| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COMPONENTS_COMPONENT_UPDATER_CRX_DOWNLOADER_H_ |
| #define COMPONENTS_COMPONENT_UPDATER_CRX_DOWNLOADER_H_ |
| |
| #include <stdint.h> |
| #include <vector> |
| |
| #include "base/callback.h" |
| #include "base/files/file_path.h" |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/scoped_ptr.h" |
| #include "base/threading/thread_checker.h" |
| #include "url/gurl.h" |
| |
| namespace base { |
| class SequencedTaskRunner; |
| class SingleThreadTaskRunner; |
| } |
| |
| namespace net { |
| class URLRequestContextGetter; |
| } |
| |
| namespace component_updater { |
| |
| // 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 thread only. |
| class CrxDownloader { |
| public: |
| struct DownloadMetrics { |
| enum Downloader { kNone = 0, kUrlFetcher, kBits }; |
| |
| DownloadMetrics(); |
| |
| GURL url; |
| |
| Downloader downloader; |
| |
| int error; |
| |
| int64_t downloaded_bytes; // -1 means that the byte count is unknown. |
| int64_t total_bytes; |
| |
| uint64_t download_time_ms; |
| }; |
| |
| // Contains the progress or the outcome of the download. |
| struct Result { |
| Result(); |
| |
| // Download error: 0 indicates success. |
| int error; |
| |
| // Path of the downloaded file if the download was successful. |
| base::FilePath response; |
| |
| // Number of bytes actually downloaded, not including the bytes downloaded |
| // as a result of falling back on urls. |
| int64_t downloaded_bytes; |
| |
| // Number of bytes expected to be downloaded. |
| int64_t total_bytes; |
| }; |
| |
| // The callback fires only once, regardless of how many urls are tried, and |
| // how many successors in the chain of downloaders have handled the |
| // download. The callback interface can be extended if needed to provide |
| // more visibility into how the download has been handled, including |
| // specific error codes and download metrics. |
| typedef base::Callback<void(const Result& result)> DownloadCallback; |
| |
| // The callback may fire 0 or many times during a download. Since this |
| // class implements a chain of responsibility, the callback can fire for |
| // different urls and different downloaders. The number of actual downloaded |
| // bytes is not guaranteed to monotonically increment over time. |
| typedef base::Callback<void(const Result& result)> ProgressCallback; |
| |
| // Factory method to create an instance of this class and build the |
| // chain of responsibility. |is_background_download| specifies that a |
| // background downloader be used, if the platform supports it. |
| // |url_fetcher_task_runner| should be an IO capable task runner able to |
| // support UrlFetcherDownloader. |background_task_runner| should be an |
| // IO capable thread able to support BackgroundDownloader. |
| static CrxDownloader* Create( |
| bool is_background_download, |
| net::URLRequestContextGetter* context_getter, |
| scoped_refptr<base::SequencedTaskRunner> url_fetcher_task_runner, |
| scoped_refptr<base::SingleThreadTaskRunner> background_task_runner); |
| virtual ~CrxDownloader(); |
| |
| void set_progress_callback(const ProgressCallback& progress_callback); |
| |
| // Starts the download. One instance of the class handles one download only. |
| // One instance of CrxDownloader can only be started once, otherwise the |
| // behavior is undefined. The callback gets invoked if the download can't |
| // be started. |
| void StartDownloadFromUrl(const GURL& url, |
| const DownloadCallback& download_callback); |
| void StartDownload(const std::vector<GURL>& urls, |
| const DownloadCallback& download_callback); |
| |
| const std::vector<DownloadMetrics> download_metrics() const; |
| |
| protected: |
| explicit CrxDownloader(scoped_ptr<CrxDownloader> successor); |
| |
| // Handles the fallback in the case of multiple urls and routing of the |
| // download to the following successor in the chain. Derived classes must call |
| // this function after each attempt at downloading the urls provided |
| // in the StartDownload function. |
| // In case of errors, |is_handled| indicates that a server side error has |
| // occured for the current url and the url should not be retried down |
| // the chain to avoid DDOS of the server. This url will be removed from the |
| // list of url and never tried again. |
| void OnDownloadComplete(bool is_handled, |
| const Result& result, |
| const DownloadMetrics& download_metrics); |
| |
| // Calls the callback when progress is made. |
| void OnDownloadProgress(const Result& result); |
| |
| // Returns the url which is currently being downloaded from. |
| GURL url() const; |
| |
| private: |
| virtual void DoStartDownload(const GURL& url) = 0; |
| |
| base::ThreadChecker thread_checker_; |
| |
| std::vector<GURL> urls_; |
| scoped_ptr<CrxDownloader> successor_; |
| DownloadCallback download_callback_; |
| ProgressCallback progress_callback_; |
| |
| std::vector<GURL>::iterator current_url_; |
| |
| std::vector<DownloadMetrics> download_metrics_; |
| |
| DISALLOW_COPY_AND_ASSIGN(CrxDownloader); |
| }; |
| |
| } // namespace component_updater |
| |
| #endif // COMPONENTS_COMPONENT_UPDATER_CRX_DOWNLOADER_H_ |