Refactor target cache key and entry to separate files and targets

11 files changed, 368 insertions, 209 deletions

diff --git a/src/buildtool/build_engine/target_map/TARGETS b/src/buildtool/build_engine/target_map/TARGETS
index f7bd8cb3..ee65b3e3 100644
--- a/src/buildtool/build_engine/target_map/TARGETS
+++ b/src/buildtool/build_engine/target_map/TARGETS
@@ -52,6 +52,7 @@
   , "stage": ["src", "buildtool", "build_engine", "target_map"]
   , "private-deps":
     [ "target_cache"
+    , "target_cache_key"
     , ["src/buildtool/common", "common"]
     , ["src/buildtool/build_engine/base_maps", "entity_name"]
     , ["src/buildtool/build_engine/base_maps", "field_reader"]
@@ -85,18 +86,62 @@
   , "hdrs": ["target_cache.hpp"]
   , "srcs": ["target_cache.cpp"]
   , "deps":
-    [ ["src/buildtool/build_engine/analysed_target", "target"]
-    , ["src/buildtool/build_engine/base_maps", "entity_name"]
+    [ "target_cache_key"
+    , "target_cache_entry"
+    , ["@", "gsl-lite", "", "gsl-lite"]
+    , ["@", "json", "", "json"]
+    , ["src/buildtool/common", "common"]
     , ["src/buildtool/execution_api/local", "local"]
+    , ["src/buildtool/file_system", "object_type"]
     , ["src/buildtool/logging", "logging"]
-    , ["src/buildtool/common", "common"]
     , ["src/buildtool/execution_api/common", "common"]
+    ]
+  , "stage": ["src", "buildtool", "build_engine", "target_map"]
+  , "private-deps":
+    [ ["@", "fmt", "", "fmt"]
+    , ["src/buildtool/compatibility", "compatibility"]
+    , ["src/buildtool/execution_api/local", "config"]
+    , ["src/buildtool/execution_api/remote", "config"]
     , ["src/buildtool/file_system", "file_system_manager"]
+    , ["src/buildtool/logging", "log_level"]
+    ]
+  }
+, "target_cache_key":
+  { "type": ["@", "rules", "CC", "library"]
+  , "name": ["target_cache_key"]
+  , "hdrs": ["target_cache_key.hpp"]
+  , "srcs": ["target_cache_key.cpp"]
+  , "deps":
+    [ ["src/buildtool/build_engine/base_maps", "entity_name_data"]
+    , ["src/buildtool/build_engine/expression", "expression"]
+    , ["src/buildtool/common", "common"]
+    ]
+  , "stage": ["src", "buildtool", "build_engine", "target_map"]
+  , "private-deps":
+    [ ["src/buildtool/common", "config"]
+    , ["src/buildtool/execution_api/local", "local"]
+    , ["src/buildtool/file_system", "object_type"]
+    , ["src/buildtool/logging", "logging"]
+    , ["src/buildtool/logging", "log_level"]
+    ]
+  }
+, "target_cache_entry":
+  { "type": ["@", "rules", "CC", "library"]
+  , "name": ["target_cache_entry"]
+  , "hdrs": ["target_cache_entry.hpp"]
+  , "srcs": ["target_cache_entry.cpp"]
+  , "deps":
+    [ ["@", "gsl-lite", "", "gsl-lite"]
+    , ["@", "json", "", "json"]
+    , ["src/buildtool/build_engine/analysed_target", "target"]
+    , ["src/buildtool/build_engine/expression", "expression"]
+    , ["src/buildtool/common", "common"]
+    , ["src/buildtool/common", "artifact_description"]
     ]
   , "stage": ["src", "buildtool", "build_engine", "target_map"]
   , "private-deps":
-    [ ["src/buildtool/execution_api/remote", "config"]
-    , ["src/buildtool/file_system", "file_root"]
+    [ ["src/buildtool/logging", "logging"]
+    , ["src/buildtool/logging", "log_level"]
     ]
   }
 }
diff --git a/src/buildtool/build_engine/target_map/export.cpp b/src/buildtool/build_engine/target_map/export.cpp
index 657ca73b..7a53e78e 100644
--- a/src/buildtool/build_engine/target_map/export.cpp
+++ b/src/buildtool/build_engine/target_map/export.cpp
@@ -19,6 +19,7 @@
 #include "src/buildtool/build_engine/base_maps/field_reader.hpp"
 #include "src/buildtool/build_engine/expression/configuration.hpp"
 #include "src/buildtool/build_engine/target_map/target_cache.hpp"
+#include "src/buildtool/build_engine/target_map/target_cache_key.hpp"
 #include "src/buildtool/common/statistics.hpp"
 #include "src/buildtool/execution_api/local/local_cas.hpp"
 
