refactor: registry source cleanup

src/cargo/sources/registry/download.rs

@@ -4,10 +4,7 @@ use cargo_util::Sha256;
 use crate::core::PackageId;
 use crate::sources::registry::make_dep_prefix;
 use crate::sources::registry::MaybeLock;
-use crate::sources::registry::{
-    RegistryConfig, CHECKSUM_TEMPLATE, CRATE_TEMPLATE, LOWER_PREFIX_TEMPLATE, PREFIX_TEMPLATE,
-    VERSION_TEMPLATE,
-};
+use crate::sources::registry::RegistryConfig;
 use crate::util::auth;
 use crate::util::errors::CargoResult;
 use crate::util::{Config, Filesystem};
@@ -17,6 +14,12 @@ use std::io::prelude::*;
 use std::io::SeekFrom;
 use std::str;
 
+const CRATE_TEMPLATE: &str = "{crate}";
+const VERSION_TEMPLATE: &str = "{version}";
+const PREFIX_TEMPLATE: &str = "{prefix}";
+const LOWER_PREFIX_TEMPLATE: &str = "{lowerprefix}";
+const CHECKSUM_TEMPLATE: &str = "{sha256-checksum}";
+
 pub(super) fn filename(pkg: PackageId) -> String {
     format!("{}-{}.crate", pkg.name(), pkg.version())
 }

src/cargo/sources/registry/index.rs

@@ -86,7 +86,7 @@
 //! [`Dependency`]: crate::core::Dependency
 
 use crate::core::{PackageId, SourceId, Summary};
-use crate::sources::registry::{LoadResponse, RegistryData, RegistryPackage, INDEX_V_MAX};
+use crate::sources::registry::{LoadResponse, RegistryData, RegistryPackage};
 use crate::util::interning::InternedString;
 use crate::util::{internal, CargoResult, Config, Filesystem, OptVersionReq, ToSemver};
 use anyhow::bail;
@@ -100,6 +100,13 @@ use std::path::Path;
 use std::str;
 use std::task::{ready, Poll};
 
+/// The current version of [`SummariesCache`].
+const CURRENT_CACHE_VERSION: u8 = 3;
+
+/// The maximum schema version of the `v` field in the index this version of
+/// cargo understands. See [`RegistryPackage::v`] for the detail.
+const INDEX_V_MAX: u32 = 2;
+
 /// Manager for handling the on-disk index.
 ///
 /// Different kinds of registries store the index differently:
@@ -202,7 +209,7 @@ pub struct IndexSummary {
 ///
 /// ```text
 /// +---------------+----------------------+--------------------+---+
-/// | cache version | index format version | index file version | 0 |
+/// | cache version | index schema version | index file version | 0 |
 /// +---------------+----------------------+--------------------+---+
 /// ```
 ///
@@ -219,7 +226,7 @@ pub struct IndexSummary {
 /// * _cache version_ --- Intended to ensure that there's some level of
 ///   future compatibility against changes to this cache format so if different
 ///   versions of Cargo share the same cache they don't get too confused.
-/// * _index format version_ --- The version of the raw index file.
+/// * _index schema version_ --- The schema version of the raw index file.
 ///   See [`RegistryPackage::v`] for the detail.
 /// * _index file version_ --- Tracks when a cache needs to be regenerated.
 ///   A cache regeneration is required whenever the index file itself updates.
@@ -231,7 +238,7 @@ pub struct IndexSummary {
 /// # Changes between each cache version
 ///
 /// * `1`: The original version.
-/// * `2`: Added the "index format version" field so that if the index format
+/// * `2`: Added the "index schema version" field so that if the index schema
 ///   changes, different versions of cargo won't get confused reading each
 ///   other's caches.
 /// * `3`: Bumped the version to work around an issue where multiple versions of
@@ -697,9 +704,6 @@ impl Summaries {
     }
 }
 
