Auto merge of #6853 - Eh2406:caching-the-dependency, r=alexcrichton

Caching the dependencies

There are 2 sources of facts for the resolver:
1. The `Registry` tells us for a Dependency what versions are available to fulfil it.
2. The `Summary` tells us for a version (and features) what dependencies need to be fulfilled for it to be activated.

The `Registry` was cached with a `RegistryQueryer` back in #5112. This adds a `DepsCache` to cache the calculation of which dependencies are activated by features.

In the happy path `flag_activated` means that we don't get to reuse `build_deps`, but the more we backtrack the more time we save. In pathological cases like #6258 (comment), I have measured this as a 10% improvement with release.

This also means that `build_deps` can be run in a context free way, which may be useful in a follow up PR to solve #6258 (comment).

src/cargo/core/compiler/fingerprint.rs

@@ -478,9 +478,7 @@ enum LocalFingerprint {
     /// The `dep_info` file, when present, also lists a number of other files
     /// for us to look at. If any of those files are newer than this file then
     /// we need to recompile.
-    CheckDepInfo {
-        dep_info: PathBuf,
-    },
+    CheckDepInfo { dep_info: PathBuf },
 
     /// This represents a nonempty set of `rerun-if-changed` annotations printed
     /// out by a build script. The `output` file is a arelative file anchored at
@@ -500,10 +498,7 @@ enum LocalFingerprint {
     /// build script. The exact env var and value are hashed here. There's no
     /// filesystem dependence here, and if the values are changed the hash will
     /// change forcing a recompile.
-    RerunIfEnvChanged {
-        var: String,
-        val: Option<String>,
-    },
+    RerunIfEnvChanged { var: String, val: Option<String> },
 }
 
 enum StaleFile {
@@ -762,7 +757,7 @@ impl Fingerprint {
                     let t = FileTime::from_system_time(SystemTime::now());
                     drop(filetime::set_file_times(f, t, t));
                 }
-                return mtime;
+                mtime
             })
             .min();
 
@@ -1350,7 +1345,7 @@ fn compare_old_fingerprint(
     debug_assert_eq!(util::to_hex(old_fingerprint.hash()), old_fingerprint_short);
     let result = new_fingerprint.compare(&old_fingerprint);
     assert!(result.is_err());
-    return result;
+    result
 }
 
 fn log_compare(unit: &Unit<'_>, compare: &CargoResult<()>) {
@@ -1444,7 +1439,7 @@ where
         });
     }
 
-    return None;
+    None
 }
 
 fn filename<'a, 'cfg>(cx: &mut Context<'a, 'cfg>, unit: &Unit<'a>) -> String {

src/cargo/core/package_id_spec.rs

@@ -5,6 +5,7 @@ use semver::Version;
 use serde::{de, ser};
 use url::Url;
 
+use crate::core::interning::InternedString;
 use crate::core::PackageId;
 use crate::util::errors::{CargoResult, CargoResultExt};
 use crate::util::{validate_package_name, ToSemver, ToUrl};
@@ -20,7 +21,7 @@ use crate::util::{validate_package_name, ToSemver, ToUrl};
 /// sufficient to uniquely define a package ID.
 #[derive(Clone, PartialEq, Eq, Debug, Hash, Ord, PartialOrd)]
 pub struct PackageIdSpec {
-    name: String,
+    name: InternedString,
     version: Option<Version>,
     url: Option<Url>,
 }
@@ -66,7 +67,7 @@ impl PackageIdSpec {
         };
         validate_package_name(name, "pkgid", "")?;
         Ok(PackageIdSpec {
-            name: name.to_string(),
+            name: InternedString::new(name),
             version,
             url: None,
         })
@@ -86,7 +87,7 @@ impl PackageIdSpec {
     /// fields filled in.
     pub fn from_package_id(package_id: PackageId) -> PackageIdSpec {
         PackageIdSpec {
-            name: package_id.name().to_string(),
+            name: package_id.name(),
             version: Some(package_id.version().clone()),
             url: Some(package_id.source_id().url().clone()),
         }
@@ -117,19 +118,19 @@ impl PackageIdSpec {
                     match parts.next() {
                         Some(part) => {
                             let version = part.to_semver()?;
-                            (name_or_version.to_string(), Some(version))
+                            (InternedString::new(name_or_version), Some(version))
                         }
                         None => {
                             if name_or_version.chars().next().unwrap().is_alphabetic() {
-                                (name_or_version.to_string(), None)
+                                (InternedString::new(name_or_version), None)
                             } else {
                                 let version = name_or_version.to_semver()?;
-                                (path_name.to_string(), Some(version))
+                                (InternedString::new(path_name), Some(version))
                             }
                         }
                     }
                 }
-                None => (path_name.to_string(), None),
+                None => (InternedString::new(path_name), None),
             }
         };
         Ok(PackageIdSpec {
@@ -139,8 +140,8 @@ impl PackageIdSpec {
         })
     }
 