@@ -35,7 +36,7 @@ void FinalizeExport(
     const BuildMaps::Base::EntityName& target,
     const std::vector<std::string>& vars,
     const Configuration& effective_config,
-    const std::optional<TargetCache::Key>& target_cache_key,
+    const std::optional<TargetCacheKey>& target_cache_key,
     const BuildMaps::Target::TargetMap::LoggerPtr& logger,
     const BuildMaps::Target::TargetMap::SetterPtr& setter,
     const gsl::not_null<BuildMaps::Target::ResultTargetMap*>& result_map) {
@@ -129,7 +130,7 @@ void ExportRule(
     auto target_config = effective_config.Update(fixed_config);
 
     auto target_cache_key =
-        TargetCache::Key::Create(*exported_target, target_config);
+        TargetCacheKey::Create(*exported_target, target_config);
     if (target_cache_key) {
         if (auto target_cache_value =
                 TargetCache::Instance().Read(*target_cache_key)) {
diff --git a/src/buildtool/build_engine/target_map/result_map.hpp b/src/buildtool/build_engine/target_map/result_map.hpp
index 700cf7bb..edb1a472 100644
--- a/src/buildtool/build_engine/target_map/result_map.hpp
+++ b/src/buildtool/build_engine/target_map/result_map.hpp
@@ -31,6 +31,7 @@
 #include "src/buildtool/build_engine/expression/expression.hpp"
 #include "src/buildtool/build_engine/target_map/configured_target.hpp"
 #include "src/buildtool/build_engine/target_map/target_cache.hpp"
+#include "src/buildtool/build_engine/target_map/target_cache_key.hpp"
 #include "src/buildtool/common/statistics.hpp"
 #include "src/buildtool/common/tree.hpp"
 #include "src/buildtool/logging/logger.hpp"
@@ -68,7 +69,7 @@ class ResultTargetMap {
         BuildMaps::Base::EntityName name,
         Configuration conf,
         gsl::not_null<AnalysedTargetPtr> result,
-        std::optional<TargetCache::Key> target_cache_key = std::nullopt,
+        std::optional<TargetCacheKey> target_cache_key = std::nullopt,
         bool is_export_target = false) -> AnalysedTargetPtr {
         auto part = std::hash<BuildMaps::Base::EntityName>{}(name) % width_;
         std::unique_lock lock{m_[part]};
@@ -142,11 +143,11 @@ class ResultTargetMap {
     }
 
     [[nodiscard]] auto CacheTargets() const noexcept
-        -> std::unordered_map<TargetCache::Key, AnalysedTargetPtr> {
+        -> std::unordered_map<TargetCacheKey, AnalysedTargetPtr> {
         return std::accumulate(
             cache_targets_.begin(),
             cache_targets_.end(),
-            std::unordered_map<TargetCache::Key, AnalysedTargetPtr>{},
+            std::unordered_map<TargetCacheKey, AnalysedTargetPtr>{},
             [](auto&& l, auto const& r) {
                 l.insert(r.begin(), r.end());
                 return std::forward<decltype(l)>(l);
@@ -361,7 +362,7 @@ class ResultTargetMap {
         std::unordered_map<ConfiguredTarget, gsl::not_null<AnalysedTargetPtr>>>
         targets_{width_};
     std::vector<
-        std::unordered_map<TargetCache::Key, gsl::not_null<AnalysedTargetPtr>>>
+        std::unordered_map<TargetCacheKey, gsl::not_null<AnalysedTargetPtr>>>
         cache_targets_{width_};
     std::vector<std::unordered_set<ConfiguredTarget>> export_targets_{width_};
     std::vector<std::size_t> num_actions_{std::vector<std::size_t>(width_)};
diff --git a/src/buildtool/build_engine/target_map/target_cache.cpp b/src/buildtool/build_engine/target_map/target_cache.cpp
index b2f3b209..727b7404 100644
--- a/src/buildtool/build_engine/target_map/target_cache.cpp
+++ b/src/buildtool/build_engine/target_map/target_cache.cpp
@@ -14,123 +14,20 @@
 
