Do not confirmSelect more than once per channel

src/main/java/com/rabbitmq/client/impl/ChannelN.java

@@ -82,6 +82,9 @@ public class ChannelN extends AMQChannel implements com.rabbitmq.client.Channel
     private final SortedSet<Long> unconfirmedSet =
             Collections.synchronizedSortedSet(new TreeSet<Long>());
 
+    /** Whether the confirm select method has been successfully activated */
+    private boolean confirmSelectActivated = false;
+
     /** Whether any nacks have been received since the last waitForConfirms(). */
     private volatile boolean onlyAcksReceived = true;
 
@@ -1553,10 +1556,16 @@ public Tx.RollbackOk txRollback()
     public Confirm.SelectOk confirmSelect()
         throws IOException
     {
+        if (confirmSelectActivated) {
+            return new Confirm.SelectOk();
+        }
+
         if (nextPublishSeqNo == 0) nextPublishSeqNo = 1;
-        return (Confirm.SelectOk)
+        Confirm.SelectOk result = (Confirm.SelectOk)
             exnWrappingRpc(new Confirm.Select(false)).getMethod();
 
+        confirmSelectActivated = true;
+        return result;
     }
 
     /** Public API - {@inheritDoc} */

src/test/java/com/rabbitmq/client/test/ChannelNTest.java

@@ -15,7 +15,9 @@
 
 package com.rabbitmq.client.test;
 
+import com.rabbitmq.client.Command;
 import com.rabbitmq.client.Method;
+import com.rabbitmq.client.TrafficListener;
 import com.rabbitmq.client.impl.*;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -26,6 +28,7 @@
 import java.util.concurrent.Executors;
 import java.util.stream.Stream;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 
 public class ChannelNTest {
 
@@ -81,6 +84,29 @@ public TestConfig(int value, Consumer call) {
                 .forEach(config -> assertThatThrownBy(() -> config.call.apply(config.value)).isInstanceOf(IllegalArgumentException.class));
     }
 
+    @Test
+    public void confirmSelectOnlySendsRPCCallOnce() throws Exception {
+        AMQConnection connection = Mockito.mock(AMQConnection.class);
+        TrafficListener trafficListener = Mockito.mock(TrafficListener.class);
+
+        Mockito.when(connection.getTrafficListener()).thenReturn(trafficListener);
+
+        ChannelN channel = new ChannelN(connection, 1, consumerWorkService);
+
+        new Thread(() -> {
+            try {
+                Thread.sleep(15);
+                channel.handleCompleteInboundCommand(new AMQCommand(new AMQImpl.Confirm.SelectOk()));
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+        }).start();
+
+        assertNotNull(channel.confirmSelect());
+        assertNotNull(channel.confirmSelect());
+        Mockito.verify(trafficListener, Mockito.times(1)).write(Mockito.any(Command.class));
+    }
+
     interface Consumer {
 
         void apply(int value) throws Exception;