database_pool.hpp

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#ifndef NEFORCE_DATABASE_DATABASE_POOL_HPP__
#define NEFORCE_DATABASE_DATABASE_POOL_HPP__

 
#include "NeForce/core/async/atomic.hpp"
#include "NeForce/core/async/condition_variable.hpp"
#include "NeForce/core/async/thread.hpp"
#include "NeForce/core/container/queue.hpp"
#include "NeForce/core/memory/shared_ptr.hpp"
#include "NeForce/db/db_interface.hpp"
NEFORCE_BEGIN_NAMESPACE__


class NEFORCE_API database_pool {
public:
    struct pool_config {
        size_t init_size = 5;               
        size_t min_size = 5;                
        size_t max_size = 64;               
        seconds max_idle_time{60};          
        milliseconds acquire_timeout{3000}; 
    };
 
private:
    struct connection_entry {
        idb_connect* conn = nullptr;
        milliseconds idle_at{0};
 
        connection_entry() noexcept = default;
 
        explicit connection_entry(idb_connect* c) :
        conn(c),
        idle_at(current_ms()) {}
 
        milliseconds idle_duration() const noexcept { return current_ms() - idle_at; }
 
        static milliseconds current_ms() noexcept { return time_cast<milliseconds>(steady_clock::now().since_epoch()); }
    };
 
    db_config config_;                
    pool_config pool_cfg_;            
    unique_ptr<idb_factory> factory_; 
 
    queue<connection_entry> idle_queue_; 
    mutable mutex queue_mtx_;            
    condition_variable cv_;              
 
    atomic<size_t> total_count_{0}; 
    atomic<bool> running_{false};   
 
    thread replenish_thread_; 
    thread scanner_thread_;   
 
    idb_connect* try_create_connect() noexcept;
 
    void return_connect(idb_connect* conn);
 
    void replenish_task();
    void scanner_task();
 
    template <typename T>
    shared_ptr<T> acquire_impl();
 
public:
    database_pool(db_type type, const db_config& config) :
    database_pool(type, config, pool_config()) {}

    database_pool(db_type type, const db_config& config, const pool_config& pool_config);

    ~database_pool();
 
    database_pool(const database_pool&) = delete;
    database_pool& operator=(const database_pool&) = delete;
    database_pool(database_pool&&) = delete;
    database_pool& operator=(database_pool&&) = delete;

    shared_ptr<idb_connect> get_connect();

    shared_ptr<idb_tb_connect> get_tb_connect();

    shared_ptr<idb_kv_connect> get_kv_connect();

    size_t idle_count() const noexcept;

    size_t total_count() const noexcept;

    bool is_running() const noexcept { return running_.load(memory_order_acquire); }

    void stop();
};

template <typename T>
shared_ptr<T> database_pool::acquire_impl() {
    unique_lock<mutex> lk(queue_mtx_);
 
    const bool got = cv_.wait_for(lk, pool_cfg_.acquire_timeout,
                                  [this] { return !idle_queue_.empty() || !running_.load(memory_order_relaxed); });
 
    if (!running_.load(memory_order_relaxed)) {
        return nullptr;
    }
 
    if (!got || idle_queue_.empty()) {
        const size_t cur = total_count_.load(memory_order_relaxed);
        if (cur >= pool_cfg_.max_size) {
            return nullptr;
        }
        idb_connect* raw = try_create_connect();
        if (raw == nullptr) {
            return nullptr;
        }
 
        total_count_.fetch_add(1, memory_order_relaxed);
        T* typed = dynamic_cast<T*>(raw);
        if (typed == nullptr) {
            delete raw;
            total_count_.fetch_sub(1, memory_order_relaxed);
            return nullptr;
        }
        return shared_ptr<T>(typed, [this](T* p) { this->return_connect(p); });
    }
 
    const connection_entry entry = idle_queue_.front();
    idle_queue_.pop();
    lk.unlock_quiet();
 
    idb_connect* raw = entry.conn;
 
    if (!raw->is_valid()) {
        if (!raw->reconnect(config_)) {
            delete raw;
            total_count_.fetch_sub(1, memory_order_relaxed);
            cv_.notify_one();
            return nullptr;
        }
    }
 
    T* typed = dynamic_cast<T*>(raw);
    if (typed == nullptr) {
        this->return_connect(raw);
        return nullptr;
    }
 
    return shared_ptr<T>(typed, [this](T* p) { this->return_connect(p); });
}
 // Database
 
NEFORCE_END_NAMESPACE__
#endif // NEFORCE_DATABASE_DATABASE_POOL_HPP__