[21233] Mitigate buffer recover test flakiness on mac (backport #5035)

test/unittest/transport/SharedMemTests.cpp

@@ -1433,7 +1433,7 @@ TEST_F(SHMTransportTests, buffer_recover)
                         {
                             auto buffer = listener1->pop();
 
-                            if (buffer)
+                            if (nullptr != buffer)
                             {
                                 listener1_recv_count.fetch_add(1);
                                 // This is a slow listener
@@ -1453,7 +1453,7 @@ TEST_F(SHMTransportTests, buffer_recover)
                         {
                             auto buffer = listener2->pop();
 
-                            if (buffer)
+                            if (nullptr != buffer)
                             {
                                 listener2_recv_count.fetch_add(1);
                                 std::this_thread::sleep_for(std::chrono::milliseconds(listener2_sleep_ms));
@@ -1554,17 +1554,48 @@ TEST_F(SHMTransportTests, buffer_recover)
 
     exit_listeners = true;
 
+    // This third part of the test just tries to cleanly
+    // exit the threads.
+
+    // At this point, listeners are blocked
+    // in the pop() method, and the ring buffers
+    // may (or not) be full.
+
+    //  In order to make the listeners exit the pop() method
+    //  we have to options:
+    //  - Waiting for the port_timeout_ms
+    //  - try pushing another buffer, so that cv could be
+    //   notified.
+
+    // Sleeping the thread waiting for the port timeout
+    // is more risky as the healthy timeout port watchdog
+    // can be triggered, so we choose the second option.
+
     {
         auto buf = segment->alloc_buffer(1u, std::chrono::steady_clock::time_point());
+        bool buffer_pushed = false;
         {
             is_port_ok = false;
-            ASSERT_TRUE(pub_sub1_write->try_push(buf, is_port_ok));
-            ASSERT_TRUE(is_port_ok);
+            while (!buffer_pushed)
+            {
+                buffer_pushed = pub_sub1_write->try_push(buf, is_port_ok);
+                //! In any case port should not be ok
+                ASSERT_TRUE(is_port_ok);
+                std::this_thread::sleep_for(std::chrono::milliseconds(150));
+            }
         }
+
+        buffer_pushed = false;
+
         {
             is_port_ok = false;
-            ASSERT_TRUE(pub_sub2_write->try_push(buf, is_port_ok));
-            ASSERT_TRUE(is_port_ok);
+            while (!buffer_pushed)
+            {
+                buffer_pushed = pub_sub2_write->try_push(buf, is_port_ok);
+                //! In any case port should not be ok
+                ASSERT_TRUE(is_port_ok);
+                std::this_thread::sleep_for(std::chrono::milliseconds(150));
+            }
         }
     }