Object responsible for reading in a stream of bytes over the modem interface and forming the stream of bytes into complete messages. More...

#include <TractionModem.hxx>

Inheritance diagram for traction_modem::RxFlow:

Public Types
using	BufferType = Buffer< TxMessage >

using	Receiver = PacketFlowInterface

Public Member Functions
	RxFlow (Service *service)
	Constructor.

void	start (int fd)
	Start the flow using the given interface.

void	set_listener (Receiver *rcv)
	Register a listener to send incoming messages to.

long long	get_character_nsec ()
	Get the wire time for a single character.

Public Member Functions inherited from StateFlowBase
void	run () override
	Callback from the executor.

void	notify () override
	Wakeup call arrived.

Service *	service ()
	Return a pointer to the service I am bound to.

Public Member Functions inherited from Executable
void	test_deletion ()

Public Member Functions inherited from QMember
void	init ()
	Initiailize a QMember, in place of a public placement construction.

Private Member Functions
Action	reset ()
	Resets the message reception state machine.

Action	wait_for_base_data ()
	Wait until we have at least as much data as a minimum size message.

Action	base_data_received ()
	Received at least as much data as the minimum message size.

Action	header_complete ()
	We think we have a complete header because we just validated a preamble.

Action	maybe_message_complete ()
	We might have a complete message if we have received enough data.

Action	resync ()
	Something went wrong in decoding the data stream.

Private Attributes
StateFlowTimedSelectHelper	helper_ {this}
	Helper for reading in a select flow.

string	payload_
	We assemble the message here.

size_t	recvCnt_
	Number of bytes that have been received into payload_, which may be less than payload_.size() since we reserve space ahead of time.

Receiver *	receiver_
	Incoming messages get routed to this object.

int	fd_ = -1
	Interface fd.

Static Private Attributes
static constexpr long long	CHARACTER_NSEC = 10 * SEC_TO_NSEC(1) / 250000
	Used to place a bounds on a timeout of a message.

static constexpr unsigned	MIN_MESSAGE_SIZE = Defs::LEN_BASE
	Minimum size of a message.

static constexpr unsigned	MAX_DATA_LEN = Defs::MAX_LEN
	Maximum size of the data portion of a message.

Additional Inherited Members
Static Public Member Functions inherited from StateFlowBase
template<class T , typename... Args>
static void	invoke_subflow_and_ignore_result (FlowInterface< Buffer< T > > *target_flow, Args &&... args)
	Calls a helper flow to perform some actions.

Protected Types inherited from StateFlowBase
typedef Action(StateFlowBase::*	Callback) ()
	State Flow callback prototype.

Protected Member Functions inherited from StateFlowBase
	StateFlowBase (Service *service)
	Constructor.

	~StateFlowBase ()
	Destructor.

void	reset_flow (Callback c)
	Resets the flow to the specified state.

bool	is_state (Callback c)

bool	is_terminated ()

void	start_flow (Callback c)
	Resets the flow to the specified state and starts it.

Action	again ()
	Call the current state again via call_immediately.

Action	exit ()
	Terminate current StateFlow activity.

Action	delete_this ()
	Terminates the flow and deletes *this.

Action	set_terminated ()
	Sets the flow to terminated state.

Action	call_immediately (Callback c)
	Imediately call the next state upon return.

Action	wait ()
	Wait for an asynchronous call.

Action	wait_and_call (Callback c)
	Wait for resource to become available before proceeding to next state.

template<class T >
Action	allocate_and_call (FlowInterface< Buffer< T > > target_flow, Callback c, Pool pool=nullptr)
	Allocates a buffer from a pool and proceed to the next state when allocation is successful.

Action	allocate_and_call (Callback c, QAsync *queue)
	Allocates an entry from an asynchronous queue, and transitions to a state once the allocation is complete.

template<class T >
Buffer< T > *	full_allocation_result (FlowInterface< Buffer< T > > *target_flow)
	Takes the result of the asynchronous allocation without resetting the object.

template<class T >
T *	full_allocation_result (TypedQAsync< T > *queue)
	Takes the result of the asynchronous allocation without resetting the object.

template<class T >
void	cast_allocation_result (T **member)
	Takes the result of the asynchronous allocation without resetting the object.

template<class T >
Buffer< T > *	get_allocation_result (FlowInterface< Buffer< T > > *target_flow)
	Takes the result of the asynchronous allocation.