 #include "src/buildtool/build_engine/target_map/target_cache.hpp"
 
-#include <gsl-lite/gsl-lite.hpp>
+#include <exception>
+#include <vector>
 
-#include "src/buildtool/common/repository_config.hpp"
+#include <fmt/core.h>
+
+#include "src/buildtool/common/artifact_digest.hpp"
+#include "src/buildtool/compatibility/native_support.hpp"
 #include "src/buildtool/execution_api/local/config.hpp"
-#include "src/buildtool/execution_api/local/file_storage.hpp"
-#include "src/buildtool/execution_api/local/local_cas.hpp"
 #include "src/buildtool/execution_api/remote/config.hpp"
 #include "src/buildtool/file_system/file_system_manager.hpp"
-#include "src/buildtool/logging/logger.hpp"
-
-auto TargetCache::Key::Create(BuildMaps::Base::EntityName const& target,
-                              Configuration const& effective_config) noexcept
-    -> std::optional<TargetCache::Key> {
-    static auto const& repos = RepositoryConfig::Instance();
-    try {
-        if (auto repo_key =
-                repos.RepositoryKey(target.GetNamedTarget().repository)) {
-            // target's repository is content-fixed, we can compute a cache key
-            auto const& name = target.GetNamedTarget();
-            auto target_desc = nlohmann::json{
-                {{"repo_key", *repo_key},
-                 {"target_name", nlohmann::json{name.module, name.name}.dump()},
-                 {"effective_config", effective_config.ToString()}}};
-            static auto const& cas = LocalCAS<ObjectType::File>::Instance();
-            if (auto target_key = cas.StoreBlobFromBytes(target_desc.dump(2))) {
-                return Key{{ArtifactDigest{*target_key}, ObjectType::File}};
-            }
-        }
-    } catch (std::exception const& ex) {
-        Logger::Log(LogLevel::Error,
-                    "Creating target cache key failed with:\n{}",
-                    ex.what());
-    }
-    return std::nullopt;
-}
-
-auto TargetCache::Entry::FromTarget(
-    AnalysedTargetPtr const& target,
-    std::unordered_map<ArtifactDescription, Artifact::ObjectInfo> const&
-        replacements) noexcept -> std::optional<TargetCache::Entry> {
-    auto result = TargetResult{
-        target->Artifacts(), target->Provides(), target->RunFiles()};
-    if (auto desc = result.ReplaceNonKnownAndToJson(replacements)) {
-        return Entry{*desc};
-    }
-    return std::nullopt;
-}
-
-auto TargetCache::Entry::ToResult() const noexcept
-    -> std::optional<TargetResult> {
-    return TargetResult::FromJson(desc_);
-}
-
-[[nodiscard]] auto ToObjectInfo(nlohmann::json const& json)
-    -> Artifact::ObjectInfo {
-    auto const& desc = ArtifactDescription::FromJson(json);
-    // The assumption is that all artifacts mentioned in a target cache
-    // entry are KNOWN to the remote side.
-    gsl_ExpectsAudit(desc and desc->IsKnown());
-    auto const& info = desc->ToArtifact().Info();
-    gsl_ExpectsAudit(info);
-    return *info;
-}
-
-[[nodiscard]] auto ScanArtifactMap(
-    gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos,
-    nlohmann::json const& json) -> bool {
-    if (not json.is_object()) {
-        return false;
-    }
-    infos->reserve(infos->size() + json.size());
-    std::transform(json.begin(),
-                   json.end(),
-                   std::back_inserter(*infos),
-                   [](auto const& item) { return ToObjectInfo(item); });
-    return true;
-}
-
-[[nodiscard]] auto ScanProvidesMap(
-    gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos,
-    nlohmann::json const& json) -> bool {
-    if (not json.is_object()) {
-        return false;
-    }
-    auto const& nodes = json["nodes"];
-    auto const& provided_artifacts = json["provided_artifacts"];
-    infos->reserve(infos->size() + provided_artifacts.size());
-    std::transform(
-        provided_artifacts.begin(),
-        provided_artifacts.end(),
-        std::back_inserter(*infos),
-        [&nodes](auto const& item) {
-            return ToObjectInfo(nodes[item.template get<std::string>()]);
-        });
-    return true;
-}
-
-auto TargetCache::Entry::ToArtifacts(
-    gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos)
-    const noexcept -> bool {
-    try {
-        if (ScanArtifactMap(infos, desc_["artifacts"]) and
-            ScanArtifactMap(infos, desc_["runfiles"]) and
-            ScanProvidesMap(infos, desc_["provides"])) {
-            return true;
-        }
-    } catch (std::exception const& ex) {
-        Logger::Log(
-            LogLevel::Error,
-            "Scanning target cache entry for artifacts failed with:\n{}",
-            ex.what());
-    }
-    return false;
-}
+#include "src/buildtool/logging/log_level.hpp"
 
