RTI Connext DDS Micro C API  Version 3.0.2
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups
The max_instance resource-limit limits the maximum number of instances a DDS_DataReader can manage. Instance state is one of the most expensive resources to maintain as well as often being the highest one.
The resources allocated by an instance is normally only released when an instance is disposed and all known owners have unregistered the instance, please refer to FooDataWriter_unregister_instance and FooDataWriter_dispose.
The DDS_DataReaderResourceLimitsQosPolicy::instance_replacement policy is useful to maintain state for only the last N instances and when it is not necessary to keep samples in the DDS_DataReader history cache. When the DDS_DataReaderResourceLimitsQosPolicy::instance_replacement policy is set to replace the oldest instance (DDS_REPLACE_OLDEST_INSTANCE_REPLACEMENT_QOS), information about the oldest instance is automatically removed and the newly discovered instance is received. The disadvantage is that DDS_NOT_ALIVE_NO_WRITERS_INSTANCE_STATE state cannot be maintained. The DDS_NOT_ALIVE_DISPOSED_INSTANCE_STATE is maintained for an instance that is accepted (either there is space or another instance is replaced), regardless of whether any samples have previously been received.
DDS_DataReaderResourceLimitsInstanceReplacementKind instance_replacement

RTI Connext DDS Micro C API Version 3.0.2 Copyright © Thu Dec 12 2019 Real-Time Innovations, Inc