hsm_migration_service.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_storage.h"
#include "hsm_types.h"
 
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <functional>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <thread>
#include <vector>
 
namespace kcenon::thread {
class thread_pool;
}  // namespace kcenon::thread
 
namespace kcenon::logger {
class logger;
}  // namespace kcenon::logger
 
namespace kcenon::pacs::storage {
 
struct migration_service_config {
    std::chrono::seconds migration_interval{3600};  // 1 hour default
 
    std::size_t max_concurrent_migrations{4};
 
    bool auto_start{false};
 
    using progress_callback =
        std::function<void(const migration_result& result)>;
    progress_callback on_cycle_complete;
 
    using error_callback =
        std::function<void(const std::string& uid, const std::string& error)>;
    error_callback on_migration_error;
};
 
class hsm_migration_service {
public:
    // =========================================================================
    // Construction
    // =========================================================================
 
    explicit hsm_migration_service(hsm_storage& storage,
                                   const migration_service_config& config = {});
 
    hsm_migration_service(
        hsm_storage& storage,
        std::shared_ptr<kcenon::thread::thread_pool> thread_pool,
        const migration_service_config& config = {});
 
    ~hsm_migration_service();
 
    hsm_migration_service(const hsm_migration_service&) = delete;
    hsm_migration_service& operator=(const hsm_migration_service&) = delete;
 
    hsm_migration_service(hsm_migration_service&&) = delete;
    hsm_migration_service& operator=(hsm_migration_service&&) = delete;
 
    // =========================================================================
    // Lifecycle Management
    // =========================================================================
 
    void start();
 
    void stop(bool wait_for_completion = true);
 
    [[nodiscard]] auto is_running() const noexcept -> bool;
 
    // =========================================================================
    // Manual Operations
    // =========================================================================
 
    [[nodiscard]] auto run_migration_cycle() -> migration_result;
 
    void trigger_cycle();
 
    // =========================================================================
    // Statistics and Monitoring
    // =========================================================================
 
    [[nodiscard]] auto get_last_result() const
        -> std::optional<migration_result>;
 
    [[nodiscard]] auto get_cumulative_stats() const -> migration_result;
 
    [[nodiscard]] auto time_until_next_cycle() const
        -> std::optional<std::chrono::seconds>;
 
    [[nodiscard]] auto cycles_completed() const noexcept -> std::size_t;
 
    // =========================================================================
    // Configuration
    // =========================================================================
 
    void set_migration_interval(std::chrono::seconds interval);
 
    [[nodiscard]] auto get_migration_interval() const noexcept
        -> std::chrono::seconds;
 
    void set_progress_callback(migration_service_config::progress_callback callback);
 
    void set_error_callback(migration_service_config::error_callback callback);
 
private:
    // =========================================================================
    // Internal Methods
    // =========================================================================
 
    void run_loop();
 
    [[nodiscard]] auto execute_cycle() -> migration_result;
 
    void update_stats(const migration_result& result);
 
    // =========================================================================
    // Member Variables
    // =========================================================================
 
    hsm_storage& storage_;
 
    std::shared_ptr<kcenon::thread::thread_pool> thread_pool_;
 
    migration_service_config config_;
 
    std::thread worker_thread_;
 
    mutable std::mutex mutex_;
 
    std::condition_variable cv_;
 
    std::atomic<bool> stop_requested_{false};
 
    std::atomic<bool> running_{false};
 
    std::atomic<bool> cycle_in_progress_{false};
 
    std::optional<migration_result> last_result_;
 
    migration_result cumulative_stats_;
 
    std::atomic<std::size_t> cycles_count_{0};
 
    std::chrono::steady_clock::time_point next_cycle_time_;
};
 
}  // namespace kcenon::pacs::storage