#
cargo/core/resolver/
dep_cache.rs

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394
    395
    396
    397
    398
    399
    400
    401
    402
    403
    404
    405
    406
    407
    408
    409
    410
    411
    412
    413
    414
    415
    416
    417
    418
    419
    420
    421
    422
    423
    424
    425
    426
    427
    428
    429
    430
    431
    432
    433
    434
    435
    436
    437
    438
    439
    440
    441
    442
    443
    444
    445
    446
    447
    448
    449
    450
    451
    452
    453
    454
    455
    456
    457
    458
    459
    460
    461
    462
    463
    464
    465
    466
    467
    468
    469
    470
    471
    472
    473
    474
    475
    476
    477
    478
    479
    480
    481
    482
    483
    484
    485
    486
    487
    488
    489
    490
    491
    492
    493
    494
    495
    496
    497
    498
    499
    500
    501
    502
    503
    504
    505
    506
    507
    508
    509
    510
    511
    512
    513
    514
    515
    516
    517
    518
    519
    520
    521
    522
    523
    524
    525
    526
    527
    528
    529
    530
    531
    532
    533
    534
    535
    536
    537
    538
    539
    540
    541
    542
    543
    544
    545
    546
    547
    548
    549
    550
    551
    552
    553
    554
    555
    556
    557
    558
    559
    560
    561
    562
    563
    564
    565
    566
    567
    568
    569
    570
    571
    572
    573
    574
    575
    576

    //! There are 2 sources of facts for the resolver:
    //!
    //! - The `Registry` tells us for a `Dependency` what versions are available to fulfil it.
    //! - The `Summary` tells us for a version (and features) what dependencies need to be fulfilled for it to be activated.
    //!
    //! These constitute immutable facts, the soled ground truth that all other inference depends on.
    //! Theoretically this could all be enumerated ahead of time, but we want to be lazy and only
    //! look up things we need to. The compromise is to cache the results as they are computed.
    //!
    //! This module impl that cache in all the gory details

    use crate::core::resolver::context::ResolverContext;
    use crate::core::resolver::errors::describe_path_in_context;
    use crate::core::resolver::types::{ConflictReason, DepInfo, FeaturesSet};
    use crate::core::resolver::{
        ActivateError, ActivateResult, CliFeatures, RequestedFeatures, ResolveOpts, VersionOrdering,
        VersionPreferences,
    };
    use crate::core::{
        Dependency, FeatureValue, PackageId, PackageIdSpec, PackageIdSpecQuery, Registry, Summary,
    };
    use crate::sources::source::QueryKind;
    use crate::util::errors::CargoResult;
    use crate::util::interning::{InternedString, INTERNED_DEFAULT};

    use anyhow::Context as _;
    use std::collections::{BTreeSet, HashMap, HashSet};
    use std::rc::Rc;
    use std::task::Poll;
    use tracing::debug;

    pub struct RegistryQueryer<'a> {
        pub registry: &'a mut (dyn Registry + 'a),
        replacements: &'a [(PackageIdSpec, Dependency)],
        version_prefs: &'a VersionPreferences,
        /// a cache of `Candidate`s that fulfil a `Dependency` (and whether `first_version`)
        registry_cache: HashMap<(Dependency, Option<VersionOrdering>), Poll<Rc<Vec<Summary>>>>,
        /// a cache of `Dependency`s that are required for a `Summary`
        ///
        /// HACK: `first_version` is not kept in the cache key is it is 1:1 with
        /// `parent.is_none()` (the first element of the cache key) as it doesn't change through
        /// execution.
        summary_cache: HashMap<
            (Option<PackageId>, Summary, ResolveOpts),
            (Rc<(HashSet<InternedString>, Rc<Vec<DepInfo>>)>, bool),
        >,
        /// all the cases we ended up using a supplied replacement
        used_replacements: HashMap<PackageId, Summary>,
    }