-auto TargetCache::Store(Key const& key, Entry const& value) const noexcept
-    -> bool {
+auto TargetCache::Store(TargetCacheKey const& key,
+                        TargetCacheEntry const& value) const noexcept -> bool {
     // Before a target-cache entry is stored in local CAS, make sure any created
     // artifact for this target is downloaded from the remote CAS to the local
     // CAS.
@@ -150,8 +47,8 @@ auto TargetCache::Store(Key const& key, Entry const& value) const noexcept
     return false;
 }
 
-auto TargetCache::Read(Key const& key) const noexcept
-    -> std::optional<std::pair<Entry, Artifact::ObjectInfo>> {
+auto TargetCache::Read(TargetCacheKey const& key) const noexcept
+    -> std::optional<std::pair<TargetCacheEntry, Artifact::ObjectInfo>> {
     auto entry_path = file_store_.GetPath(key.Id().digest.hash());
     auto const entry =
         FileSystemManager::ReadFile(entry_path, ObjectType::File);
@@ -165,8 +62,9 @@ auto TargetCache::Read(Key const& key) const noexcept
         if (auto path = CAS().BlobPath(info->digest)) {
             if (auto value = FileSystemManager::ReadFile(*path)) {
                 try {
-                    return std::make_pair(Entry{nlohmann::json::parse(*value)},
-                                          std::move(*info));
+                    return std::make_pair(
+                        TargetCacheEntry{nlohmann::json::parse(*value)},
+                        std::move(*info));
                 } catch (std::exception const& ex) {
                     logger_.Emit(LogLevel::Warning,
                                  "Parsing entry for key {} failed with:\n{}",
@@ -182,8 +80,8 @@ auto TargetCache::Read(Key const& key) const noexcept
     return std::nullopt;
 }
 
-auto TargetCache::DownloadKnownArtifacts(Entry const& value) const noexcept
-    -> bool {
+auto TargetCache::DownloadKnownArtifacts(
+    TargetCacheEntry const& value) const noexcept -> bool {
     std::vector<Artifact::ObjectInfo> artifacts_info;
     if (not value.ToArtifacts(&artifacts_info)) {
         return false;
diff --git a/src/buildtool/build_engine/target_map/target_cache.hpp b/src/buildtool/build_engine/target_map/target_cache.hpp
index fe32d3dd..b6b54ce0 100644
--- a/src/buildtool/build_engine/target_map/target_cache.hpp
+++ b/src/buildtool/build_engine/target_map/target_cache.hpp
@@ -15,80 +15,28 @@
 #ifndef INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_HPP
 #define INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_HPP
 
-#include <unordered_map>
+#include <filesystem>
+#include <functional>
+#include <optional>
+#include <string>
+#include <utility>
 
+#include <gsl-lite/gsl-lite.hpp>
 #include <nlohmann/json.hpp>
 
-#include "src/buildtool/build_engine/analysed_target/analysed_target.hpp"
-#include "src/buildtool/build_engine/base_maps/entity_name.hpp"
+#include "src/buildtool/build_engine/target_map/target_cache_entry.hpp"
+#include "src/buildtool/build_engine/target_map/target_cache_key.hpp"
 #include "src/buildtool/common/artifact.hpp"
-#ifndef BOOTSTRAP_BUILD_TOOL
-#include "src/buildtool/execution_api/common/execution_api.hpp"
-#endif
 #include "src/buildtool/execution_api/local/file_storage.hpp"
 #include "src/buildtool/execution_api/local/local_cas.hpp"
-#include "src/buildtool/file_system/file_system_manager.hpp"
+#include "src/buildtool/file_system/object_type.hpp"
 #include "src/buildtool/logging/logger.hpp"
+#ifndef BOOTSTRAP_BUILD_TOOL
+#include "src/buildtool/execution_api/common/execution_api.hpp"
+#endif
 
