hsm_storage.h

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// BSD 3-Clause License
// Copyright (c) 2021-2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include "hsm_types.h"
#include "storage_interface.h"
 
#include <memory>
#include <shared_mutex>
#include <unordered_map>
 
namespace kcenon::pacs::storage {
 
struct hsm_storage_config {
    tier_policy policy;
 
    bool track_access_time{true};
 
    bool verify_after_migration{true};
 
    bool delete_after_migration{true};
};
 
class hsm_storage : public storage_interface {
public:
    // =========================================================================
    // Construction
    // =========================================================================
 
    hsm_storage(std::unique_ptr<storage_interface> hot_tier,
                std::unique_ptr<storage_interface> warm_tier,
                std::unique_ptr<storage_interface> cold_tier,
                const hsm_storage_config& config = {});
 
    ~hsm_storage() override = default;
 
    hsm_storage(const hsm_storage&) = delete;
    hsm_storage& operator=(const hsm_storage&) = delete;
 
    hsm_storage(hsm_storage&&) = delete;
    hsm_storage& operator=(hsm_storage&&) = delete;
 
    // =========================================================================
    // storage_interface Implementation
    // =========================================================================
 
    [[nodiscard]] auto store(const core::dicom_dataset& dataset)
        -> VoidResult override;
 
    [[nodiscard]] auto retrieve(std::string_view sop_instance_uid)
        -> Result<core::dicom_dataset> override;
 
    [[nodiscard]] auto remove(std::string_view sop_instance_uid)
        -> VoidResult override;
 
    [[nodiscard]] auto exists(std::string_view sop_instance_uid) const
        -> bool override;
 
    [[nodiscard]] auto find(const core::dicom_dataset& query)
        -> Result<std::vector<core::dicom_dataset>> override;
 
    [[nodiscard]] auto get_statistics() const -> storage_statistics override;
 
    [[nodiscard]] auto verify_integrity() -> VoidResult override;
 
    // =========================================================================
    // HSM-specific Operations
    // =========================================================================
 
    [[nodiscard]] auto get_tier(std::string_view sop_instance_uid) const
        -> std::optional<storage_tier>;
 
    [[nodiscard]] auto get_tier_metadata(std::string_view sop_instance_uid) const
        -> std::optional<tier_metadata>;
 
    [[nodiscard]] auto migrate(std::string_view sop_instance_uid,
                                storage_tier target_tier) -> VoidResult;
 
    [[nodiscard]] auto get_migration_candidates(storage_tier from_tier,
                                                 storage_tier to_tier) const
        -> std::vector<tier_metadata>;
 
    [[nodiscard]] auto run_migration_cycle() -> migration_result;
 
    [[nodiscard]] auto get_tier_policy() const -> tier_policy;
 
    void set_tier_policy(const tier_policy& policy);
 
    [[nodiscard]] auto get_hsm_statistics() const -> hsm_statistics;
 
    [[nodiscard]] auto get_tier_storage(storage_tier tier) const
        -> storage_interface*;
 
private:
    // =========================================================================
    // Internal Helper Methods
    // =========================================================================
 
    [[nodiscard]] auto find_tier(std::string_view sop_instance_uid) const
        -> std::optional<storage_tier>;
 
    [[nodiscard]] auto get_storage(storage_tier tier) const
        -> storage_interface*;
 
    void update_metadata(std::string_view sop_instance_uid, storage_tier tier,
                         const core::dicom_dataset& dataset);
 
    void update_access_time(std::string_view sop_instance_uid);
 
    void remove_metadata(std::string_view sop_instance_uid);
 
    [[nodiscard]] auto migrate_instance(std::string_view uid,
                                         storage_tier from_tier,
                                         storage_tier to_tier) -> VoidResult;
 
    // =========================================================================
    // Member Variables
    // =========================================================================
 
    std::unique_ptr<storage_interface> hot_tier_;
 
    std::unique_ptr<storage_interface> warm_tier_;
 
    std::unique_ptr<storage_interface> cold_tier_;
 
    hsm_storage_config config_;
 
    std::unordered_map<std::string, tier_metadata> metadata_index_;
 
    mutable std::shared_mutex mutex_;
};
 
}  // namespace kcenon::pacs::storage