connection_pool.h

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// BSD 3-Clause License
// Copyright (c) 2024, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <memory>
#include <mutex>
#include <queue>
#include <string>
 
#include "internal/core/messaging_client.h"
#include "kcenon/network/detail/utils/result_types.h"
 
namespace kcenon::network::core
{
 
    class connection_pool
    {
    public:
        connection_pool(
            std::string host, unsigned short port, size_t pool_size = 10,
            std::chrono::seconds acquire_timeout = std::chrono::seconds(30));
 
        ~connection_pool() noexcept;
 
        auto initialize() -> VoidResult;
 
        auto acquire() -> std::unique_ptr<messaging_client>;
 
        auto release(std::unique_ptr<messaging_client> client) -> void;
 
        [[nodiscard]] auto active_count() const noexcept -> size_t
        {
            return active_count_.load(std::memory_order_relaxed);
        }
 
        [[nodiscard]] auto pool_size() const noexcept -> size_t
        {
            return pool_size_;
        }
 
    private:
        std::string host_;              
        unsigned short port_;           
        size_t pool_size_;              
        std::chrono::seconds acquire_timeout_;
        std::queue<std::unique_ptr<messaging_client>> available_;
        std::atomic<size_t> active_count_{0};
        std::mutex mutex_;              
        std::condition_variable cv_;    
        std::atomic<bool> is_shutdown_{false};
    };
 
} // namespace kcenon::network::core