RTI Connext .NET API (legacy)
Version 6.1.0
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<<interface>> <<generic>> User data type-specific data reader. More...
#include <managed_subscription.h>
Public Member Functions | |
DDS::Ext::LoanedSamples< T > ^ | read () |
Reads all the samples. More... | |
DDS::Ext::LoanedSamples< T > ^ | take () |
Takes all the samples. More... | |
DDS::Selector< T > ^ | select () |
Get a Selector to perform data selections, such as per-instance selection or content filtering. More... | |
void | read (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Access a collection of data samples from the DDS::DataReader. More... | |
void | take (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Access a collection of data-samples from the DDS::DataReader. More... | |
void | read_w_condition (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::ReadCondition^ condition) |
Accesses via DDS::TypedDataReader::read the samples that match the criteria specified in the DDS::ReadCondition. More... | |
void | take_w_condition (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::ReadCondition^ condition) |
Analogous to DDS::TypedDataReader::read_w_condition except it accesses samples via the DDS::TypedDataReader::take operation. More... | |
void | read_next_sample (T received_data, DDS::SampleInfo^ sample_info) |
Copies the next not-previously-accessed data value from the DDS::DataReader. More... | |
void | take_next_sample (T received_data, DDS::SampleInfo^ sample_info) |
Copies the next not-previously-accessed data value from the DDS::DataReader. More... | |
void | read_instance (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% a_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Access a collection of data samples from the DDS::DataReader. More... | |
void | take_instance (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% a_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Access a collection of data samples from the DDS::DataReader. More... | |
void | read_next_instance (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Access a collection of data samples from the DDS::DataReader. More... | |
void | take_next_instance (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Access a collection of data samples from the DDS::DataReader. More... | |
void | read_next_instance_w_condition (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, DDS::ReadCondition^ condition) |
Accesses via DDS::TypedDataReader::read_next_instance the samples that match the criteria specified in the DDS::ReadCondition. More... | |
void | take_next_instance_w_condition (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, DDS::ReadCondition^ condition) |
Accesses via DDS::TypedDataReader::take_next_instance the samples that match the criteria specified in the DDS::ReadCondition. More... | |
void | return_loan (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq) |
Indicates to the DDS::DataReader that the application is done accessing the collection of received_data and info_seq obtained by some earlier invocation of read or take on the DDS::DataReader. More... | |
void | get_key_value (T key_holder, DDS::InstanceHandle_t% handle) |
Retrieve the instance key that corresponds to an instance handle . More... | |
DDS::InstanceHandle_t | lookup_instance (T key_holder) |
Retrieves the instance handle that corresponds to an instance key_holder . More... | |
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ReadCondition ^ | create_readcondition (System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Creates a DDS::ReadCondition. More... | |
ReadCondition ^ | create_readcondition_w_params (ReadConditionParams ^ params) |
<<extension>> Creates a DDS::ReadCondition with parameters. More... | |
QueryCondition ^ | create_querycondition (System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states, System::String^ query_expression, StringSeq^ query_parameters) |
Creates a DDS::QueryCondition. More... | |
QueryCondition ^ | create_querycondition_w_params (QueryConditionParams ^ params) |
<<extension>> Creates a DDS::QueryCondition with parameters. More... | |
void | delete_readcondition (ReadCondition^% condition) |
Deletes a DDS::ReadCondition or DDS::QueryCondition attached to the DDS::DataReader. More... | |
void | delete_contained_entities () |
Deletes all the entities that were created by means of the "create" operations on the DDS::DataReader. More... | |
void | wait_for_historical_data (Duration_t% max_wait) |
Waits until all "historical" data is received for DDS::DataReader entities that have a non-VOLATILE Durability Qos kind. More... | |
void | acknowledge_sample (SampleInfo ^ sample_info, AckResponseData_t ^ response_data) |
<<extension>> Acknowledges a single sample explicitly. More... | |
void | acknowledge_sample (SampleInfo ^ sample_info) |
<<extension>> Acknowledges a single sample explicitly. More... | |
void | acknowledge_all (AckResponseData_t ^ response_data) |
<<extension>> Acknowledges all previously accessed samples. More... | |
void | acknowledge_all () |
<<extension>> Acknowledges all previously accessed samples. More... | |
void | get_matched_publications (InstanceHandleSeq^ publication_handles) |
Retrieves the list of publications currently "associated" with this DDS::DataReader. More... | |
void | get_matched_publication_data (PublicationBuiltinTopicData^ publication_data, InstanceHandle_t% publication_handle) |
Retrieves the information on a publication that is currently "associated" with the DDS::DataReader. More... | |
bool | is_matched_publication_alive (InstanceHandle_t% publication_handle) |
Check if a publication currently matched with a DataReader is alive. More... | |
void | get_matched_publication_participant_data (ParticipantBuiltinTopicData^ participant_data, InstanceHandle_t% publication_handle) |
<<extension>> Retrieves the information on the discovered DDS::DomainParticipant associated with the publication that is currently matching with the DDS::DataReader. More... | |
ITopicDescription ^ | get_topicdescription () |
Returns the ITopicDescription associated with the DDS::DataReader. More... | |
Subscriber ^ | get_subscriber () |
