Discovery
=========

.. Release Notes from this point.

:critical:`[Critical]` Lost INFO_DST messages with GUIDPREFIX_UNKNOWN
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|me| may have silently discarded RTPS INFO_DST messages
containing a *guidPrefix* of ``0x0`` (GUIDPREFIX_UNKNOWN).

[RTI Issue ID MICRO-8751]

:major:`[Major]` DomainParticipants stopped sending announcements to initial peer locator after a discovered DomainParticipant went away
----------------------------------------------------------------------------------------------------------------------------------------
*This issue only affected patch release 4.1.0.1.*

If *DomainParticipant A* discovered *DomainParticipant B* on an initial peer
locator, then lost *DomainParticipant B* and attempted to rediscover it,
*DomainParticipant A* would stop sending discovery announcements to that initial
peer locator.

[RTI Issue ID MICRO-10899]

.. _MICRO-10044:

:major:`[Major]` Possible mismatched endpoint messages during discovery
-----------------------------------------------------------------------
If a *DomainParticipant* receives an endpoint discovery message and lacks
sufficient resources to store the endpoint, |me| will (by default)
acknowledge the message as received, but discard the discovery information.
This can lead to a mismatch in discovery states between *DomainParticipants*. 

This release adds a new field,
``DomainParticipantQos.discovery.enable_endpoint_discovery_queue``, and if this
field is set to ``DDS_BOOLEAN_TRUE``, endpoint discovery messages will instead be
queued for later processing when resources become available.

.. note::

  This new field assumes that there are sufficient resources available for
  discovery information and that the lack of resources is temporary (such as
  during a system restart). Setting this value to ``DDS_BOOLEAN_TRUE`` without
  sufficient resources may cause undefined behavior.

[RTI Issue ID MICRO-10044]

:major:`[Major]` DomainParticipants continued to send DATA(p) messages to nonexistent remote participants
---------------------------------------------------------------------------------------------------------
A *DomainParticipant* might have continued to send DATA(p) discovery
messages to remote *DomainParticipants* that were once discovered but no
longer exist.

[RTI Issue ID MICRO-8747]

:major:`[Major]` DataReader failed to acknowledge samples when it received more instances than it could store
-------------------------------------------------------------------------------------------------------------
A *DataReader* failed to add key instances or acknowledge samples when it
received more instances than its QoS supported.

[RTI Issue ID MICRO-8872]

:minor:`[Minor]` Participants using DPDE sent one extra announcement message
----------------------------------------------------------------------------
Participants using DPDE sent one more participant announcement message than
expected for discovery purposes.

[RTI Issue ID MICRO-8257]

:minor:`[Minor]` Failed to delete a participant before sending at least one participant announcement
----------------------------------------------------------------------------------------------------
If ``DomainParticipantFactory_delete_participant`` was called before
sending at least one participant announcement,
``DomainParticipantFactory_delete_participant`` would return a failure.

[RTI Issue ID MICRO-9828]