Class RotatingWriteStream

packages/next/src/trace/report/to-json.ts:39–96

  encoding: 'utf8' as const,
}
class RotatingWriteStream {
  file: string
  writeStream!: fs.WriteStream
  size: number
  sizeLimit: number
  private rotatePromise: Promise<void> | undefined
  private drainPromise: Promise<void> | undefined
  constructor(file: string, sizeLimit: number) {
    this.file = file
    this.size = 0
    this.sizeLimit = sizeLimit
    this.createWriteStream()
  }
  private createWriteStream() {
    this.writeStream = fs.createWriteStream(this.file, writeStreamOptions)
  }
  // Recreate the file
  private async rotate() {
    await this.end()
    try {
      fs.unlinkSync(this.file)
    } catch (err: any) {
      // It's fine if the file does not exist yet
      if (err.code !== 'ENOENT') {
        throw err
      }
    }
    this.size = 0
    this.createWriteStream()
    this.rotatePromise = undefined
  }
  async write(data: string): Promise<void> {
    if (this.rotatePromise) await this.rotatePromise

    this.size += data.length
    if (this.size > this.sizeLimit) {
      await (this.rotatePromise = this.rotate())
    }

    if (!this.writeStream.write(data, 'utf8')) {
      if (this.drainPromise === undefined) {
        this.drainPromise = new Promise<void>((resolve, _reject) => {
          this.writeStream.once('drain', () => {
            this.drainPromise = undefined
            resolve()
          })
        })
      }
      await this.drainPromise
    }
  }

  end(): Promise<void> {
    return new Promise((resolve) => {
      this.writeStream.end(resolve)
    })
  }
}