feat(app): add concurrent message queue

tests/app/message_queue_test.cpp

@@ -0,0 +1,105 @@
+#include <cassert>
+#include <thread>
+#include <vector>
+
+#include "log_level.hpp"
+#include "message_queue.hpp"
+#include "thread_test_utils.hpp"
+
+namespace app::tests {
+
+using namespace app;
+
+void testPushAndPop() {
+  MessageQueue queue;
+
+  queue.push({logger::LogLevel::info(), "Hello"});
+
+  auto message = queue.pop();
+
+  assert(message.level == logger::LogLevel::info());
+  assert(message.message == "Hello");
+}
+
+void testFifoOrder() {
+  MessageQueue queue;
+
+  queue.push({logger::LogLevel::debug(), "first"});
+  queue.push({logger::LogLevel::info(), "second"});
+  queue.push({logger::LogLevel::error(), "third"});
+
+  assert(queue.pop().message == "first");
+  assert(queue.pop().message == "second");
+  assert(queue.pop().message == "third");
+}
+
+void testPopWaitsForMessage() {
+  MessageQueue queue;
+
+  bool received = false;
+
+  std::thread worker([&]() {
+    auto message = queue.pop();
+
+    assert(message.level == logger::LogLevel::error());
+    assert(message.message == "Delayed");
+
+    received = true;
+  });
+
+  // Даём потоку worker возможность дойти до queue.pop()
+  // и заблокироваться в ожидании сообщения.
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+  assert(!received);
+
+  // Добавляем сообщение и тем самым разблокируем worker.
+  queue.push({logger::LogLevel::error(), "Delayed"});
+
+  // Ожидаем полного завершения потока worker.
+  worker.join();
+
+  assert(received);
+}
+
+void testConcurrentPushAndPop() {
+  MessageQueue queue;
+
+  constexpr std::size_t threadCount = 8;
+  constexpr std::size_t messagesPerThread = 1000;
+
+  std::vector<std::thread> producers;
+
+  for (std::size_t i = 0; i < threadCount; ++i) {
+    producers.emplace_back(
+        helpers::createProducer(queue, i, messagesPerThread));
+  }
+  const auto expectedMessages = threadCount * messagesPerThread;
+
+  for (std::size_t i = 0; i < expectedMessages; ++i) {
+    auto message = queue.pop();
+
+    assert(!message.message.empty());
+  }
+
+  for (auto &producer : producers) {
+    producer.join();
+  }
+
+  assert(queue.empty());
+}
+
+void runTests() {
+  testPushAndPop();
+  testFifoOrder();
+  testPopWaitsForMessage();
+  testConcurrentPushAndPop();
+}
+
+} // namespace app::tests
+
+int main() {
+  app::tests::runTests();
+
+  return 0;
+}