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_COMPONENT_UPDATER_CRX_DOWNLOADER_H_ 6 #define COMPONENTS_COMPONENT_UPDATER_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 component_updater { 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 component_updater 155 156 #endif // COMPONENTS_COMPONENT_UPDATER_CRX_DOWNLOADER_H_ 157