General fixups (#18)

This changes the `SparseIndex` API slightly to allow for zero disk I/O
when making requests to the remote HTTP index.

Resolves: #16

CHANGELOG.md

@@ -9,6 +9,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- next-header -->
 ## [Unreleased] - ReleaseDate
+### Fixed
+- [PR#18](https://github.com/EmbarkStudios/tame-index/pull/18) resolved [#16](https://github.com/EmbarkStudios/tame-index/issues/16) by marking `ComboIndexCache` and `ComboIndex` as `#[non_exhaustive]`. This avoids build breaks if the `local` feature is enabled in one transitive dependency and not in another, as much as I hate `non_exhaustive`.
+
+### Changed
+- [PR#18](https://github.com/EmbarkStudios/tame-index/pull/18) changed `SparseIndex::make_remote_request` to take an optional [ETag](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag), completely avoiding disk I/O, which allows `SparseIndex` to be used for making and parsing requests without worrying about cargo's global package lock.
+
 ## [0.4.1] - 2023-08-21
 ### Added
 - [PR#15](https://github.com/EmbarkStudios/tame-index/pull/15) added the `native-certs` feature to be able to use the OS certificate store instead of `webpki-roots`. Thanks [@Shnatsel](https://github.com/Shnatsel)!

Cargo.toml

@@ -59,7 +59,7 @@ twox-hash = { version = "1.6", default-features = false }
 
 [dependencies.gix]
 optional = true
-version = "0.51"
+version = "0.52"
 default-features = false
 features = [
     "max-performance-safe",

deny.toml

@@ -46,20 +46,14 @@ deny = [{ name = "openssl" }, { name = "curl" }]
 skip = [
     # several users of this old version
     { name = "bitflags", version = "=1.3.2" },
-    # tempfile uses an old version
-    { name = "fastrand", version = "=1.9.0" },
     # imara-diff uses an old version
     { name = "hashbrown", version = "=0.12.3" },
-    # trust-dns-proto uses an old version
-    { name = "idna", version = "=0.2.3" },
     # toml-edit is user a newer version :p
     { name = "indexmap", version = "=1.9.3" },
     # trust-dns-resolver pulls in a new version than the rest of them use (including itself)
     { name = "socket2", version = "=0.4.9" },
     # A bunch of users still of syn 1.0 :p
     { name = "syn", version = "=1.0.109" },
-    # Reqwest depends on 2 versions :p
-    { name = "winreg", version = "=0.10.1" },
 ]
 skip-tree = []
 

src/error.rs

@@ -180,6 +180,9 @@ pub enum HttpError {
     /// A [`http::Error`]
     #[error(transparent)]
     Http(#[from] http::Error),
+    /// A string could not be parsed as a valid header value
+    #[error(transparent)]
+    InvalidHeaderValue(#[from] http::header::InvalidHeaderValue),
     /// Unable to complete an async request for an `AsyncRemoteSparseIndex` within
     /// the user allotted time
     #[error("request could not be completed in the allotted timeframe")]

src/index.rs

@@ -101,6 +101,7 @@ impl IndexConfig {
 use crate::Error;
 
 /// Provides simpler access to the cache for an index, regardless of the registry kind
+#[non_exhaustive]
 pub enum ComboIndexCache {
     /// A git index
     Git(GitIndex),

src/index/combo.rs

@@ -6,6 +6,7 @@ use crate::{
 };
 
 /// A wrapper around either a [`RemoteGitIndex`] or [`RemoteSparseIndex`]
+#[non_exhaustive]
 pub enum ComboIndex {
     /// A standard git based registry index. No longer the default for crates.io
     /// as of 1.70.0

src/index/sparse.rs

@@ -79,6 +79,10 @@ impl SparseIndex {
     /// Creates an HTTP request that can be sent via your HTTP client of choice
     /// to retrieve the current metadata for the specified crate
     ///
+    /// If specified, the etag is used instead of the possible etag stored in
+    /// a local cache entry, resulting in no disk I/O being performed by this
+    /// method
+    ///
     /// See [`Self::parse_remote_response`] processing the response from the remote
     /// index
     ///
@@ -87,6 +91,7 @@ impl SparseIndex {
     pub fn make_remote_request(
         &self,
         name: KrateName<'_>,
+        etag: Option<&str>,
     ) -> Result<http::Request<&'static [u8]>, Error> {
         use http::header;
 
@@ -145,7 +150,15 @@ impl SparseIndex {
                 None
             };
 
-            let _ = set_cache_version(headers);
+            if let Some(etag) = etag {
+                let hv =
+                    header::HeaderValue::from_str(etag.trim()).map_err(crate::HttpError::from)?;
+                headers.insert(header::IF_NONE_MATCH, hv);
+            } else {
+                // Use the etag (or last modified, though crates.io does not use this AFAICT)
+                // from the cache entry if it exists
+                let _ = set_cache_version(headers);
+            }
         }
 
         const EMPTY: &[u8] = &[];

src/index/sparse_remote.rs

@@ -31,7 +31,7 @@ impl RemoteSparseIndex {
         name: KrateName<'_>,
         write_cache_entry: bool,
     ) -> Result<Option<IndexKrate>, Error> {
-        let req = self.index.make_remote_request(name)?;
+        let req = self.index.make_remote_request(name, None)?;
         let req = req.try_into()?;
 
         let res = self.client.execute(req)?;
@@ -109,7 +109,7 @@ impl AsyncRemoteSparseIndex {
         name: KrateName<'_>,
         write_cache_entry: bool,
     ) -> Result<Option<IndexKrate>, Error> {
-        let req = self.index.make_remote_request(name)?.try_into()?;
+        let req = self.index.make_remote_request(name, None)?.try_into()?;
         let res = Self::exec_request(&self.client, req).await?;
 
         self.index
@@ -181,7 +181,7 @@ impl AsyncRemoteSparseIndex {
             match kname
                 .as_str()
                 .try_into()
-                .and_then(|name| Ok(self.index.make_remote_request(name)?.try_into()?))
+                .and_then(|name| Ok(self.index.make_remote_request(name, None)?.try_into()?))
             {
                 Ok(req) => {
                     let client = self.client.clone();

src/lib.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
 #![doc = include_str!("../README.md")]
 
 pub mod error;

tests/sparse.rs

@@ -29,7 +29,7 @@ fn make_request_without_cache() {
     let index = crates_io(env!("CARGO_MANIFEST_DIR"));
 
     let req = index
-        .make_remote_request("serde".try_into().unwrap())
+        .make_remote_request("serde".try_into().unwrap(), None)
         .unwrap();
 
     let hdrs = req.headers();
@@ -61,7 +61,15 @@ fn make_request_with_cache() {
             .unwrap();
 
         let req = index
-            .make_remote_request("etag-krate".try_into().unwrap())
+            .make_remote_request("etag-krate".try_into().unwrap(), None)
+            .unwrap();
+
+        assert_eq!(req.headers().get(header::IF_NONE_MATCH).unwrap(), ETAG);
+    }
+
+    {
+        let req = index
+            .make_remote_request("etag-specified-krate".try_into().unwrap(), Some(ETAG))
             .unwrap();
 
         assert_eq!(req.headers().get(header::IF_NONE_MATCH).unwrap(), ETAG);
@@ -78,7 +86,7 @@ fn make_request_with_cache() {
             .unwrap();
 
         let req = index
-            .make_remote_request("modified-krate".try_into().unwrap())
+            .make_remote_request("modified-krate".try_into().unwrap(), None)
             .unwrap();
 
         assert_eq!(req.headers().get(header::IF_MODIFIED_SINCE).unwrap(), DATE);