Simplify test with new understanding

ecal/tests/cpp/pubsub_test/src/pubsub_test_shm.cpp

@@ -151,20 +151,30 @@ TEST(core_cpp_pubsub, MultipleSendsSHM)
   eCAL::Finalize();
 }
 
-TEST(core_cpp_pubsub, SubscriberReconnectionSHM) {
+TEST(core_cpp_pubsub, SubscriberFastReconnectionSHM) {
   /* Test setup :
-   * publishers runs permanently in a thread
-   * subscriber A start reading topic A
+   * publisher runs permanently in a thread
+   * subscriber A start reading topic
    * subscriber A gets out of scope (destruction)
-   * subscriber B start reading topic B
+   * Small delay less than the registration refresh
+   * subscriber B start reading topic again
    * subscriber B gets out of scope (destruction)
-   * subscriber A starts again in a new scope
    * Test ensures that subscriber is reconnecting and all sync mechanism are
    * working properly again. Previously the test suite was not catching a case
    * where a delay between the destruction of the topic A subscriber and its
    * recreation would create a subscriber that was not receiving messages.
    */
 
+  constexpr auto REGISTRATION_REFRESH_MS = 100;
+  constexpr auto REGISTRATION_TIMEOUT_MS = 10 * REGISTRATION_REFRESH_MS;
+  // The delay between the destruction of the subscriber and its recreation
+  // must be between the registration refresh and the registration timeout
+  constexpr auto RESUBSCRIBE_DELAY =
+      std::chrono::milliseconds(2 * REGISTRATION_REFRESH_MS);
+  // Ensure we wait at least one timeout period
+  constexpr auto RECEIVE_TIMEOUT =
+      std::chrono::milliseconds(2 * REGISTRATION_TIMEOUT_MS);
+
   // Prepare config
   auto config = eCAL::Init::Configuration();
   config.publisher.layer.shm.enable = true;
@@ -173,13 +183,13 @@ TEST(core_cpp_pubsub, SubscriberReconnectionSHM) {
   config.subscriber.layer.shm.enable = true;
   config.subscriber.layer.tcp.enable = false;
   config.subscriber.layer.udp.enable = false;
+  config.registration.registration_refresh = REGISTRATION_REFRESH_MS;
+  config.registration.registration_timeout = REGISTRATION_TIMEOUT_MS;
 
   // initialize eCAL API
   eCAL::Initialize(config, "SubscriberReconnectionSHM");
 
-  constexpr auto RECEIVE_TIMEOUT = std::chrono::seconds(5);
-  constexpr auto TOPIC_A = "shm_reconnect_test_A";
-  constexpr auto TOPIC_B = "shm_reconnect_test_B";
+  constexpr auto TOPIC = "shm_reconnect_test";
 
   // start publishing thread
   std::atomic<bool> stop_publishing(false);
@@ -191,12 +201,9 @@ TEST(core_cpp_pubsub, SubscriberReconnectionSHM) {
     std::cout << "Stopped publishing" << std::endl;
   };
 
-  eCAL::CPublisher pub_foo(TOPIC_A);
+  eCAL::CPublisher pub_foo(TOPIC);
   std::thread pub_foo_t(publish_messages, std::ref(pub_foo));
 
-  eCAL::CPublisher pub_bar(TOPIC_B);
-  std::thread pub_bar_t(publish_messages, std::ref(pub_bar));
-
   std::condition_variable cv;
   std::mutex cv_m;
   bool data_received(false);
@@ -215,9 +222,9 @@ TEST(core_cpp_pubsub, SubscriberReconnectionSHM) {
       };
   std::unique_lock<std::mutex> cv_lk(cv_m);
 
-  // 1 - Subscribe to topic A and receive a message
+  // 1 - Subscribe to topic and receive a message
   {
-    eCAL::CSubscriber sub_foo(TOPIC_A);
+    eCAL::CSubscriber sub_foo(TOPIC);
     sub_foo.SetReceiveCallback(receive_lambda);
 
     // We should receive something within the timeout period
@@ -227,28 +234,14 @@ TEST(core_cpp_pubsub, SubscriberReconnectionSHM) {
     EXPECT_TRUE(data_received);
     std::cout << "Closing first subscriber scope (A)" << std::endl;
   }
-
   data_received = false; // Reset for next scope
 
-  // 2 - Subscribe to topic B and receive a message
-  {
-    eCAL::CSubscriber sub_foo(TOPIC_B);
-    sub_foo.SetReceiveCallback(receive_lambda);
-
-    // We should receive something within the timeout period
-    cv.wait_for(cv_lk, RECEIVE_TIMEOUT,
-                [&data_received]() { return data_received; });
-
-    EXPECT_TRUE(data_received);
-    std::cout << "Closing second subscriber scope (B)" << std::endl;
-  }
-
-  data_received = false; // Reset for next scope
+  // 2 - Small delay to unlink the SHM file but not timeout the observer
+  std::this_thread::sleep_for(RESUBSCRIBE_DELAY);
 
-  // 3 - Subscribe to topic A again and receive a message
-  // TODO: Figure out why this now fails
+  // 3 - Subscribe to topic again and try to receive a message
   {
-    eCAL::CSubscriber sub_foo(TOPIC_A);
+    eCAL::CSubscriber sub_foo(TOPIC);
     sub_foo.SetReceiveCallback(receive_lambda);
 
     // We should receive something within the timeout period
@@ -262,7 +255,6 @@ TEST(core_cpp_pubsub, SubscriberReconnectionSHM) {
   // stop publishing and join thread
   stop_publishing = true;
   pub_foo_t.join();
-  pub_bar_t.join();
 
   // finalize eCAL API
   // without destroying any pub / sub