Re-add resource speculative prefetching code

chrome/browser/predictors/resource_prefetch_predictor.h

Index: chrome/browser/predictors/resource_prefetch_predictor.h
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.h b/chrome/browser/predictors/resource_prefetch_predictor.h
new file mode 100644
index 0000000000000000000000000000000000000000..5e6157badcbb47a013747c28c5b5b5667a5e72ea
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+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -0,0 +1,314 @@
+// 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 CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_
+#define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/gtest_prod_util.h"
+#include "base/memory/linked_ptr.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/task/cancelable_task_tracker.h"
+#include "base/time/time.h"
+#include "chrome/browser/history/history_types.h"
+#include "chrome/browser/predictors/resource_prefetch_common.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor_tables.h"
+#include "chrome/browser/predictors/resource_prefetcher.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/common/resource_type.h"
+#include "url/gurl.h"
+
+class PredictorsHandler;
+class Profile;
+
+namespace content {
+class WebContents;
+}
+
+namespace net {
+class URLRequest;
+}
+
+namespace predictors {
+
+class ResourcePrefetcherManager;
+
+// Contains logic for learning what can be prefetched and for kicking off
+// speculative prefetching.
+// - The class is a profile keyed service owned by the profile.
+// - All the non-static methods of this class need to be called on the UI
+//   thread.
+//
+// The overall flow of the resource prefetching algorithm is as follows:
+//
+// * ResourcePrefetchPredictorObserver - Listens for URL requests, responses and
+//   redirects on the IO thread (via ResourceDispatcherHostDelegate) and posts
+//   tasks to the ResourcePrefetchPredictor on the UI thread. This is owned by
+//   the ProfileIOData for the profile.
+// * ResourcePrefetchPredictorTables - Persists ResourcePrefetchPredictor data
+//   to a sql database. Runs entirely on the DB thread. Owned by the
+//   PredictorDatabase.
+// * ResourcePrefetchPredictor - Learns about resource requirements per URL in
+//   the UI thread through the ResourcePrefetchPredictorObserver and persists
+//   it to disk in the DB thread through the ResourcePrefetchPredictorTables. It
+//   initiates resource prefetching using the ResourcePrefetcherManager. Owned
+//   by profile.
+// * ResourcePrefetcherManager - Manages the ResourcePrefetchers that do the
+//   prefetching on the IO thread. The manager is owned by the
+//   ResourcePrefetchPredictor and interfaces between the predictor on the UI
+//   thread and the prefetchers on the IO thread.
+// * ResourcePrefetcher - Lives entirely on the IO thread, owned by the
+//   ResourcePrefetcherManager, and issues net::URLRequest to fetch resources.
+//
+// TODO(shishir): Do speculative prefetching for https resources and/or https
+// main frame urls.
+// TODO(zhenw): Currently only main frame requests/redirects/responses are
+// recorded. Consider recording sub-frame responses independently or together
+// with main frame.
+class ResourcePrefetchPredictor
+    : public KeyedService,
+      public content::NotificationObserver,
+      public base::SupportsWeakPtr<ResourcePrefetchPredictor> {
+ public:
+  // Stores the data that we need to get from the URLRequest.
+  struct URLRequestSummary {
+    URLRequestSummary();
+    URLRequestSummary(const URLRequestSummary& other);
+    ~URLRequestSummary();
+
+    NavigationID navigation_id;
+    GURL resource_url;
+    content::ResourceType resource_type;
+
+    // Only for responses.
+    std::string mime_type;
+    bool was_cached;
+    GURL redirect_url;  // Empty unless request was redirected to a valid url.
+  };
+
+  ResourcePrefetchPredictor(const ResourcePrefetchPredictorConfig& config,
+                            Profile* profile);
+  virtual ~ResourcePrefetchPredictor();
+
+  // Thread safe.
+  static bool ShouldRecordRequest(net::URLRequest* request,
+                                  content::ResourceType resource_type);
+  static bool ShouldRecordResponse(net::URLRequest* response);
+  static bool ShouldRecordRedirect(net::URLRequest* response);
+
+  // Determines the ResourceType from the mime type, defaulting to the
+  // |fallback| if the ResourceType could not be determined.
