io_handle
.as_ref()
.read_to_end(&path)
.open(&path)
.map_err(|e| ErrorKind::IO {
path: Some(path),
error: e.into(),
})
.with_span(&span, self)?;
message = VMResponse::Value(content.into())
message = VMResponse::Reader(reader)
}
VMRequest::PathExists(path) => {
@ -730,9 +734,10 @@ pub(crate) async fn request_path_import(co: &GenCo, path: PathBuf) -> PathBuf {
}
}
pub(crate) async fn request_read_to_string(co: &GenCo, path: PathBuf) -> Value {
match co.yield_(VMRequest::ReadToString(path)).await {
VMResponse::Value(value) => value,
/// Request that the VM open a [std::io::Read] for the specified file.
pub async fn request_open_file(co: &GenCo, path: PathBuf) -> Box<dyn std::io::Read> {
match co.yield_(VMRequest::OpenFile(path)).await {
VMResponse::Reader(value) => value,
msg => panic!(
"Tvix bug: VM responded with incorrect generator message: {}",
msg