    impl<'a> RegistryQueryer<'a> {
        pub fn new(
            registry: &'a mut dyn Registry,
            replacements: &'a [(PackageIdSpec, Dependency)],
            version_prefs: &'a VersionPreferences,
        ) -> Self {
            RegistryQueryer {
                registry,
                replacements,
                version_prefs,
                registry_cache: HashMap::new(),
                summary_cache: HashMap::new(),
                used_replacements: HashMap::new(),
            }
        }

        pub fn reset_pending(&mut self) -> bool {
            let mut all_ready = true;
            self.registry_cache.retain(|_, r| {
                if !r.is_ready() {
                    all_ready = false;
                }
                r.is_ready()
            });
            self.summary_cache.retain(|_, (_, r)| {
                if !*r {
                    all_ready = false;
                }
                *r
            });
            all_ready
        }

        pub fn used_replacement_for(&self, p: PackageId) -> Option<(PackageId, PackageId)> {
            self.used_replacements.get(&p).map(|r| (p, r.package_id()))
        }

        pub fn replacement_summary(&self, p: PackageId) -> Option<&Summary> {
            self.used_replacements.get(&p)
        }

        /// Queries the `registry` to return a list of candidates for `dep`.
        ///
        /// This method is the location where overrides are taken into account. If
        /// any candidates are returned which match an override then the override is
        /// applied by performing a second query for what the override should
        /// return.
        pub fn query(
            &mut self,
            dep: &Dependency,
            first_version: Option<VersionOrdering>,
        ) -> Poll<CargoResult<Rc<Vec<Summary>>>> {
            let registry_cache_key = (dep.clone(), first_version);
            if let Some(out) = self.registry_cache.get(&registry_cache_key).cloned() {
                return out.map(Result::Ok);
            }

            let mut ret = Vec::new();
            let ready = self.registry.query(dep, QueryKind::Exact, &mut |s| {
                ret.push(s.into_summary());
            })?;
            if ready.is_pending() {
                self.registry_cache
                    .insert((dep.clone(), first_version), Poll::Pending);
                return Poll::Pending;
            }
            for summary in ret.iter() {
                let mut potential_matches = self
                    .replacements
                    .iter()
                    .filter(|(spec, _)| spec.matches(summary.package_id()));

                let Some((spec, dep)) = potential_matches.next() else {
                    continue;
                };
                debug!(
                    "found an override for {} {}",
                    dep.package_name(),
                    dep.version_req()
                );

                let mut summaries = match self.registry.query_vec(dep, QueryKind::Exact)? {
                    Poll::Ready(s) => s.into_iter(),
                    Poll::Pending => {
                        self.registry_cache
                            .insert((dep.clone(), first_version), Poll::Pending);
                        return Poll::Pending;
                    }
                };
                let s = summaries
                    .next()
                    .ok_or_else(|| {
                        anyhow::format_err!(
                            "no matching package for override `{}` found\n\
                         location searched: {}\n\
                         version required: {}",
                            spec,
                            dep.source_id(),
                            dep.version_req()
                        )
                    })?
                    .into_summary();
                let summaries = summaries.collect::<Vec<_>>();
                if !summaries.is_empty() {
                    let bullets = summaries
                        .iter()
                        .map(|s| format!("  * {}", s.package_id()))
                        .collect::<Vec<_>>();
                    return Poll::Ready(Err(anyhow::anyhow!(
                        "the replacement specification `{}` matched \
                         multiple packages:\n  * {}\n{}",
                        spec,
                        s.package_id(),
                        bullets.join("\n")
                    )));
                }

                assert_eq!(
                    s.name(),
                    summary.name(),
                    "dependency should be hard coded to have the same name"
                );
                if s.version() != summary.version() {
                    return Poll::Ready(Err(anyhow::anyhow!(
                        "replacement specification `{}` matched {} and tried to override it with {}\n\
                         avoid matching unrelated packages by being more specific",
                        spec,
                        summary.version(),
                        s.version(),
                    )));
                }

                let replace = if s.source_id() == summary.source_id() {
                    debug!("Preventing\n{:?}\nfrom replacing\n{:?}", summary, s);
                    None
                } else {
                    Some(s)
                };
                let matched_spec = spec.clone();

