execution_response: Allow failures to be reported while populating

As populating the containers from remote response only takes place
once, no assumptions should be made that this cannot fail (for
example if wrong or invalid entries were produced). Instead, return
error messages on failure to callers that can log accordingly.

1 files changed, 9 insertions, 3 deletions

diff --git a/src/buildtool/execution_api/remote/bazel/bazel_response.hpp b/src/buildtool/execution_api/remote/bazel/bazel_response.hpp
index 6e37d344..ec3e9748 100644
--- a/src/buildtool/execution_api/remote/bazel/bazel_response.hpp
+++ b/src/buildtool/execution_api/remote/bazel/bazel_response.hpp
@@ -20,9 +20,11 @@
 #include <utility>  // std::move
 #include <vector>
 
+#include "gsl/gsl"
 #include "src/buildtool/execution_api/common/execution_api.hpp"
 #include "src/buildtool/execution_api/remote/bazel/bazel_execution_client.hpp"
 #include "src/buildtool/execution_api/remote/bazel/bazel_network.hpp"
+#include "src/utils/cpp/expected.hpp"
 
 class BazelAction;
 
@@ -58,8 +60,10 @@ class BazelResponse final : public IExecutionResponse {
         return action_id_;
     }
 
-    auto Artifacts() noexcept -> ArtifactInfos const& final;
-    auto DirectorySymlinks() noexcept -> DirSymlinks const& final;
+    auto Artifacts() noexcept
+        -> expected<gsl::not_null<ArtifactInfos const*>, std::string> final;
+    auto DirectorySymlinks() noexcept
+        -> expected<gsl::not_null<DirSymlinks const*>, std::string> final;
 
   private:
     std::string action_id_{};
@@ -84,7 +88,9 @@ class BazelResponse final : public IExecutionResponse {
         return id.size_bytes() != 0;
     }
 
-    void Populate() noexcept;
+    /// \brief Populates the stored data, once.
+    /// \returns Error message on failure, nullopt on success.
+    [[nodiscard]] auto Populate() noexcept -> std::optional<std::string>;
 
     [[nodiscard]] auto UploadTreeMessageDirectories(
         bazel_re::Tree const& tree) const -> std::optional<ArtifactDigest>;