cache the output of build_deps

Author: Eh2406

src/cargo/core/resolver/context.rs

@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{BTreeSet, HashMap};
 use std::num::NonZeroU64;
 use std::rc::Rc;
 
@@ -18,7 +18,6 @@ use super::types::{ConflictMap, Method};
 pub use super::encode::{EncodableDependency, EncodablePackageId, EncodableResolve};
 pub use super::encode::{Metadata, WorkspaceResolve};
 pub use super::resolve::Resolve;
-use std::collections::btree_set::BTreeSet;
 
 // A `Context` is basically a bunch of local resolution information which is
 // kept around for all `BacktrackFrame` instances. As a result, this runs the

src/cargo/core/resolver/dep_cache.rs

@@ -177,34 +177,63 @@ impl<'a> RegistryQueryer<'a> {
     }
 }
 
-pub fn build_deps(
-    registry: &mut RegistryQueryer<'_>,
-    parent: Option<PackageId>,
-    candidate: &Summary,
-    method: &Method,
-) -> ActivateResult<(HashSet<InternedString>, Vec<DepInfo>)> {
-    // First, figure out our set of dependencies based on the requested set
-    // of features. This also calculates what features we're going to enable
-    // for our own dependencies.
-    let (used_features, deps) = resolve_features(parent, candidate, method)?;
-
-    // Next, transform all dependencies into a list of possible candidates
-    // which can satisfy that dependency.
-    let mut deps = deps
-        .into_iter()
-        .map(|(dep, features)| {
-            let candidates = registry.query(&dep)?;
-            Ok((dep, candidates, Rc::new(features)))
-        })
-        .collect::<CargoResult<Vec<DepInfo>>>()?;
-
-    // Attempt to resolve dependencies with fewer candidates before trying
-    // dependencies with more candidates. This way if the dependency with
-    // only one candidate can't be resolved we don't have to do a bunch of
-    // work before we figure that out.
-    deps.sort_by_key(|&(_, ref a, _)| a.len());
-
-    Ok((used_features, deps))
+pub struct DepsCache<'a> {
+    pub registry: RegistryQueryer<'a>,
+    cache: HashMap<
+        (Option<PackageId>, Summary, Method),
+        Rc<(HashSet<InternedString>, Rc<Vec<DepInfo>>)>,
+    >,
+}
+
+impl<'a> DepsCache<'a> {
+    pub fn new(registry: RegistryQueryer<'a>) -> Self {
+        DepsCache {
+            registry,
+            cache: HashMap::new(),
+        }
+    }
+
+    pub fn build_deps(
+        &mut self,
+        parent: Option<PackageId>,
+        candidate: &Summary,
+        method: &Method,
+    ) -> ActivateResult<Rc<(HashSet<InternedString>, Rc<Vec<DepInfo>>)>> {
+        if let Some(out) = self
+            .cache
+            .get(&(parent, candidate.clone(), method.clone()))
+            .cloned()
+        {
+            return Ok(out);
+        }
+        // First, figure out our set of dependencies based on the requested set
+        // of features. This also calculates what features we're going to enable
+        // for our own dependencies.
+        let (used_features, deps) = resolve_features(parent, candidate, method)?;
+
+        // Next, transform all dependencies into a list of possible candidates
+        // which can satisfy that dependency.
+        let mut deps = deps
+            .into_iter()
+            .map(|(dep, features)| {
+                let candidates = self.registry.query(&dep)?;
+                Ok((dep, candidates, Rc::new(features)))
+            })
+            .collect::<CargoResult<Vec<DepInfo>>>()?;
+
+        // Attempt to resolve dependencies with fewer candidates before trying
+        // dependencies with more candidates. This way if the dependency with
+        // only one candidate can't be resolved we don't have to do a bunch of
+        // work before we figure that out.
+        deps.sort_by_key(|&(_, ref a, _)| a.len());
+
+        let out = Rc::new((used_features, Rc::new(deps)));
+
+        self.cache
+            .insert((parent, candidate.clone(), method.clone()), out.clone());
+
+        Ok(out)
+    }
 }
 
 /// Returns all dependencies and the features we want from them.

src/cargo/core/resolver/mod.rs

@@ -62,7 +62,7 @@ use crate::util::errors::CargoResult;
 use crate::util::profile;
 
 use self::context::{Activations, Context};
-use self::dep_cache::RegistryQueryer;
+use self::dep_cache::{DepsCache, RegistryQueryer};
 use self::types::{Candidate, ConflictMap, ConflictReason, DepsFrame};
 use self::types::{RcVecIter, RemainingDeps, ResolverProgress};
 
