1_q.md

https://mond.how/ja/topics/9ce6dxpx23p1otu/c2iavyegnvsxu48

2_main.scala

// 雑に書いているので、あろうことかエラーメッセージは日本語です。

import scala.collection.mutable

// Domain Layer (unchanged)
case class ProductId(value: String)
case class ShippingProviderId(value: String)

enum ProductStatus:
  case Draft, Published

case class Product(
                    id: ProductId,
                    name: String,
                    status: ProductStatus,
                    shippingProviderId: Option[ShippingProviderId]
                  )

enum DomainError:
  case BusinessRuleViolation(message: String)
  case RepositoryError(message: String)

// Purely Functional Domain Service
object ProductPublicationDomainService:
  private def canPublish(product: Product): Boolean =
    product.shippingProviderId.isDefined

  private def publishProduct(product: Product): Either[DomainError, Product] =
    if canPublish(product) then
      Right(product.copy(status = ProductStatus.Published))
    else
      Left(DomainError.BusinessRuleViolation(s"配送業者が設定されていません: ${product.id.value}"))

  def publishProducts: LazyList[Product] => LazyList[Either[DomainError, Product]] =
    _.map(publishProduct)

// Repository Interface
trait ProductRepository:
  def findDraftProducts(): LazyList[Product]
  def saveProducts(products: Seq[Product]): Either[DomainError, Unit]

// In-Memory Repository Implementation (Mutable Object)
class InMemoryProductRepository extends ProductRepository:
  private val products = mutable.Map[ProductId, Product]()

  def addProduct(product: Product): Unit =
    products += (product.id -> product)

  def findDraftProducts(): LazyList[Product] =
    LazyList.from(products.values).filter(_.status == ProductStatus.Draft)

  def saveProducts(products: Seq[Product]): Either[DomainError, Unit] =
    try
      products.foreach(p => this.products += (p.id -> p))
      Right(())
    catch
      case e: Exception => Left(DomainError.RepositoryError(s"バッチ保存中にエラーが発生しました: ${e.getMessage}"))

// Application Layer
case class PublishProductsResult(
                                  successCount: Int,
                                  failureCount: Int,
                                  errors: LazyList[DomainError]
                                )

object PublishProductsUseCase:
  def execute(
               productRepository: ProductRepository,
               batchSize: Int = 1000
             ): LazyList[PublishProductsResult] =
    ProductPublicationDomainService.publishProducts(productRepository.findDraftProducts())
      .grouped(batchSize)
      .map { batch =>
        val (successes, failures) = batch.partition(_.isRight)
        val successProducts = successes.collect { case Right(product) => product }
        val saveResult = productRepository.saveProducts(successProducts)

        PublishProductsResult(
          successCount = if saveResult.isRight then successProducts.size else 0,
          failureCount = failures.size + (if saveResult.isLeft then successProducts.size else 0),
          errors = failures.collect { case Left(error) => error } ++ saveResult.left.toSeq
        )
      }.to(LazyList)

// Usage example
@main def run(): Unit =
  // リポジトリの初期化とサンプルデータの追加
  val repository = new InMemoryProductRepository()
  (1 to 1000000).foreach { i =>
    repository.addProduct(
      Product(
        ProductId(s"P$i"),
        s"Product $i",
        ProductStatus.Draft,
        if i % 3 == 0 then Some(ShippingProviderId(s"SP$i")) else None
      )
    )
  }

  println("リポジトリにサンプルデータを追加しました。処理を開始します。")

  // Execute use case
  val results = PublishProductsUseCase.execute(repository)

  // Process and print results
  var totalSuccess = 0
  var totalFailure = 0
  var totalErrors = List.empty[DomainError]

  results.zipWithIndex.foreach { case (result, index) =>
    totalSuccess += result.successCount
    totalFailure += result.failureCount
    totalErrors = totalErrors ++ result.errors.take(5) // 各バッチから最大5つのエラーを記録

    // 10万件ごとに中間結果を表示
    if (index + 1) * 1000 % 100000 == 0 then
      println(s"Processed ${(index + 1) * 1000} products")
      println(s"Current success: $totalSuccess, Current failure: $totalFailure")
  }

  println(s"""
             |最終処理結果:
             |  成功: $totalSuccess
             |  失敗: $totalFailure
             |  エラーサンプル (最大15件):
             |    ${totalErrors.take(15).mkString("\n    ")}
    """.stripMargin)