Returns the DDS::Subscriber to which the DDS::DataReader belongs. More... | |
void | get_sample_rejected_status (SampleRejectedStatus% status) |
Accesses the SAMPLE_REJECTED_STATUS communication status. More... | |
void | get_liveliness_changed_status (LivelinessChangedStatus% status) |
Accesses the LIVELINESS_CHANGED_STATUS communication status. More... | |
void | get_requested_deadline_missed_status (RequestedDeadlineMissedStatus% status) |
Accesses the REQUESTED_DEADLINE_MISSED_STATUS communication status. More... | |
void | get_requested_incompatible_qos_status (RequestedIncompatibleQosStatus^ status) |
Accesses the REQUESTED_INCOMPATIBLE_QOS_STATUS communication status. More... | |
void | get_sample_lost_status (SampleLostStatus% status) |
Accesses the SAMPLE_LOST_STATUS communication status. More... | |
void | get_subscription_matched_status (SubscriptionMatchedStatus% status) |
Accesses the SUBSCRIPTION_MATCHED_STATUS communication status. More... | |
virtual void | get_datareader_cache_status (DataReaderCacheStatus% status) |
<<extension>> Gets the datareader cache status for this reader. More... | |
virtual void | get_datareader_protocol_status (DataReaderProtocolStatus% status) |
<<extension>> Gets the datareader protocol status for this reader. More... | |
virtual void | get_matched_publication_datareader_protocol_status (DataReaderProtocolStatus% status, InstanceHandle_t% publication_handle) |
<<extension>> Gets the datareader protocol status for this reader, per matched publication identified by the publication_handle. More... | |
void | set_qos (DataReaderQos^ qos) |
Sets the reader QoS. More... | |
void | set_qos_with_profile (System::String^ library_name, System::String^ profile_name) |
<<extension>> Changes the QoS of this reader using the input XML QoS profile. More... | |
void | get_qos (DataReaderQos^ qos) |
Gets the reader QoS. More... | |
void | set_listener (DataReaderListener^ l, StatusMask mask) |
Sets the reader listener. More... | |
DataReaderListener ^ | get_listener () |
Gets the reader listener. More... | |
TopicQuery ^ | create_topic_query (TopicQuerySelection^ selection) |
Creates a DDS::TopicQuery. More... | |
void | delete_topic_query (TopicQuery^% query) |
Deletes a DDS::TopicQuery. More... | |
TopicQuery ^ | lookup_topic_query (GUID_t% guid) |
Retrieves an existing DDS::TopicQuery. More... | |
template<typename T > | |
void | read_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Reads data samples, if any are available. More... | |
template<typename T > | |
void | take_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Takes data samples, if any are available. More... | |
template<typename T > | |
void | read_w_condition_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::ReadCondition^ condition) |
Reads data samples, if any are available. More... | |
template<typename T > | |
void | take_w_condition_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::ReadCondition^ condition) |
Takes data samples, if any are available. More... | |
void | read_next_sample_untyped (System::Object^ received_data, DDS::SampleInfo^ sample_info) |
Reads data samples, if any are available. More... | |
void | take_next_sample_untyped (System::Object^ received_data, DDS::SampleInfo^ sample_info) |
Takes data samples, if any are available. More... | |
template<typename T > | |
void | read_instance_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% a_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Reads data samples, if any are available. More... | |
template<typename T > | |
void | take_instance_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% a_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Takes data samples, if any are available. More... | |
template<typename T > | |
void | read_next_instance_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Reads data samples, if any are available. More... | |
template<typename T > | |
void | take_next_instance_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states) |
Takes data samples, if any are available. More... | |
template<typename T > | |
void | read_next_instance_w_condition_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, DDS::ReadCondition^ condition) |
Reads data samples, if any are available. More... | |
template<typename T > | |
void | take_next_instance_w_condition_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, DDS::ReadCondition^ condition) |
Takes data samples, if any are available. More... | |
template<typename T > | |
void | return_loan_untyped (DDS::LoanableSequence< T >^ received_data, DDS::SampleInfoSeq^ info_seq) |
Returns loaned sample data and meta-data. More... | |
void | get_key_value_untyped (System::Object^ key_holder, DDS::InstanceHandle_t% handle) |
Fills in the key fields of the given data sample. More... | |
DDS::InstanceHandle_t | lookup_instance_untyped (System::Object^ key_holder) |
virtual void | enable () override |
Enables the DDS::Entity. More... | |
virtual StatusCondition ^ | get_statuscondition () override |
Allows access to the DDS::StatusCondition associated with the DDS::Entity. More... | |
virtual StatusMask | get_status_changes () override |
Retrieves the list of communication statuses in the DDS::Entity that are triggered. More... | |
virtual InstanceHandle_t | get_instance_handle () override |
Allows access to the DDS::InstanceHandle_t associated with the DDS::Entity. More... | |
Additional Inherited Members | |
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static TopicQuerySelection^ | TOPIC_QUERY_SELECTION_USE_READER_CONTENT_FILTER [get] |
Special value for creating a DDS::TopicQuery that applies the same filter as the DataReader's DDS::ContentFilteredTopic. More... | |
static TopicQuerySelection^ | TOPIC_QUERY_SELECTION_SELECT_ALL [get] |
Special value for creating a DDS::TopicQuery that selects all the samples in a DDS::DataWriter cache. More... | |
<<interface>> <<generic>> User data type-specific data reader.
Defines the user data type specific reader interface generated for each application class.
The concrete user data type reader automatically generated by the implementation is an incarnation of this class.
