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Refactor RegistryData::load to handle management of the index cache i…
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…tself.

This enables registry implementations to signal if the cache is valid
on a per-request basis.

Fixes a bug introduced by rust-lang#10064 that caused Cargo not to update for
several cases in a release build because it believed the index cache to
be valid when it was not.
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@arlosi @Hezuikn
arlosi authored and Hezuikn committed Sep 22, 2022
1 parent c566fb6 commit a459cd0
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Showing 4 changed files with 148 additions and 135 deletions.
177 changes: 92 additions & 85 deletions src/cargo/sources/registry/index.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@
use crate::core::dependency::Dependency;
use crate::core::{PackageId, SourceId, Summary};
use crate::sources::registry::{RegistryData, RegistryPackage, INDEX_V_MAX};
use crate::sources::registry::{LoadResponse, RegistryData, RegistryPackage, INDEX_V_MAX};
use crate::util::interning::InternedString;
use crate::util::{internal, CargoResult, Config, Filesystem, OptVersionReq, ToSemver};
use anyhow::bail;
Expand Down Expand Up @@ -247,6 +247,7 @@ pub struct IndexSummary {
#[derive(Default)]
struct SummariesCache<'a> {
versions: Vec<(Version, &'a [u8])>,
index_version: &'a str,
}

impl<'cfg> RegistryIndex<'cfg> {
Expand Down Expand Up @@ -358,7 +359,6 @@ impl<'cfg> RegistryIndex<'cfg> {

let root = load.assert_index_locked(&self.path);
let cache_root = root.join(".cache");
let index_version = load.current_version();

// See module comment in `registry/mod.rs` for why this is structured
// the way it is.
Expand All @@ -376,7 +376,6 @@ impl<'cfg> RegistryIndex<'cfg> {
// along the way produce helpful "did you mean?" suggestions.
for (i, path) in UncanonicalizedIter::new(&raw_path).take(1024).enumerate() {
let summaries = Summaries::parse(
index_version.as_deref(),
root,
&cache_root,
path.as_ref(),
Expand Down Expand Up @@ -559,7 +558,6 @@ impl Summaries {
/// * `load` - the actual index implementation which may be very slow to
/// call. We avoid this if we can.
pub fn parse(
index_version: Option<&str>,
root: &Path,
cache_root: &Path,
relative: &Path,
Expand All @@ -571,88 +569,101 @@ impl Summaries {
// of reasons, but consider all of them non-fatal and just log their
// occurrence in case anyone is debugging anything.
let cache_path = cache_root.join(relative);
let mut cache_contents = None;
if let Some(index_version) = index_version {
match fs::read(&cache_path) {
Ok(contents) => match Summaries::parse_cache(contents, index_version) {
Ok(s) => {
log::debug!("fast path for registry cache of {:?}", relative);
if cfg!(debug_assertions) {
cache_contents = Some(s.raw_data);
} else {
return Poll::Ready(Ok(Some(s)));
}
}
Err(e) => {
log::debug!("failed to parse {:?} cache: {}", relative, e);
}
},
Err(e) => log::debug!("cache missing for {:?} error: {}", relative, e),
}
let mut cached_summaries = None;
let mut index_version = None;
match fs::read(&cache_path) {
Ok(contents) => match Summaries::parse_cache(contents) {
Ok((s, v)) => {
cached_summaries = Some(s);
index_version = Some(v);
}
Err(e) => {
log::debug!("failed to parse {:?} cache: {}", relative, e);
}
},
Err(e) => log::debug!("cache missing for {:?} error: {}", relative, e),
}

// This is the fallback path where we actually talk to the registry backend to load
// information. Here we parse every single line in the index (as we need
// to find the versions)
log::debug!("slow path for {:?}", relative);
let mut response = load.load(root, relative, index_version.as_deref())?;
// In debug builds, perform a second load without the cache so that
// we can validate that the cache is correct.
if cfg!(debug_assertions) && matches!(response, Poll::Ready(LoadResponse::CacheValid)) {
response = load.load(root, relative, None)?;
}
let response = match response {
Poll::Pending => return Poll::Pending,
Poll::Ready(response) => response,
};