-/// The current version of [`SummariesCache`].
-const CURRENT_CACHE_VERSION: u8 = 3;
-
 impl<'a> SummariesCache<'a> {
     /// Deserializes an on-disk cache.
     fn parse(data: &'a [u8]) -> CargoResult<SummariesCache<'a>> {
@@ -712,13 +716,11 @@ impl<'a> SummariesCache<'a> {
         }
         let index_v_bytes = rest
             .get(..4)
-            .ok_or_else(|| anyhow::anyhow!("cache expected 4 bytes for index version"))?;
+            .ok_or_else(|| anyhow::anyhow!("cache expected 4 bytes for index schema version"))?;
         let index_v = u32::from_le_bytes(index_v_bytes.try_into().unwrap());
         if index_v != INDEX_V_MAX {
             bail!(
-                "index format version {} doesn't match the version I know ({})",
-                index_v,
-                INDEX_V_MAX
+                "index schema version {index_v} doesn't match the version I know ({INDEX_V_MAX})",
             );
         }
         let rest = &rest[4..];

src/cargo/sources/registry/mod.rs

@@ -220,15 +220,6 @@ pub const CRATES_IO_HTTP_INDEX: &str = "sparse+https://index.crates.io/";
 pub const CRATES_IO_REGISTRY: &str = "crates-io";
 pub const CRATES_IO_DOMAIN: &str = "crates.io";
 
-const CRATE_TEMPLATE: &str = "{crate}";
-const VERSION_TEMPLATE: &str = "{version}";
-const PREFIX_TEMPLATE: &str = "{prefix}";
-const LOWER_PREFIX_TEMPLATE: &str = "{lowerprefix}";
-const CHECKSUM_TEMPLATE: &str = "{sha256-checksum}";
-
-const MAX_UNPACK_SIZE: u64 = 512 * 1024 * 1024;
-const MAX_COMPRESSION_RATIO: usize = 20; // 20:1
-
 /// A [`Source`] implementation for a local or a remote registry.
 ///
 /// This contains common functionality that is shared between each registry
@@ -303,10 +294,6 @@ pub struct RegistryConfig {
     pub auth_required: bool,
 }
 
-/// The maximum schema version of the `v` field in the index this version of
-/// cargo understands. See [`RegistryPackage::v`] for the detail.
-pub(crate) const INDEX_V_MAX: u32 = 2;
-
 /// A single line in the index representing a single version of a package.
 #[derive(Deserialize)]
 pub struct RegistryPackage<'a> {
@@ -348,10 +335,10 @@ pub struct RegistryPackage<'a> {
     rust_version: Option<InternedString>,
     /// The schema version for this entry.
     ///
-    /// If this is None, it defaults to version 1. Entries with unknown
+    /// If this is None, it defaults to version `1`. Entries with unknown
     /// versions are ignored.
     ///
-    /// Version `2` format adds the `features2` field.
+    /// Version `2` schema adds the `features2` field.
     ///
     /// This provides a method to safely introduce changes to index entries
     /// and allow older versions of cargo to ignore newer entries it doesn't
@@ -362,7 +349,7 @@ pub struct RegistryPackage<'a> {
     /// The intent is that versions older than 1.51 will work with a
     /// pre-existing `Cargo.lock`, but they may not correctly process `cargo
     /// update` or build a lock from scratch. In that case, cargo may
-    /// incorrectly select a new package that uses a new index format. A
+    /// incorrectly select a new package that uses a new index schema. A
     /// workaround is to downgrade any packages that are incompatible with the
     /// `--precise` flag of `cargo update`.
     v: Option<u32>,
@@ -1076,6 +1063,9 @@ impl<'cfg> Source for RegistrySource<'cfg> {
 fn max_unpack_size(config: &Config, size: u64) -> u64 {
     const SIZE_VAR: &str = "__CARGO_TEST_MAX_UNPACK_SIZE";
     const RATIO_VAR: &str = "__CARGO_TEST_MAX_UNPACK_RATIO";
+    const MAX_UNPACK_SIZE: u64 = 512 * 1024 * 1024; // 512 MiB
+    const MAX_COMPRESSION_RATIO: usize = 20; // 20:1
+
     let max_unpack_size = if cfg!(debug_assertions) && config.get_env(SIZE_VAR).is_ok() {
         // For integration test only.
         config