Use SmallString for filenames and URLs (#11765)

## Summary

These are never mutated, so there's no need to store them as `String`.

crates/uv-client/Cargo.toml

@@ -23,6 +23,7 @@ uv-pep440 = { workspace = true }
 uv-pep508 = { workspace = true }
 uv-platform-tags = { workspace = true }
 uv-pypi-types = { workspace = true }
+uv-small-str = { workspace = true }
 uv-static = { workspace = true }
 uv-version = { workspace = true }
 uv-warnings = { workspace = true }

crates/uv-client/src/flat_index.rs

@@ -10,6 +10,7 @@ use uv_cache_key::cache_digest;
 use uv_distribution_filename::DistFilename;
 use uv_distribution_types::{File, FileLocation, IndexUrl, UrlString};
 use uv_pypi_types::HashDigests;
+use uv_small_str::SmallString;
 
 use crate::cached_client::{CacheControl, CachedClientError};
 use crate::html::SimpleHtml;
@@ -186,10 +187,13 @@ impl<'a> FlatIndexClient<'a> {
                 let SimpleHtml { base, files } = SimpleHtml::parse(&text, &url)
                     .map_err(|err| Error::from_html_err(err, url.clone()))?;
 
+                // Convert to a reference-counted string.
+                let base = SmallString::from(base.as_str());
+
                 let unarchived: Vec<File> = files
                     .into_iter()
                     .filter_map(|file| {
-                        match File::try_from(file, base.as_url()) {
+                        match File::try_from(file, &base) {
                             Ok(file) => Some(file),
                             Err(err) => {
                                 // Ignore files with unparsable version specifiers.
@@ -270,10 +274,11 @@ impl<'a> FlatIndexClient<'a> {
                 }
             }
 
-            let Ok(filename) = entry.file_name().into_string() else {
+            let filename = entry.file_name();
+            let Some(filename) = filename.to_str() else {
                 warn!(
                     "Skipping non-UTF-8 filename in `--find-links` directory: {}",
-                    entry.file_name().to_string_lossy()
+                    filename.to_string_lossy()
                 );
                 continue;
             };
@@ -283,16 +288,16 @@ impl<'a> FlatIndexClient<'a> {
 
             let file = File {
                 dist_info_metadata: false,
-                filename: filename.to_string(),
+                filename: filename.into(),
                 hashes: HashDigests::empty(),
                 requires_python: None,
                 size: None,
                 upload_time_utc_ms: None,
-                url: FileLocation::AbsoluteUrl(UrlString::from(url)),
+                url: FileLocation::AbsoluteUrl(UrlString::from(&url)),
                 yanked: None,
             };
 
-            let Some(filename) = DistFilename::try_from_normalized_filename(&filename) else {
+            let Some(filename) = DistFilename::try_from_normalized_filename(filename) else {
                 debug!(
                     "Ignoring `--find-links` entry (expected a wheel or source distribution filename): {}",
                     entry.path().display()

crates/uv-client/src/html.rs

@@ -218,8 +218,8 @@ impl SimpleHtml {
             yanked,
             requires_python,
             hashes,
-            filename: filename.to_string(),
-            url: decoded.to_string(),
+            filename: filename.into(),
+            url: decoded.into(),
             size,
             upload_time,
         }))

crates/uv-client/src/registry_client.rs

@@ -14,6 +14,12 @@ use tokio::sync::Semaphore;
 use tracing::{info_span, instrument, trace, warn, Instrument};
 use url::Url;
 
+use crate::base_client::{BaseClientBuilder, ExtraMiddleware};
+use crate::cached_client::CacheControl;
+use crate::html::SimpleHtml;
+use crate::remote_metadata::wheel_metadata_from_remote_zip;
+use crate::rkyvutil::OwnedArchive;
+use crate::{BaseClient, CachedClient, CachedClientError, Error, ErrorKind};
 use uv_cache::{Cache, CacheBucket, CacheEntry, WheelCache};
 use uv_configuration::KeyringProviderType;
 use uv_configuration::{IndexStrategy, TrustedHost};
@@ -27,13 +33,7 @@ use uv_pep440::Version;
 use uv_pep508::MarkerEnvironment;
 use uv_platform_tags::Platform;
 use uv_pypi_types::{ResolutionMetadata, SimpleJson};
-
-use crate::base_client::{BaseClientBuilder, ExtraMiddleware};
-use crate::cached_client::CacheControl;
-use crate::html::SimpleHtml;
-use crate::remote_metadata::wheel_metadata_from_remote_zip;
-use crate::rkyvutil::OwnedArchive;
-use crate::{BaseClient, CachedClient, CachedClientError, Error, ErrorKind};
+use uv_small_str::SmallString;
 
 /// A builder for an [`RegistryClient`].
 #[derive(Debug, Clone)]
@@ -894,10 +894,12 @@ impl SimpleMetadata {
     fn from_files(files: Vec<uv_pypi_types::File>, package_name: &PackageName, base: &Url) -> Self {
         let mut map: BTreeMap<Version, VersionFiles> = BTreeMap::default();
 