let mut bytes_to_cache = None;
let mut version_to_cache = None;
let mut ret = Summaries::default();
let mut hit_closure = false;
let mut cache_bytes = None;
let result = load.load(root, relative, &mut |contents| {
ret.raw_data = contents.to_vec();
let mut cache = SummariesCache::default();
hit_closure = true;
for line in split(contents, b'\n') {
// Attempt forwards-compatibility on the index by ignoring
// everything that we ourselves don't understand, that should
// allow future cargo implementations to break the
// interpretation of each line here and older cargo will simply
// ignore the new lines.
let summary = match IndexSummary::parse(config, line, source_id) {
Ok(summary) => summary,
Err(e) => {
// This should only happen when there is an index
// entry from a future version of cargo that this
// version doesn't understand. Hopefully, those future
// versions of cargo correctly set INDEX_V_MAX and
// CURRENT_CACHE_VERSION, otherwise this will skip
// entries in the cache preventing those newer
// versions from reading them (that is, until the
// cache is rebuilt).
log::info!("failed to parse {:?} registry package: {}", relative, e);
continue;
}
};
let version = summary.summary.package_id().version().clone();
cache.versions.push((version.clone(), line));
ret.versions.insert(version, summary.into());
match response {
LoadResponse::CacheValid => {
log::debug!("fast path for registry cache of {:?}", relative);
return Poll::Ready(Ok(cached_summaries));
}
if let Some(index_version) = index_version {
cache_bytes = Some(cache.serialize(index_version));
LoadResponse::NotFound => {
debug_assert!(cached_summaries.is_none());
return Poll::Ready(Ok(None));
}
LoadResponse::Data {
raw_data,
index_version,
} => {
// This is the fallback path where we actually talk to the registry backend to load
// information. Here we parse every single line in the index (as we need
// to find the versions)
log::debug!("slow path for {:?}", relative);
let mut cache = SummariesCache::default();
ret.raw_data = raw_data;
for line in split(&ret.raw_data, b'\n') {
// Attempt forwards-compatibility on the index by ignoring
// everything that we ourselves don't understand, that should
// allow future cargo implementations to break the
// interpretation of each line here and older cargo will simply
// ignore the new lines.
let summary = match IndexSummary::parse(config, line, source_id) {
Ok(summary) => summary,
Err(e) => {
// This should only happen when there is an index
// entry from a future version of cargo that this
// version doesn't understand. Hopefully, those future
// versions of cargo correctly set INDEX_V_MAX and
// CURRENT_CACHE_VERSION, otherwise this will skip
// entries in the cache preventing those newer
// versions from reading them (that is, until the
// cache is rebuilt).
log::info!("failed to parse {:?} registry package: {}", relative, e);
continue;
}
};
let version = summary.summary.package_id().version().clone();
cache.versions.push((version.clone(), line));
ret.versions.insert(version, summary.into());
}
if let Some(index_version) = index_version {
bytes_to_cache = Some(cache.serialize(index_version.as_str()));
version_to_cache = Some(index_version);
}
}
Ok(())
});

if result?.is_pending() {
assert!(!hit_closure);
return Poll::Pending;
}

if !hit_closure {
debug_assert!(cache_contents.is_none());
return Poll::Ready(Ok(None));
}

// If we've got debug assertions enabled and the cache was previously
// present and considered fresh this is where the debug assertions
// actually happens to verify that our cache is indeed fresh and
// computes exactly the same value as before.
if cfg!(debug_assertions) && cache_contents.is_some() && cache_bytes != cache_contents {
let cache_contents = cached_summaries.as_ref().map(|s| &s.raw_data);
if cfg!(debug_assertions)
&& index_version.as_deref() == version_to_cache.as_deref()
&& cached_summaries.is_some()
&& bytes_to_cache.as_ref() != cache_contents
{
panic!(
"original cache contents:\n{:?}\n\
does not equal new cache contents:\n{:?}\n",
cache_contents.as_ref().map(|s| String::from_utf8_lossy(s)),
cache_bytes.as_ref().map(|s| String::from_utf8_lossy(s)),
bytes_to_cache.as_ref().map(|s| String::from_utf8_lossy(s)),
);
}

Expand All @@ -662,7 +673,7 @@ impl Summaries {
//
// This is opportunistic so we ignore failure here but are sure to log
// something in case of error.
if let Some(cache_bytes) = cache_bytes {
if let Some(cache_bytes) = bytes_to_cache {
if paths::create_dir_all(cache_path.parent().unwrap()).is_ok() {
let path = Filesystem::new(cache_path.clone());
config.assert_package_cache_locked(&path);
Expand All @@ -677,16 +688,17 @@ impl Summaries {

/// Parses an open `File` which represents information previously cached by
/// Cargo.
pub fn parse_cache(contents: Vec<u8>, last_index_update: &str) -> CargoResult<Summaries> {
let cache = SummariesCache::parse(&contents, last_index_update)?;
pub fn parse_cache(contents: Vec<u8>) -> CargoResult<(Summaries, InternedString)> {
let cache = SummariesCache::parse(&contents)?;
let index_version = InternedString::new(cache.index_version);
let mut ret = Summaries::default();
for (version, summary) in cache.versions {
let (start, end) = subslice_bounds(&contents, summary);
ret.versions
.insert(version, MaybeIndexSummary::Unparsed { start, end });
}
ret.raw_data = contents;
return Ok(ret);
return Ok((ret, index_version));

