opencode/packages/app/e2e/performance/timeline/session-timeline-profile.ts

import type { CDPSession, Page } from "@playwright/test"

export async function startTimelineProfile(page: Page, options: { cpuThrottle: number; profileCPU: boolean }) {
  const cdp = await page.context().newCDPSession(page)
  if (options.cpuThrottle > 1) await cdp.send("Emulation.setCPUThrottlingRate", { rate: options.cpuThrottle })
  if (options.profileCPU) {
    await cdp.send("Profiler.enable")
    await cdp.send("Profiler.setSamplingInterval", { interval: 100 })
    await cdp.send("Profiler.start")
  }
  return {
    async stop() {
      if (!options.profileCPU) return
      const result = await cdp.send("Profiler.stop")
      const self = new Map<number, number>()
      result.profile.samples?.forEach((id, index) => {
        const duration = (result.profile.timeDeltas?.[index] ?? 0) / 1_000
        self.set(id, (self.get(id) ?? 0) + duration)
      })
      console.log(
        "timeline cpu profile",
        JSON.stringify(
          result.profile.nodes
            .map((node) => ({
              function: node.callFrame.functionName || "(anonymous)",
              url: node.callFrame.url,
              line: node.callFrame.lineNumber + 1,
              selfMs: self.get(node.id) ?? 0,
            }))
            .filter((node) => node.selfMs > 1)
            .sort((a, b) => b.selfMs - a.selfMs)
            .slice(0, 40),
        ),
      )
    },
    async reset() {
      if (options.cpuThrottle > 1) await cdp.send("Emulation.setCPUThrottlingRate", { rate: 1 })
    },
  }
}