[Feature Request]: Add a configVersion uint32 to allow for client app config caching

[danditomaso]

Platform

NRF52, ESP32, Cross-Platform, Linux Native

Description

I am creating a feature request to suggest improvements in how client app's handle obtaining a node's config. I am purposing a combination some small firmware changes along with several protobuf changes which will enable conditional config syncing when a user connects to their node.

Web and mobile clients currently request all configs on every connection, even when config hasn't changed. This slows down the connection process, and require additional power from a node to send the config (if running on solar or batteries).

Solution

Add config_version (uint32) to MyNodeInfo that increments on any config change. Clients cache config with its version; on reconnect, compare versions to skip unnecessary fetches.

A high level list of changes that would be required:

• mesh.proto: Add config_version and/or config_modified_at fields to MyNodeInfo
• Increment config_version on config writes
• Persist/load config_version from non-volatile memory

Benefits

• Faster reconnection (skipping all config requests when its unchanged)
• Better offline support for clients
• Improve device efficiency by avoiding unnecessary BLE/Wifi/Serial traffic.

[garthvh]

How would we know which client connected? The node db is what is slow and you can already use the nonce to control getting this.

[danditomaso]

@garthvh I wouldn’t expect the node to care which client has connected. The config_version int would be read from non-volatile memory and included as a new field in the myNodeInfo message sent to clients.

This is similar to how Git SHA hashing works: Git can tell you how many commits exist relative to a base branch without caring which machine or connection method you’re using. The identity of the client isn’t relevant, only the version state is.

[danditomaso]

Bump