Function collectTraces

scripts/trace-dd.mjs:83–129

(filePath, metadata)

 * Read generated trace from file system, augment & sent it to the remote tracer.
 */
const collectTraces = async (filePath, metadata) => {
  const tracer = Tracer.init({
    tags: metadata,
    // Setting external env variable `DD_TRACE_DEBUG=true` will emit this log
    logLevel: 'error',
    // TODO: this is due to generated trace have excessive numbers of spans
    // for build-module-*, using default flush causes overflow to the agent.
    flushInterval: 20,
    flushMinSpans: 10,
  })

  const readLineInterface = createInterface({
    input: createReadStream(filePath),
    crlfDelay: Infinity,
  })

  const traces = new Map()
  const rootTraces = []

  // Input trace file contains newline-separated sets of traces, where each line is valid JSON
  // type of Array<TraceEvent>. Read it line-by-line to manually reconstruct trace trees.
  //
  // We have to read through end of the trace -
  // Trace events in the input file can appear out of order, so we need to remodel the shape of the span tree before reporting
  for await (const line of readLineInterface) {
    JSON.parse(line).forEach((trace) => traces.set(trace.id, trace))
  }

  // Link inner, child spans to the parents to reconstruct span with correct relations
  for (const event of traces.values()) {
    if (event.parentId) {
      event.parent = traces.get(event.parentId)
      if (event.parent) {
        if (!event.parent.children) event.parent.children = []
        event.parent.children.push(event)
      }
    }

    if (!event.parent) {
      rootTraces.push(event)
    }
  }

  for (const trace of rootTraces) {
    reportSpanRecursively(tracer, trace)
  }
}

/**
 * Naively validate, collect necessary args.