-    pub fn name(&self) -> &str {
-        &self.name
+    pub fn name(&self) -> InternedString {
+        self.name
     }
 
     pub fn version(&self) -> Option<&Version> {
@@ -157,7 +158,7 @@ impl PackageIdSpec {
 
     /// Checks whether the given `PackageId` matches the `PackageIdSpec`.
     pub fn matches(&self, package_id: PackageId) -> bool {
-        if self.name() != &*package_id.name() {
+        if self.name() != package_id.name() {
             return false;
         }
 
@@ -234,7 +235,7 @@ impl fmt::Display for PackageIdSpec {
                 } else {
                     write!(f, "{}", url)?;
                 }
-                if url.path_segments().unwrap().next_back().unwrap() != self.name {
+                if url.path_segments().unwrap().next_back().unwrap() != &*self.name {
                     printed_name = true;
                     write!(f, "#{}", self.name)?;
                 }
@@ -273,6 +274,7 @@ impl<'de> de::Deserialize<'de> for PackageIdSpec {
 #[cfg(test)]
 mod tests {
     use super::PackageIdSpec;
+    use crate::core::interning::InternedString;
     use crate::core::{PackageId, SourceId};
     use crate::util::ToSemver;
     use url::Url;
@@ -288,63 +290,63 @@ mod tests {
         ok(
             "https://crates.io/foo#1.2.3",
             PackageIdSpec {
-                name: "foo".to_string(),
+                name: InternedString::new("foo"),
                 version: Some("1.2.3".to_semver().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
         );
         ok(
             "https://crates.io/foo#bar:1.2.3",
             PackageIdSpec {
-                name: "bar".to_string(),
+                name: InternedString::new("bar"),
                 version: Some("1.2.3".to_semver().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
         );
         ok(
             "crates.io/foo",
             PackageIdSpec {
-                name: "foo".to_string(),
+                name: InternedString::new("foo"),
                 version: None,
                 url: Some(Url::parse("cargo://crates.io/foo").unwrap()),
             },
         );
         ok(
             "crates.io/foo#1.2.3",
             PackageIdSpec {
-                name: "foo".to_string(),
+                name: InternedString::new("foo"),
                 version: Some("1.2.3".to_semver().unwrap()),
                 url: Some(Url::parse("cargo://crates.io/foo").unwrap()),
             },
         );
         ok(
             "crates.io/foo#bar",
             PackageIdSpec {
-                name: "bar".to_string(),
+                name: InternedString::new("bar"),
                 version: None,
                 url: Some(Url::parse("cargo://crates.io/foo").unwrap()),
             },
         );
         ok(
             "crates.io/foo#bar:1.2.3",
             PackageIdSpec {
-                name: "bar".to_string(),
+                name: InternedString::new("bar"),
                 version: Some("1.2.3".to_semver().unwrap()),
                 url: Some(Url::parse("cargo://crates.io/foo").unwrap()),
             },
         );
         ok(
             "foo",
             PackageIdSpec {
-                name: "foo".to_string(),
+                name: InternedString::new("foo"),
                 version: None,
                 url: None,
             },
         );
         ok(
             "foo:1.2.3",
             PackageIdSpec {
-                name: "foo".to_string(),
+                name: InternedString::new("foo"),
                 version: Some("1.2.3".to_semver().unwrap()),
                 url: None,
             },

src/cargo/core/profiles.rs

@@ -282,7 +282,7 @@ impl ProfileMaker {
             let name_matches: Vec<String> = packages
                 .package_ids()
                 .filter_map(|pkg_id| {
-                    if pkg_id.name().as_str() == spec.name() {
+                    if pkg_id.name() == spec.name() {
                         Some(pkg_id.to_string())
                     } else {
                         None
@@ -292,7 +292,7 @@ impl ProfileMaker {
             if name_matches.is_empty() {
                 let suggestion = packages
                     .package_ids()
-                    .map(|p| (lev_distance(spec.name(), &p.name()), p.name()))
+                    .map(|p| (lev_distance(&*spec.name(), &p.name()), p.name()))
                     .filter(|&(d, _)| d < 4)
                     .min_by_key(|p| p.0)
                     .map(|p| p.1);

src/cargo/core/resolver/conflict_cache.rs

@@ -234,7 +234,7 @@ impl ConflictCache {
     /// all the `PackageId` entries are activated.
     pub fn contains(&self, dep: &Dependency, con: &ConflictMap) -> bool {
         if let Some(cst) = self.con_from_dep.get(dep) {
-            cst.contains(con.keys().cloned(), &con)
+            cst.contains(con.keys().cloned(), con)
         } else {
             false
         }