database_metrics_service.h

Go to the documentation of this file.

// BSD 3-Clause License
// Copyright (c) 2021-2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include "kcenon/pacs/storage/pacs_database_adapter.h"
 
#include <chrono>
#include <functional>
#include <memory>
#include <string>
#include <vector>
 
#ifdef PACS_WITH_DATABASE_SYSTEM
 
namespace kcenon::pacs::services::monitoring {
 
struct database_health {
    enum class status {
        healthy,   
        degraded,  
        unhealthy  
    };
 
    status current_status;                             
    std::string message;                               
    std::chrono::milliseconds response_time{0};        
    size_t active_connections{0};                      
    double error_rate{0.0};                            
    std::vector<std::string> warnings;                 
};
 
struct database_metrics {
    // Query statistics
    size_t total_queries{0};       
    size_t successful_queries{0};  
    size_t failed_queries{0};      
    double queries_per_second{0.0};  
 
    // Latency (microseconds)
    uint64_t avg_latency_us{0};  
    uint64_t min_latency_us{0};  
    uint64_t max_latency_us{0};  
    uint64_t p95_latency_us{0};  
    uint64_t p99_latency_us{0};  
 
    // Connections
    size_t active_connections{0};     
    size_t pool_size{0};              
    double connection_utilization{0.0};  
 
    // Errors
    double error_rate{0.0};       
    size_t slow_query_count{0};   
};
 
struct slow_query {
    std::string query_hash;     
    std::string query_preview;  
    uint64_t duration_us;       
    std::string timestamp;      
    size_t rows_affected;       
};
 
class database_metrics_service {
public:
    using slow_query_callback = std::function<void(const slow_query&)>;
 
    explicit database_metrics_service(
        std::shared_ptr<storage::pacs_database_adapter> db);
 
    ~database_metrics_service();
 
    // Non-copyable, movable
    database_metrics_service(const database_metrics_service&) = delete;
    auto operator=(const database_metrics_service&)
        -> database_metrics_service& = delete;
    database_metrics_service(database_metrics_service&&) noexcept;
    auto operator=(database_metrics_service&&) noexcept
        -> database_metrics_service&;
 
    // ========================================================================
    // Configuration
    // ========================================================================
 
    void set_slow_query_threshold(std::chrono::microseconds threshold);
 
    void set_metrics_retention(std::chrono::minutes retention);
 
    void register_slow_query_callback(slow_query_callback callback);
 
    // ========================================================================
    // Health Checks
    // ========================================================================
 
    [[nodiscard]] auto check_health() -> database_health;
 
    [[nodiscard]] auto is_healthy() -> bool;
 
    // ========================================================================
    // Metrics Retrieval
    // ========================================================================
 
    [[nodiscard]] auto get_current_metrics() -> database_metrics;
 
    [[nodiscard]] auto get_slow_queries(
        std::chrono::minutes since = std::chrono::minutes(5))
        -> std::vector<slow_query>;
 
    [[nodiscard]] auto get_top_slow_queries(size_t limit = 10)
        -> std::vector<slow_query>;
 
    // ========================================================================
    // Metrics Export
    // ========================================================================
 
    [[nodiscard]] auto export_prometheus_metrics() -> std::string;
 
private:
    struct impl;
    std::unique_ptr<impl> impl_;
};
 
[[nodiscard]] auto health_status_to_string(database_health::status status)
    -> std::string;
 
}  // namespace kcenon::pacs::services::monitoring
 
#endif  // PACS_WITH_DATABASE_SYSTEM