demarches-normaliennes/app/lib/active_storage/download_manager.rb

87 lines
2.8 KiB
Ruby

require 'async'
require 'async/barrier'
require 'async/http/internet'
class ActiveStorage::DownloadManager
include Utils::Retryable
DOWNLOAD_MAX_PARALLEL = ENV.fetch('DOWNLOAD_MAX_PARALLEL') { 10 }
attr_reader :download_to_dir, :errors
def download_all(attachments:, on_failure:)
Async do
internet = Async::HTTP::Internet.new
barrier = Async::Barrier.new
semaphore = Async::Semaphore.new(DOWNLOAD_MAX_PARALLEL, parent: barrier)
attachments.map do |attachment, path|
semaphore.async do
begin
with_retry(max_attempt: 1) do
download_one(attachment: attachment,
path_in_download_dir: path,
async_internet: internet)
end
rescue => e
on_failure.call(attachment, path, e)
end
end
end
barrier.wait
write_error_manifest if !errors.empty?
ensure
internet&.close
end
end
# beware, must be re-entrant because retryable
def download_one(attachment:, path_in_download_dir:, async_internet:)
byte_written = 0
attachment_path = File.join(download_to_dir, path_in_download_dir)
attachment_dir = File.dirname(attachment_path)
FileUtils.mkdir_p(attachment_dir) if !Dir.exist?(attachment_dir) # defensive, do not write in undefined dir
if attachment.is_a?(PiecesJustificativesService::FakeAttachment)
byte_written = File.write(attachment_path, attachment.file.read, mode: 'wb')
else
response = async_internet.get(attachment.url)
File.open(attachment_path, mode: 'wb') do |fd|
response.body.each do |chunk|
byte_written = byte_written + fd.write(chunk)
end
response.body.close
end
end
track_retryable_download_state(attachment_path: attachment_path, state: true) # -> fail once, success after -> no failure
byte_written
rescue
track_retryable_download_state(attachment_path: attachment_path, state: false) #
File.delete(attachment_path) if File.exist?(attachment_path) # -> case of retries failed, must cleanup partialy downloaded file
raise
end
private
def initialize(download_to_dir:)
@download_to_dir = download_to_dir
@errors = {}
end
def track_retryable_download_state(attachment_path:, state:)
key = File.basename(attachment_path)
if state
errors.delete(key) # do not keep track of success, otherwise errors map grows
else
errors[key] = state
end
end
def write_error_manifest
manifest_path = File.join(download_to_dir, 'LISEZMOI.txt')
manifest_content = errors.map do |file_basename, _failed|
"Impossible de récupérer le fichier #{file_basename}"
end
.join("\n")
File.write(manifest_path, manifest_content)
end
end