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https://issues.apache.org/jira/browse/ARTEMIS-4646?focusedWorklogId=906093&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-906093
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ASF GitHub Bot logged work on ARTEMIS-4646:
-------------------------------------------

                Author: ASF GitHub Bot
            Created on: 20/Feb/24 21:06
            Start Date: 20/Feb/24 21:06
    Worklog Time Spent: 10m 
      Work Description: thezbyg commented on code in PR #4823:
URL: https://github.com/apache/activemq-artemis/pull/4823#discussion_r1496507334


##########
tests/integration-tests/src/test/java/org/apache/activemq/artemis/tests/integration/mqtt/MQTTTest.java:
##########
@@ -447,6 +447,59 @@ public void testSendMoreThanUniqueId() throws Exception {
       publisher.disconnect();
    }
 
+   @Ignore
+   @Test(timeout = 600 * 1000)
+   public void testNoMessageIdReuseBeforeAcknowledgment() throws Exception {

Review Comment:
   Fixed test by using two initial messages. Previously it would not fail as 
first message had ID 1 and first ID after wraparound was 2.





Issue Time Tracking
-------------------

    Worklog Id:     (was: 906093)
    Time Spent: 1h  (was: 50m)

> Unacknowledged MQTT message ID is reused after ID generator wraparound
> ----------------------------------------------------------------------
>
>                 Key: ARTEMIS-4646
>                 URL: https://issues.apache.org/jira/browse/ARTEMIS-4646
>             Project: ActiveMQ Artemis
>          Issue Type: Bug
>          Components: MQTT
>            Reporter: Albertas Vyšniauskas
>            Priority: Major
>          Time Spent: 1h
>  Remaining Estimate: 0h
>
> Hello,
> MQTT message IDs are currently generated by incrementing *ids* variable in 
> *{color:#000000}{color:#000000}OutboundStore{color}{color}* class and do not 
> perform any additional checks before trusting that it is unique. This works 
> great until one or more MQTT messages are not acknowledged in timely manner 
> while receiving and acknowledging other messages. A different message with 
> the same ID will be sent after 32767 additional messages are received and 
> acknowledged.
> There are also more issues with MQTT message ID generation:
>  # *AtomicInteger* is used for *ids* variable, but all accesses and 
> modifications are done in synchronized context, so there is no need for it to 
> be atomic.
>  # Maximum allowed *ids* value before wraparound is {*}Short.MAX_VALUE{*}, 
> but MQTT protocol allows values in the range of 1 to 65535 (all unsigned 
> short values except 0).
>  # Wraparound is done to value 1 and is immediately incremented thus skipping 
> message ID 1 and using 2 as first ID after wraparound.
>  # There is a harmless but wrong attempt to remove from *mqttToServerIds* 
> hash map by non-MQTT message ID in the following code: 
> \{_}mqttToServerIds.remove(p.getA());{_}. It is harmless because _p.getA()_ 
> returns *Long* value and will never match any key in *mqttToServerIds* hash 
> map which uses *Integer* keys.{*}{*}



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