class Sprockets::Manifest

def compile(*args)
  unless environment
    raise Error, "manifest requires environment for compilation"
  end
  filenames            = []
  concurrent_exporters = []
  assets_to_export = Concurrent::Array.new
  find(*args) do |asset|
    assets_to_export << asset
  end
  assets_to_export.each do |asset|
    mtime = Time.now.iso8601
    files[asset.digest_path] = {
      'logical_path' => asset.logical_path,
      'mtime'        => mtime,
      'size'         => asset.bytesize,
      'digest'       => asset.hexdigest,
      # Deprecated: Remove beta integrity attribute in next release.
      # Callers should DigestUtils.hexdigest_integrity_uri to compute the
      # digest themselves.
      'integrity'    => DigestUtils.hexdigest_integrity_uri(asset.hexdigest)
    }
    assets[asset.logical_path] = asset.digest_path
    filenames << asset.filename
    promise      = nil
    exporters_for_asset(asset) do |exporter|
      next if exporter.skip?(logger)
      if promise.nil?
        promise = Concurrent::Promise.new(executor: executor) { exporter.call }
        concurrent_exporters << promise.execute
      else
        concurrent_exporters << promise.then { exporter.call }
      end
    end
  end
  # make sure all exporters have finished before returning the main thread
  concurrent_exporters.each(&:wait!)
  save
  filenames
end