async_operations_demo.cpp

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// BSD 3-Clause License
// Copyright (c) 2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#ifndef HAS_COROUTINES
#include <iostream>
int main() {
    std::cout << "This demo requires C++20 coroutines support.\n";
    std::cout << "Please build with -DCMAKE_CXX_STANDARD=20 and ensure your compiler supports coroutines.\n";
    return 1;
}
#else
 
#include <iostream>
#include <string>
#include <chrono>
#include <future>
#include <memory>
#include <vector>
#include <coroutine>
#include "database/database_manager.h"
#include "database/async/async_operations.h"
 
using namespace database;
using namespace database::async;
 
void demonstrate_basic_async_operations() {
    std::cout << "=== Basic Asynchronous Database Operations ===\n";
 
    async_executor& executor = async_executor::instance();
 
    // Configure async executor
    async_config config;
    config.thread_pool_size = 8;
    config.max_concurrent_operations = 100;
    config.operation_timeout = std::chrono::seconds(30);
    config.enable_coroutines = true;
 
    executor.configure(config);
    std::cout << "Async executor configured with " << config.thread_pool_size << " threads\n";
 
    // Demonstrate async query execution
    std::cout << "\nExecuting asynchronous queries...\n";
 
    // Submit multiple async queries
    std::vector<std::future<query_result>> futures;
 
    for (int i = 0; i < 5; ++i) {
        std::string query = "SELECT * FROM users WHERE department_id = " + std::to_string(i + 1);
 
        auto future = executor.execute_async([query, i]() -> query_result {
            // Simulate database query execution
            std::this_thread::sleep_for(std::chrono::milliseconds(100 + (i * 50)));
 
            query_result result;
            result.success = true;
            result.rows_affected = (i + 1) * 10;
            result.execution_time = std::chrono::milliseconds(100 + (i * 50));
            result.query = query;
 
            return result;
        });
 
        futures.push_back(std::move(future));
        std::cout << "  🚀 Query " << (i + 1) << " submitted asynchronously\n";
    }
 
    // Collect results as they complete
    std::cout << "\nCollecting async query results:\n";
    for (size_t i = 0; i < futures.size(); ++i) {
        auto& future = futures[i];
        auto result = future.get();
 
        std::cout << "  ✅ Query " << (i + 1) << " completed: "
                  << result.rows_affected << " rows, "
                  << result.execution_time.count() << "ms\n";
    }
}
 
// C++20 Coroutine demonstration
struct task {
    struct promise_type {
        task get_return_object() { return task{std::coroutine_handle<promise_type>::from_promise(*this)}; }
        std::suspend_never initial_suspend() { return {}; }
        std::suspend_never final_suspend() noexcept { return {}; }
        void return_void() {}
        void unhandled_exception() {}
    };
 
    std::coroutine_handle<promise_type> h;
    task(std::coroutine_handle<promise_type> handle) : h(handle) {}
    ~task() { if (h) h.destroy(); }
 
    task(const task&) = delete;
    task& operator=(const task&) = delete;
    task(task&& other) noexcept : h(std::exchange(other.h, {})) {}
    task& operator=(task&& other) noexcept {
        if (this != &other) {
            if (h) h.destroy();
            h = std::exchange(other.h, {});
        }
        return *this;
    }
};
 
task async_database_operation(const std::string& operation_name) {
    std::cout << "  🔄 Starting " << operation_name << "\n";
 
    // Simulate async database work
    std::this_thread::sleep_for(std::chrono::milliseconds(200));
 
    std::cout << "  ✅ Completed " << operation_name << "\n";
    co_return;
}
 
void demonstrate_coroutine_operations() {
    std::cout << "\n=== C++20 Coroutine Database Operations ===\n";
 
    std::cout << "Using coroutines for non-blocking database operations...\n";
 
    // Execute multiple coroutine-based operations
    std::vector<task> tasks;
 
    tasks.push_back(async_database_operation("User authentication"));
    tasks.push_back(async_database_operation("Data validation"));
    tasks.push_back(async_database_operation("Cache update"));
    tasks.push_back(async_database_operation("Audit logging"));
 
    std::cout << "All coroutine operations initiated and completed.\n";
 
    std::cout << "\nCoroutine Benefits:\n";
    std::cout << "  • Non-blocking execution\n";
    std::cout << "  • Efficient memory usage\n";
    std::cout << "  • Natural async/await syntax\n";
    std::cout << "  • Better exception handling\n";
}
 
void demonstrate_async_connection_pool() {
    std::cout << "\n=== Asynchronous Connection Pool ===\n";
 
    async_connection_pool pool;
 
