mm::node::NotificationBus::Source Struct Reference

One feature's contribution: when to speak, and what to say. More...

#include <notification_bus.h>

Public Attributes
std::function< std::uint64_t()>	revision
std::function< std::optional< nlohmann::json >()>	render
std::chrono::milliseconds	interval {20}

Detailed Description

One feature's contribution: when to speak, and what to say.

Member Data Documentation

interval

std::chrono::milliseconds mm::node::NotificationBus::Source::interval {20}

How often this source is looked at, which is both its latency floor and its ceiling on messages. The two are the same thing: a source read once a second cannot speak more often than that, so a producer bumping its counter every real-time cycle needs no separate rate limit. Nothing is lost to a slow cadence — the counter is cumulative and the last-seen mark advances only when a message is sent, so a change is reported whole at the next reading.

Pick it from what the event is, and from how fast its producer bumps the counter. A lifecycle change a person is waiting on wants tens of milliseconds; a counter the real-time loop raises every cycle wants about a second, or it reports at the rate of the fault. Each source pays only for its own cadence: the bus sleeps until the earliest one is due.

render

std::function<std::optional<nlohmann::json>()> mm::node::NotificationBus::Source::render

Builds the data object of the message, off the RT thread. Called only when revision has changed and the quiet window has passed, so it may do real work — including logging what it found, which is how a source reaches a support log as well as a client.

Returns

The payload, or nullopt to say nothing after all. A source that has gone idle between the counter read and this call answers nullopt rather than inventing an event.

revision

std::function<std::uint64_t()> mm::node::NotificationBus::Source::revision

Cheap read of the producer's version counter. Called every poll, so it must not lock or allocate. Only compared for inequality against the previous reading.

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

• libs/node/notification_bus.h