dd-trace/packages/dd-trace/src/profiling/exporters/file.js

Datadog APM tracing client for JavaScript

'use strict'

const fs = require('fs')
const { promisify } = require('util')
const { pathToFileURL } = require('url')
const { threadId } = require('worker_threads')
const writeFile = promisify(fs.writeFile)
const { EventSerializer } = require('./event_serializer')

const pad = (n) => String(n).padStart(2, '0')

function formatDateTime (t) {
  return `${t.getUTCFullYear()}${pad(t.getUTCMonth() + 1)}${pad(t.getUTCDate())}` +
    `T${pad(t.getUTCHours())}${pad(t.getUTCMinutes())}${pad(t.getUTCSeconds())}Z`
}

class FileExporter extends EventSerializer {
  #pprofPrefix

  /**
   * @param {import('./event_serializer').TracerConfig} config
   * @param {string} [pprofPrefix] - File path prefix. Defaults to the config value, but the OOM
   *   export subprocess passes a path derived from a `file:` URL, which is not a config value.
   */
  constructor (config, pprofPrefix = config.DD_PROFILING_PPROF_PREFIX) {
    super(config)
    this.#pprofPrefix = pprofPrefix
  }

  getExportUrl () {
    return pathToFileURL(this.#pprofPrefix)
  }

  export (exportSpec) {
    const { profiles, end } = exportSpec
    const types = Object.keys(profiles)
    const dateStr = formatDateTime(end)
    const tasks = types.map(type => {
      return writeFile(`${this.#pprofPrefix}${type}_worker_${threadId}_${dateStr}.pprof`, profiles[type])
    })
    tasks.push(writeFile(`event_worker_${threadId}_${dateStr}.json`, this.getEventJSON(exportSpec)))
    return Promise.all(tasks)
  }
}

module.exports = { FileExporter }