    // Configure async connection pool
    async_pool_config config;
    config.min_connections = 5;
    config.max_connections = 20;
    config.acquire_timeout = std::chrono::milliseconds(5000);
    config.idle_timeout = std::chrono::minutes(10);
    config.health_check_interval = std::chrono::seconds(30);
 
    pool.configure(config);
    std::cout << "Async connection pool configured:\n";
    std::cout << "  Min connections: " << config.min_connections << "\n";
    std::cout << "  Max connections: " << config.max_connections << "\n";
    std::cout << "  Acquire timeout: " << config.acquire_timeout.count() << "ms\n";
 
    // Simulate concurrent connection requests
    std::cout << "\nSimulating concurrent connection requests...\n";
 
    std::vector<std::future<connection_result>> connection_futures;
 
    for (int i = 0; i < 15; ++i) {
        auto future = pool.get_connection_async();
        connection_futures.push_back(std::move(future));
        std::cout << "  📡 Connection request " << (i + 1) << " submitted\n";
    }
 
    // Process connection results
    std::cout << "\nProcessing connection acquisitions:\n";
    int successful_connections = 0;
 
    for (size_t i = 0; i < connection_futures.size(); ++i) {
        auto& future = connection_futures[i];
 
        try {
            auto result = future.get();
            if (result.success) {
                successful_connections++;
                std::cout << "  ✅ Connection " << (i + 1) << " acquired in "
                          << result.acquisition_time.count() << "ms\n";
            } else {
                std::cout << "  ❌ Connection " << (i + 1) << " failed: " << result.error_message << "\n";
            }
        } catch (const std::exception& e) {
            std::cout << "  ❌ Connection " << (i + 1) << " exception: " << e.what() << "\n";
        }
    }
 
    std::cout << "\nConnection Pool Summary:\n";
    std::cout << "  Successful connections: " << successful_connections << "/" << connection_futures.size() << "\n";
    std::cout << "  Pool utilization: " << pool.get_utilization_percentage() << "%\n";
}
 
void demonstrate_real_time_streams() {
    std::cout << "\n=== Real-Time Data Streams ===\n";
 
    // PostgreSQL NOTIFY/LISTEN demonstration
    std::cout << "🔔 PostgreSQL NOTIFY/LISTEN Stream:\n";
 
    postgres_stream_listener listener;
    listener.subscribe("user_changes", [](const notification& notif) {
        std::cout << "  📢 Received notification: " << notif.channel
                  << " → " << notif.payload << "\n";
    });
 
    // Simulate notifications
    std::vector<std::string> notifications = {
        "User alice.smith logged in",
        "User bob.jones updated profile",
        "User carol.wilson changed password",
        "New user david.brown registered"
    };
 
    for (const auto& msg : notifications) {
        listener.simulate_notification("user_changes", msg);
        std::this_thread::sleep_for(std::chrono::milliseconds(500));
    }
 
    // MongoDB Change Streams demonstration
    std::cout << "\n📊 MongoDB Change Streams:\n";
 
    mongodb_change_stream stream;
    stream.watch_collection("users", [](const change_event& event) {
        std::cout << "  🔄 Change detected: " << event.operation_type
                  << " on document " << event.document_id << "\n";
    });
 
    // Simulate change events
    std::vector<std::tuple<std::string, std::string>> changes = {
        {"insert", "user_001"},
        {"update", "user_002"},
        {"delete", "user_003"},
        {"replace", "user_004"}
    };
 
    for (const auto& [op, doc_id] : changes) {
        stream.simulate_change(op, doc_id);
        std::this_thread::sleep_for(std::chrono::milliseconds(300));
    }
 
    std::cout << "\nReal-time stream capabilities:\n";
    std::cout << "  • Low-latency event processing\n";
    std::cout << "  • Automatic reconnection handling\n";
    std::cout << "  • Backpressure management\n";
    std::cout << "  • Event filtering and routing\n";
}
 
void demonstrate_distributed_transactions() {
    std::cout << "\n=== Distributed Transaction Coordination ===\n";
 
    distributed_transaction_coordinator coordinator;
 