 class TargetCache {
   public:
-    // Key for target cache. Created from target name and effective config.
-    class Key {
-      public:
-        [[nodiscard]] static auto Create(
-            BuildMaps::Base::EntityName const& target,
-            Configuration const& effective_config) noexcept
-            -> std::optional<Key>;
-
-        [[nodiscard]] auto Id() const& -> Artifact::ObjectInfo const& {
-            return id_;
-        }
-        [[nodiscard]] auto Id() && -> Artifact::ObjectInfo {
-            return std::move(id_);
-        }
-        [[nodiscard]] auto operator==(Key const& other) const -> bool {
-            return this->Id() == other.Id();
-        }
-
-      private:
-        explicit Key(Artifact::ObjectInfo id) : id_{std::move(id)} {}
-        Artifact::ObjectInfo id_;
-    };
-
-    // Entry for target cache. Created from target, contains TargetResult.
-    class Entry {
-        friend class TargetCache;
-
-      public:
-        // Create the entry from target with replacement artifacts/infos.
-        // Replacement artifacts must replace all non-known artifacts by known.
-        [[nodiscard]] static auto FromTarget(
-            AnalysedTargetPtr const& target,
-            std::unordered_map<ArtifactDescription, Artifact::ObjectInfo> const&
-                replacements) noexcept -> std::optional<Entry>;
-
-        // Obtain TargetResult from cache entry.
-        [[nodiscard]] auto ToResult() const noexcept
-            -> std::optional<TargetResult>;
-
-        // Obtain all artifacts from cache entry (all should be known
-        // artifacts).
-        [[nodiscard]] auto ToArtifacts(
-            gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos)
-            const noexcept -> bool;
-
-      private:
-        nlohmann::json desc_;
-
-        explicit Entry(nlohmann::json desc) : desc_(std::move(desc)) {}
-        [[nodiscard]] auto ToJson() const& -> nlohmann::json const& {
-            return desc_;
-        }
-        [[nodiscard]] auto ToJson() && -> nlohmann::json {
-            return std::move(desc_);
-        }
-    };
-
     TargetCache() = default;
     TargetCache(TargetCache const&) = delete;
     TargetCache(TargetCache&&) = delete;
@@ -102,12 +50,13 @@ class TargetCache {
     }
 
     // Store new key entry pair in the target cache.
-    [[nodiscard]] auto Store(Key const& key, Entry const& value) const noexcept
+    [[nodiscard]] auto Store(TargetCacheKey const& key,
+                             TargetCacheEntry const& value) const noexcept
         -> bool;
 
     // Read existing entry and object info for given key from the target cache.
-    [[nodiscard]] auto Read(Key const& key) const noexcept
-        -> std::optional<std::pair<Entry, Artifact::ObjectInfo>>;
+    [[nodiscard]] auto Read(TargetCacheKey const& key) const noexcept
+        -> std::optional<std::pair<TargetCacheEntry, Artifact::ObjectInfo>>;
 
 #ifndef BOOTSTRAP_BUILD_TOOL
     auto SetLocalApi(gsl::not_null<IExecutionApi*> const& api) noexcept
@@ -132,12 +81,8 @@ class TargetCache {
     IExecutionApi* remote_api_{};
 #endif
 
-    [[nodiscard]] auto DownloadKnownArtifacts(Entry const& value) const noexcept
-        -> bool;
-    [[nodiscard]] auto CollectKnownArtifacts(
-        gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos,
-        gsl::not_null<std::unordered_set<std::string>*> const& hashes,
-        ExpressionPtr const& expr) const noexcept -> bool;
+    [[nodiscard]] auto DownloadKnownArtifacts(
+        TargetCacheEntry const& value) const noexcept -> bool;
     [[nodiscard]] static auto CAS() noexcept -> LocalCAS<ObjectType::File>& {
         return LocalCAS<ObjectType::File>::Instance();
     }
@@ -147,8 +92,8 @@ class TargetCache {
 
