dd-trace/packages/dd-trace/src/debugger/devtools_client/snapshot/index.js

Datadog APM tracing client for JavaScript

'use strict'

const { getRuntimeObject } = require('./collector')
const { processRawState } = require('./processor')

const DEFAULT_MAX_REFERENCE_DEPTH = 3
const DEFAULT_MAX_COLLECTION_SIZE = 100
const DEFAULT_MAX_FIELD_COUNT = 20
const DEFAULT_MAX_LENGTH = 255

module.exports = {
  getLocalStateForCallFrame
}

async function getLocalStateForCallFrame (
  callFrame,
  {
    maxReferenceDepth = DEFAULT_MAX_REFERENCE_DEPTH,
    maxCollectionSize = DEFAULT_MAX_COLLECTION_SIZE,
    maxFieldCount = DEFAULT_MAX_FIELD_COUNT,
    maxLength = DEFAULT_MAX_LENGTH
  } = {}
) {
  const rawState = []
  let processedState = null

  await Promise.all(callFrame.scopeChain.map(async (scope) => {
    if (scope.type === 'global') return // The global scope is too noisy
    rawState.push(...await getRuntimeObject(
      scope.object.objectId,
      { maxReferenceDepth, maxCollectionSize, maxFieldCount }
    ))
  }))

  // Deplay calling `processRawState` so the caller gets a chance to resume the main thread before processing `rawState`
  return () => {
    processedState = processedState ?? processRawState(rawState, maxLength)
    return processedState
  }
}