    // Configure distributed transaction
    transaction_config config;
    config.enable_two_phase_commit = true;
    config.transaction_timeout = std::chrono::seconds(30);
    config.max_participants = 5;
    config.isolation_level = isolation_level::serializable;
 
    coordinator.configure(config);
    std::cout << "Distributed transaction coordinator configured:\n";
    std::cout << "  Two-phase commit: enabled\n";
    std::cout << "  Timeout: " << config.transaction_timeout.count() << "s\n";
    std::cout << "  Max participants: " << config.max_participants << "\n";
 
    // Register transaction participants
    std::vector<std::string> participants = {
        "postgres_primary",
        "postgres_replica",
        "mongodb_cluster",
        "redis_cache"
    };
 
    std::cout << "\nRegistering transaction participants:\n";
    for (const auto& participant : participants) {
        coordinator.register_participant(participant);
        std::cout << "  📝 Registered: " << participant << "\n";
    }
 
    // Execute distributed transaction
    std::cout << "\nExecuting distributed transaction...\n";
 
    auto transaction_future = coordinator.begin_transaction_async();
 
    // Simulate transaction operations on each participant
    std::vector<std::future<operation_result>> operation_futures;
 
    for (const auto& participant : participants) {
        auto future = coordinator.execute_operation_async(participant, [participant]() -> operation_result {
            // Simulate operation on this participant
            std::this_thread::sleep_for(std::chrono::milliseconds(100));
 
            operation_result result;
            result.success = true;
            result.participant = participant;
            result.operation_time = std::chrono::milliseconds(100);
 
            return result;
        });
 
        operation_futures.push_back(std::move(future));
        std::cout << "  🔄 Operation submitted to " << participant << "\n";
    }
 
    // Collect operation results
    std::cout << "\nCollecting operation results:\n";
    bool all_successful = true;
 
    for (auto& future : operation_futures) {
        auto result = future.get();
        std::cout << "  " << (result.success ? "✅" : "❌")
                  << " " << result.participant
                  << " (" << result.operation_time.count() << "ms)\n";
 
        if (!result.success) {
            all_successful = false;
        }
    }
 
    // Commit or rollback based on results
    if (all_successful) {
        auto commit_result = coordinator.commit_transaction_async().get();
        std::cout << "\n🎉 Distributed transaction COMMITTED successfully\n";
        std::cout << "  All " << participants.size() << " participants confirmed\n";
    } else {
        auto rollback_result = coordinator.rollback_transaction_async().get();
        std::cout << "\n🔄 Distributed transaction ROLLED BACK\n";
        std::cout << "  All participants restored to original state\n";
    }
}
 
void demonstrate_saga_pattern() {
    std::cout << "\n=== Saga Pattern for Long-Running Transactions ===\n";
 
    saga_coordinator saga;
 
    std::cout << "Implementing saga pattern for order processing workflow...\n";
 
    // Define saga steps
    std::vector<saga_step> steps = {
        {"validate_payment", "Payment validation and authorization"},
        {"reserve_inventory", "Reserve products in inventory"},
        {"create_shipment", "Create shipping label and schedule"},
        {"update_customer", "Update customer order history"},
        {"send_confirmation", "Send order confirmation email"}
    };
 
    std::cout << "\nSaga workflow steps:\n";
    for (size_t i = 0; i < steps.size(); ++i) {
        saga.add_step(steps[i]);
        std::cout << "  " << (i + 1) << ". " << steps[i].description << "\n";
    }
 
    // Execute saga
    std::cout << "\nExecuting saga workflow...\n";
 
    auto saga_future = saga.execute_async();
 
    // Simulate step execution
    for (size_t i = 0; i < steps.size(); ++i) {
        std::this_thread::sleep_for(std::chrono::milliseconds(200));
 
        bool step_success = (i != 2); // Simulate failure at step 3
 
        if (step_success) {
            std::cout << "  ✅ Step " << (i + 1) << " (" << steps[i].name << ") completed\n";
        } else {
            std::cout << "  ❌ Step " << (i + 1) << " (" << steps[i].name << ") FAILED\n";
            std::cout << "  🔄 Initiating compensating actions...\n";
 
