From c7d30a299982178974b18a8088943cdd9f1c256f Mon Sep 17 00:00:00 2001
From: Maksim Denisov <denisov.maksim@huawei.com>
Date: Mon, 26 Aug 2024 14:49:22 +0200
Subject: Store LocalAC keys as ArtifactDigests

---
 CHANGELOG.md                       |  3 +++
 src/buildtool/storage/local_ac.hpp |  5 +++--
 src/buildtool/storage/local_ac.tpp | 24 ++++++++++++++++--------
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c120f104..6cb40fbd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,6 +57,9 @@ A feature release on top of `1.3.0`, backwards compatible.
 - The size of large object entries has been reduced. The cache and
   CAS must be cleaned up since stable versions before `1.4.0` cannot use
   the new format.
+- The way of storing intermediate keys of the action cache has been changed. 
+  The cache must be cleaned up since stable versions before `1.4.0` cannot 
+  use the new format.
 - Various improvements to the tests: dispatching of the summary
   action is now possible, tests are independent of a .just-mrrc
   file the user might have in their home directory
diff --git a/src/buildtool/storage/local_ac.hpp b/src/buildtool/storage/local_ac.hpp
index cb4aa171..a93130a5 100644
--- a/src/buildtool/storage/local_ac.hpp
+++ b/src/buildtool/storage/local_ac.hpp
@@ -20,6 +20,7 @@
 #include <string>
 
 #include "gsl/gsl"
+#include "src/buildtool/common/artifact_digest.hpp"
 #include "src/buildtool/file_system/file_storage.hpp"
 #include "src/buildtool/file_system/file_system_manager.hpp"
 #include "src/buildtool/file_system/object_type.hpp"
@@ -104,8 +105,8 @@ class LocalAC {
     /// \param cas_key The key pointing at an ActionResult in the LocalCAS.
     /// \return True if an entry was successfully added to the storage.
     [[nodiscard]] auto WriteActionKey(
-        bazel_re::Digest const& action_id,
-        bazel_re::Digest const& cas_key) const noexcept -> bool;
+        ArtifactDigest const& action_id,
+        ArtifactDigest const& cas_key) const noexcept -> bool;
 
     /// \brief Get the key pointing at an ActionResult in the LocalCAS.
     /// \param action_id The id of the action that produced the result.
diff --git a/src/buildtool/storage/local_ac.tpp b/src/buildtool/storage/local_ac.tpp
index 835027ac..5fee10ff 100644
--- a/src/buildtool/storage/local_ac.tpp
+++ b/src/buildtool/storage/local_ac.tpp
@@ -19,6 +19,7 @@
 #include <utility>  // std::move
 
 #include "fmt/core.h"
+#include "nlohmann/json.hpp"
 #include "src/buildtool/common/bazel_types.hpp"
 #include "src/buildtool/logging/log_level.hpp"
 #include "src/buildtool/storage/local_ac.hpp"
@@ -28,7 +29,9 @@ auto LocalAC<kDoGlobalUplink>::StoreResult(
     bazel_re::Digest const& action_id,
     bazel_re::ActionResult const& result) const noexcept -> bool {
     auto const cas_key = WriteAction(result);
-    return cas_key.has_value() and WriteActionKey(action_id, *cas_key);
+    return cas_key.has_value() and
+           WriteActionKey(static_cast<ArtifactDigest>(action_id),
+                          static_cast<ArtifactDigest>(*cas_key));
 }
 
 template <bool kDoGlobalUplink>
@@ -117,10 +120,10 @@ requires(kIsLocalGeneration) auto LocalAC<kDoGlobalUplink>::LocalUplinkEntry(
 
 template <bool kDoGlobalUplink>
 auto LocalAC<kDoGlobalUplink>::WriteActionKey(
-    bazel_re::Digest const& action_id,
-    bazel_re::Digest const& cas_key) const noexcept -> bool {
-    return file_store_.AddFromBytes(NativeSupport::Unprefix(action_id.hash()),
-                                    cas_key.SerializeAsString());
+    ArtifactDigest const& action_id,
+    ArtifactDigest const& cas_key) const noexcept -> bool {
+    nlohmann::json const content = {cas_key.hash(), cas_key.size()};
+    return file_store_.AddFromBytes(action_id.hash(), content.dump());
 }
 
 template <bool kDoGlobalUplink>
@@ -141,13 +144,18 @@ auto LocalAC<kDoGlobalUplink>::ReadActionKey(bazel_re::Digest const& action_id)
             fmt::format("Cache miss, entry not found {}", key_path.string())};
     }
 
-    bazel_re::Digest action_key{};
-    if (not action_key.ParseFromString(*key_content)) {
+    std::optional<bazel_re::Digest> action_key;
+    try {
+        nlohmann::json j = nlohmann::json::parse(*key_content);
+        action_key = ArtifactDigest{j[0].template get<std::string>(),
+                                    j[1].template get<std::size_t>(),
+                                    /*is_tree=*/false};
+    } catch (...) {
         return unexpected{
             fmt::format("Parsing cache entry failed for action {}",
                         NativeSupport::Unprefix(action_id.hash()))};
     }
-    return std::move(action_key);
+    return *std::move(action_key);
 }
 
 template <bool kDoGlobalUplink>
-- 
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