// Returns the start/end offsets of `inner` with `outer`. Asserts that
// `inner` is a subslice of `outer`.
Expand Down Expand Up @@ -742,7 +754,7 @@ impl Summaries {
const CURRENT_CACHE_VERSION: u8 = 3;

impl<'a> SummariesCache<'a> {
fn parse(data: &'a [u8], last_index_update: &str) -> CargoResult<SummariesCache<'a>> {
fn parse(data: &'a [u8]) -> CargoResult<SummariesCache<'a>> {
// NB: keep this method in sync with `serialize` below
let (first_byte, rest) = data
.split_first()
Expand All @@ -764,18 +776,13 @@ impl<'a> SummariesCache<'a> {
let rest = &rest[4..];

let mut iter = split(rest, 0);
if let Some(update) = iter.next() {
if update != last_index_update.as_bytes() {
bail!(
"cache out of date: current index ({}) != cache ({})",
last_index_update,
str::from_utf8(update)?,
)
}
let last_index_update = if let Some(update) = iter.next() {
str::from_utf8(update)?
} else {
bail!("malformed file");
}
};
let mut ret = SummariesCache::default();
ret.index_version = last_index_update;
while let Some(version) = iter.next() {
let version = str::from_utf8(version)?;
let version = Version::parse(version)?;
Expand Down
16 changes: 7 additions & 9 deletions src/cargo/sources/registry/local.rs
View file
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
use crate::core::PackageId;
use crate::sources::registry::{MaybeLock, RegistryConfig, RegistryData};
use crate::sources::registry::{LoadResponse, MaybeLock, RegistryConfig, RegistryData};
use crate::util::errors::CargoResult;
use crate::util::interning::InternedString;
use crate::util::{Config, Filesystem};
use cargo_util::{paths, Sha256};
use std::fs::File;
Expand Down Expand Up @@ -48,18 +47,17 @@ impl<'cfg> RegistryData for LocalRegistry<'cfg> {
path.as_path_unlocked()
}

fn current_version(&self) -> Option<InternedString> {
None
}

fn load(
&self,
root: &Path,
path: &Path,
data: &mut dyn FnMut(&[u8]) -> CargoResult<()>,
) -> Poll<CargoResult<()>> {
_index_version: Option<&str>,
) -> Poll<CargoResult<LoadResponse>> {
if self.updated {
Poll::Ready(Ok(data(&paths::read_bytes(&root.join(path))?)?))
Poll::Ready(Ok(LoadResponse::Data {
raw_data: paths::read_bytes(&root.join(path))?,
index_version: None,
}))
} else {
Poll::Pending
}
Expand Down
31 changes: 17 additions & 14 deletions src/cargo/sources/registry/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -411,6 +411,20 @@ impl<'a> RegistryDependency<'a> {
}
}

pub enum LoadResponse {
/// The cache is valid. The cached data should be used.
CacheValid,

/// The cache is out of date. Returned data should be used.
Data {
raw_data: Vec<u8>,
index_version: Option<String>,
},

/// The requested crate was found.
NotFound,
}

/// An abstract interface to handle both a local (see `local::LocalRegistry`)
/// and remote (see `remote::RemoteRegistry`) registry.
///
Expand All @@ -432,15 +446,13 @@ pub trait RegistryData {
///
/// * `root` is the root path to the index.
/// * `path` is the relative path to the package to load (like `ca/rg/cargo`).
/// * `data` is a callback that will receive the raw bytes of the index JSON file.
///
/// If `load` returns a `Poll::Pending` then it must not have called data.
/// * `index_version` is the version of the requested crate data currently in cache.
fn load(
&self,
root: &Path,
path: &Path,
data: &mut dyn FnMut(&[u8]) -> CargoResult<()>,
) -> Poll<CargoResult<()>>;
index_version: Option<&str>,
) -> Poll<CargoResult<LoadResponse>>;

/// Loads the `config.json` file and returns it.
///
Expand Down Expand Up @@ -495,15 +507,6 @@ pub trait RegistryData {
/// Returns the [`Path`] to the [`Filesystem`].
fn assert_index_locked<'a>(&self, path: &'a Filesystem) -> &'a Path;

/// Returns the current "version" of the index.
///
/// For local registries, this returns `None` because there is no
/// versioning. For remote registries, this returns the SHA hash of the
/// git index on disk (or None if the index hasn't been downloaded yet).
///
/// This is used by index caching to check if the cache is out of date.
fn current_version(&self) -> Option<InternedString>;

/// Block until all outstanding Poll::Pending requests are Poll::Ready.
fn block_until_ready(&mut self) -> CargoResult<()>;
}
Expand Down
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