dfx::Core::UdpDestination Class Reference

A network destination transport using UDP with automatic fragmentation. More...

#include <dfx-core/transports/destinations/UdpDestination.hpp>

Inheritance diagram for dfx::Core::UdpDestination:

Collaboration diagram for dfx::Core::UdpDestination:

Public Member Functions
	UdpDestination (Endpoint endpoint, nlohmann::json config)
	Constructs a UdpDestination.
void	start (FdWatch::Poller &poller) override
	Initializes the UDP socket and enables PMTUD.
void	stop () noexcept override
	Closes the socket and releases resources.
bool	deliver (MessagePtr message) override
	Delivers a message over the network.
Public Member Functions inherited from dfx::Core::DestinationTransport
	DestinationTransport (Endpoint endpoint, nlohmann::json config)
	Constructs a DestinationTransport with the Role::Destination role.
virtual int64_t	pendingMessageCount () const noexcept
	Return the number of pending message in this transport or -1 if unknown.
Public Member Functions inherited from dfx::Core::Transport
	Transport (Role role, Endpoint endpoint, nlohmann::json config)
	Constructs a transport instance.
	DFX_DISABLE_COPY_AND_MOVE (Transport)
	Transport is not copiable nor movable.
virtual	~Transport ()=default
	Virtual destructor ensuring proper cleanup of derived transports.
template<DerivedFromTransport T>
bool	is () const noexcept
	Check whether this transport is of a given derived type.
template<DerivedFromTransport T>
T &	as () noexcept
	Cast this transport to a derived type (unchecked).
template<DerivedFromTransport T>
T const &	as () const noexcept
	Cast this transport to a derived type (unchecked).
Role	role () const noexcept
	Returns the Role (Source or Destination) of this transport.
bool	isSource () const noexcept
	Returns true if this transport is a source.
bool	isDestination () const noexcept
	Returns true if this transport is a destination.
Endpoint const &	endpoint () const noexcept
	Gets the endpoint descriptor associated with this transport.
Channel *	channel () const noexcept
	Gets the channel which this transport is attached to if any.
Port *	port () const noexcept
	Gets the port associated with this transport.
NodePtr	node () const noexcept
	Gets the node associated with this transport.
nlohmann::json const &	config () const noexcept
	Gets the JSON configuration used to initialize this transport.

Static Public Attributes
static constexpr auto	defaultMtuNetworkOverhead = 64
	Prepares the UDP socket and performs initial MTU discovery.

Additional Inherited Members
Public Types inherited from dfx::Core::Transport
enum class	Role { Source , Destination }
	Defines the operational role of a transport relative to a channel. More...
Protected Attributes inherited from dfx::Core::Transport
Role const	_role
Endpoint	_endpoint
nlohmann::json	_config

Detailed Description

A network destination transport using UDP with automatic fragmentation.

UdpDestination implements a robust "Reliable-ish" UDP transport. Because UDP does not support large payloads natively without kernel fragmentation, this class utilizes the Framer to split messages into MTU-sized frames.

Key Features

• PMTUD: Sets IP_PMTUDISC_DO to prevent kernel-level fragmentation.
• Dynamic MTU: Automatically updates MTU and network overhead estimates when receiving EMSGSIZE errors.
• Vectorized I/O: Uses sendmmsg and iovec to transmit multiple frames with minimal system call overhead.

Note

The default network overhead is 64 bytes to account for IP/UDP headers.

Constructor & Destructor Documentation

UdpDestination()

dfx::Core::UdpDestination::UdpDestination	(	Endpoint	endpoint,
		nlohmann::json	config )

Constructs a UdpDestination.

Parameters

endpoint	The UDP endpoint (e.g., udp://127.0.0.1:5000).
config	Transport-specific JSON configuration.

Member Function Documentation

deliver()

bool dfx::Core::UdpDestination::deliver ( MessagePtr message )

overridevirtual

Delivers a message over the network.

This method performs the following:

1. Packs the message into a binary buffer using Packer.
2. Generates a unique 32-bit MessageID.
3. Calculates the available payload size per frame: MTU - Overhead.
4. Segments the data into a vector of mmsghdr.
5. Executes sendmmsg.
6. Error Recovery: If EMSGSIZE is caught, it triggers MTU re-discovery, reframes the remaining data with the new smaller size, and retries.

Parameters

message

The message to transmit.

Returns

true if all fragments were successfully sent; false on fatal pipe errors.

Implements dfx::Core::DestinationTransport.

start()

void dfx::Core::UdpDestination::start ( FdWatch::Poller & poller )

overridevirtual

Initializes the UDP socket and enables PMTUD.

Sets IP_MTU_DISCOVER to IP_PMTUDISC_DO. Fetches the initial interface MTU.

Parameters

poller

The poller instance.

Implements dfx::Core::Transport.

stop()

void dfx::Core::UdpDestination::stop ( )

overridevirtualnoexcept

Closes the socket and releases resources.

Implements dfx::Core::Transport.

Member Data Documentation

defaultMtuNetworkOverhead

auto dfx::Core::UdpDestination::defaultMtuNetworkOverhead = 64

staticconstexpr

Prepares the UDP socket and performs initial MTU discovery.

---

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

• lib/dfx-core/transports/destinations/UdpDestination.hpp