 namespace std {
 template <>
-struct hash<TargetCache::Key> {
-    [[nodiscard]] auto operator()(TargetCache::Key const& k) const {
+struct hash<TargetCacheKey> {
+    [[nodiscard]] auto operator()(TargetCacheKey const& k) const {
         return std::hash<Artifact::ObjectInfo>{}(k.Id());
     }
 };
diff --git a/src/buildtool/build_engine/target_map/target_cache_entry.cpp b/src/buildtool/build_engine/target_map/target_cache_entry.cpp
new file mode 100644
index 00000000..45815056
--- /dev/null
+++ b/src/buildtool/build_engine/target_map/target_cache_entry.cpp
@@ -0,0 +1,101 @@
+// Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/buildtool/build_engine/target_map/target_cache_entry.hpp"
+
+#include <algorithm>
+#include <exception>
+#include <iterator>
+
+#include "src/buildtool/logging/log_level.hpp"
+#include "src/buildtool/logging/logger.hpp"
+
+auto TargetCacheEntry::FromTarget(
+    AnalysedTargetPtr const& target,
+    std::unordered_map<ArtifactDescription, Artifact::ObjectInfo> const&
+        replacements) noexcept -> std::optional<TargetCacheEntry> {
+    auto result = TargetResult{
+        target->Artifacts(), target->Provides(), target->RunFiles()};
+    if (auto desc = result.ReplaceNonKnownAndToJson(replacements)) {
+        return TargetCacheEntry{*desc};
+    }
+    return std::nullopt;
+}
+
+auto TargetCacheEntry::ToResult() const noexcept
+    -> std::optional<TargetResult> {
+    return TargetResult::FromJson(desc_);
+}
+
+[[nodiscard]] auto ToObjectInfo(nlohmann::json const& json)
+    -> Artifact::ObjectInfo {
+    auto const& desc = ArtifactDescription::FromJson(json);
+    // The assumption is that all artifacts mentioned in a target cache
+    // entry are KNOWN to the remote side.
+    gsl_ExpectsAudit(desc and desc->IsKnown());
+    auto const& info = desc->ToArtifact().Info();
+    gsl_ExpectsAudit(info);
+    return *info;
+}
+
+[[nodiscard]] auto ScanArtifactMap(
+    gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos,
+    nlohmann::json const& json) -> bool {
+    if (not json.is_object()) {
+        return false;
+    }
+    infos->reserve(infos->size() + json.size());
+    std::transform(json.begin(),
+                   json.end(),
+                   std::back_inserter(*infos),
+                   [](auto const& item) { return ToObjectInfo(item); });
+    return true;
+}
+
+[[nodiscard]] auto ScanProvidesMap(
+    gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos,
+    nlohmann::json const& json) -> bool {
+    if (not json.is_object()) {
+        return false;
+    }
+    auto const& nodes = json["nodes"];
+    auto const& provided_artifacts = json["provided_artifacts"];
+    infos->reserve(infos->size() + provided_artifacts.size());
+    std::transform(
+        provided_artifacts.begin(),
+        provided_artifacts.end(),
+        std::back_inserter(*infos),
+        [&nodes](auto const& item) {
+            return ToObjectInfo(nodes[item.template get<std::string>()]);
+        });
+    return true;
+}
+
+auto TargetCacheEntry::ToArtifacts(
+    gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos)
+    const noexcept -> bool {
+    try {
+        if (ScanArtifactMap(infos, desc_["artifacts"]) and
+            ScanArtifactMap(infos, desc_["runfiles"]) and
+            ScanProvidesMap(infos, desc_["provides"])) {
+            return true;
+        }
+    } catch (std::exception const& ex) {
+        Logger::Log(
+            LogLevel::Error,
+            "Scanning target cache entry for artifacts failed with:\n{}",
+            ex.what());
+    }
+    return false;
+}
diff --git a/src/buildtool/build_engine/target_map/target_cache_entry.hpp b/src/buildtool/build_engine/target_map/target_cache_entry.hpp
new file mode 100644
index 00000000..b6d1351c
--- /dev/null
+++ b/src/buildtool/build_engine/target_map/target_cache_entry.hpp
@@ -0,0 +1,64 @@
+// Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_ENTRY_HPP
+#define INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_ENTRY_HPP
+
+#include <optional>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+#include <gsl-lite/gsl-lite.hpp>
+#include <nlohmann/json.hpp>
+
+#include "src/buildtool/build_engine/analysed_target/analysed_target.hpp"
+#include "src/buildtool/build_engine/expression/target_result.hpp"
+#include "src/buildtool/common/artifact.hpp"
+#include "src/buildtool/common/artifact_description.hpp"
+
+// Entry for target cache. Created from target, contains TargetResult.
+class TargetCacheEntry {
+    friend class TargetCache;
+
+  public:
+    // Create the entry from target with replacement artifacts/infos.
+    // Replacement artifacts must replace all non-known artifacts by known.
+    [[nodiscard]] static auto FromTarget(
+        AnalysedTargetPtr const& target,
+        std::unordered_map<ArtifactDescription, Artifact::ObjectInfo> const&
+            replacements) noexcept -> std::optional<TargetCacheEntry>;
+
+    // Obtain TargetResult from cache entry.
+    [[nodiscard]] auto ToResult() const noexcept -> std::optional<TargetResult>;
+
+    // Obtain all artifacts from cache entry (all should be known
+    // artifacts).
+    [[nodiscard]] auto ToArtifacts(
+        gsl::not_null<std::vector<Artifact::ObjectInfo>*> const& infos)
+        const noexcept -> bool;
+
+  private:
+    nlohmann::json desc_;