            // Execute compensating actions for completed steps
            for (int j = i - 1; j >= 0; --j) {
                std::this_thread::sleep_for(std::chrono::milliseconds(100));
                std::cout << "    ↩️  Compensating step " << (j + 1) << " (" << steps[j].name << ")\n";
            }
 
            std::cout << "  🔄 Saga compensation completed - system restored to consistent state\n";
            break;
        }
    }
 
    std::cout << "\nSaga Pattern Benefits:\n";
    std::cout << "  • Eventual consistency for distributed systems\n";
    std::cout << "  • Automatic compensation on failures\n";
    std::cout << "  • Better resilience than distributed transactions\n";
    std::cout << "  • Suitable for long-running business processes\n";
}
 
void demonstrate_async_batch_processing() {
    std::cout << "\n=== Asynchronous Batch Processing ===\n";
 
    batch_processor processor;
 
    // Configure batch processing
    batch_config config;
    config.batch_size = 100;
    config.max_parallel_batches = 4;
    config.processing_timeout = std::chrono::minutes(5);
    config.retry_attempts = 3;
 
    processor.configure(config);
    std::cout << "Batch processor configured:\n";
    std::cout << "  Batch size: " << config.batch_size << " records\n";
    std::cout << "  Parallel batches: " << config.max_parallel_batches << "\n";
    std::cout << "  Timeout: " << config.processing_timeout.count() << " minutes\n";
 
    // Submit large dataset for processing
    std::cout << "\nProcessing large dataset asynchronously...\n";
 
    const int total_records = 1000;
    auto processing_future = processor.process_async(total_records);
 
    // Monitor progress
    std::cout << "Batch processing progress:\n";
    for (int progress = 0; progress <= 100; progress += 20) {
        std::this_thread::sleep_for(std::chrono::milliseconds(300));
        std::cout << "  📊 Progress: " << progress << "% ("
                  << (progress * total_records / 100) << "/" << total_records << " records)\n";
    }
 
    auto result = processing_future.get();
    std::cout << "\n🎉 Batch processing completed:\n";
    std::cout << "  Total records: " << result.total_records << "\n";
    std::cout << "  Successful: " << result.successful_records << "\n";
    std::cout << "  Failed: " << result.failed_records << "\n";
    std::cout << "  Processing time: " << result.total_time.count() << "ms\n";
    std::cout << "  Throughput: " << (result.successful_records * 1000 / result.total_time.count()) << " records/sec\n";
}
 
int main() {
    std::cout << "=== Asynchronous Operations Framework Demonstration ===\n";
    std::cout << "This sample demonstrates C++20 coroutines, async database operations,\n";
    std::cout << "and distributed transaction patterns for modern applications.\n";
 
    try {
        demonstrate_basic_async_operations();
        demonstrate_coroutine_operations();
        demonstrate_async_connection_pool();
        demonstrate_real_time_streams();
        demonstrate_distributed_transactions();
        demonstrate_saga_pattern();
        demonstrate_async_batch_processing();
 
        std::cout << "\n=== Async Operations Features Summary ===\n";
        std::cout << "✓ C++20 coroutines with co_await support\n";
        std::cout << "✓ std::future-based asynchronous operations\n";
        std::cout << "✓ Non-blocking connection pool management\n";
        std::cout << "✓ Real-time data streams (PostgreSQL NOTIFY, MongoDB Change Streams)\n";
        std::cout << "✓ Distributed transaction coordination with 2PC\n";
        std::cout << "✓ Saga pattern for long-running transactions\n";
        std::cout << "✓ Asynchronous batch processing with progress tracking\n";
        std::cout << "✓ Exception handling and automatic retries\n";
 
        std::cout << "\nFor production deployment:\n";
        std::cout << "  async_executor::instance().configure(async_config);\n";
        std::cout << "  auto result = async_executor::instance().execute_async(operation);\n";
        std::cout << "  // Use co_await for coroutine-based operations\n";
 
    } catch (const std::exception& e) {
        std::cout << "Error: " << e.what() << std::endl;
        return 1;
    }
 
    return 0;
}
 
#endif // HAS_COROUTINES