DDS::Ext::LoanedSamples<T> ^ DDS::TypedDataReader< T >::read | ( | ) |
Reads all the samples.
This operation reads the same data as
But unlike the previous operation, this function returns a LoanedSamples container and doesn't throw Retcode_NoData (it returns an empty collection).
This operation is exactly equivalent to select().read().
DDS::Ext::LoanedSamples<T> ^ DDS::TypedDataReader< T >::take | ( | ) |
Takes all the samples.
This operation takes the same data as
But unlike the previous operation, this function returns a LoanedSamples container and doesn't throw Retcode_NoData (it returns an empty collection).
This operation is exactly equivalent to select().take().
DDS::Selector<T> ^ DDS::TypedDataReader< T >::select | ( | ) |
Get a Selector to perform data selections, such as per-instance selection or content filtering.
This functions returns a Selector object that can be configured with any of the parameters to a read or take operation.
The samples selected by this operation are returned in a LoanedSamples container, which implements IDisposable (to return the loan), and IEnumerable.
In addition, when a select() operation reads no samples, instead of throwing the exception DDS::Retcode_NoData, the Selector returns an empty collection.
select() is the preferred way to read or take data samples and can replace the following methods (and their corresponding *_take() methods):
The following C# example code shows how to use select() to read up to 100 not-previously-read samples for a given instance:
The previous code is equivalent to the following one, using the function read_instance():
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inline |
Access a collection of data samples from the DDS::DataReader.
This operation offers the same functionality and API as DDS::TypedDataReader::take except that the samples returned remain in the DDS::DataReader such that they can be retrieved again by means of a read or take operation.
Please refer to the documentation of DDS::TypedDataReader::take() for details on the number of samples returned within the received_data and info_seq as well as the order in which the samples appear in these sequences.
The act of reading a sample changes its sample_state
to DDS::SampleStateKind::READ_SAMPLE_STATE. If the sample belongs to the most recent generation of the instance, it will also set the view_state
of the instance to be DDS::ViewStateKind::NOT_NEW_VIEW_STATE. It will not affect the instance_state
of the instance.
Once the application completes its use of the samples, it must 'return the loan' to the DDS::DataReader by calling the DDS::TypedDataReader::return_loan operation.
Important: When you loan data from the middleware, you must not keep any pointers to any part of the data samples or the DDS::SampleInfo objects after the call to DDS::TypedDataReader::return_loan. Returning the loan places the objects back into a pool, allowing the middleware to overwrite them with new data.
Note: While you must call DDS::TypedDataReader::return_loan at some point, you do not have to do so before the next DDS::TypedDataReader::take call. However, failure to return the loan will eventually deplete the DDS::DataReader of the buffers it needs to receive new samples and eventually samples will start to be lost. The total number of buffers available to the DDS::DataReader is specified by the DDS::ResourceLimitsQosPolicy and the DDS::DataReaderResourceLimitsQosPolicy.
Important: If the samples "returned" by this method are loaned from RTI Connext (see DDS::TypedDataReader::take for more information on memory loaning), it is important that their contents not be changed. Because the memory in which the data is stored belongs to the middleware, any modifications made to the data will be seen the next time the same samples are read or taken; the samples will no longer reflect the state that was received from the network.
received_data | <<inout>> User data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> A DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
sample_states | <<in>> Data samples matching one of these sample_states are returned. See the valid values for this parameter here: DDS::SampleStateKind. |
view_states | <<in>> Data samples matching one of these view_state are returned. See the valid values for this parameter here: DDS::ViewStateKind. |
instance_states | <<in>> Data samples matching ones of these instance_state are returned. See the valid values for this parameter here: DDS::InstanceStateKind. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
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inline |
Access a collection of data-samples from the DDS::DataReader.
The operation will return the list of samples received by the DDS::DataReader since the last DDS::TypedDataReader::take operation that matches the specified sample_states
, view_states
and instance_states
.
This operation may fail with DDS::Retcode_Error if the DDS::DataReaderResourceLimitsQosPolicy::max_outstanding_reads limit has been exceeded.
The actual number of samples returned depends on the information that has been received by the middleware as well as the DDS::HistoryQosPolicy, DDS::ResourceLimitsQosPolicy, DDS::DataReaderResourceLimitsQosPolicy and the characteristics of the data-type that is associated with the DDS::DataReader:
If the read or take succeeds and the number of samples returned has been limited (by means of a maximum limit, as listed above, or insufficient DDS::SampleInfo resources), the call will complete successfully and provide those samples the reader is able to return. The user may need to make additional calls, or return outstanding loaned buffers in the case of insufficient resources, in order to access remaining samples.
Note that in the case where the DDS::Topic associated with the DDS::DataReader is bound to a data-type that has no key definition, then there will be at most one instance in the DDS::DataReader. So the per-sample limits will apply.
The act of taking a sample removes it from RTI Connext so it cannot be read or taken again. If the sample belongs to the most recent generation of the instance, it will also set the view_state
of the sample's instance to DDS::ViewStateKind::NOT_NEW_VIEW_STATE. It will not affect the instance_state
of the sample's instance.
After DDS::TypedDataReader::take completes, received_data
and info_seq
will be of the same length and contain the received data.
If the sequences are empty (maximum size equals 0) when the DDS::TypedDataReader::take is called, the samples returned in the received_data
and the corresponding info_seq
are 'loaned' to the application from buffers provided by the DDS::DataReader. The application can use them as desired and has guaranteed exclusive access to them.
