test: add browse instrumentation helpers

server/utils/queries/libraryBrowseInstrumentation.js

@@ -0,0 +1,57 @@
+const { performance } = require('perf_hooks')
+
+function getPhaseName(markName) {
+  return String(markName || '').split(':')[0]
+}
+
+function createBrowseRequestProfile(context = {}) {
+  const now = typeof context.now === 'function' ? context.now : () => performance.now()
+  const marks = []
+
+  return {
+    route: context.route || null,
+    libraryId: context.libraryId || null,
+    now,
+    startedAt: now(),
+    marks,
+    mark(name) {
+      marks.push({ name, at: now() })
+    }
+  }
+}
+
+function finishBrowseRequestProfile(profile, { slowMs = 1000 } = {}) {
+  const endedAt = profile.now()
+  const phases = {}
+  const openPhases = new Map()
+
+  profile.marks.forEach((mark) => {
+    const phaseName = getPhaseName(mark.name)
+    if (!phaseName) return
+
+    if (String(mark.name).endsWith(':start')) {
+      openPhases.set(phaseName, mark.at)
+      return
+    }
+
+    if (String(mark.name).endsWith(':end') && openPhases.has(phaseName)) {
+      phases[phaseName] = Math.round(mark.at - openPhases.get(phaseName))
+      openPhases.delete(phaseName)
+    }
+  })
+
+  const totalMs = Math.round(endedAt - profile.startedAt)
+
+  return {
+    route: profile.route || null,
+    libraryId: profile.libraryId || null,
+    totalMs,
+    phases,
+    isSlow: totalMs >= slowMs
+  }
+}
+
+module.exports = {
+  createBrowseRequestProfile,
+  finishBrowseRequestProfile
+}