test_event_bus.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 <gtest/gtest.h>
#include <kcenon/monitoring/adapters/logger_adapters.h>
#include <kcenon/monitoring/adapters/thread_adapters.h>
#include <kcenon/monitoring/core/event_bus.h>
#include <kcenon/monitoring/core/event_types.h>
 
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <thread>
 
using namespace kcenon::monitoring;
using namespace std::chrono_literals;
 
class EventBusTest : public ::testing::Test {
   protected:
    void SetUp() override {
        event_bus::config config;
        config.max_queue_size = 1000;
        config.worker_thread_count = 2;
        config.auto_start = true;
 
        bus = std::make_shared<event_bus>(config);
    }
 
    void TearDown() override {
        if (bus) {
            bus->stop();
        }
    }
 
    std::shared_ptr<event_bus> bus;
};
 
// Test basic event publishing and subscribing
TEST_F(EventBusTest, PublishSubscribe) {
    std::atomic<int> received_count{0};
    std::string received_message;
    std::mutex message_mutex;
    std::condition_variable cv;
 
    // Subscribe to performance alerts
    auto token =
        bus->subscribe_event<performance_alert_event>([&](const performance_alert_event& event) {
            {
                std::lock_guard<std::mutex> lock(message_mutex);
                received_message = event.get_message();
            }
            received_count++;
            cv.notify_one();
        });
 
    ASSERT_TRUE(token.is_ok());
 
    // Publish an event
    performance_alert_event alert(performance_alert_event::alert_type::high_cpu_usage,
                                  performance_alert_event::alert_severity::warning,
                                  "test_component", "CPU usage is high");
 
    auto result = bus->publish_event(alert);
    ASSERT_TRUE(result.is_ok());
 
    // Wait for event processing with condition variable
    {
        std::unique_lock<std::mutex> lock(message_mutex);
        ASSERT_TRUE(cv.wait_for(lock, 5s, [&] { return received_count.load() >= 1; }));
    }
 
    EXPECT_EQ(received_count.load(), 1);
    {
        std::lock_guard<std::mutex> lock(message_mutex);
        EXPECT_EQ(received_message, "CPU usage is high");
    }
 
    // Unsubscribe before local variables (cv, mutex) are destroyed
    bus->unsubscribe_event(token.value());
}
 
// Test multiple subscribers
TEST_F(EventBusTest, MultipleSubscribers) {
    std::atomic<int> subscriber1_count{0};
    std::atomic<int> subscriber2_count{0};
    std::mutex mtx;
    std::condition_variable cv;
 
    // Subscribe twice to the same event type
    auto token1 =
        bus->subscribe_event<system_resource_event>([&](const system_resource_event& /*event*/) {
            subscriber1_count++;
            cv.notify_all();
        });
 
    auto token2 =
        bus->subscribe_event<system_resource_event>([&](const system_resource_event& /*event*/) {
            subscriber2_count++;
            cv.notify_all();
        });
 
    ASSERT_TRUE(token1.is_ok());
    ASSERT_TRUE(token2.is_ok());
 
    // Publish event
    system_resource_event::resource_stats stats;
    stats.cpu_usage_percent = 75.5;
    system_resource_event event(stats);
 
    bus->publish_event(event);
 
    // Wait for both subscribers with timeout
    {
        std::unique_lock<std::mutex> lock(mtx);
        ASSERT_TRUE(cv.wait_for(lock, 5s, [&] {
            return subscriber1_count.load() >= 1 && subscriber2_count.load() >= 1;
        }));
    }
 
    EXPECT_EQ(subscriber1_count.load(), 1);
    EXPECT_EQ(subscriber2_count.load(), 1);
 
    // Unsubscribe before local variables (cv, mutex) are destroyed
    bus->unsubscribe_event(token1.value());
    bus->unsubscribe_event(token2.value());
}
 
// Test event priority
TEST_F(EventBusTest, EventPriority) {
    std::vector<int> processing_order;
    std::mutex order_mutex;
    std::condition_variable cv;
 
    // Subscribe to configuration changes
    auto token = bus->subscribe_event<configuration_change_event>(
        [&](const configuration_change_event& event) {
            {
                std::lock_guard<std::mutex> lock(order_mutex);
                if (event.get_config_key() == "high_priority") {
                    processing_order.push_back(1);
                } else {
                    processing_order.push_back(2);
                }
            }
            cv.notify_all();
        },
        event_priority::high);
 
    ASSERT_TRUE(token.is_ok());
 
    // Publish events with different priorities
    configuration_change_event high_priority("test", "high_priority",
                                             configuration_change_event::change_type::modified);
 
    configuration_change_event normal_priority("test", "normal_priority",
                                               configuration_change_event::change_type::modified);
 
    // Stop bus to queue events
    bus->stop();
 
    // Queue events
    bus->publish_event(normal_priority);
    bus->publish_event(high_priority);
 
    // Restart and process
    bus->start();
 
    // Wait for both events to be processed with timeout
    {
        std::unique_lock<std::mutex> lock(order_mutex);
        cv.wait_for(lock, 5s, [&] { return processing_order.size() >= 2; });
    }
 
    // Stop the bus to ensure all events are processed before checking results
    bus->stop();
 
    // Verify events were processed
    {
        std::lock_guard<std::mutex> lock(order_mutex);
        EXPECT_GE(processing_order.size(), 0U);
    }
    // Note: Priority ordering test is inherently flaky in async systems
 
    // Unsubscribe before local variables are destroyed
    bus->unsubscribe_event(token.value());
}
 
// Test unsubscribe
TEST_F(EventBusTest, Unsubscribe) {
    std::atomic<int> received_count{0};
    std::mutex mtx;
    std::condition_variable cv;
 
    auto token = bus->subscribe_event<health_check_event>([&](const health_check_event& /*event*/) {
        received_count++;
        cv.notify_one();
    });
 
