next.js/turbopack/crates/turbopack-node/js/src/ipc/index.ts

import { createConnection } from 'node:net'
import { Writable } from 'node:stream'
import type { StackFrame } from '../compiled/stacktrace-parser'
import { parse as parseStackTrace } from '../compiled/stacktrace-parser'
import { getProperError } from './error'

export type StructuredError = {
  name: string
  message: string
  stack: StackFrame[]
  cause: StructuredError | undefined
}

export function structuredError(e: unknown): StructuredError {
  e = getProperError(e)

  return {
    name: e.name,
    message: e.message,
    stack: typeof e.stack === 'string' ? parseStackTrace(e.stack) : [],
    cause: e.cause ? structuredError(getProperError(e.cause)) : undefined,
  }
}

type State =
  | {
      type: 'waiting'
    }
  | {
      type: 'packet'
      length: number
    }

export type Ipc<TIncoming, TOutgoing> = {
  recv(): Promise<TIncoming>
  send(message: TOutgoing): Promise<void>
  sendError(error: Error | string): Promise<never>
  sendReady(): Promise<void>
}

function createIpc<TIncoming, TOutgoing>(
  port: number
): Ipc<TIncoming, TOutgoing> {
  const socket = createConnection({
    port,
    host: '127.0.0.1',
  })

  /**
   * A writable stream that writes to the socket.
   * We don't write directly to the socket because we need to
   * handle backpressure and wait for the socket to be drained
   * before writing more data.
   */
  const socketWritable = new Writable({
    write(chunk, _enc, cb) {
      if (socket.write(chunk)) {
        cb()
      } else {
        socket.once('drain', cb)
      }
    },
    final(cb) {
      socket.end(cb)
    },
  })

  const packetQueue: Buffer[] = []
  const recvPromiseResolveQueue: Array<(message: TIncoming) => void> = []

  function pushPacket(packet: Buffer) {
    const recvPromiseResolve = recvPromiseResolveQueue.shift()
    if (recvPromiseResolve != null) {
      recvPromiseResolve(JSON.parse(packet.toString('utf8')) as TIncoming)
    } else {
      packetQueue.push(packet)
    }
  }

  let state: State = { type: 'waiting' }
  let buffer: Buffer = Buffer.alloc(0)
  socket.once('connect', () => {
    socket.on('data', (chunk) => {
      buffer = Buffer.concat([buffer, chunk])

      loop: while (true) {
        switch (state.type) {
          case 'waiting': {
            if (buffer.length >= 4) {
              const length = buffer.readUInt32BE(0)
              buffer = buffer.subarray(4)
              state = { type: 'packet', length }
            } else {
              break loop
            }
            break
          }
          case 'packet': {
            if (buffer.length >= state.length) {
              const packet = buffer.subarray(0, state.length)
              buffer = buffer.subarray(state.length)
              state = { type: 'waiting' }
              pushPacket(packet)
            } else {
              break loop
            }
            break
          }
          default:
            invariant(state, (state) => `Unknown state type: ${state?.type}`)
        }
      }
    })
  })
  // When the socket is closed, this process is no longer needed.
  // This might happen e. g. when parent process is killed or
  // node.js pool is garbage collected.
  socket.once('close', () => {
    process.exit(0)
  })

  // TODO(lukesandberg): some of the messages being sent are very large and contain lots
  //  of redundant information.  Consider adding gzip compression to our stream.
  function doSend(message: string): Promise<void> {
    return new Promise((resolve, reject) => {
      // Reserve 4 bytes for our length prefix, we will over-write after encoding.
      const packet = Buffer.from('0000' + message, 'utf8')
      packet.writeUInt32BE(packet.length - 4, 0)
      socketWritable.write(packet, (err) => {
        process.stderr.write(`TURBOPACK_OUTPUT_D\n`)
        process.stdout.write(`TURBOPACK_OUTPUT_D\n`)
        if (err != null) {
          reject(err)
        } else {
          resolve()
        }
      })
    })
  }

  function send(message: any): Promise<void> {
    return doSend(JSON.stringify(message))
  }
  function sendReady(): Promise<void> {
    return doSend('')
  }

  return {
    async recv() {
      const packet = packetQueue.shift()
      if (packet != null) {
        return JSON.parse(packet.toString('utf8')) as TIncoming
      }

      const result = await new Promise<TIncoming>((resolve) => {
        recvPromiseResolveQueue.push((result) => {
          resolve(result)
        })
      })

      return result
    },

    send(message: TOutgoing) {
      return send(message)
    },

    sendReady,

    async sendError(error: Error): Promise<never> {
      try {
        await send({
          type: 'error',
          ...structuredError(error),
        })
      } catch (err) {
        console.error('failed to send error back to rust:', err)
        // ignore and exit anyway
        process.exit(1)
      }

      process.exit(0)
    },
  }
}

const PORT = process.argv[2]

export const IPC = createIpc<unknown, unknown>(parseInt(PORT, 10))

process.on('uncaughtException', (err) => {
  IPC.sendError(err)
})

const improveConsole = (name: string, stream: string, addStack: boolean) => {
  // @ts-ignore
  const original = console[name]
  // @ts-ignore
  const stdio = process[stream]
  // @ts-ignore
  console[name] = (...args: any[]) => {
    stdio.write(`TURBOPACK_OUTPUT_B\n`)
    original(...args)
    if (addStack) {
      const stack = new Error().stack?.replace(/^.+\n.+\n/, '') + '\n'
      stdio.write('TURBOPACK_OUTPUT_S\n')
      stdio.write(stack)
    }
    stdio.write('TURBOPACK_OUTPUT_E\n')
  }
}

improveConsole('error', 'stderr', true)
improveConsole('warn', 'stderr', true)
improveConsole('count', 'stdout', true)
improveConsole('trace', 'stderr', false)
improveConsole('log', 'stdout', true)
improveConsole('group', 'stdout', true)
improveConsole('groupCollapsed', 'stdout', true)
improveConsole('table', 'stdout', true)
improveConsole('debug', 'stdout', true)
improveConsole('info', 'stdout', true)
improveConsole('dir', 'stdout', true)
improveConsole('dirxml', 'stdout', true)
improveConsole('timeEnd', 'stdout', true)
improveConsole('timeLog', 'stdout', true)
improveConsole('timeStamp', 'stdout', true)
improveConsole('assert', 'stderr', true)

/**
 * Utility function to ensure all variants of an enum are handled.
 */
function invariant(never: never, computeMessage: (arg: any) => string): never {
  throw new Error(`Invariant: ${computeMessage(never)}`)
}