+
+    explicit TargetCacheEntry(nlohmann::json desc) : desc_(std::move(desc)) {}
+    [[nodiscard]] auto ToJson() const& -> nlohmann::json const& {
+        return desc_;
+    }
+    [[nodiscard]] auto ToJson() && -> nlohmann::json {
+        return std::move(desc_);
+    }
+};
+
+#endif  // INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_ENTRY_HPP
diff --git a/src/buildtool/build_engine/target_map/target_cache_key.cpp b/src/buildtool/build_engine/target_map/target_cache_key.cpp
new file mode 100644
index 00000000..1ee6a7ef
--- /dev/null
+++ b/src/buildtool/build_engine/target_map/target_cache_key.cpp
@@ -0,0 +1,53 @@
+// Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/buildtool/build_engine/target_map/target_cache_key.hpp"
+
+#include <exception>
+
+#include <nlohmann/json.hpp>
+
+#include "src/buildtool/common/artifact_digest.hpp"
+#include "src/buildtool/common/repository_config.hpp"
+#include "src/buildtool/execution_api/local/local_cas.hpp"
+#include "src/buildtool/file_system/object_type.hpp"
+#include "src/buildtool/logging/log_level.hpp"
+#include "src/buildtool/logging/logger.hpp"
+
+auto TargetCacheKey::Create(BuildMaps::Base::EntityName const& target,
+                            Configuration const& effective_config) noexcept
+    -> std::optional<TargetCacheKey> {
+    static auto const& repos = RepositoryConfig::Instance();
+    try {
+        if (auto repo_key =
+                repos.RepositoryKey(target.GetNamedTarget().repository)) {
+            // target's repository is content-fixed, we can compute a cache key
+            auto const& name = target.GetNamedTarget();
+            auto target_desc = nlohmann::json{
+                {{"repo_key", *repo_key},
+                 {"target_name", nlohmann::json{name.module, name.name}.dump()},
+                 {"effective_config", effective_config.ToString()}}};
+            static auto const& cas = LocalCAS<ObjectType::File>::Instance();
+            if (auto target_key = cas.StoreBlobFromBytes(target_desc.dump(2))) {
+                return TargetCacheKey{
+                    {ArtifactDigest{*target_key}, ObjectType::File}};
+            }
+        }
+    } catch (std::exception const& ex) {
+        Logger::Log(LogLevel::Error,
+                    "Creating target cache key failed with:\n{}",
+                    ex.what());
+    }
+    return std::nullopt;
+}
diff --git a/src/buildtool/build_engine/target_map/target_cache_key.hpp b/src/buildtool/build_engine/target_map/target_cache_key.hpp
new file mode 100644
index 00000000..bc648135
--- /dev/null
+++ b/src/buildtool/build_engine/target_map/target_cache_key.hpp
@@ -0,0 +1,48 @@
+// Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_KEY_HPP
+#define INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_KEY_HPP
+
+#include <optional>
+#include <utility>
+
+#include "src/buildtool/build_engine/base_maps/entity_name_data.hpp"
+#include "src/buildtool/build_engine/expression/configuration.hpp"
+#include "src/buildtool/common/artifact.hpp"
+
+// Key for target cache. Created from target name and effective config.
+class TargetCacheKey {
+  public:
+    [[nodiscard]] static auto Create(
+        BuildMaps::Base::EntityName const& target,
+        Configuration const& effective_config) noexcept
+        -> std::optional<TargetCacheKey>;
+
+    [[nodiscard]] auto Id() const& -> Artifact::ObjectInfo const& {
+        return id_;
+    }
+    [[nodiscard]] auto Id() && -> Artifact::ObjectInfo {
+        return std::move(id_);
+    }
+    [[nodiscard]] auto operator==(TargetCacheKey const& other) const -> bool {
+        return this->Id() == other.Id();
+    }
+
+  private:
+    explicit TargetCacheKey(Artifact::ObjectInfo id) : id_{std::move(id)} {}
+    Artifact::ObjectInfo id_;
+};
+
+#endif  // INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_TARGET_MAP_TARGET_CACHE_KEY_HPP
diff --git a/src/buildtool/main/TARGETS b/src/buildtool/main/TARGETS
index 70e361a2..d139d1d8 100644
--- a/src/buildtool/main/TARGETS
+++ b/src/buildtool/main/TARGETS
@@ -12,6 +12,8 @@
     , ["src/buildtool/progress_reporting", "base_progress_reporter"]
     , ["src/buildtool/build_engine/target_map", "result_map"]
     , ["src/buildtool/build_engine/target_map", "target_cache"]
+    , ["src/buildtool/build_engine/target_map", "target_cache_key"]
+    , ["src/buildtool/build_engine/target_map", "target_cache_entry"]
     , ["src/buildtool/build_engine/target_map", "target_map"]
     , ["src/buildtool/multithreading", "task_system"]
     , ["src/utils/cpp", "concepts"]
diff --git a/src/buildtool/main/main.cpp b/src/buildtool/main/main.cpp
index cf98bcf3..5bb707f5 100644
--- a/src/buildtool/main/main.cpp
+++ b/src/buildtool/main/main.cpp
@@ -25,6 +25,8 @@
 #include "src/buildtool/build_engine/expression/evaluator.hpp"
 #include "src/buildtool/build_engine/expression/expression.hpp"
 #include "src/buildtool/build_engine/target_map/target_cache.hpp"
+#include "src/buildtool/build_engine/target_map/target_cache_entry.hpp"
+#include "src/buildtool/build_engine/target_map/target_cache_key.hpp"
 #include "src/buildtool/build_engine/target_map/target_map.hpp"
 #include "src/buildtool/common/artifact_description.hpp"
 #include "src/buildtool/common/cli.hpp"
@@ -1073,8 +1075,8 @@ void DumpArtifactsToBuild(
 }
 
