Function watchNode

packages/platform-node-shared/src/internal/fileSystem.ts:538–579

(path: string, options?: FileSystem.WatchOptions)

// == watch

const watchNode = (path: string, options?: FileSystem.WatchOptions) =>
  Stream.asyncScoped<FileSystem.WatchEvent, Error.PlatformError>((emit) =>
    Effect.acquireRelease(
      Effect.sync(() => {
        const watcher = NFS.watch(path, { recursive: options?.recursive }, (event, path) => {
          if (!path) return
          switch (event) {
            case "rename": {
              emit.fromEffect(Effect.matchEffect(stat(path), {
                onSuccess: (_) => Effect.succeed(FileSystem.WatchEventCreate({ path })),
                onFailure: (err) =>
                  err._tag === "SystemError" && err.reason === "NotFound"
                    ? Effect.succeed(FileSystem.WatchEventRemove({ path }))
                    : Effect.fail(err)
              }))
              return
            }
            case "change": {
              emit.single(FileSystem.WatchEventUpdate({ path }))
              return
            }
          }
        })
        watcher.on("error", (error) => {
          emit.fail(
            new Error.SystemError({
              module: "FileSystem",
              reason: "Unknown",
              method: "watch",
              pathOrDescriptor: path,
              cause: error
            })
          )
        })
        watcher.on("close", () => {
          emit.end()
        })
        return watcher
      }),
      (watcher) => Effect.sync(() => watcher.close())
    )
  )

const watch = (
  backend: Option.Option<Context.Tag.Service<FileSystem.WatchBackend>>,