+        // Convert to a reference-counted string.
+        let base = SmallString::from(base.as_str());
+
         // Group the distributions by version and kind
         for file in files {
-            let Some(filename) =
-                DistFilename::try_from_filename(file.filename.as_str(), package_name)
+            let Some(filename) = DistFilename::try_from_filename(&file.filename, package_name)
             else {
                 warn!("Skipping file for {package_name}: {}", file.filename);
                 continue;
@@ -906,7 +908,7 @@ impl SimpleMetadata {
                 DistFilename::SourceDistFilename(ref inner) => &inner.version,
                 DistFilename::WheelFilename(ref inner) => &inner.version,
             };
-            let file = match File::try_from(file, base) {
+            let file = match File::try_from(file, &base) {
                 Ok(file) => file,
                 Err(err) => {
                     // Ignore files with unparsable version specifiers.

crates/uv-distribution-types/Cargo.toml

@@ -27,6 +27,7 @@ uv-pep440 = { workspace = true }
 uv-pep508 = { workspace = true }
 uv-platform-tags = { workspace = true }
 uv-pypi-types = { workspace = true }
+uv-small-str = { workspace = true }
 
 arcstr = { workspace = true }
 bitflags = { workspace = true }

crates/uv-distribution-types/src/file.rs

@@ -8,6 +8,7 @@ use url::Url;
 use uv_pep440::{VersionSpecifiers, VersionSpecifiersParseError};
 use uv_pep508::split_scheme;
 use uv_pypi_types::{CoreMetadata, HashDigests, Yanked};
+use uv_small_str::SmallString;
 
 /// Error converting [`uv_pypi_types::File`] to [`distribution_type::File`].
 #[derive(Debug, thiserror::Error)]
@@ -23,7 +24,7 @@ pub enum FileConversionError {
 #[rkyv(derive(Debug))]
 pub struct File {
     pub dist_info_metadata: bool,
-    pub filename: String,
+    pub filename: SmallString,
     pub hashes: HashDigests,
     pub requires_python: Option<VersionSpecifiers>,
     pub size: Option<u64>,
@@ -38,7 +39,10 @@ pub struct File {
 
 impl File {
     /// `TryFrom` instead of `From` to filter out files with invalid requires python version specifiers
-    pub fn try_from(file: uv_pypi_types::File, base: &Url) -> Result<Self, FileConversionError> {
+    pub fn try_from(
+        file: uv_pypi_types::File,
+        base: &SmallString,
+    ) -> Result<Self, FileConversionError> {
         Ok(Self {
             dist_info_metadata: file
                 .core_metadata
@@ -56,7 +60,7 @@ impl File {
             upload_time_utc_ms: file.upload_time.map(Timestamp::as_millisecond),
             url: match split_scheme(&file.url) {
                 Some(..) => FileLocation::AbsoluteUrl(UrlString::new(file.url)),
-                None => FileLocation::RelativeUrl(base.to_string(), file.url),
+                None => FileLocation::RelativeUrl(base.clone(), file.url),
             },
             yanked: file.yanked,
         })
@@ -68,7 +72,7 @@ impl File {
 #[rkyv(derive(Debug))]
 pub enum FileLocation {
     /// URL relative to the base URL.
-    RelativeUrl(String, String),
+    RelativeUrl(SmallString, SmallString),
     /// Absolute URL.
     AbsoluteUrl(UrlString),
 }
@@ -89,30 +93,19 @@ impl FileLocation {
         match *self {
             FileLocation::RelativeUrl(ref base, ref path) => {
                 let base_url = Url::parse(base).map_err(|err| ToUrlError::InvalidBase {
-                    base: base.clone(),
+                    base: base.to_string(),
                     err,
                 })?;
                 let joined = base_url.join(path).map_err(|err| ToUrlError::InvalidJoin {
-                    base: base.clone(),
-                    path: path.clone(),
+                    base: base.to_string(),
+                    path: path.to_string(),
                     err,
                 })?;
                 Ok(joined)
             }
             FileLocation::AbsoluteUrl(ref absolute) => absolute.to_url(),
         }
     }
-
-    /// Convert this location to a URL.
-    ///
-    /// This method is identical to [`FileLocation::to_url`] except it avoids parsing absolute URLs
-    /// as they are already guaranteed to be valid.
-    pub fn to_url_string(&self) -> Result<UrlString, ToUrlError> {
-        match *self {
-            FileLocation::AbsoluteUrl(ref absolute) => Ok(absolute.clone()),
-            FileLocation::RelativeUrl(_, _) => Ok(self.to_url()?.into()),
-        }
-    }
 }
 
 impl Display for FileLocation {
@@ -143,18 +136,18 @@ impl Display for FileLocation {
 )]
 #[serde(transparent)]
 #[rkyv(derive(Debug))]
-pub struct UrlString(String);
+pub struct UrlString(SmallString);
 
 impl UrlString {
     /// Create a new [`UrlString`] from a [`String`].
-    pub fn new(url: String) -> Self {
+    pub fn new(url: SmallString) -> Self {
         Self(url)
     }
 
