Collaboration diagram for DDS.DurabilityServiceQosPolicy:

Public Attributes
int	HistoryDepth

HistoryQosPolicyKind	HistoryKind

int	MaxInstances

int	MaxSamples

int	MaxSamplesPerInstance

Duration	ServiceCleanupDelay

Detailed Description

This QosPolicy controls the behaviour of the durability service regarding transient and persistent data.

Attributes

Value	Meaning	Concerns	RxO	Changeable
A duration: service_cleanup_delay	Specifies how long the durability service must wait before it is allowed to remove the information on the transient or persistent topic data-instances as a result of incoming dispose messages.	Topic, DataWriter	No	No
A HistoryQosPolicyKind: history_kind	Specifies the type of history, which may be KEEP_LAST_HISTORY_QOS or KEEP_ALL_HISTORY_QOS, the durability service must apply for the transient or persistent topic data-instances.
A long: history_depth	Specifies the number of samples of each instance of data (identified by its key) that is managed by the durability service for the transient or persistent topic data-instances. If history_kind is KEEP_LAST_HISTORY_QOS, history_depth must be smaller than or equal to max_samples_per_instance for this QosPolicy to be consistent.
A long: max_samples	Specifies the maximum number of data-samples the DataWriter (or DataReader) can manage across all the instances associated with it. Represents the maximum samples the middleware can store for any one DataWriter (or DataReader). It is inconsistent for this value to be less than max_samples_per_instance. By default, LENGTH_UNLIMITED.
A long: max_instances	Represents the maximum number of instances DataWriter (or DataReader) can manage. By default, LENGTH_UNLIMITED.
A long: max_samples_per_instance	Represents the maximum number of samples of any one instance a DataWriter (or DataReader) can manage. It is inconsistent for this value to be greater than max_samples. By default, LENGTH_UNLIMITED.

This QosPolicy controls the behaviour of the durability service regarding transient and persistent data. It controls for the transient or persistent topic; the time at which information regarding the topic may be discarded, the history policy it must set and the resource limits it must apply.

The setting of the DurabilityServiceQosPolicy only applies when kind of the DurabilityQosPolicy is either TRANSIENT_DURABILITY_QOS or PERSISTENT_DURABILITY_QOS. The service_cleanup_delay setting controls at which time the durability service” is allowed to remove all information regarding a data-instance. Information on a data-instance is maintained until the following conditions are met:

The instance has been explicitly disposed of (instance_state = NOT_ALIVE_DISPOSED_INSTANCE_STATE)
The system detects that there are no more “live” DataWriter objects writing the instance, that is, all DataWriter either unregister_instance the instance (call unregister_instance operation) or lose their liveliness
A time interval longer than service_cleanup_delay has elapsed since the moment the Data Distribution Service detected that the previous two conditions were met.

The use of the attribute service_cleanup_delay is apparent in the situation where an application disposes of an instance and it crashes before having a chance to complete additional tasks related to the disposition. Upon re-start the application may ask for initial data to regain its state and the delay introduced by the service_cleanup_delay allows the re-started application to receive the information on the disposed of instance and complete the interrupted tasks.

The attributes history_kind and history_depth apply to the history settings of the durability service’s internal DataWriter and DataReader managing the topic. The HistoryQosPolicy behaviour, applies to these attributes.

The attributes max_samples, max_instances and max_samples_per_instance apply to the resource limits of the Durability Service’s internal DataWriter and DataReader managing the topic. The ResourceLimitsQosPolicy behaviour, applies to these attributes.

Definition at line 1613 of file DdsDcpsStructs.cs.

Member Data Documentation

◆ HistoryDepth

int DDS.DurabilityServiceQosPolicy.HistoryDepth

Definition at line 1617 of file DdsDcpsStructs.cs.

◆ HistoryKind

HistoryQosPolicyKind DDS.DurabilityServiceQosPolicy.HistoryKind

Definition at line 1616 of file DdsDcpsStructs.cs.

◆ MaxInstances

int DDS.DurabilityServiceQosPolicy.MaxInstances

Definition at line 1619 of file DdsDcpsStructs.cs.

◆ MaxSamples

int DDS.DurabilityServiceQosPolicy.MaxSamples

Definition at line 1618 of file DdsDcpsStructs.cs.

◆ MaxSamplesPerInstance

int DDS.DurabilityServiceQosPolicy.MaxSamplesPerInstance

Definition at line 1620 of file DdsDcpsStructs.cs.

◆ ServiceCleanupDelay

Duration DDS.DurabilityServiceQosPolicy.ServiceCleanupDelay

Definition at line 1615 of file DdsDcpsStructs.cs.

The documentation for this struct was generated from the following file:

src/api/dcps/sacs/code/DDS/DdsDcpsStructs.cs

Public Attributes