Once the application completes its use of the samples it must 'return the loan' to the DDS::DataReader by calling the DDS::TypedDataReader::return_loan operation.
Important: When you loan data from the middleware, you must not keep any pointers to any part of the data samples or the DDS::SampleInfo objects after the call to DDS::TypedDataReader::return_loan. Returning the loan places the objects back into a pool, allowing the middleware to overwrite them with new data.
Note: While you must call DDS::TypedDataReader::return_loan at some point, you do not have to do so before the next DDS::TypedDataReader::take call. However, failure to return the loan will eventually deplete the DDS::DataReader of the buffers it needs to receive new samples and eventually samples will start to be lost. The total number of buffers available to the DDS::DataReader is specified by the DDS::ResourceLimitsQosPolicy and the DDS::DataReaderResourceLimitsQosPolicy.
If the sequences are not empty (maximum size not equal to 0 and length not equal to 0) when DDS::TypedDataReader::take is called, samples are copied to received_data and info_seq. The application will not need to call DDS::TypedDataReader::return_loan.
The order of the samples returned to the caller depends on the DDS::PresentationQosPolicy.
In any case, the relative order between the samples of one instance is consistent with the DESTINATION_ORDER policy:
source_timestamp
(FIFO, smaller values of source_timestamp
ahead of the larger values). If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
In addition to the collection of samples, the read and take operations also use a collection of DDS::SampleInfo structures.
The initial (input) properties of the received_data
and info_seq
collections will determine the precise behavior of the read or take operation. For the purposes of this description, the collections are modeled as having these properties:
owns
, see DDS::Sequence::has_ownership) len
, see DDS::Sequence::length) max_len
, see DDS::Sequence::maximum) The initial values of the owns
, len
and max_len
properties for the received_data
and info_seq
collections govern the behavior of the read and take operations as specified by the following rules:
The values of owns
, len
and max_len
properties for the two collections must be identical. Otherwise read/take will fail with DDS::Retcode_PreconditionNotMet.
On successful output, the values of owns
, len
and max_len
will be the same for both collections.
If the initial max_len==0
, then the received_data
and info_seq
collections will be filled with elements that are loaned by the DDS::DataReader. On output, owns
will be FALSE, len
will be set to the number of values returned, and max_len
will be set to a value verifying max_len
>= len
. The use of this variant allows for Zero Copy access to the data and the application will need to return the loan to the DDS::DataWriter using DDS::TypedDataReader::return_loan.
If the initial max_len>0
and owns==FALSE
, then the read or take operation will fail with DDS::Retcode_PreconditionNotMet. This avoids the potential hard-to-detect memory leaks caused by an application forgetting to return the loan.
If initial max_len>0
and owns==TRUE
, then the read or take operation will copy the received_data
values and DDS::SampleInfo values into the elements already inside the collections. On output, owns
will be TRUE, len
will be set to the number of values copied and max_len
will remain unchanged. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to return the loan. The number of samples copied depends on the relative values of max_len
and max_samples:
If max_samples
== LENGTH_UNLIMITED, then at most max_len
values will be copied. The use of this variant lets the application limit the number of samples returned to what the sequence can accommodate.
If max_samples
<= max_len
, then at most max_samples
values will be copied. The use of this variant lets the application limit the number of samples returned to fewer that what the sequence can accommodate.
max_samples
> max_len
, then the read or take operation will fail with DDS::Retcode_PreconditionNotMet. This avoids the potential confusion where the application expects to be able to access up to max_samples
, but that number can never be returned, even if they are available in the DDS::DataReader, because the output sequence cannot accommodate them. As described above, upon completion, the received_data
and info_seq
collections may contain elements loaned from the DDS::DataReader. If this is the case, the application will need to use DDS::TypedDataReader::return_loan to return the loan once it is no longer using the received_data
in the collection. When DDS::TypedDataReader::return_loan completes, the collection will have owns=FALSE
and max_len=0
. The application can determine whether it is necessary to return the loan or not based on how the state of the collections when the read/take operation was called or by accessing the owns
property. However, in many cases it may be simpler to always call DDS::TypedDataReader::return_loan, as this operation is harmless (i.e., it leaves all elements unchanged) if the collection does not have a loan. To avoid potential memory leaks, the implementation of the Foo and DDS::SampleInfo collections should disallow changing the length of a collection for which owns==FALSE
. Furthermore, deleting a collection for which owns==FALSE
should be considered an error.
On output, the collection of Foo values and the collection of DDS::SampleInfo structures are of the same length and are in a one-to-one correspondence. Each DDS::SampleInfo provides information, such as the source_timestamp, the sample_state, view_state, and instance_state, etc., about the corresponding sample. Some elements in the returned collection may not have valid data. If the instance_state in the DDS::SampleInfo is DDS::InstanceStateKind::NOT_ALIVE_DISPOSED_INSTANCE_STATE or DDS::InstanceStateKind::NOT_ALIVE_NO_WRITERS_INSTANCE_STATE, then the last sample for that instance in the collection (that is, the one whose DDS::SampleInfo has sample_rank==0) does not contain valid data.
Samples that contain no data do not count towards the limits imposed by the DDS::ResourceLimitsQosPolicy. The act of reading/taking a sample sets its sample_state to DDS::SampleStateKind::READ_SAMPLE_STATE.
