chronon::Connection

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#include <Connection.hpp>

Inherits from chronon::sender::ConnectionBase

Public Functions

	Name
bool	transfer(T data, uint64_t send_cycle)
InPort< T > *	to() const
virtual Unit *	source() const override Source unit (for dependency analysis).
virtual void	setThreadQueueId(size_t queue_id) override
virtual void	setConnId(uint32_t conn_id) override
virtual size_t	registerProducerThread(size_t thread_id) override
virtual IArbitratablePort *	registerOnDestMPSC() override
virtual void	optimizeForSameThread() override
virtual void	optimizeForSPSC() override
virtual void	optimizeForMPSC() override
bool	isDestinationFull() const
virtual bool	hasThreadQueueId() const override True if this connection uses thread-specific queue (MPSC mode).
OutPort< T > *	from() const
virtual Unit *	destination() const override Destination unit (for dependency analysis).
virtual void *	destPortPtr() const override Destination port pointer (type-erased) for port-level grouping.
virtual uint32_t	delay() const override Delay in cycles between push and arrival.
virtual uint32_t	connId() const override
virtual void	cancelInFlight() override
bool	canTransfer() const True if the destination can accept data (back-pressure preflight).
virtual size_t	arbitrateAdmitErased(size_t budget) override
virtual size_t	arbitrateAdmitBoundedErased(size_t budget, uint64_t max_send_cycle) override
	Connection(OutPort< T > * from, InPort< T > * to, uint32_t delay)

Additional inherited members

Public Functions inherited from chronon::sender::ConnectionBase

	Name
virtual	~ConnectionBase() =default
bool	isTight() const True if this is a zero-delay (tight) connection.

Detailed Description

template <typename T >
class chronon::Connection;

Connection - Typed connection between OutPort and InPort.

Connections specify the communication delay:

• delay=0: Tight coupling, same-cycle delivery (delta cycles)
• delay>0: Loose coupling, future delivery (lookahead possible)

Usage: auto conn = sim.connect(producer->out, consumer->in, 5); // Messages sent at cycle N arrive at cycle N+5

Public Functions Documentation

function transfer

inline bool transfer(
    T data,
    uint64_t send_cycle
)

Parameters:

• data The data to transfer
• send_cycle The current cycle when sending

Return: true if transfer succeeded, false if destination full (back pressure)

Transfer data through the connection.

The data will arrive at the destination port after the configured delay. Uses thread-specific queue if in multi-producer mode.

function to

inline InPort< T > * to() const

function source

virtual Unit * source() const override

Source unit (for dependency analysis).

Reimplements: chronon::sender::ConnectionBase::source

function setThreadQueueId

inline virtual void setThreadQueueId(
    size_t queue_id
) override

Parameters:

• queue_id The queue ID for this connection's source thread

Reimplements: chronon::sender::ConnectionBase::setThreadQueueId

Set the thread queue ID for multi-producer mode.

Called during initialization when the destination InPort is in multi-producer mode (multiple source threads writing to it). All connections from the same source thread share the same queue_id.

function setConnId

inline virtual void setConnId(
    uint32_t conn_id
) override

Reimplements: chronon::sender::ConnectionBase::setConnId

Stable connection identifier assigned at simulation build time.

Equal to this connection's index in TickSimulation::connections_. Used by MultiProducerQueueAdapter as a cross-num_workers-stable tiebreaker in the k-way merge, replacing the partition-dependent queue_id. The value is deterministic given a fixed topology, regardless of thread count / cluster assignment.

function registerProducerThread

inline virtual size_t registerProducerThread(
    size_t thread_id
) override

Parameters:

• thread_id Source thread identifier

Return: Queue ID for this producer thread, or SIZE_MAX on failure

Reimplements: chronon::sender::ConnectionBase::registerProducerThread

Register a producer thread for MPSC mode.

function registerOnDestMPSC

virtual IArbitratablePort * registerOnDestMPSC() override

Reimplements: chronon::sender::ConnectionBase::registerOnDestMPSC

Register this MPSC connection on its destination InPort and return the InPort's type-erased IArbitratablePort interface so the TickSimulation can drive cycle-boundary arbitration without ever knowing the Connection's message type. Returns nullptr when the connection is not in MPSC mode.

function optimizeForSameThread

inline virtual void optimizeForSameThread() override

Reimplements: chronon::sender::ConnectionBase::optimizeForSameThread

Optimize destination port for same-thread access.

