thread_safe_rcu_example.cpp

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// BSD 3-Clause License
// Copyright (c) 2021-2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
 
#include "container.h"
 
#include <atomic>
#include <iostream>
#include <mutex>
#include <string>
#include <thread>
#include <vector>
 
using namespace kcenon::container;
 
int main()
{
    std::cout << "=== Thread-Safe RCU Container Example ===" << std::endl;
 
    // Shared container with mutex for thread safety
    value_container shared_container;
    std::mutex container_mutex;
 
    shared_container.set("counter", static_cast<int64_t>(0));
    shared_container.set("status", std::string("initializing"));
 
    // 1. Concurrent writes
    std::cout << "\n1. Concurrent writes (5 threads):" << std::endl;
    std::atomic<int> write_count{0};
    std::vector<std::thread> writers;
 
    for (int i = 0; i < 5; ++i)
    {
        writers.emplace_back(
            [&, i]()
            {
                for (int j = 0; j < 10; ++j)
                {
                    std::lock_guard<std::mutex> lock(container_mutex);
                    std::string key = "thread_" + std::to_string(i) + "_item_" + std::to_string(j);
                    shared_container.set(key, std::string("value_" + std::to_string(j)));
                    write_count.fetch_add(1);
                }
            });
    }
 
    for (auto& t : writers)
    {
        t.join();
    }
    std::cout << "   Total writes: " << write_count.load() << std::endl;
    std::cout << "   Container size: " << shared_container.size() << std::endl;
 
    // 2. Concurrent reads
    std::cout << "\n2. Concurrent reads (3 threads):" << std::endl;
    std::atomic<int> read_count{0};
    std::vector<std::thread> readers;
 
    for (int i = 0; i < 3; ++i)
    {
        readers.emplace_back(
            [&, i]()
            {
                std::lock_guard<std::mutex> lock(container_mutex);
                auto size = shared_container.size();
                read_count.fetch_add(1);
                std::cout << "   Reader " << i << " sees " << size << " entries" << std::endl;
            });
    }
 
    for (auto& t : readers)
    {
        t.join();
    }
    std::cout << "   Total reads: " << read_count.load() << std::endl;
 
    // 3. Container copy for snapshot
    std::cout << "\n3. Snapshot (copy-on-read):" << std::endl;
    std::shared_ptr<value_container> snapshot;
    {
        std::lock_guard<std::mutex> lock(container_mutex);
        snapshot = shared_container.copy(true);
    }
    std::cout << "   Snapshot size: " << snapshot->size() << std::endl;
    std::cout << "   Original size: " << shared_container.size() << std::endl;
 
    std::cout << "\nDone." << std::endl;
    return 0;
}