Action	yield_and_call (Callback c)
	Place the current flow to the back of the executor, and transition to a new state after we get the CPU again.

Action	yield ()
	Place the current flow to the back of the executor, and re-try the current state after we get the CPU again.

Action	sleep_and_call (::Timer *timer, long long timeout_nsec, Callback c)
	Suspends execution of this control flow for a specified time.

template<class T , typename... Args>
Action	invoke_subflow_and_wait (FlowInterface< Buffer< T > > *target_flow, Callback c, Args &&... args)
	Calls a helper flow to perform some actions.

Action	read_repeated (StateFlowSelectHelper helper, int fd, void buf, size_t size, Callback c, unsigned priority=Selectable::MAX_PRIO)
	Blocks until size bytes are read and then invokes the next state.

Action	read_single (StateFlowSelectHelper helper, int fd, void buf, size_t size, Callback c, unsigned priority=Selectable::MAX_PRIO)
	Attempts to read at most size_t bytes, and blocks the caller until at least one byte is read.

Action	read_nonblocking (StateFlowSelectHelper helper, int fd, void buf, size_t size, Callback c, unsigned priority=Selectable::MAX_PRIO)
	Attempts to read at most size bytes, and then invokes the next state, even if only zero bytes are available right now.

Action	read_repeated_with_timeout (StateFlowTimedSelectHelper helper, long long timeout_nsec, int fd, void buf, size_t size, Callback c, unsigned priority=Selectable::MAX_PRIO)
	Blocks until size bytes are read, or a timeout expires.

Action	internal_try_read ()
	Implementation state that gets repeatedly called upon every wakeup and tries to make progress on reading.

Action	write_repeated (StateFlowSelectHelper helper, int fd, const void buf, size_t size, Callback c, unsigned priority=Selectable::MAX_PRIO)
	Writes some data into a file descriptor, repeating the operation as necessary until all bytes are written.

Action	internal_try_write ()
	Implementation state that gets repeatedly called upon every wakeup and tries to make progress on writing.

Protected Member Functions inherited from QMember
	QMember ()
	Constructor.

	~QMember ()
	Destructor.

Protected Attributes inherited from QMember
QMember *	next
	pointer to the next member in the queue

Detailed Description

Object responsible for reading in a stream of bytes over the modem interface and forming the stream of bytes into complete messages.

Definition at line 142 of file TractionModem.hxx.

Member Typedef Documentation

◆ BufferType

using traction_modem::RxFlow::BufferType = Buffer<TxMessage>

Definition at line 145 of file TractionModem.hxx.

◆ Receiver

using traction_modem::RxFlow::Receiver = PacketFlowInterface

Definition at line 146 of file TractionModem.hxx.

Constructor & Destructor Documentation

◆ RxFlow()

traction_modem::RxFlow::RxFlow ( Service * service )

inline

Constructor.

Parameters

service service that the flow is bound to

Definition at line 150 of file TractionModem.hxx.

Member Function Documentation

◆ base_data_received()

Action traction_modem::RxFlow::base_data_received ( )

inlineprivate

Received at least as much data as the minimum message size.

Returns: next state is header_complete if valid preamble found, else next state is resync to look for a valid header.

Definition at line 238 of file TractionModem.hxx.

◆ get_character_nsec()

long long traction_modem::RxFlow::get_character_nsec ( )

inline

Get the wire time for a single character.

Parameters

wire	time for a single character in nanoseconds

Todo:: Once we support multi-baud, this should be modified to provide the character nsec at the current baud rate.

Definition at line 172 of file TractionModem.hxx.

◆ header_complete()

Action traction_modem::RxFlow::header_complete ( )

inlineprivate

We think we have a complete header because we just validated a preamble.

Validate that the header meta data (data length) is legit.

Returns: next state is resync on error (invalid data length), else next state is maybe_message_complete.

Definition at line 263 of file TractionModem.hxx.

