[Media Router] Add DialMediaSinkService and DeviceDescriptionService

chrome/browser/media/router/discovery/dial/device_description_service.h

+// Copyright 2017 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 CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DEVICE_DESCRIPTION_SERVICE_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DEVICE_DESCRIPTION_SERVICE_H_
+
+#include <memory>
+#include <set>
+#include <string>
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/threading/thread_checker.h"
+#include "base/timer/timer.h"
+#include "chrome/browser/media/router/discovery/dial/dial_device_data.h"
+#include "chrome/browser/media/router/discovery/dial/parsed_dial_device_description.h"
+#include "chrome/common/media_router/mojo/dial_device_description_parser.mojom.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace media_router {
+
+class DeviceDescriptionFetcher;
+class SafeDialDeviceDescriptionParser;
+
+// This class fetches and parses device description XML for DIAL devices. Actual
+// parsing happens in a separate utility process via SafeDeviceDescriptionParser
+// (instead of in this class). This class lives on IO thread.
+class DeviceDescriptionService {
+ public:
+  // Represents cached device description data parsed from device description
+  // XML.
+  struct CacheEntry {
+    CacheEntry();
+    CacheEntry(const CacheEntry& other);
+    ~CacheEntry();
+
+    // The expiration time from the cache.
+    base::Time expire_time;
+
+    // The device description version number (non-negative).
+    int32_t config_id;
+
+    // Parsed device description data from XML.
+    ParsedDialDeviceDescription description_data;
+  };
+
+  // Called if parsing device description XML in utility process succeeds, and
+  // all fields are valid.
+  // |device_data|: The device to look up.
+  // |description_data|: Device description data from device description XML.
+  using DeviceDescriptionParseSuccessCallback =
+      base::Callback<void(const DialDeviceData& device_data,
+                          const ParsedDialDeviceDescription& description_data)>;
+
+  // Called if parsing device description XML in utility process fails, or some
+  // parsed fields are missing or invalid.
+  using DeviceDescriptionParseErrorCallback =
+      base::Callback<void(const DialDeviceData& device_data,
+                          const std::string& error_message)>;
+
+  DeviceDescriptionService(
+      const DeviceDescriptionParseSuccessCallback& success_cb,
+      const DeviceDescriptionParseErrorCallback& error_cb);
+  virtual ~DeviceDescriptionService();
+
+  // For each device in |devices|, if there is a valid cache entry for it, call
+  // |success_cb_| with cached device description; otherwise start fetching
+  // device description XML and parsing XML in utility process. Call
+  // |success_cb_| if both fetching and parsing succeeds; otherwise call
+  // |error_cb_|.
+  // |request_context|: Used by the background URLFetchers.
+  virtual void GetDeviceDescriptions(
+      const std::vector<DialDeviceData>& devices,
+      net::URLRequestContextGetter* request_context);
+
+  // Remove expired cache entries from |description_map_|.
+  void CleanUpCacheEntries();

[imcheng, 2017/04/25 01:40:12]

Does this need to be public?

[zhaobin, 2017/04/26 18:50:04]

Done.