If the sample belongs to the most recent generation of the instance, it will also set the view_state of the instance to DDS::ViewStateKind::NOT_NEW_VIEW_STATE. It will not affect the instance_state of the instance.
This operation must be provided on the specialized class that is generated for the particular application data-type that is being read (Foo).
If the DDS::DataReader has no samples that meet the constraints, the operations fails with DDS::Retcode_NoData. For an example on how take
can be used, please refer to the receive example.
received_data | <<inout>> User data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> A DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described above. |
sample_states | <<in>> Data samples matching one of these sample_states are returned. See the valid values for this parameter here: DDS::SampleStateKind. |
view_states | <<in>> Data samples matching one of these view_state are returned. See the valid values for this parameter here: DDS::ViewStateKind. |
instance_states | <<in>> Data samples matching one of these instance_state are returned. See the valid values for this parameter here: DDS::InstanceStateKind. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Accesses via DDS::TypedDataReader::read the samples that match the criteria specified in the DDS::ReadCondition.
This operation is especially useful in combination with DDS::QueryCondition to filter data samples based on the content.
The specified DDS::ReadCondition must be attached to the DDS::DataReader; otherwise the operation will fail with DDS::Retcode_PreconditionNotMet.
In case the DDS::ReadCondition is a plain DDS::ReadCondition and not the specialized DDS::QueryCondition, the operation is equivalent to calling DDS::TypedDataReader::read and passing as sample_states
, view_states
and instance_states
the value of the corresponding attributes in the read_condition
. Using this operation, the application can avoid repeating the same parameters specified when creating the DDS::ReadCondition.
The samples are accessed with the same semantics as DDS::TypedDataReader::read.
If the DDS::DataReader has no samples that meet the constraints, the operation will fail with DDS::Retcode_NoData.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
condition | <<in>> the DDS::ReadCondition to select samples of interest. Cannot be NULL. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Analogous to DDS::TypedDataReader::read_w_condition except it accesses samples via the DDS::TypedDataReader::take operation.
This operation is analogous to DDS::TypedDataReader::read_w_condition except that it accesses samples via the DDS::TypedDataReader::take operation.
The specified DDS::ReadCondition must be attached to the DDS::DataReader; otherwise the operation will fail with DDS::Retcode_PreconditionNotMet.
The samples are accessed with the same semantics as DDS::TypedDataReader::take.
This operation is especially useful in combination with DDS::QueryCondition to filter data samples based on the content.
If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
condition | <<in>> the DDS::ReadCondition to select samples of interest. Cannot be NULL. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Copies the next not-previously-accessed data value from the DDS::DataReader.
This operation copies the next not-previously-accessed data value from the DDS::DataReader. This operation also copies the corresponding DDS::SampleInfo. The implied order among the samples stored in the DDS::DataReader is the same as for the DDS::TypedDataReader::read operation.
The DDS::TypedDataReader::read_next_sample operation is semantically equivalent to the DDS::TypedDataReader::read operation, where the input data sequences has max_len=1, the sample_states=NOT_READ, the view_states=ANY_VIEW_STATE, and the instance_states=ANY_INSTANCE_STATE.
The DDS::TypedDataReader::read_next_sample operation provides a simplified API to 'read' samples, avoiding the need for the application to manage sequences and specify states.
If there is no unread data in the DDS::DataReader, the operation will fail with DDS::Retcode_NoData and nothing is copied.
received_data | <<inout>> user data type-specific Foo object where the next received data sample will be returned. The received_data must have been fully allocated. Otherwise, this operation may fail. Must be a valid non-NULL Foo. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
sample_info | <<inout>> a DDS::SampleInfo object where the next received sample info will be returned. Must be a valid non-NULL DDS::SampleInfo. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
One | of the Standard Return Codes, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Copies the next not-previously-accessed data value from the DDS::DataReader.
This operation copies the next not-previously-accessed data value from the DDS::DataReader and 'removes' it from the DDS::DataReader so that it is no longer accessible. This operation also copies the corresponding DDS::SampleInfo. This operation is analogous to the DDS::TypedDataReader::read_next_sample except for the fact that the sample is removed from the DDS::DataReader.
The DDS::TypedDataReader::take_next_sample operation is semantically equivalent to the DDS::TypedDataReader::take operation, where the input data sequences has max_len=1, the sample_states=NOT_READ, the view_states=ANY_VIEW_STATE, and the instance_states=ANY_INSTANCE_STATE.
The DDS::TypedDataReader::take_next_sample operation provides a simplified API to 'take' samples, avoiding the need for the application to manage sequences and specify states.
If there is no unread data in the DDS::DataReader, the operation will fail with DDS::Retcode_NoData and nothing is copied.
received_data | <<inout>> user data type-specific Foo object where the next received data sample will be returned. The received_data must have been fully allocated. Otherwise, this operation may fail. Must be a valid non-NULL Foo. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
sample_info | <<inout>> a DDS::SampleInfo object where the next received sample info will be returned. Must be a valid non-NULL DDS::SampleInfo. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
One | of the Standard Return Codes, |
DDS::Retcode_NoData or DDS::Retcode_NotEnabled.
|
inline |
Access a collection of data samples from the DDS::DataReader.
This operation accesses a collection of data values from the DDS::DataReader. The behavior is identical to DDS::TypedDataReader::read, except that all samples returned belong to the single specified instance whose handle is a_handle
.