 auto CollectNonKnownArtifacts(
-    std::unordered_map<TargetCache::Key, AnalysedTargetPtr> const&
-        cache_targets) -> std::vector<ArtifactDescription> {
+    std::unordered_map<TargetCacheKey, AnalysedTargetPtr> const& cache_targets)
+    -> std::vector<ArtifactDescription> {
     auto cache_artifacts = std::unordered_set<ArtifactDescription>{};
     for (auto const& [_, target] : cache_targets) {
         auto artifacts = target->ContainedNonKnownArtifacts();
@@ -1087,8 +1089,7 @@ auto CollectNonKnownArtifacts(
 
 #ifndef BOOTSTRAP_BUILD_TOOL
 void WriteTargetCacheEntries(
-    std::unordered_map<TargetCache::Key, AnalysedTargetPtr> const&
-        cache_targets,
+    std::unordered_map<TargetCacheKey, AnalysedTargetPtr> const& cache_targets,
     std::unordered_map<ArtifactDescription, Artifact::ObjectInfo> const&
         extra_infos,
     std::size_t jobs,
@@ -1100,7 +1101,7 @@ void WriteTargetCacheEntries(
     for (auto const& [key, target] : cache_targets) {
         ts.QueueTask([&key = key, &target = target, &extra_infos]() {
             if (auto entry =
-                    TargetCache::Entry::FromTarget(target, extra_infos)) {
+                    TargetCacheEntry::FromTarget(target, extra_infos)) {
                 if (not TargetCache::Instance().Store(key, *entry)) {
                     Logger::Log(LogLevel::Warning,
                                 "Failed writing target cache entry for {}",