Drawing of link statistics in GUI - Tx power and Rx RSSI #738

EskoDijk · 2026-01-13T16:47:17Z

Aims to add drawing of link statistics in the GUI, under control of the Go code: so it's easier to add new visualizations for links in the future by only updating the Go code (server side).

As a start/try, it can now visualize latest Tx power (dBm) and Rx RSSI (dBm) between nodes, based on the radio model. This requires no changes in OpenThread w.r.t. reporting of internal changes in link quality or the like.

Multiple commits will later be squashed. Currently in draft.

…only.

…g for links in JS.

gemini-code-assist · 2026-01-13T16:48:10Z

Summary of Changes

Hello @EskoDijk, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the simulation's visualization capabilities by introducing dynamic display of radio link quality metrics (Tx power and Rx RSSI) between nodes in the GUI. The architectural approach centralizes the control of these visualizations on the Go backend, streamlining future development. This change provides users with more immediate and detailed insights into network performance and link health during simulations.

Highlights

New Link Statistics Visualization: Introduced the ability to visualize link statistics, specifically Transmit Power (Tx power) and Received Signal Strength Indicator (Rx RSSI), directly in the GUI. These values are displayed as labels between connected nodes.
Server-Side Control for Visualizations: The control logic for these new link visualizations resides on the Go backend, allowing for easier expansion and addition of new link-related visualizations in the future without extensive frontend changes.
CLI Command Integration: New CLI commands (LinkTxPower and LinkRxRssi) have been added to enable or disable the display of Tx power and Rx RSSI in the visualization options.
gRPC and Frontend Updates: The gRPC protobuf definitions and the frontend (PixiJS) have been updated to support the new link statistics events, including new message types for adding and removing link stats, and rendering logic for the labels.
Node Selection Event Handling: A new SelectNode gRPC method and corresponding backend/frontend logic have been added to handle node selection events, which can trigger the display of link statistics for the selected node.

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Code Review

This pull request introduces a valuable feature for visualizing link statistics, specifically Tx power and Rx RSSI, in the GUI. The implementation spans across the Go backend, gRPC definitions, and the JavaScript frontend, and is well-structured. The backend logic correctly hooks into the radio frame dispatching process to gather statistics, and the frontend introduces a new LinkStats visual component to display this data. While the overall implementation is solid, I've identified a few potential issues concerning correctness and robustness that I recommend addressing.

gemini-code-assist · 2026-01-13T16:51:11Z

visualize/grpc/grpcField.go

+	logger.AssertNotNil(gn.extaddr)
+	logger.AssertTrue(gn.extaddr > 0)
 	f.nodes[id] = gn
+	f.extAddrMap[gn.extaddr] = id


There's a potential race condition here. When a new node is added, its extaddr is InvalidExtAddr. The line f.extAddrMap[gn.extaddr] = id maps InvalidExtAddr to the new node's ID. If another node is added before the first one gets a valid extaddr, this map entry will be overwritten, leading to incorrect state. The extAddrMap should only be updated with valid extended addresses, which is correctly handled in onExtAddrChange.

Additionally, logger.AssertNotNil(gn.extaddr) is called on a uint64, which is not a pointer type and will never be nil. This assertion might not be behaving as intended.

Consider removing these lines. The extAddrMap is correctly managed in onExtAddrChange.

gemini-code-assist · 2026-01-13T16:51:11Z

dispatcher/dispatcher.go

+			childId := d.extaddrMap[extaddr].Id
+			d.vis.SetParent(childId, node.ExtAddr)


Accessing d.extaddrMap[extaddr].Id could cause a panic if extaddr is not present in the map, as d.extaddrMap[extaddr] would be nil. While it's likely that a child node is known at this point, adding a check for existence would make the code more robust against unexpected states.

Suggested change

childId := d.extaddrMap[extaddr].Id

d.vis.SetParent(childId, node.ExtAddr)

child := d.extaddrMap[extaddr]

if child != nil {

d.vis.SetParent(child.Id, node.ExtAddr)

}

gemini-code-assist · 2026-01-13T16:51:11Z

visualize/grpc/grpcVisualizer.go

+			}
+
+			if opt.RxRssi {
+				if nbInfo.lastTxPower == RssiInvalid {


There seems to be a copy-paste error here. When checking if the RSSI value is available to create the label, nbInfo.lastTxPower is checked instead of nbInfo.lastRssi. This will result in "N/A" being displayed for RSSI even when a valid RSSI value is available, if lastTxPower is invalid.

Suggested change

if nbInfo.lastTxPower == RssiInvalid {

if nbInfo.lastRssi == RssiInvalid {

EskoDijk added 13 commits January 13, 2026 11:51

WIP link labels - test with single sprite

78e51ab

WIP: readable number labels

53b3b52

WIP: convert to Go controlled link stats and labels. Add gRPC event.

a9ffc7e

WIP: add RPC for selection of nodes by user

daabc7b

WIP: selection and unselection; showing link values on selected node …

1fa05ba

…only.

WIP: RSSI values viz test

8ea0de4

WIP: new design

c495032

WIP: Tx power plotting and Rx Rssi tracking fix

b7c13d2

WIP: multi-selection (Tx power only)

5040471

WIP: add cv CLI command for 'ltx' = link tx

a23b0ed

WIP: prototype RSSI display

c396425

WIP: various fixes; add rss and txp cv options. Enhanced batch drawin…

4da5170

…g for links in JS.

WIP: make ClipRssi internal again.

6074c8a

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Drawing of link statistics in GUI - Tx power and Rx RSSI #738

Drawing of link statistics in GUI - Tx power and Rx RSSI #738

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		childId := d.extaddrMap[extaddr].Id
		d.vis.SetParent(childId, node.ExtAddr)

-			childId := d.extaddrMap[extaddr].Id
-			d.vis.SetParent(childId, node.ExtAddr)
+            child := d.extaddrMap[extaddr]
+            if child != nil {
+                d.vis.SetParent(child.Id, node.ExtAddr)
+            }

	if nbInfo.lastTxPower == RssiInvalid {
	if nbInfo.lastRssi == RssiInvalid {

Drawing of link statistics in GUI - Tx power and Rx RSSI #738

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Drawing of link statistics in GUI - Tx power and Rx RSSI #738

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EskoDijk commented Jan 13, 2026

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