Upon successful completion, the data collection will contain samples all belonging to the same instance. The corresponding DDS::SampleInfo verifies DDS::SampleInfo::instance_handle == a_handle
.
The DDS::TypedDataReader::read_instance operation is semantically equivalent to the DDS::TypedDataReader::read operation, except in building the collection, the DDS::DataReader will check that the sample belongs to the specified instance and otherwise it will not place the sample in the returned collection.
The behavior of the DDS::TypedDataReader::read_instance operation follows the same rules as the DDS::TypedDataReader::read operation regarding the pre-conditions and post-conditions for the received_data
and sample_info
. Similar to the DDS::TypedDataReader::read, the DDS::TypedDataReader::read_instance operation may 'loan' elements to the output collections, which must then be returned by means of DDS::TypedDataReader::return_loan.
Similar to the DDS::TypedDataReader::read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
This operation may fail with DDS::Retcode_BadParameter if the DDS::InstanceHandle_t a_handle
does not correspond to an existing data-object known to the DDS::DataReader.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
a_handle | <<in>> The specified instance to return samples for. Must be a valid non-NULL DDS::InstanceHandle_t. The method will fail with DDS::Retcode_BadParameter if it is NULL The method will fail with DDS::Retcode_BadParameter if the handle does not correspond to an existing data-object known to the DDS::DataReader. |
sample_states | <<in>> data samples matching ones of these sample_states are returned. See the valid values for this parameter here: DDS::SampleStateKind. |
view_states | <<in>> data samples matching ones of these view_state are returned. See the valid values for this parameter here: DDS::ViewStateKind. |
instance_states | <<in>> data samples matching ones of these instance_state are returned. See the valid values for this parameter here: DDS::InstanceStateKind. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Access a collection of data samples from the DDS::DataReader.
This operation accesses a collection of data values from the DDS::DataReader. The behavior is identical to DDS::TypedDataReader::take, except for that all samples returned belong to the single specified instance whose handle is a_handle
.
The semantics are the same for the DDS::TypedDataReader::take operation, except in building the collection, the DDS::DataReader will check that the sample belongs to the specified instance, and otherwise it will not place the sample in the returned collection.
The behavior of the DDS::TypedDataReader::take_instance operation follows the same rules as the DDS::TypedDataReader::read operation regarding the pre-conditions and post-conditions for the received_data
and sample_info
. Similar to the DDS::TypedDataReader::read, the DDS::TypedDataReader::take_instance operation may 'loan' elements to the output collections, which must then be returned by means of DDS::TypedDataReader::return_loan.
Similar to the DDS::TypedDataReader::read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
If the DDS::DataReader has no samples that meet the constraints, the method fails with DDS::Retcode_NoData.
This operation may fail with DDS::Retcode_BadParameter if the DDS::InstanceHandle_t a_handle
does not correspond to an existing data-object known to the DDS::DataReader.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
a_handle | <<in>> The specified instance to return samples for. Must be a valid non-NULL DDS::InstanceHandle_t. The method will fail with DDS::Retcode_BadParameter if it is NULL. The method will fail with DDS::Retcode_BadParameter if the handle does not correspond to an existing data-object known to the DDS::DataReader. |
sample_states | <<in>> data samples matching ones of these sample_states are returned. See the valid values for this parameter here: DDS::SampleStateKind. |
view_states | <<in>> data samples matching ones of these view_state are returned. See the valid values for this parameter here: DDS::ViewStateKind. |
instance_states | <<in>> data samples matching ones of these instance_state are returned. See the valid values for this parameter here: DDS::InstanceStateKind. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Access a collection of data samples from the DDS::DataReader.
This operation accesses a collection of data values from the DDS::DataReader where all the samples belong to a single instance. The behavior is similar to DDS::TypedDataReader::read_instance, except that the actual instance is not directly specified. Rather, the samples will all belong to the 'next' instance with instance_handle
'greater' than the specified 'previous_handle' that has available samples.
This operation implies the existence of a total order 'greater-than' relationship between the instance handles. The specifics of this relationship are not all important and are implementation specific. The important thing is that, according to the middleware, all instances are ordered relative to each other. This ordering is between the instance handles; It should not depend on the state of the instance (e.g. whether it has data or not) and must be defined even for instance handles that do not correspond to instances currently managed by the DDS::DataReader. For the purposes of the ordering, it should be 'as if' each instance handle was represented as unique integer.
The behavior of DDS::TypedDataReader::read_next_instance is 'as if' the DDS::DataReader invoked DDS::TypedDataReader::read_instance, passing the smallest instance_handle
among all the ones that: (a) are greater than previous_handle
, and (b) have available samples (i.e. samples that meet the constraints imposed by the specified states).
The special value DDS::InstanceHandle_t::HANDLE_NIL is guaranteed to be 'less than' any valid instance_handle
. So the use of the parameter value previous_handle
== DDS::InstanceHandle_t::HANDLE_NIL will return the samples for the instance which has the smallest instance_handle
among all the instances that contain available samples.
The operation DDS::TypedDataReader::read_next_instance is intended to be used in an application-driven iteration, where the application starts by passing previous_handle
== DDS::InstanceHandle_t::HANDLE_NIL, examines the samples returned, and then uses the instance_handle
returned in the DDS::SampleInfo as the value of the previous_handle
argument to the next call to DDS::TypedDataReader::read_next_instance. The iteration continues until DDS::TypedDataReader::read_next_instance fails with the value DDS::Retcode_NoData .