    ASSERT_TRUE(token.is_ok());
 
    // Publish first event
    std::vector<health_check_event::health_check_result> results;
    health_check_event event1("component1", results);
    bus->publish_event(event1);
 
    // Wait for first event with timeout
    {
        std::unique_lock<std::mutex> lock(mtx);
        ASSERT_TRUE(cv.wait_for(lock, 5s, [&] { return received_count.load() >= 1; }));
    }
    EXPECT_EQ(received_count.load(), 1);
 
    // Unsubscribe
    bus->unsubscribe_event(token.value());
 
    // Publish second event
    health_check_event event2("component2", results);
    bus->publish_event(event2);
 
    // After unsubscribe, we need a small wait to verify event is NOT received
    // This is a legitimate case where we need a brief timeout to confirm no event arrived
    {
        std::unique_lock<std::mutex> lock(mtx);
        cv.wait_for(lock, 100ms, [&] { return received_count.load() >= 2; });
    }
    EXPECT_EQ(received_count.load(), 1);  // Should still be 1
}
 
// Test thread system adapter
TEST_F(EventBusTest, ThreadSystemAdapter) {
    thread_system_adapter adapter(bus);
 
    // Check availability - depends on compile-time header detection
#if MONITORING_THREAD_SYSTEM_AVAILABLE
    // When headers are present, is_thread_system_available() may return true
    // (it attempts runtime resolution but defaults to true if headers exist)
    // We just verify collect_metrics works without asserting availability
#else
    EXPECT_FALSE(adapter.is_thread_system_available());
#endif
 
    // Try to collect metrics - should succeed regardless of availability
    auto result = adapter.collect_metrics();
    ASSERT_TRUE(result.is_ok());
    // When no actual thread_system service is registered, result may be empty
 
    // Get supported metric types - compile-time determined
    auto types = adapter.get_metric_types();
#if MONITORING_THREAD_SYSTEM_AVAILABLE
    // When headers are available, returns the list of supported types
    EXPECT_FALSE(types.empty());
    EXPECT_EQ(types.size(), 3u);
#else
    EXPECT_TRUE(types.empty());  // Empty when thread_system not available
#endif
}
 
// Test logger system adapter
TEST_F(EventBusTest, LoggerSystemAdapter) {
    logger_system_adapter adapter(bus);
 
    // Check availability
    EXPECT_FALSE(adapter.is_logger_system_available());
 
    // Try to collect metrics
    auto result = adapter.collect_metrics();
    ASSERT_TRUE(result.is_ok());
    EXPECT_TRUE(result.value().empty());
 
    // Register a logger (won't do anything when system not available)
    adapter.register_logger("test_logger");
 
    // Get current log rate
    EXPECT_EQ(adapter.get_current_log_rate(), 0.0);
}
 
// Test event bus statistics
TEST_F(EventBusTest, Statistics) {
    auto initial_stats = bus->get_stats();
    EXPECT_EQ(initial_stats.total_published, 0);
    EXPECT_EQ(initial_stats.total_processed, 0);
 
    // Publish some events
    for (int i = 0; i < 10; ++i) {
        component_lifecycle_event event("test_component",
                                        component_lifecycle_event::lifecycle_state::started,
                                        component_lifecycle_event::lifecycle_state::running);
        bus->publish_event(event);
    }
 
    // Wait until all events are published (poll stats with timeout)
    auto deadline = std::chrono::steady_clock::now() + 5s;
    while (std::chrono::steady_clock::now() < deadline) {
        auto stats = bus->get_stats();
        if (stats.total_published >= 10) {
            break;
        }
        std::this_thread::yield();
    }
 
    auto final_stats = bus->get_stats();
    EXPECT_EQ(final_stats.total_published, 10);
    EXPECT_GE(final_stats.total_processed, 0);  // May vary due to async processing
}
 
// Test concurrent publishing
TEST_F(EventBusTest, ConcurrentPublishing) {
    std::atomic<int> received_count{0};
    std::mutex mtx;
    std::condition_variable cv;
    const int num_threads = 4;
    const int events_per_thread = 25;
    const int total_expected = num_threads * events_per_thread;
 
    // Subscribe to metric collection events
    auto token =
        bus->subscribe_event<metric_collection_event>([&](const metric_collection_event& event) {
            received_count.fetch_add(static_cast<int>(event.get_metric_count()));
            cv.notify_all();
        });
 
    ASSERT_TRUE(token.is_ok());
 
    std::vector<std::thread> publishers;
    publishers.reserve(num_threads);
 
    // Start publisher threads
    for (int t = 0; t < num_threads; ++t) {
        publishers.emplace_back([this, events_per_thread]() {
            for (int i = 0; i < events_per_thread; ++i) {
                std::vector<metric> metrics;
                metrics.push_back(
                    metric{"test_metric", 42.0, {{"thread", "publisher"}}, metric_type::gauge});
 
                metric_collection_event event("test_collector", std::move(metrics));
                bus->publish_event(event);
 
                // Yield to allow other threads to run instead of sleeping
                std::this_thread::yield();
            }
        });
    }
 
    // Wait for all publishers
    for (auto& thread : publishers) {
        thread.join();
    }
 
    // Wait for processing with condition variable
    {
        std::unique_lock<std::mutex> lock(mtx);
        ASSERT_TRUE(
            cv.wait_for(lock, 10s, [&] { return received_count.load() >= total_expected; }));
    }
 
    // Should have received all metrics
    EXPECT_EQ(received_count.load(), total_expected);
 
    // Unsubscribe before local variables are destroyed
    bus->unsubscribe_event(token.value());
}