persistent_storage_impl.h

#ifndef PRODUCTION_BORG_MGMT_NODE_PROXY_SAFEPOWER_SAFEPOWER_AGENT_PERSISTENT_STORAGE_IMPL_H_
#define PRODUCTION_BORG_MGMT_NODE_PROXY_SAFEPOWER_SAFEPOWER_AGENT_PERSISTENT_STORAGE_IMPL_H_

#include <cstdint>
#include <string>
#include <vector>

#include "persistent_storage.h"
#include "safepower_agent_config.pb.h"
#include "state_persistence.pb.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "absl/types/span.h"

namespace persistent_storage {
constexpr std::uintmax_t kMaxFileSize = 16384;  // 16 k
constexpr absl::string_view kDefaultPath =
 "/var/google/gPowerD/SavedActions";
constexpr uint32_t kProtoKeepNumber = 10;

constexpr absl::string_view kfileNamePrefix = "savedactions";

class PersistentStorageManagerImpl
    : public safepower_agent::PersistentStorageManager {
 public:
  explicit PersistentStorageManagerImpl(
      const safepower_agent_config::PersistentStorageConfig& config =
          safepower_agent_config::PersistentStorageConfig::default_instance());

  ~PersistentStorageManagerImpl() override = default;

  // Writes a delta to the saved actions to persistent storage.
  absl::Status WriteSavedActionsChange(
      const safepower_agent_persistence_proto::SavedActions& actions) override;

  absl::Status WriteSavedActionsChange(
      const safepower_agent_persistence_proto::SavedActions& actions,
      absl::string_view dir_path);

  // Reads all saved actions from persistent storage.
  absl::StatusOr<safepower_agent_persistence_proto::SavedActions>
  ReadSavedActions() override;

  absl::StatusOr<safepower_agent_persistence_proto::SavedActions>
  ReadSavedActions(absl::string_view dir_path);

  absl::Status InitializeSavedActions() override;
 private:
  struct FlightRecordHash {
    std::size_t operator()(
        const borg_mgmt::node_proxy::safepower::utils::FlightRecordRequest&
          flight_record) const {
      return absl::HashOf(std::make_pair(flight_record.flight_name(),
                                         flight_record.step_id()));
    }
  };
  struct FlightRecordEq {
    bool operator()(
      const borg_mgmt::node_proxy::safepower::utils::FlightRecordRequest& lhs,
      const borg_mgmt::node_proxy::safepower::utils::FlightRecordRequest& rhs)
         const {
      return lhs.flight_name() == rhs.flight_name() &&
             lhs.step_id() == rhs.step_id();
    }
  };

  absl::Status ConvertAppendToMap(
      absl::flat_hash_map<
  borg_mgmt::node_proxy::safepower::utils::FlightRecordRequest,
      safepower_agent_persistence_proto::SavedAction, FlightRecordHash,
                      FlightRecordEq>& map,
    const safepower_agent_persistence_proto::SavedActions& saved_actions);

  // keep the most recent protos is called when the size of the saved files is
  // larger then the kmaxFileSize. In the event of large protos we will always
  // have at least kProtoKeepNumber of messages. That garuantees was more
  // important then miniziains the file size. From a design perspective it would
  // be ideal if kMaxFileSize was reached at 2*kProtoKeepNumber, but that is not
  // necessary.
  absl::Status keepMostRecentProtos(
        absl::flat_hash_map<
            borg_mgmt::node_proxy::safepower::utils::FlightRecordRequest,
            safepower_agent_persistence_proto::SavedAction, FlightRecordHash,
                      FlightRecordEq>& map);
  absl::StatusOr<uint64_t> findLargestFileId(
      absl::Span<const std::string> files);
  absl::StatusOr<std::vector<std::string> > listFiles(
      absl::string_view file_path);
  absl::Status deleteAllFilesExceptLargest(absl::string_view file_path);
  std::string MakeFileName(absl::string_view file_path, uint64_t file_id);
  absl::StatusOr<safepower_agent_persistence_proto::SavedActions>
    CompressLogs(const safepower_agent_persistence_proto::SavedActions&
        saved_actions);

  std::string dir_path_{kDefaultPath};
  std::uintmax_t max_file_size_ = kMaxFileSize;
  uint32_t proto_keep_number_ = kProtoKeepNumber;
};


}  // namespace persistent_storage

#endif  // PRODUCTION_BORG_MGMT_NODE_PROXY_SAFEPOWER_SAFEPOWER_AGENT_PERSISTENT_STORAGE_IMPL_H_