     /// Converts a [`UrlString`] to a [`Url`].
     pub fn to_url(&self) -> Result<Url, ToUrlError> {
         Url::from_str(&self.0).map_err(|err| ToUrlError::InvalidAbsolute {
-            absolute: self.0.clone(),
+            absolute: self.0.to_string(),
             err,
         })
     }
@@ -175,8 +168,8 @@ impl UrlString {
             self.as_ref()
                 .split_once('#')
                 .map(|(path, _)| path)
-                .unwrap_or(self.as_ref())
-                .to_string(),
+                .map(SmallString::from)
+                .unwrap_or_else(|| self.0.clone()),
         )
     }
 }
@@ -189,13 +182,13 @@ impl AsRef<str> for UrlString {
 
 impl From<Url> for UrlString {
     fn from(value: Url) -> Self {
-        UrlString(value.to_string())
+        Self(value.as_str().into())
     }
 }
 
 impl From<&Url> for UrlString {
     fn from(value: &Url) -> Self {
-        UrlString(value.to_string())
+        Self(value.as_str().into())
     }
 }
 
@@ -248,28 +241,28 @@ mod tests {
 
     #[test]
     fn base_str() {
-        let url = UrlString("https://example.com/path?query#fragment".to_string());
+        let url = UrlString("https://example.com/path?query#fragment".into());
         assert_eq!(url.base_str(), "https://example.com/path");
 
-        let url = UrlString("https://example.com/path#fragment".to_string());
+        let url = UrlString("https://example.com/path#fragment".into());
         assert_eq!(url.base_str(), "https://example.com/path");
 
-        let url = UrlString("https://example.com/path".to_string());
+        let url = UrlString("https://example.com/path".into());
         assert_eq!(url.base_str(), "https://example.com/path");
     }
 
     #[test]
     fn without_fragment() {
-        let url = UrlString("https://example.com/path?query#fragment".to_string());
+        let url = UrlString("https://example.com/path?query#fragment".into());
         assert_eq!(
             url.without_fragment(),
-            UrlString("https://example.com/path?query".to_string())
+            UrlString("https://example.com/path?query".into())
         );
 
-        let url = UrlString("https://example.com/path#fragment".to_string());
+        let url = UrlString("https://example.com/path#fragment".into());
         assert_eq!(url.base_str(), "https://example.com/path");
 
-        let url = UrlString("https://example.com/path".to_string());
+        let url = UrlString("https://example.com/path".into());
         assert_eq!(url.base_str(), "https://example.com/path");
     }
 }

crates/uv-pypi-types/src/base_url.rs

@@ -43,6 +43,11 @@ impl BaseUrl {
     pub fn as_url(&self) -> &Url {
         &self.0
     }
+
+    /// Return the underlying [`Url`] as a serialized string.
+    pub fn as_str(&self) -> &str {
+        self.0.as_str()
+    }
 }
 
 impl From<Url> for BaseUrl {

crates/uv-pypi-types/src/simple_json.rs

@@ -40,10 +40,12 @@ fn sorted_simple_json_files<'de, D: Deserializer<'de>>(d: D) -> Result<Vec<File>
 pub struct File {
     // PEP 714-renamed field, followed by PEP 691-compliant field, followed by non-PEP 691-compliant
     // alias used by PyPI.
+    //
+    // TODO(charlie): Use a single value here and move this into the deserializer, to save space.
     pub core_metadata: Option<CoreMetadata>,
     pub dist_info_metadata: Option<CoreMetadata>,
     pub data_dist_info_metadata: Option<CoreMetadata>,
-    pub filename: String,
+    pub filename: SmallString,
     pub hashes: Hashes,
     /// There are a number of invalid specifiers on PyPI, so we first try to parse it into a
     /// [`VersionSpecifiers`] according to spec (PEP 440), then a [`LenientVersionSpecifiers`] with
@@ -53,7 +55,7 @@ pub struct File {
     pub requires_python: Option<Result<VersionSpecifiers, VersionSpecifiersParseError>>,
     pub size: Option<u64>,
     pub upload_time: Option<Timestamp>,
-    pub url: String,
+    pub url: SmallString,
     pub yanked: Option<Box<Yanked>>,
 }
 

crates/uv-resolver/Cargo.toml

@@ -34,6 +34,7 @@ uv-platform-tags = { workspace = true }
 uv-pypi-types = { workspace = true }
 uv-python = { workspace = true }
 uv-requirements-txt = { workspace = true }
+uv-small-str = { workspace = true }
 uv-static = { workspace = true }
 uv-types = { workspace = true }
 uv-warnings = { workspace = true }