◆ maybe_message_complete()

Action traction_modem::RxFlow::maybe_message_complete ( )

inlineprivate

We might have a complete message if we have received enough data.

Returns: next state is resync if a timeout occurred or a CRC error is detected, else if we have the likely start to the next message next state is wait_for_base_data, else next state is reset.

Definition at line 295 of file TractionModem.hxx.

◆ reset()

Action traction_modem::RxFlow::reset ( )

inlineprivate

Resets the message reception state machine.

Returns: next state wait_for_base_data()

Definition at line 186 of file TractionModem.hxx.

◆ resync()

Action traction_modem::RxFlow::resync ( )

inlineprivate

Something went wrong in decoding the data stream.

Try to resync on a preamble word.

Returns: next state is wait_for_base_data if a valid preamble word is found, else next state is reset to start over with new data.

Todo:: Should we be sending out a framing error? I think so. How to dispatch that? Maybe an error field in the TxMessage? If we send this to the dispatcher, be sure to add the appropriate EXPECT_CALL(s) to the unit tests.

Definition at line 360 of file TractionModem.hxx.

◆ set_listener()

void traction_modem::RxFlow::set_listener ( Receiver * rcv )

inline

Register a listener to send incoming messages to.

Parameters

rcv	lister that will receive incoming messages

Definition at line 165 of file TractionModem.hxx.

◆ start()

void traction_modem::RxFlow::start ( int fd )

inline

Start the flow using the given interface.

Parameters

fd	interface to receive messages on

Definition at line 157 of file TractionModem.hxx.

◆ wait_for_base_data()

Action traction_modem::RxFlow::wait_for_base_data ( )

inlineprivate

Wait until we have at least as much data as a minimum size message.

Returns: next state base_data_received

Definition at line 206 of file TractionModem.hxx.

Member Data Documentation

◆ CHARACTER_NSEC

constexpr long long traction_modem::RxFlow::CHARACTER_NSEC = 10 * SEC_TO_NSEC(1) / 250000

staticconstexprprivate

Used to place a bounds on a timeout of a message.

Definition at line 399 of file TractionModem.hxx.

◆ fd_

int traction_modem::RxFlow::fd_ = -1

private

Interface fd.

Definition at line 418 of file TractionModem.hxx.

◆ helper_

StateFlowTimedSelectHelper traction_modem::RxFlow::helper_ {this}

private

Helper for reading in a select flow.

Definition at line 408 of file TractionModem.hxx.

◆ MAX_DATA_LEN

constexpr unsigned traction_modem::RxFlow::MAX_DATA_LEN = Defs::MAX_LEN

staticconstexprprivate

Maximum size of the data portion of a message.

Definition at line 405 of file TractionModem.hxx.

◆ MIN_MESSAGE_SIZE

constexpr unsigned traction_modem::RxFlow::MIN_MESSAGE_SIZE = Defs::LEN_BASE

staticconstexprprivate

Minimum size of a message.

Definition at line 402 of file TractionModem.hxx.

◆ payload_

string traction_modem::RxFlow::payload_

private

We assemble the message here.

Definition at line 410 of file TractionModem.hxx.

◆ receiver_

Receiver* traction_modem::RxFlow::receiver_

private

Incoming messages get routed to this object.

Definition at line 415 of file TractionModem.hxx.

◆ recvCnt_

size_t traction_modem::RxFlow::recvCnt_

private

Number of bytes that have been received into payload_, which may be less than payload_.size() since we reserve space ahead of time.

Definition at line 413 of file TractionModem.hxx.

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

TractionModem.hxx

Public Types

Public Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ BufferType

◆ Receiver

Constructor & Destructor Documentation

◆ RxFlow()

Member Function Documentation

◆ base_data_received()

◆ get_character_nsec()

◆ header_complete()

◆ maybe_message_complete()

◆ reset()

◆ resync()

◆ set_listener()

◆ start()

◆ wait_for_base_data()

Member Data Documentation

◆ CHARACTER_NSEC

◆ fd_

◆ helper_

◆ MAX_DATA_LEN

◆ MIN_MESSAGE_SIZE

◆ payload_

◆ receiver_

◆ recvCnt_