From 2d0e0b73b777e5e0940a1ec241635aeb651c23f2 Mon Sep 17 00:00:00 2001
From: Klaus Aehlig <klaus.aehlig@huawei.com>
Date: Tue, 3 Dec 2024 12:40:04 +0100
Subject: Cache lookup: support rehash function

---
 src/buildtool/computed_roots/TARGETS          |  1 +
 src/buildtool/computed_roots/lookup_cache.cpp | 16 +++-------------
 src/buildtool/computed_roots/lookup_cache.hpp | 11 +++++++----
 3 files changed, 11 insertions(+), 17 deletions(-)

(limited to 'src')

diff --git a/src/buildtool/computed_roots/TARGETS b/src/buildtool/computed_roots/TARGETS
index e1d9bd79..4ff979b0 100644
--- a/src/buildtool/computed_roots/TARGETS
+++ b/src/buildtool/computed_roots/TARGETS
@@ -72,6 +72,7 @@
     , ["src/buildtool/common", "cli"]
     , ["src/buildtool/common", "common"]
     , ["src/buildtool/crypto", "hash_function"]
+    , ["src/buildtool/execution_api/utils", "rehash_utils"]
     , ["src/buildtool/file_system", "file_root"]
     , ["src/buildtool/file_system", "file_system_manager"]
     , ["src/buildtool/file_system", "git_cas"]
diff --git a/src/buildtool/computed_roots/lookup_cache.cpp b/src/buildtool/computed_roots/lookup_cache.cpp
index 000cdbee..0555c74b 100644
--- a/src/buildtool/computed_roots/lookup_cache.cpp
+++ b/src/buildtool/computed_roots/lookup_cache.cpp
@@ -27,7 +27,6 @@
 #include "src/buildtool/build_engine/expression/configuration.hpp"
 #include "src/buildtool/build_engine/expression/target_result.hpp"
 #include "src/buildtool/computed_roots/artifacts_root.hpp"
-#include "src/buildtool/crypto/hash_function.hpp"
 #include "src/buildtool/file_system/file_root.hpp"
 #include "src/buildtool/multithreading/task_system.hpp"
 #include "src/buildtool/storage/target_cache_entry.hpp"
@@ -36,7 +35,8 @@
 auto LookupCache(BuildMaps::Target::ConfiguredTarget const& ctarget,
                  gsl::not_null<RepositoryConfig*> const& repository_config,
                  Storage const& storage,
-                 AsyncMapConsumerLoggerPtr const& logger)
+                 AsyncMapConsumerLoggerPtr const& logger,
+                 std::optional<RehashUtils::Rehasher> const& rehash)
     -> expected<std::optional<std::string>, std::monostate> {
     auto const* target_root =
         repository_config->TargetRoot(ctarget.target.ToModule().repository);
@@ -102,16 +102,6 @@ auto LookupCache(BuildMaps::Target::ConfiguredTarget const& ctarget,
     if (not flexible_vars) {
         return unexpected(std::monostate{});
     }
-    // TODO(aehlig): Support re-hashing in case of compatible mode, so that
-    // cache lookups can be used in this case as well.
-    if (storage.GetHashFunction().GetType() != HashFunction::Type::GitSHA1) {
-        // So far, transforming the result of a cache hit in memory into
-        // a git root is only implemented for GitSHA1. Therefore, do not
-        // try to look up cache hits, and simply pretend a non hit.
-        return expected<std::optional<std::string>, std::monostate>(
-            std::nullopt);
-    }
-
     auto effective_config = ctarget.config.Prune(*flexible_vars);
     auto cache_key = storage.TargetCache().ComputeKey(
         *repo_key, ctarget.target.GetNamedTarget(), effective_config);
@@ -141,7 +131,7 @@ auto LookupCache(BuildMaps::Target::ConfiguredTarget const& ctarget,
                             msg),
                 fatal);
         });
-    auto root = ArtifactsRoot(result->artifact_stage, wrapped_logger);
+    auto root = ArtifactsRoot(result->artifact_stage, wrapped_logger, rehash);
     if (not root) {
         return unexpected(std::monostate{});
     }
diff --git a/src/buildtool/computed_roots/lookup_cache.hpp b/src/buildtool/computed_roots/lookup_cache.hpp
index 0f8096d1..a613313e 100644
--- a/src/buildtool/computed_roots/lookup_cache.hpp
+++ b/src/buildtool/computed_roots/lookup_cache.hpp
@@ -22,14 +22,17 @@
 #include "gsl/gsl"
 #include "src/buildtool/build_engine/target_map/configured_target.hpp"
 #include "src/buildtool/common/repository_config.hpp"
+#include "src/buildtool/execution_api/utils/rehash_utils.hpp"
 #include "src/buildtool/multithreading/async_map_consumer.hpp"
 #include "src/buildtool/storage/storage.hpp"
 #include "src/utils/cpp/expected.hpp"
 
-auto LookupCache(BuildMaps::Target::ConfiguredTarget const& ctarget,
-                 gsl::not_null<RepositoryConfig*> const& repository_config,
-                 Storage const& storage,
-                 AsyncMapConsumerLoggerPtr const& logger)
+auto LookupCache(
+    BuildMaps::Target::ConfiguredTarget const& ctarget,
+    gsl::not_null<RepositoryConfig*> const& repository_config,
+    Storage const& storage,
+    AsyncMapConsumerLoggerPtr const& logger,
+    std::optional<RehashUtils::Rehasher> const& rehash = std::nullopt)
     -> expected<std::optional<std::string>, std::monostate>;
 
 #endif
-- 
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