                // Make sure no duplicates
                if let Some((spec, _)) = potential_matches.next() {
                    return Poll::Ready(Err(anyhow::anyhow!(
                        "overlapping replacement specifications found:\n\n  \
                         * {}\n  * {}\n\nboth specifications match: {}",
                        matched_spec,
                        spec,
                        summary.package_id()
                    )));
                }

                for dep in summary.dependencies() {
                    debug!("\t{} => {}", dep.package_name(), dep.version_req());
                }
                if let Some(r) = replace {
                    self.used_replacements.insert(summary.package_id(), r);
                }
            }

            self.version_prefs.sort_summaries(&mut ret, first_version);

            let out = Poll::Ready(Rc::new(ret));

            self.registry_cache.insert(registry_cache_key, out.clone());

            out.map(Result::Ok)
        }

        /// Find out what dependencies will be added by activating `candidate`,
        /// with features described in `opts`. Then look up in the `registry`
        /// the candidates that will fulfil each of these dependencies, as it is the
        /// next obvious question.
        pub fn build_deps(
            &mut self,
            cx: &ResolverContext,
            parent: Option<PackageId>,
            candidate: &Summary,
            opts: &ResolveOpts,
            first_version: Option<VersionOrdering>,
        ) -> ActivateResult<Rc<(HashSet<InternedString>, Rc<Vec<DepInfo>>)>> {
            // if we have calculated a result before, then we can just return it,
            // as it is a "pure" query of its arguments.
            if let Some(out) = self
                .summary_cache
                .get(&(parent, candidate.clone(), opts.clone()))
            {
                return Ok(out.0.clone());
            }
            // 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, opts)?;

            // Next, transform all dependencies into a list of possible candidates
            // which can satisfy that dependency.
            let mut all_ready = true;
            let mut deps = deps
                .into_iter()
                .filter_map(|(dep, features)| match self.query(&dep, first_version) {
                    Poll::Ready(Ok(candidates)) => Some(Ok((dep, candidates, features))),
                    Poll::Pending => {
                        all_ready = false;
                        // we can ignore Pending deps, resolve will be repeatedly called
                        // until there are none to ignore
                        None
                    }
                    Poll::Ready(Err(e)) => Some(Err(e).with_context(|| {
                        format!(
                            "failed to get `{}` as a dependency of {}",
                            dep.package_name(),
                            describe_path_in_context(cx, &candidate.package_id()),
                        )
                    })),
                })
                .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(|(_, a, _)| a.len());

            let out = Rc::new((used_features, Rc::new(deps)));

            // If we succeed we add the result to the cache so we can use it again next time.
            // We don't cache the failure cases as they don't impl Clone.
            self.summary_cache.insert(
                (parent, candidate.clone(), opts.clone()),
                (out.clone(), all_ready),
            );

            Ok(out)
        }
    }

    /// Returns the features we ended up using and
    /// all dependencies and the features we want from each of them.
    pub fn resolve_features<'b>(
        parent: Option<PackageId>,
        s: &'b Summary,
        opts: &'b ResolveOpts,
    ) -> ActivateResult<(HashSet<InternedString>, Vec<(Dependency, FeaturesSet)>)> {
        // First, filter by dev-dependencies.
        let deps = s.dependencies();
        let deps = deps.iter().filter(|d| d.is_transitive() || opts.dev_deps);

        let reqs = build_requirements(parent, s, opts)?;
        let mut ret = Vec::new();
        let default_dep = BTreeSet::new();
        let mut valid_dep_names = HashSet::new();

        // Next, collect all actually enabled dependencies and their features.
        for dep in deps {
            // Skip optional dependencies, but not those enabled through a
            // feature
            if dep.is_optional() && !reqs.deps.contains_key(&dep.name_in_toml()) {
                continue;
            }
            valid_dep_names.insert(dep.name_in_toml());
            // So we want this dependency. Move the features we want from
            // `feature_deps` to `ret` and register ourselves as using this
            // name.
            let mut base = reqs
                .deps
                .get(&dep.name_in_toml())
                .unwrap_or(&default_dep)
                .clone();
            base.extend(dep.features().iter());
            ret.push((dep.clone(), Rc::new(base)));
        }