Note that it is possible to call the DDS::TypedDataReader::read_next_instance operation with a previous_handle
that does not correspond to an instance currently managed by the DDS::DataReader. This is because as stated earlier the 'greater-than' relationship is defined even for handles not managed by the DDS::DataReader. One practical situation where this may occur is when an application is iterating though all the instances, takes all the samples of a DDS::InstanceStateKind::NOT_ALIVE_NO_WRITERS_INSTANCE_STATE instance, returns the loan (at which point the instance information may be removed, and thus the handle becomes invalid), and tries to read the next instance. The behavior of the DDS::TypedDataReader::read_next_instance operation follows the same rules as the DDS::TypedDataReader::read operation regarding the pre-conditions and post-conditions for the received_data
and sample_info
. Similar to the DDS::TypedDataReader::read, the DDS::TypedDataReader::read_instance operation may 'loan' elements to the output collections, which must then be returned by means of DDS::TypedDataReader::return_loan.
Similar to the DDS::TypedDataReader::read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
previous_handle | <<in>> The 'next smallest' instance with a value greater than this value that has available samples will be returned. Must be a valid non-NULL DDS::InstanceHandle_t. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
sample_states | <<in>> data samples matching ones of these sample_states are returned. See the valid values for this parameter here: DDS::SampleStateKind. |
view_states | <<in>> data samples matching ones of these view_state are returned. See the valid values for this parameter here: DDS::ViewStateKind. |
instance_states | <<in>> data samples matching ones of these instance_state are returned. See the valid values for this parameter here: DDS::InstanceStateKind. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Access a collection of data samples from the DDS::DataReader.
This operation accesses a collection of data values from the DDS::DataReader and 'removes' them from the DDS::DataReader.
This operation has the same behavior as DDS::TypedDataReader::read_next_instance, except that the samples are 'taken' from the DDS::DataReader such that they are no longer accessible via subsequent 'read' or 'take' operations.
Similar to the operation DDS::TypedDataReader::read_next_instance, it is possible to call DDS::TypedDataReader::take_next_instance with a previous_handle
that does not correspond to an instance currently managed by the DDS::DataReader.
The behavior of the DDS::TypedDataReader::take_next_instance operation follows the same rules as the DDS::TypedDataReader::read operation regarding the pre-conditions and post-conditions for the received_data
and sample_info
. Similar to the DDS::TypedDataReader::read, the DDS::TypedDataReader::take_next_instance operation may 'loan' elements to the output collections, which must then be returned by means of DDS::TypedDataReader::return_loan.
Similar to the DDS::TypedDataReader::read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
previous_handle | <<in>> The 'next smallest' instance with a value greater than this value that has available samples will be returned. Must be a valid non-NULL DDS::InstanceHandle_t. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
sample_states | <<in>> data samples matching ones of these sample_states are returned. See the valid values for this parameter here: DDS::SampleStateKind. |
view_states | <<in>> data samples matching ones of these view_state are returned. See the valid values for this parameter here: DDS::ViewStateKind. |
instance_states | <<in>> data samples matching ones of these instance_state are returned. See the valid values for this parameter here: DDS::InstanceStateKind. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Accesses via DDS::TypedDataReader::read_next_instance the samples that match the criteria specified in the DDS::ReadCondition.
This operation accesses a collection of data values from the DDS::DataReader. The behavior is identical to DDS::TypedDataReader::read_next_instance, except that all returned samples satisfy the specified condition. In other words, on success, all returned samples belong to the same instance, and the instance is the instance with 'smallest' instance_handle
among the ones that verify: (a) instance_handle
>= previous_handle
, and (b) have samples for which the specified DDS::ReadCondition evaluates to TRUE.
Similar to the operation DDS::TypedDataReader::read_next_instance, it is possible to call DDS::TypedDataReader::read_next_instance_w_condition with a previous_handle
that does not correspond to an instance currently managed by the DDS::DataReader.
The behavior of the DDS::TypedDataReader::read_next_instance_w_condition operation follows the same rules as the DDS::TypedDataReader::read operation regarding the pre-conditions and post-conditions for the received_data
and sample_info
. Similar to the DDS::TypedDataReader::read, the DDS::TypedDataReader::read_next_instance_w_condition operation may 'loan' elements to the output collections, which must then be returned by means of DDS::TypedDataReader::return_loan.
Similar to the DDS::TypedDataReader::read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
previous_handle | <<in>> The 'next smallest' instance with a value greater than this value that has available samples will be returned. Must be a valid non-NULL DDS::InstanceHandle_t. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
condition | <<in>> the DDS::ReadCondition to select samples of interest. Cannot be NULL. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet DDS::Retcode_NoData or DDS::Retcode_NotEnabled. |
|
inline |
Accesses via DDS::TypedDataReader::take_next_instance the samples that match the criteria specified in the DDS::ReadCondition.
This operation accesses a collection of data values from the DDS::DataReader and 'removes' them from the DDS::DataReader.
The operation has the same behavior as DDS::TypedDataReader::read_next_instance_w_condition, except that the samples are 'taken' from the DDS::DataReader such that they are no longer accessible via subsequent 'read' or 'take' operations.
