DDS_ResourceLimitsQosPolicy Struct Reference

<<cert>> Specifies the resources that RTI Connext Micro can consume in order to meet the requested QoS. More...

#include <dds_c_infrastructure.h>

Data Fields
DDS_Long	max_samples
	Represents the maximum samples the middleware can store for any one DDS_DataWriter (or DDS_DataReader).
DDS_Long	max_instances
	Represents the maximum number of instances a DDS_DataWriter (or DDS_DataReader) can manage.
DDS_Long	max_samples_per_instance
	Represents the maximum number of samples of any one instance a DDS_DataWriter (or DDS_DataReader) can manage.

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Detailed Description

<<cert>> Specifies the resources that RTI Connext Micro can consume in order to meet the requested QoS.

Entity:

DDS_Topic, DDS_DataReader, DDS_DataWriter

Status:

DDS_SAMPLE_REJECTED_STATUS, DDS_SampleRejectedStatus

Properties:

RxO = NO
Changeable = UNTIL ENABLE

Usage

This policy controls the resources that RTI Connext Micro can use in order to meet the requirements imposed by the application and other QoS settings. If DDS_DataWriter objects are communicating samples faster than they are ultimately taken by the DDS_DataReader objects, the middleware will eventually hit against some of the QoS-imposed resource limits. Note that this may occur when just a single DDS_DataReader cannot keep up with its corresponding DDS_DataWriter. The behavior in this case depends on the setting for the RELIABILITY. If reliability is DDS_BEST_EFFORT_RELIABILITY_QOS then RTI Connext Micro is allowed to drop samples. If the reliability is DDS_RELIABLE_RELIABILITY_QOS, RTI Connext Micro will block the DDS_DataWriter or discard the sample at the DDS_DataReader in order not to lose existing samples.

See also:

DDS_ReliabilityQosPolicy

DDS_HistoryQosPolicy

Consistency

All limits must be set to positive finite values. Furthermore, max_samples must be large enough to contain all samples for all instances:

 max_samples >= max_instances * max_samples_per_instance 

The setting of RESOURCE_LIMITS max_samples_per_instance must be consistent with the HISTORY depth. For these two QoS to be consistent, they must verify that depth <= max_samples_per_instance.

See also:

DDS_HistoryQosPolicy

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Field Documentation

DDS_Long DDS_ResourceLimitsQosPolicy::max_samples

Represents the maximum samples the middleware can store for any one DDS_DataWriter (or DDS_DataReader).

Specifies the maximum number of data samples a DDS_DataWriter (or DDS_DataReader) can manage across all the instances associated with it. For unkeyed types this value has to be equal to max_samples_per_instance. [default] 1 [range] [1, 100 million] >= (max_samples_per_instance * max_instances),

DDS_Long DDS_ResourceLimitsQosPolicy::max_instances

Represents the maximum number of instances a DDS_DataWriter (or DDS_DataReader) can manage.

[default] 1 [range] [1, 1 million]

DDS_Long DDS_ResourceLimitsQosPolicy::max_samples_per_instance

Represents the maximum number of samples of any one instance a DDS_DataWriter (or DDS_DataReader) can manage.

For unkeyed types this value has to be equal to max_samples. [default] 1 [range] [1, 100 million], <= max_samples, >= DDS_HistoryQosPolicy::depth