        // This is a special case for command-line `--features
        // dep_name/feat_name` where `dep_name` does not exist. All other
        // validation is done either in `build_requirements` or
        // `build_feature_map`.
        if parent.is_none() {
            for dep_name in reqs.deps.keys() {
                if !valid_dep_names.contains(dep_name) {
                    let e = RequirementError::MissingDependency(*dep_name);
                    return Err(e.into_activate_error(parent, s));
                }
            }
        }

        Ok((reqs.into_features(), ret))
    }

    /// Takes requested features for a single package from the input `ResolveOpts` and
    /// recurses to find all requested features, dependencies and requested
    /// dependency features in a `Requirements` object, returning it to the resolver.
    fn build_requirements<'a, 'b: 'a>(
        parent: Option<PackageId>,
        s: &'a Summary,
        opts: &'b ResolveOpts,
    ) -> ActivateResult<Requirements<'a>> {
        let mut reqs = Requirements::new(s);

        let handle_default = |uses_default_features, reqs: &mut Requirements<'_>| {
            if uses_default_features && s.features().contains_key("default") {
                if let Err(e) = reqs.require_feature(INTERNED_DEFAULT) {
                    return Err(e.into_activate_error(parent, s));
                }
            }
            Ok(())
        };

        match &opts.features {
            RequestedFeatures::CliFeatures(CliFeatures {
                features,
                all_features,
                uses_default_features,
            }) => {
                if *all_features {
                    for key in s.features().keys() {
                        if let Err(e) = reqs.require_feature(*key) {
                            return Err(e.into_activate_error(parent, s));
                        }
                    }
                }

                for fv in features.iter() {
                    if let Err(e) = reqs.require_value(fv) {
                        return Err(e.into_activate_error(parent, s));
                    }
                }
                handle_default(*uses_default_features, &mut reqs)?;
            }
            RequestedFeatures::DepFeatures {
                features,
                uses_default_features,
            } => {
                for feature in features.iter() {
                    if let Err(e) = reqs.require_feature(*feature) {
                        return Err(e.into_activate_error(parent, s));
                    }
                }
                handle_default(*uses_default_features, &mut reqs)?;
            }
        }

        Ok(reqs)
    }

    /// Set of feature and dependency requirements for a package.
    #[derive(Debug)]
    struct Requirements<'a> {
        summary: &'a Summary,
        /// The deps map is a mapping of dependency name to list of features enabled.
        ///
        /// The resolver will activate all of these dependencies, with the given
        /// features enabled.
        deps: HashMap<InternedString, BTreeSet<InternedString>>,
        /// The set of features enabled on this package which is later used when
        /// compiling to instruct the code what features were enabled.
        features: HashSet<InternedString>,
    }

    /// An error for a requirement.
    ///
    /// This will later be converted to an `ActivateError` depending on whether or
    /// not this is a dependency or a root package.
    enum RequirementError {
        /// The package does not have the requested feature.
        MissingFeature(InternedString),
        /// The package does not have the requested dependency.
        MissingDependency(InternedString),
        /// A feature has a direct cycle to itself.
        ///
        /// Note that cycles through multiple features are allowed (but perhaps
        /// they shouldn't be?).
        Cycle(InternedString),
    }

    impl Requirements<'_> {
        fn new(summary: &Summary) -> Requirements<'_> {
            Requirements {
                summary,
                deps: HashMap::new(),
                features: HashSet::new(),
            }
        }

        fn into_features(self) -> HashSet<InternedString> {
            self.features
        }

        fn require_dep_feature(
            &mut self,
            package: InternedString,
            feat: InternedString,
            weak: bool,
        ) -> Result<(), RequirementError> {
            // If `package` is indeed an optional dependency then we activate the
            // feature named `package`, but otherwise if `package` is a required
            // dependency then there's no feature associated with it.
            if !weak
                && self
                    .summary
                    .dependencies()
                    .iter()
                    .any(|dep| dep.name_in_toml() == package && dep.is_optional())
            {
                // This optional dependency may not have an implicit feature of
                // the same name if the `dep:` syntax is used to avoid creating
                // that implicit feature.
                if self.summary.features().contains_key(&package) {
                    self.require_feature(package)?;
                }
            }
            self.deps.entry(package).or_default().insert(feat);
            Ok(())
        }

