chromium/components/update_client/crx_downloader.h

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_
#define COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_

#include <stdint.h>

#include <memory>
#include <string>
#include <vector>

#include "base/files/file_path.h"
#include "base/functional/callback.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "url/gurl.h"

namespace update_client {

// Defines a download interface for downloading components, with retrying on
// fallback urls in case of errors. This class implements a chain of
// responsibility design pattern. It can give successors in the chain a chance
// to handle a download request, until one of them succeeds, or there are no
// more urls or successors to try. A callback is always called at the end of
// the download, one time only.
// When multiple urls and downloaders exists, first all the urls are tried, in
// the order they are provided in the StartDownload function argument. After
// that, the download request is routed to the next downloader in the chain.
// The members of this class expect to be called from the main sequence only.
class CrxDownloader : public base::RefCountedThreadSafe<CrxDownloader> { … };

}  // namespace update_client

#endif  // COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_