func createFiles()

in benchmarks/stat_files/main.go [50:113]
49 lines of code
9 McCabe index (conditional complexity)

func createFiles(
	dir string,
	numFiles int) (files []*os.File, err error) {
	group, ctx := errgroup.WithContext(context.Background())

	// Create files in parallel, and write them to a channel.
	const parallelism = 128

	var counter uint64
	fileChan := make(chan *os.File)
	var wg sync.WaitGroup

	for i := 0; i < parallelism; i++ {
		wg.Add(1)
		group.Go(func() (err error) {
			defer wg.Done()
			for {
				// Should we create another?
				count := atomic.AddUint64(&counter, 1)
				if count > uint64(numFiles) {
					return
				}

				// Create it.
				var f *os.File
				f, err = fsutil.AnonymousFile(dir)
				if err != nil {
					err = fmt.Errorf("AnonymousFile: %w", err)
					return
				}

				// Write it to the channel.
				select {
				case fileChan <- f:
				case <-ctx.Done():
					err = ctx.Err()
					return
				}
			}
		})
	}

	go func() {
		wg.Wait()
		close(fileChan)
	}()

	// Accumulate into the slice.
	group.Go(func() (err error) {
		for f := range fileChan {
			files = append(files, f)
		}

		return
	})

	err = group.Wait()
	if err != nil {
		closeAll(files)
		files = nil
	}

	return
}