Similar to the operation DDS::TypedDataReader::read_next_instance, it is possible to call DDS::TypedDataReader::take_next_instance_w_condition with a previous_handle
that does not correspond to an instance currently managed by the DDS::DataReader.
The behavior of the DDS::TypedDataReader::take_next_instance_w_condition operation follows the same rules as the DDS::TypedDataReader::read operation regarding the pre-conditions and post-conditions for the received_data
and sample_info
. Similar to DDS::TypedDataReader::read, the DDS::TypedDataReader::take_next_instance_w_condition operation may 'loan' elements to the output collections, which must then be returned by means of DDS::TypedDataReader::return_loan.
Similar to the DDS::TypedDataReader::read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
If the DDS::DataReader has no samples that meet the constraints, the method will fail with DDS::Retcode_NoData.
received_data | <<inout>> user data type-specific DDS::Sequence object where the received data samples will be returned. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<inout>> a DDS::SampleInfoSeq object where the received sample info will be returned. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
max_samples | <<in>> The maximum number of samples to be returned. If the special value DDS::ResourceLimitsQosPolicy::LENGTH_UNLIMITED is provided, as many samples will be returned as are available, up to the limits described in the documentation for DDS::TypedDataReader::take(). |
previous_handle | <<in>> The 'next smallest' instance with a value greater than this value that has available samples will be returned. Must be a valid non-NULL DDS::InstanceHandle_t. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
condition | <<in>> the DDS::ReadCondition to select samples of interest. Cannot be NULL. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet, or DDS::Retcode_NoData, DDS::Retcode_NotEnabled. |
|
inline |
Indicates to the DDS::DataReader that the application is done accessing the collection of received_data
and info_seq
obtained by some earlier invocation of read or take on the DDS::DataReader.
This operation indicates to the DDS::DataReader that the application is done accessing the collection of received_data
and info_seq
obtained by some earlier invocation of read or take on the DDS::DataReader.
The received_data
and info_seq
must belong to a single related "pair"; that is, they should correspond to a pair returned from a single call to read or take. The received_data
and info_seq
must also have been obtained from the same DDS::DataReader to which they are returned. If either of these conditions is not met, the operation will fail with DDS::Retcode_PreconditionNotMet.
The operation DDS::TypedDataReader::return_loan allows implementations of the read and take operations to "loan" buffers from the DDS::DataReader to the application and in this manner provide "zerocopy" access to the data. During the loan, the DDS::DataReader will guarantee that the data and sample-information are not modified.
It is not necessary for an application to return the loans immediately after the read or take calls. However, as these buffers correspond to internal resources inside the DDS::DataReader, the application should not retain them indefinitely.
The use of DDS::TypedDataReader::return_loan is only necessary if the read or take calls "loaned" buffers to the application. This only occurs if the received_data
and info_Seq
collections had max_len=0
at the time read or take was called.
The application may also examine the "owns" property of the collection to determine where there is an outstanding loan. However, calling DDS::TypedDataReader::return_loan on a collection that does not have a loan is safe and has no side effects.
If the collections had a loan, upon completion of DDS::TypedDataReader::return_loan, the collections will have max_len=0
.
Similar to read, this operation must be provided on the specialized class that is generated for the particular application data-type that is being taken.
received_data | <<in>> user data type-specific DDS::Sequence object where the received data samples was obtained from earlier invocation of read or take on the DDS::DataReader. Must be a valid non-NULL FooSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
info_seq | <<in>> a DDS::SampleInfoSeq object where the received sample info was obtained from earlier invocation of read or take on the DDS::DataReader. Must be a valid non-NULL DDS::SampleInfoSeq. The method will fail with DDS::Retcode_BadParameter if it is NULL. |
One | of the Standard Return Codes, DDS::Retcode_PreconditionNotMet or DDS::Retcode_NotEnabled. |
|
inline |
Retrieve the instance key
that corresponds to an instance handle
.
Useful for keyed data types.
The operation will only fill the fields that form the key
inside the key_holder
instance.
For keyed data types, this operation may fail with DDS::Retcode_BadParameter if the handle
does not correspond to an existing data-object known to the DDS::DataReader.
key_holder | <<inout>> a user data type specific key holder, whose key fields are filled by this operation. If Foo has no key, this method has no effect. This method will fail with DDS::Retcode_BadParameter if key_holder is NULL. |
handle | <<in>> the instance whose key is to be retrieved. If Foo has a key, handle must represent an existing instance of type Foo known to the DDS::DataReader. Otherwise, this method will fail with DDS::Retcode_BadParameter. |
If Foo has a key and handle
is DDS::InstanceHandle_t::HANDLE_NIL, this method will fail with DDS::Retcode_BadParameter.
If Foo has a key and handle
represents an instance of another type or an instance of type Foo that has been unregistered, this method will fail with DDS::Retcode_BadParameter. If Foo has no key, this method has no effect.
This method will fail with DDS::Retcode_BadParameter if handle
is NULL.
One | of the Standard Return Codes or DDS::Retcode_NotEnabled. |
|
inline |
Retrieves the instance handle
that corresponds to an instance key_holder
.
Useful for keyed data types.
This operation takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument. The instance parameter is only used for the purpose of examining the fields that define the key. If the instance is unknown to the DataReader, or if for any other reason the Service is unable to provide an instance handle, the Service will return the special value DDS::InstanceHandle_t::HANDLE_NIL.
key_holder | <<in>> a user data type specific key holder. |