mm::node::DeviceSet Struct Reference

One published generation of the bus: the driver that owns the socket, and the devices found on it. More...

#include <device_manager.h>

Collaboration diagram for mm::node::DeviceSet:

Public Member Functions
Device *	find (uint16_t slavePosition)
	Device at slavePosition, or nullptr when the set holds none.
const Device *	find (uint16_t slavePosition) const
	Const overload of find. Same contract.

Public Attributes
std::shared_ptr< mm::comm::FieldbusDriver >	driver
	The driver every device in this set talks through. Shared, so a retired set keeps it alive.
std::vector< Device >	devices
	The devices in bus order: index 0 is position 1. Frozen once the set is published.
uint64_t	topologyGeneration = 0
	The value DeviceManager::topologyGeneration reported when this set was published.

Detailed Description

One published generation of the bus: the driver that owns the socket, and the devices found on it.

A set is built by init or scan, published once, and never modified after that. Publishing freezes the devices vector, not the devices in it — each Device guards its own parameter map with its own mutex.

The set is what makes device lifetime a refcount rather than a lock. Every off-RT caller works through a std::shared_ptr to one (DeviceManager::deviceSet), so a Device& stays valid for as long as the caller holds that pointer. A concurrent scan does not wait for the caller and does not invalidate the reference: it publishes a new set, and the old one dies when its last holder drops it. The retired devices keep working against their own driver, which the set also owns, so a transfer against hardware that is no longer on the bus fails cleanly instead of touching freed memory.

The RT thread does not touch the shared_ptr, because std::atomic<std::shared_ptr<T>> is not lock-free (and libc++ does not implement it at all). It reads a raw published pointer instead, drained by ProcessData::pauseCycle exactly as the process image is.

Member Function Documentation

find() [1/2]

Device * mm::node::DeviceSet::find

(

uint16_t

slavePosition

)

Device at slavePosition, or nullptr when the set holds none.

find() [2/2]

const Device * mm::node::DeviceSet::find

(

uint16_t

slavePosition

)

const

Const overload of find. Same contract.

Member Data Documentation

devices

std::vector<Device> mm::node::DeviceSet::devices

The devices in bus order: index 0 is position 1. Frozen once the set is published.

driver

std::shared_ptr<mm::comm::FieldbusDriver> mm::node::DeviceSet::driver

The driver every device in this set talks through. Shared, so a retired set keeps it alive.

topologyGeneration

uint64_t mm::node::DeviceSet::topologyGeneration = 0

The value DeviceManager::topologyGeneration reported when this set was published.

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The documentation for this struct was generated from the following files:

• libs/node/device_manager.h
• libs/node/device_manager.cc