target_block Class

The target_block class is an abstract base class that provides basic link management functionality and error checking for target only blocks.

Syntax

template<class _SourceLinkRegistry, class _MessageProcessorType = ordered_message_processor<typename _SourceLinkRegistry::type::source_type>>
class target_block : public ITarget<typename _SourceLinkRegistry::type::source_type>;

Parameters

_SourceLinkRegistry
The link registry to be used for holding the source links.

_MessageProcessorType
The processor type for message processing.

Members

Public Typedefs

Name	Description
source_iterator	The type of the iterator for the source_link_manager for this target_block object.

Public Constructors

Name	Description
target_block	Constructs a target_block object.
~target_block Destructor	Destroys the target_block object.

Public Methods

Name	Description
propagate	Asynchronously passes a message from a source block to this target block.
send	Synchronously passes a message from a source block to this target block.

Protected Methods

Name	Description
async_send	Asynchronously sends a message for processing.
decline_incoming_messages	Indicates to the block that new messages should be declined.
enable_batched_processing	Enables batched processing for this block.
initialize_target	Initializes the base object. Specifically, the message_processor object needs to be initialized.
link_source	Links a specified source block to this target_block object.
process_input_messages	Processes messages that are received as inputs.
process_message	When overridden in a derived class, processes a message that was accepted by this target_block object.
propagate_message	When overridden in a derived class, this method asynchronously passes a message from an ISource block to this target_block object. It is invoked by the propagate method, when called by a source block.
register_filter	Registers a filter method that will be invoked on every message received.
remove_sources	Unlinks all sources after waiting for outstanding asynchronous send operations to complete.
send_message	When overridden in a derived class, this method synchronously passes a message from an ISource block to this target_block object. It is invoked by the send method, when called by a source block.
sync_send	Synchronously send a message for processing.
unlink_source	Unlinks a specified source block from this target_block object.
unlink_sources	Unlinks all source blocks from this target_block object. (Overrides ITarget::unlink_sources.)
wait_for_async_sends	Waits for all asynchronous propagations to complete.

Inheritance Hierarchy

ITarget

target_block

Requirements

Header: agents.h

Namespace: concurrency

async_send

Asynchronously sends a message for processing.

void async_send(_Inout_opt_ message<_Source_type>* _PMessage);

Parameters

_PMessage
A pointer to the message being sent.

decline_incoming_messages

Indicates to the block that new messages should be declined.

void decline_incoming_messages();

Remarks

This method is called by the destructor to ensure that new messages are declined while destruction is in progress.

enable_batched_processing

Enables batched processing for this block.

void enable_batched_processing();

initialize_target

Initializes the base object. Specifically, the message_processor object needs to be initialized.

void initialize_target(
    _Inout_opt_ Scheduler* _PScheduler = NULL,
    _Inout_opt_ ScheduleGroup* _PScheduleGroup = NULL);

Parameters

_PScheduler
The scheduler to be used for scheduling tasks.

_PScheduleGroup
The schedule group to be used for scheduling tasks.

link_source

Links a specified source block to this target_block object.

virtual void link_source(_Inout_ ISource<_Source_type>* _PSource);

Parameters

_PSource
A pointer to the ISource block that is to be linked.

Remarks

This function should not be called directly on a target_block object. Blocks should be connected together using the link_target method on ISource blocks, which will invoke the link_source method on the corresponding target.

process_input_messages

Processes messages that are received as inputs.

virtual void process_input_messages(_Inout_ message<_Source_type>* _PMessage);

Parameters

_PMessage
A pointer to the message that is to be processed.

process_message

When overridden in a derived class, processes a message that was accepted by this target_block object.

virtual void process_message(message<_Source_type> *);

propagate

Asynchronously passes a message from a source block to this target block.

virtual message_status propagate(
    _Inout_opt_ message<_Source_type>* _PMessage,
    _Inout_opt_ ISource<_Source_type>* _PSource);

Parameters

_PMessage
A pointer to the message object.

_PSource
A pointer to the source block offering the message.

Return Value

A message_status indication of what the target decided to do with the message.

Remarks

The method throws an invalid_argument exception if either the _PMessage or _PSource parameter is NULL.

propagate_message

When overridden in a derived class, this method asynchronously passes a message from an ISource block to this target_block object. It is invoked by the propagate method, when called by a source block.

virtual message_status propagate_message(
    _Inout_ message<_Source_type>* _PMessage,
    _Inout_ ISource<_Source_type>* _PSource) = 0;

Parameters

_PMessage
A pointer to the message object.

_PSource
A pointer to the source block offering the message.

Return Value

A message_status indication of what the target decided to do with the message.

register_filter

Registers a filter method that will be invoked on every message received.

void register_filter(filter_method const& _Filter);

Parameters

_Filter
The filter method.

remove_sources

Unlinks all sources after waiting for outstanding asynchronous send operations to complete.

void remove_sources();

Remarks

All target blocks should call this routine to remove the sources in their destructor.

send

Synchronously passes a message from a source block to this target block.

virtual message_status send(
    _Inout_ message<_Source_type>* _PMessage,
    _Inout_ ISource<_Source_type>* _PSource);

Parameters

_PMessage
A pointer to the message object.

_PSource
A pointer to the source block offering the message.

Return Value

A message_status indication of what the target decided to do with the message.

Remarks

The method throws an invalid_argument exception if either the _PMessage or _PSource parameter is NULL.

Using the send method outside of message initiation and to propagate messages within a network is dangerous and can lead to deadlock.

When send returns, the message has either already been accepted, and transferred into the target block, or it has been declined by the target.

send_message

When overridden in a derived class, this method synchronously passes a message from an ISource block to this target_block object. It is invoked by the send method, when called by a source block.

virtual message_status send_message(
    _Inout_ message<_Source_type> *,
    _Inout_ ISource<_Source_type> *);

Return Value

A message_status indication of what the target decided to do with the message.

Remarks

By default, this block returns declined unless overridden by a derived class.

sync_send

Synchronously send a message for processing.

void sync_send(_Inout_opt_ message<_Source_type>* _PMessage);

Parameters

_PMessage
A pointer to the message being sent.

target_block

Constructs a target_block object.

target_block();

~target_block

Destroys the target_block object.

virtual ~target_block();

unlink_source

Unlinks a specified source block from this target_block object.

virtual void unlink_source(_Inout_ ISource<_Source_type>* _PSource);

Parameters

_PSource
A pointer to the ISource block that is to be unlinked.

unlink_sources

Unlinks all source blocks from this target_block object.

virtual void unlink_sources();

wait_for_async_sends

Waits for all asynchronous propagations to complete.

void wait_for_async_sends();

Remarks

This method is used by message block destructors to ensure all asynchronous operations have had time to finish before destroying the block.

See also

concurrency Namespace
ITarget Class