        fn require_dependency(&mut self, pkg: InternedString) {
            self.deps.entry(pkg).or_default();
        }

        fn require_feature(&mut self, feat: InternedString) -> Result<(), RequirementError> {
            if !self.features.insert(feat) {
                // Already seen this feature.
                return Ok(());
            }

            let Some(fvs) = self.summary.features().get(&feat) else {
                return Err(RequirementError::MissingFeature(feat));
            };

            for fv in fvs {
                if let FeatureValue::Feature(dep_feat) = fv {
                    if *dep_feat == feat {
                        return Err(RequirementError::Cycle(feat));
                    }
                }
                self.require_value(fv)?;
            }
            Ok(())
        }

        fn require_value(&mut self, fv: &FeatureValue) -> Result<(), RequirementError> {
            match fv {
                FeatureValue::Feature(feat) => self.require_feature(*feat)?,
                FeatureValue::Dep { dep_name } => self.require_dependency(*dep_name),
                FeatureValue::DepFeature {
                    dep_name,
                    dep_feature,
                    // Weak features are always activated in the dependency
                    // resolver. They will be narrowed inside the new feature
                    // resolver.
                    weak,
                } => self.require_dep_feature(*dep_name, *dep_feature, *weak)?,
            };
            Ok(())
        }
    }

    impl RequirementError {
        fn into_activate_error(self, parent: Option<PackageId>, summary: &Summary) -> ActivateError {
            match self {
                RequirementError::MissingFeature(feat) => {
                    let deps: Vec<_> = summary
                        .dependencies()
                        .iter()
                        .filter(|dep| dep.name_in_toml() == feat)
                        .collect();
                    if deps.is_empty() {
                        return match parent {
                            None => ActivateError::Fatal(anyhow::format_err!(
                                "Package `{}` does not have the feature `{}`",
                                summary.package_id(),
                                feat
                            )),
                            Some(p) => {
                                ActivateError::Conflict(p, ConflictReason::MissingFeatures(feat))
                            }
                        };
                    }
                    if deps.iter().any(|dep| dep.is_optional()) {
                        match parent {
                            None => ActivateError::Fatal(anyhow::format_err!(
                                "Package `{}` does not have feature `{}`. It has an optional dependency \
                                 with that name, but that dependency uses the \"dep:\" \
                                 syntax in the features table, so it does not have an implicit feature with that name.",
                                summary.package_id(),
                                feat
                            )),
                            Some(p) => ActivateError::Conflict(
                                p,
                                ConflictReason::NonImplicitDependencyAsFeature(feat),
                            ),
                        }
                    } else {
                        match parent {
                            None => ActivateError::Fatal(anyhow::format_err!(
                                "Package `{}` does not have feature `{}`. It has a required dependency \
                                 with that name, but only optional dependencies can be used as features.",
                                summary.package_id(),
                                feat
                            )),
                            Some(p) => ActivateError::Conflict(
                                p,
                                ConflictReason::RequiredDependencyAsFeature(feat),
                            ),
                        }
                    }
                }
                RequirementError::MissingDependency(dep_name) => {
                    match parent {
                        None => ActivateError::Fatal(anyhow::format_err!(
                            "package `{}` does not have a dependency named `{}`",
                            summary.package_id(),
                            dep_name
                        )),
                        // This code path currently isn't used, since `foo/bar`
                        // and `dep:` syntax is not allowed in a dependency.
                        Some(p) => {
                            ActivateError::Conflict(p, ConflictReason::MissingFeatures(dep_name))
                        }
                    }
                }
                RequirementError::Cycle(feat) => ActivateError::Fatal(anyhow::format_err!(
                    "cyclic feature dependency: feature `{}` depends on itself",
                    feat
                )),
            }
        }
    }