+
+ private:
+  friend class DeviceDescriptionServiceTest;
+  friend class TestDeviceDescriptionService;
+  FRIEND_TEST_ALL_PREFIXES(DeviceDescriptionServiceTest,
+                           TestGetDeviceDescriptionRemoveOutDatedFetchers);
+  FRIEND_TEST_ALL_PREFIXES(DeviceDescriptionServiceTest,
+                           TestGetDeviceDescriptionFetchURLError);
+  FRIEND_TEST_ALL_PREFIXES(DeviceDescriptionServiceTest,
+                           TestSafeParserProperlyCreated);
+
+  // Checks the cache for a valid device description. If the entry is found but
+  // is expired, it is removed from the cache. Returns cached entry of
+  // parsed device description. Returns nullptr if cache entry does not exist or
+  // is not valid.
+  // |device_data|: The device to look up.
+  const CacheEntry* CheckAndUpdateCache(const DialDeviceData& device_data);
+
+  // Issues a HTTP GET request for the device description. No-op if there is
+  // already a pending request.
+  // |device_data|: The device to look up.
+  // |request_context|: Used by the background URLFetchers.
+  void FetchDeviceDescription(const DialDeviceData& device_data,
+                              net::URLRequestContextGetter* request_context);
+
+  // Invoked when HTTP GET request finishes.
+  // |device_data|: Device data initiating the HTTP request.
+  // |description_data|: Response from HTTP request.
+  void OnDeviceDescriptionFetchComplete(
+      const DialDeviceData& device_data,
+      const DialDeviceDescriptionData& description_data);
+
+  // Invoked when HTTP GET request fails.
+  // |device_data|: Device data initiating the HTTP request.
+  // |error_message|: Error message from HTTP request.
+  void OnDeviceDescriptionFetchError(const DialDeviceData& device_data,
+                                     const std::string& error_message);
+
+  // Invoked when SafeDialDeviceDescriptionParser finishes parsing device
+  // description XML.
+  // |device_data|: Device data initiating XML parsing in utility process.
+  // |app_url|: The app Url.
+  // |device_description_ptr|: Parsed device description from utility process.
+  // Returns nullptr if parsing fails.

[imcheng, 2017/04/25 01:40:12]

... process, or nullptr if parsing failed.

[zhaobin, 2017/04/26 18:50:04]

Done.

+  void OnParsedDeviceDescription(
+      const DialDeviceData& device_data,
+      const GURL& app_url,
+      chrome::mojom::DialDeviceDescriptionPtr device_description_ptr);
+
+  // Used by unit tests.
+  virtual base::Time GetNow();
+
+  // Map of current device description fetches in progress, keyed by device
+  // label.
+  std::map<std::string, std::unique_ptr<DeviceDescriptionFetcher>>
+      device_description_fetcher_map_;
+
+  // Set of device labels to be parsed in current utility process.
+  std::set<std::string> pending_device_labels_;
+
+  // Map of current cached device descriptions, keyed by device label.
+  std::map<std::string, CacheEntry> description_map_;

[mark a. foltz, 2017/04/25 21:06:25]

Maybe description_cache_ ?

[zhaobin, 2017/04/26 18:50:04]

Done.

+
+  // See comments for DeviceDescriptionParseSuccessCallback.
+  DeviceDescriptionParseSuccessCallback success_cb_;
+
+  // See comments for DeviceDescriptionParseErrorCallback.
+  DeviceDescriptionParseErrorCallback error_cb_;
+
+  // Timer for clean up expired cache entries.
+  std::unique_ptr<base::RepeatingTimer,
+                  content::BrowserThread::DeleteOnIOThread>

[imcheng, 2017/04/25 01:40:12]

Why do you need this? I thought this object lives on the IO thread already?

[mark a. foltz, 2017/04/25 21:06:25]

BrowserThread::DeleteOnThread has a shortcut that avoids posting a task to the
same thread.  So I don't think this is a big deal.

https://cs.chromium.org/chromium/src/content/public/browser/browser_thread.h?...

[zhaobin, 2017/04/26 18:50:04]

Acknowledged.

[zhaobin, 2017/04/26 18:50:04]

Will mark DialMediaSinkService object as DeleteOnIOThread. (MediaRouterMojoImpl
owns DialMediaSinkService. It is destroyed on Main thread, so does
DialMediaSinkService object. Since timers are started on IO thread, destroying
them on Main thread will cause DCHECK failures)

+      clean_up_timer_;
+
+  // Safe DIAL parser associated with utility process.
+  std::unique_ptr<SafeDialDeviceDescriptionParser> parser_;
+
+  base::ThreadChecker thread_checker_;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DEVICE_DESCRIPTION_SERVICE_H_