From 140048df5e755beb4490ffb9d2b17c79c6a8c969 Mon Sep 17 00:00:00 2001
From: Julian Gruber <julian@juliangruber.com>
Date: Thu, 14 Dec 2023 12:26:07 +0100
Subject: [PATCH] Add `tasks_per_node` retrieval stats. Closes #78

---
 lib/retrieval-stats.js       | 9 +++++++++
 test/retrieval-stats.test.js | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/lib/retrieval-stats.js b/lib/retrieval-stats.js
index 50a8d00f..7d387cca 100644
--- a/lib/retrieval-stats.js
+++ b/lib/retrieval-stats.js
@@ -33,6 +33,7 @@ export const buildRetrievalStats = (measurements, telemetryPoint) => {
 
   const participants = new Set()
   const inetGroups = new Set()
+  const tasksPerNode = new Map()
   let downloadBandwidth = 0
 
   const ttfbValues = []
@@ -67,6 +68,9 @@ export const buildRetrievalStats = (measurements, telemetryPoint) => {
     }
     if (ttfb !== undefined && ttfb > 0 && m.status_code === 200) ttfbValues.push(ttfb)
     if (duration !== undefined && duration > 0) durationValues.push(duration)
+
+    const node = `${m.inet_group}::${m.participantAddress}`
+    tasksPerNode.set(node, (tasksPerNode.get(node) ?? 0) + 1)
   }
   const successRate = resultBreakdown.OK / totalCount
 
@@ -80,6 +84,11 @@ export const buildRetrievalStats = (measurements, telemetryPoint) => {
   addHistogramToPoint(telemetryPoint, ttfbValues, 'ttfb_')
   addHistogramToPoint(telemetryPoint, durationValues, 'duration_')
   addHistogramToPoint(telemetryPoint, sizeValues, 'car_size_')
+  addHistogramToPoint(
+    telemetryPoint,
+    Array.from(tasksPerNode.values()),
+    'tasks_per_node_'
+  )
 
   for (const [result, count] of Object.entries(resultBreakdown)) {
     telemetryPoint.floatField(`result_rate_${result}`, count / totalCount)
diff --git a/test/retrieval-stats.test.js b/test/retrieval-stats.test.js
index cad343ba..18860ffc 100644
--- a/test/retrieval-stats.test.js
+++ b/test/retrieval-stats.test.js
@@ -82,6 +82,10 @@ describe('retrieval statistics', () => {
     assertPointFieldValue(point, 'car_size_mean', '69906090i')
     assertPointFieldValue(point, 'car_size_p90', '167772569i')
     assertPointFieldValue(point, 'car_size_max', '209715200i')
+
+    assertPointFieldValue(point, 'tasks_per_node_p5', '1i')
+    assertPointFieldValue(point, 'tasks_per_node_p50', '2i')
+    assertPointFieldValue(point, 'tasks_per_node_p95', '2i')
   })
 
   it('handles first_byte_at set to unix epoch', () => {