@@ -134,7 +134,8 @@ pub fn resolve(
         Some(config) => config.cli_unstable().minimal_versions,
         None => false,
     };
-    let mut registry = RegistryQueryer::new(registry, replacements, try_to_use, minimal_versions);
+    let registry = RegistryQueryer::new(registry, replacements, try_to_use, minimal_versions);
+    let mut registry = DepsCache::new(registry);
     let cx = activate_deps_loop(cx, &mut registry, summaries, config)?;
 
     let mut cksums = HashMap::new();
@@ -144,7 +145,7 @@ pub fn resolve(
     }
     let resolve = Resolve::new(
         cx.graph(),
-        cx.resolve_replacements(&registry),
+        cx.resolve_replacements(&registry.registry),
         cx.resolve_features
             .iter()
             .map(|(k, v)| (*k, v.iter().map(|x| x.to_string()).collect()))
@@ -168,7 +169,7 @@ pub fn resolve(
 /// dependency graph, cx.resolve is returned.
 fn activate_deps_loop(
     mut cx: Context,
-    registry: &mut RegistryQueryer<'_>,
+    registry: &mut DepsCache<'_>,
     summaries: &[(Summary, Method)],
     config: Option<&Config>,
 ) -> CargoResult<Context> {
@@ -186,7 +187,7 @@ fn activate_deps_loop(
             summary: summary.clone(),
             replace: None,
         };
-        let res = activate(&mut cx, registry, None, candidate, method);
+        let res = activate(&mut cx, registry, None, candidate, method.clone());
         match res {
             Ok(Some((frame, _))) => remaining_deps.push(frame),
             Ok(None) => (),
@@ -328,7 +329,7 @@ fn activate_deps_loop(
                         debug!("no candidates found");
                         Err(errors::activation_error(
                             &cx,
-                            registry.registry,
+                            registry.registry.registry,
                             &parent,
                             &dep,
                             &conflicting_activations,
@@ -385,7 +386,7 @@ fn activate_deps_loop(
                 dep.package_name(),
                 candidate.summary.version()
             );
-            let res = activate(&mut cx, registry, Some((&parent, &dep)), candidate, &method);
+            let res = activate(&mut cx, registry, Some((&parent, &dep)), candidate, method);
 
             let successfully_activated = match res {
                 // Success! We've now activated our `candidate` in our context
@@ -594,10 +595,10 @@ fn activate_deps_loop(
 /// iterate through next.
 fn activate(
     cx: &mut Context,
-    registry: &mut RegistryQueryer<'_>,
+    registry: &mut DepsCache<'_>,
     parent: Option<(&Summary, &Dependency)>,
     candidate: Candidate,
-    method: &Method,
+    method: Method,
 ) -> ActivateResult<Option<(DepsFrame, Duration)>> {
     let candidate_pid = candidate.summary.package_id();
     if let Some((parent, dep)) = parent {
@@ -658,11 +659,11 @@ fn activate(
         }
     }
 
-    let activated = cx.flag_activated(&candidate.summary, method)?;
+    let activated = cx.flag_activated(&candidate.summary, &method)?;
 
     let candidate = match candidate.replace {
         Some(replace) => {
-            if cx.flag_activated(&replace, method)? && activated {
+            if cx.flag_activated(&replace, &method)? && activated {
                 return Ok(None);
             }
             trace!(
@@ -682,12 +683,8 @@ fn activate(
     };
 
     let now = Instant::now();
-    let (used_features, deps) = dep_cache::build_deps(
-        registry,
-        parent.map(|p| p.0.package_id()),
-        &candidate,
-        method,
-    )?;
+    let (used_features, deps) =
+        &*registry.build_deps(parent.map(|p| p.0.package_id()), &candidate, &method)?;
 
     // Record what list of features is active for this package.
     if !used_features.is_empty() {
@@ -702,7 +699,7 @@ fn activate(
     let frame = DepsFrame {
         parent: candidate,
         just_for_error_messages: false,
-        remaining_siblings: RcVecIter::new(Rc::new(deps)),
+        remaining_siblings: RcVecIter::new(Rc::clone(deps)),
     };
     Ok(Some((frame, now.elapsed())))
 }
@@ -862,7 +859,7 @@ impl RemainingCandidates {
 /// Panics if the input conflict is not all active in `cx`.
 fn generalize_conflicting(
     cx: &Context,
-    registry: &mut RegistryQueryer<'_>,
+    registry: &mut DepsCache<'_>,
     past_conflicting_activations: &mut conflict_cache::ConflictCache,
     parent: &Summary,
     dep: &Dependency,
@@ -901,6 +898,7 @@ fn generalize_conflicting(
             // Thus, if all the things it can resolve to have already ben determined
             // to be conflicting, then we can just say that we conflict with the parent.
             if registry
+                .registry
                 .query(critical_parents_dep)
                 .expect("an already used dep now error!?")
                 .iter()

src/cargo/core/resolver/types.rs

@@ -89,7 +89,7 @@ impl ResolverProgress {
     }
 }
 
-#[derive(Clone)]
+#[derive(Clone, Eq, PartialEq, Hash)]
 pub enum Method {
     Everything, // equivalent to Required { dev_deps: true, all_features: true, .. }
     Required {

src/cargo/core/summary.rs

@@ -1,6 +1,7 @@
 use std::borrow::Borrow;
 use std::collections::{BTreeMap, HashMap};
 use std::fmt::Display;
+use std::hash::{Hash, Hasher};
 use std::mem;
 use std::rc::Rc;
 
@@ -137,6 +138,14 @@ impl PartialEq for Summary {
     }
 }
 
+impl Eq for Summary {}
+
+impl Hash for Summary {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.inner.package_id.hash(state);
+    }
+}
+
 // Checks features for errors, bailing out a CargoResult:Err if invalid,
 // and creates FeatureValues for each feature.
 fn build_feature_map<K>(