Switches InPort to use lock-free SingleThreadMessageQueue. Call this during initialization when both source and destination are determined to be on the same thread (same cluster).

This eliminates mutex overhead (~18% of execution time) for intra-cluster connections.

function optimizeForSPSC

inline virtual void optimizeForSPSC() override

Reimplements: chronon::sender::ConnectionBase::optimizeForSPSC

Optimize destination port for cross-thread SPSC access.

Switches InPort to use lock-free LockFreeMessageQueue. Call this during initialization when there is exactly ONE source thread writing to the destination port on a different thread.

function optimizeForMPSC

inline virtual void optimizeForMPSC() override

Reimplements: chronon::sender::ConnectionBase::optimizeForMPSC

Optimize destination port for cross-thread MPSC access.

Switches InPort to use MultiProducerQueueAdapter with per-thread producer queues.

function isDestinationFull

inline bool isDestinationFull() const

function hasThreadQueueId

inline virtual bool hasThreadQueueId() const override

True if this connection uses thread-specific queue (MPSC mode).

Reimplements: chronon::sender::ConnectionBase::hasThreadQueueId

function from

inline OutPort< T > * from() const

function destination

virtual Unit * destination() const override

Destination unit (for dependency analysis).

Reimplements: chronon::sender::ConnectionBase::destination

function destPortPtr

inline virtual void * destPortPtr() const override

Destination port pointer (type-erased) for port-level grouping.

Reimplements: chronon::sender::ConnectionBase::destPortPtr

function delay

inline virtual uint32_t delay() const override

Delay in cycles between push and arrival.

Reimplements: chronon::sender::ConnectionBase::delay

function connId

inline virtual uint32_t connId() const override

Reimplements: chronon::sender::ConnectionBase::connId

function cancelInFlight

inline virtual void cancelInFlight() override

Reimplements: chronon::sender::ConnectionBase::cancelInFlight

Cancel all in-flight messages previously sent on this connection.

Only bumps the cancellation epoch. Staged entries are dropped lazily by the arbiter on drain (it compares each entry's epoch_snapshot against the current epoch). This matters under consumer-tick-driven arbitration (Option 1): the producer thread and the consumer-thread arbiter may access staging_ concurrently, so a producer-side staging_.clear() would race with the arbiter's drain. See R3 in docs/mpsc-atomic-publish.md.

function canTransfer

inline bool canTransfer() const

True if the destination can accept data (back-pressure preflight).

function arbitrateAdmitErased

inline virtual size_t arbitrateAdmitErased(
    size_t budget
) override

Reimplements: chronon::sender::ConnectionBase::arbitrateAdmitErased

Type-erased MPSC admission helper invoked by the InPort arbiter.

Legacy unbounded variant: drains every staging entry whose epoch matches the current cancel_epoch_. Called by the main-thread arbiter path (Sequential per-cycle loop, Barrier sync_wait, lookahead epoch-end flush).

function arbitrateAdmitBoundedErased

inline virtual size_t arbitrateAdmitBoundedErased(
    size_t budget,
    uint64_t max_send_cycle
) override

Reimplements: chronon::sender::ConnectionBase::arbitrateAdmitBoundedErased

Cycle-bounded admission: drains every staging entry whose epoch matches AND whose enqueue_cycle <= max_send_cycle. Used by the consumer-tick-driven arbiter (Option 1): the consumer at its own localCycle computes S = min(predecessor-thread completed_cycle) and passes S here, so only entries that every producer has finished writing are admitted this tick.

function Connection

inline Connection(
    OutPort< T > * from,
    InPort< T > * to,
    uint32_t delay
)

Parameters:

• from Source output port
• to Destination input port
• delay Number of cycles for message delivery

Create a connection with specified delay.

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Updated on 2026-05-26 at 05:42:32 +0000