[fix][cpp] Clear stale consumer connection after reconnect subscribe failure

lib/ConsumerImpl.cc

@@ -371,8 +371,9 @@ Result ConsumerImpl::handleCreateConsumer(const ClientConnectionPtr& cnx, Result
         }
 
         if (consumerCreatedPromise_.isComplete()) {
-            // Consumer had already been initially created, we need to retry connecting in any case
+            // Clear the connection set before SUBSCRIBE so the next reconnect is not skipped.
             LOG_WARN(getName() << "Failed to reconnect consumer: " << strResult(result));
+            resetCnx();
             handleResult = ResultRetryable;
         } else {
             // Consumer was not yet created, retry to connect to broker if it's possible

tests/ConsumerTest.cc

@@ -1596,4 +1596,40 @@ TEST(ConsumerTest, testCloseAfterSeek) {
     anotherClient.close();
 }
 
+TEST(ConsumerTest, testIsConnectedFalsePositiveAfterSubscribeRejectedOnReconnect) {
+    // A reconnect SUBSCRIBE failure happens after the initial subscribe has already completed.
+    const std::string topic =
+        "persistent://public/default/test-false-positive-" + std::to_string(time(nullptr));
+    Client client(lookupUrl);
+    Consumer consumer;
+    ASSERT_EQ(ResultOk, client.subscribe(topic, "sub", consumer));
+    ASSERT_TRUE(consumer.isConnected()) << "Precondition: consumer should be connected";
+
+    auto& consumerImpl = PulsarFriend::getConsumerImpl(consumer);
+
+    // Capture the current live connection.
+    auto cnx = consumerImpl.getCnx().lock();
+    ASSERT_TRUE(cnx != nullptr) << "Precondition: cnx should be non-null";
+    LOG_INFO("Step 1 passed: consumer subscribed, cnx=" << cnx);
+
+    // Simulate the broker rejecting the SUBSCRIBE command during reconnect.
+    Result handleResult = PulsarFriend::consumerHandleCreateConsumer(consumer, cnx, ResultAuthorizationError);
+    LOG_INFO("Step 2: handleCreateConsumer returned " << handleResult);
+    EXPECT_EQ(ResultRetryable, handleResult)
+        << "handleCreateConsumer should return ResultRetryable for an already-created consumer";
+
+    // The failed SUBSCRIBE must clear the connection set before SUBSCRIBE.
+    auto cnxAfter = consumerImpl.getCnx().lock();
+    LOG_INFO("Step 3: cnx after handleCreateConsumer failure = " << cnxAfter);
+    LOG_INFO("Step 3: isConnected() = " << consumer.isConnected());
+
+    EXPECT_EQ(nullptr, cnxAfter)
+        << "After fix: connection_ must be cleared by resetCnx() so grabCnx() can retry";
+    EXPECT_FALSE(consumer.isConnected())
+        << "After fix: isConnected() must return false after SUBSCRIBE rejection";
+
+    consumer.close();
+    client.close();
+}
+
 }  // namespace pulsar

tests/PulsarFriend.h

@@ -102,6 +102,11 @@ class PulsarFriend {
         return *consumerImpl;
     }
 
+    static Result consumerHandleCreateConsumer(Consumer consumer, const ClientConnectionPtr& cnx,
+                                               Result result) {
+        return getConsumerImpl(consumer).handleCreateConsumer(cnx, result);
+    }
+
     static std::shared_ptr<ConsumerImpl> getConsumerImplPtr(Consumer consumer) {
         return std::static_pointer_cast<ConsumerImpl>(consumer.impl_);
     }