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| 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_ |
| 6 #define COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_ |
| 7 |
| 8 #include <stdint.h> |
| 9 #include <vector> |
| 10 |
| 11 #include "base/callback.h" |
| 12 #include "base/files/file_path.h" |
| 13 #include "base/macros.h" |
| 14 #include "base/memory/ref_counted.h" |
| 15 #include "base/memory/scoped_ptr.h" |
| 16 #include "base/threading/thread_checker.h" |
| 17 #include "url/gurl.h" |
| 18 |
| 19 namespace base { |
| 20 class SequencedTaskRunner; |
| 21 class SingleThreadTaskRunner; |
| 22 } |
| 23 |
| 24 namespace net { |
| 25 class URLRequestContextGetter; |
| 26 } |
| 27 |
| 28 namespace update_client { |
| 29 |
| 30 // Defines a download interface for downloading components, with retrying on |
| 31 // fallback urls in case of errors. This class implements a chain of |
| 32 // responsibility design pattern. It can give successors in the chain a chance |
| 33 // to handle a download request, until one of them succeeds, or there are no |
| 34 // more urls or successors to try. A callback is always called at the end of |
| 35 // the download, one time only. |
| 36 // When multiple urls and downloaders exists, first all the urls are tried, in |
| 37 // the order they are provided in the StartDownload function argument. After |
| 38 // that, the download request is routed to the next downloader in the chain. |
| 39 // The members of this class expect to be called from the main thread only. |
| 40 class CrxDownloader { |
| 41 public: |
| 42 struct DownloadMetrics { |
| 43 enum Downloader { kNone = 0, kUrlFetcher, kBits }; |
| 44 |
| 45 DownloadMetrics(); |
| 46 |
| 47 GURL url; |
| 48 |
| 49 Downloader downloader; |
| 50 |
| 51 int error; |
| 52 |
| 53 int64_t downloaded_bytes; // -1 means that the byte count is unknown. |
| 54 int64_t total_bytes; |
| 55 |
| 56 uint64_t download_time_ms; |
| 57 }; |
| 58 |
| 59 // Contains the progress or the outcome of the download. |
| 60 struct Result { |
| 61 Result(); |
| 62 |
| 63 // Download error: 0 indicates success. |
| 64 int error; |
| 65 |
| 66 // Path of the downloaded file if the download was successful. |
| 67 base::FilePath response; |
| 68 |
| 69 // Number of bytes actually downloaded, not including the bytes downloaded |
| 70 // as a result of falling back on urls. |
| 71 int64_t downloaded_bytes; |
| 72 |
| 73 // Number of bytes expected to be downloaded. |
| 74 int64_t total_bytes; |
| 75 }; |
| 76 |
| 77 // The callback fires only once, regardless of how many urls are tried, and |
| 78 // how many successors in the chain of downloaders have handled the |
| 79 // download. The callback interface can be extended if needed to provide |
| 80 // more visibility into how the download has been handled, including |
| 81 // specific error codes and download metrics. |
| 82 typedef base::Callback<void(const Result& result)> DownloadCallback; |
| 83 |
| 84 // The callback may fire 0 or many times during a download. Since this |
| 85 // class implements a chain of responsibility, the callback can fire for |
| 86 // different urls and different downloaders. The number of actual downloaded |
| 87 // bytes is not guaranteed to monotonically increment over time. |
| 88 typedef base::Callback<void(const Result& result)> ProgressCallback; |
| 89 |
| 90 // Factory method to create an instance of this class and build the |
| 91 // chain of responsibility. |is_background_download| specifies that a |
| 92 // background downloader be used, if the platform supports it. |
| 93 // |url_fetcher_task_runner| should be an IO capable task runner able to |
| 94 // support UrlFetcherDownloader. |background_task_runner| should be an |
| 95 // IO capable thread able to support BackgroundDownloader. |
| 96 static CrxDownloader* Create( |
| 97 bool is_background_download, |
| 98 net::URLRequestContextGetter* context_getter, |
| 99 scoped_refptr<base::SequencedTaskRunner> url_fetcher_task_runner, |
| 100 scoped_refptr<base::SingleThreadTaskRunner> background_task_runner); |
| 101 virtual ~CrxDownloader(); |
| 102 |
| 103 void set_progress_callback(const ProgressCallback& progress_callback); |
| 104 |
| 105 // Starts the download. One instance of the class handles one download only. |
| 106 // One instance of CrxDownloader can only be started once, otherwise the |
| 107 // behavior is undefined. The callback gets invoked if the download can't |
| 108 // be started. |
| 109 void StartDownloadFromUrl(const GURL& url, |
| 110 const DownloadCallback& download_callback); |
| 111 void StartDownload(const std::vector<GURL>& urls, |
| 112 const DownloadCallback& download_callback); |
| 113 |
| 114 const std::vector<DownloadMetrics> download_metrics() const; |
| 115 |
| 116 protected: |
| 117 explicit CrxDownloader(scoped_ptr<CrxDownloader> successor); |
| 118 |
| 119 // Handles the fallback in the case of multiple urls and routing of the |
| 120 // download to the following successor in the chain. Derived classes must call |
| 121 // this function after each attempt at downloading the urls provided |
| 122 // in the StartDownload function. |
| 123 // In case of errors, |is_handled| indicates that a server side error has |
| 124 // occured for the current url and the url should not be retried down |
| 125 // the chain to avoid DDOS of the server. This url will be removed from the |
| 126 // list of url and never tried again. |
| 127 void OnDownloadComplete(bool is_handled, |
| 128 const Result& result, |
| 129 const DownloadMetrics& download_metrics); |
| 130 |
| 131 // Calls the callback when progress is made. |
| 132 void OnDownloadProgress(const Result& result); |
| 133 |
| 134 // Returns the url which is currently being downloaded from. |
| 135 GURL url() const; |
| 136 |
| 137 private: |
| 138 virtual void DoStartDownload(const GURL& url) = 0; |
| 139 |
| 140 base::ThreadChecker thread_checker_; |
| 141 |
| 142 std::vector<GURL> urls_; |
| 143 scoped_ptr<CrxDownloader> successor_; |
| 144 DownloadCallback download_callback_; |
| 145 ProgressCallback progress_callback_; |
| 146 |
| 147 std::vector<GURL>::iterator current_url_; |
| 148 |
| 149 std::vector<DownloadMetrics> download_metrics_; |
| 150 |
| 151 DISALLOW_COPY_AND_ASSIGN(CrxDownloader); |
| 152 }; |
| 153 |
| 154 } // namespace update_client |
| 155 |
| 156 #endif // COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_ |
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