+  static content::ResourceType GetResourceTypeFromMimeType(
+      const std::string& mime_type,
+      content::ResourceType fallback);
+
+  // 'ResourcePrefetchPredictorObserver' calls the below functions to inform the
+  // predictor of main frame and resource requests. Should only be called if the
+  // corresponding Should* functions return true.
+  void RecordURLRequest(const URLRequestSummary& request);
+  void RecordURLResponse(const URLRequestSummary& response);
+  void RecordURLRedirect(const URLRequestSummary& response);
+
+  // Called when the main frame of a page completes loading.
+  void RecordMainFrameLoadComplete(const NavigationID& navigation_id);
+
+  // Called by ResourcePrefetcherManager to notify that prefetching has finished
+  // for a navigation. Should take ownership of |requests|.
+  virtual void FinishedPrefetchForNavigation(
+      const NavigationID& navigation_id,
+      PrefetchKeyType key_type,
+      ResourcePrefetcher::RequestVector* requests);
+
+ private:
+  friend class ::PredictorsHandler;
+  friend class ResourcePrefetchPredictorTest;
+
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest, DeleteUrls);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest,
+                           LazilyInitializeEmpty);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest,
+                           LazilyInitializeWithData);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest,
+                           NavigationNotRecorded);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest, NavigationUrlInDB);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest, NavigationUrlNotInDB);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest,
+                           NavigationUrlNotInDBAndDBFull);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest, OnMainFrameRequest);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest, OnMainFrameRedirect);
+  FRIEND_TEST_ALL_PREFIXES(ResourcePrefetchPredictorTest,
+                           OnSubresourceResponse);
+
+  enum InitializationState {
+    NOT_INITIALIZED = 0,
+    INITIALIZING = 1,
+    INITIALIZED = 2
+  };
+
+  // Stores prefetching results.
+  struct Result {
+    // Takes ownership of requests.
+    Result(PrefetchKeyType key_type,
+           ResourcePrefetcher::RequestVector* requests);
+    ~Result();
+
+    PrefetchKeyType key_type;
+    scoped_ptr<ResourcePrefetcher::RequestVector> requests;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Result);
+  };
+
+  typedef ResourcePrefetchPredictorTables::ResourceRow ResourceRow;
+  typedef ResourcePrefetchPredictorTables::ResourceRows ResourceRows;
+  typedef ResourcePrefetchPredictorTables::PrefetchData PrefetchData;
+  typedef ResourcePrefetchPredictorTables::PrefetchDataMap PrefetchDataMap;
+  typedef std::map<NavigationID, linked_ptr<std::vector<URLRequestSummary> > >
+      NavigationMap;
+  typedef std::map<NavigationID, Result*> ResultsMap;
+
+  // Returns true if the main page request is supported for prediction.
+  static bool IsHandledMainPage(net::URLRequest* request);
+
+  // Returns true if the subresource request is supported for prediction.
+  static bool IsHandledSubresource(net::URLRequest* request);
+
+  // Returns true if the request (should have a response in it) is cacheable.
+  static bool IsCacheable(const net::URLRequest* request);
+
+  // content::NotificationObserver methods OVERRIDE.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  // KeyedService methods OVERRIDE.
+  virtual void Shutdown() OVERRIDE;
+
+  // Functions called on different network events pertaining to the loading of
+  // main frame resource or sub resources.
+  void OnMainFrameRequest(const URLRequestSummary& request);
+  void OnMainFrameResponse(const URLRequestSummary& response);
+  void OnMainFrameRedirect(const URLRequestSummary& response);
+  void OnSubresourceResponse(const URLRequestSummary& response);
+
+  // Called when onload completes for a navigation. We treat this point as the
+  // "completion" of the navigation. The resources requested by the page upto
+  // this point are the only ones considered for prefetching.
+  void OnNavigationComplete(const NavigationID& navigation_id);
+
+  // Returns true if there is PrefetchData that can be used for the
+  // navigation and fills in the |prefetch_data| to resources that need to be
+  // prefetched.
+  bool GetPrefetchData(const NavigationID& navigation_id,
+                       ResourcePrefetcher::RequestVector* prefetch_requests,
+                       PrefetchKeyType* key_type);
+
+  // Converts a PrefetchData into a ResourcePrefetcher::RequestVector.
+  void PopulatePrefetcherRequest(const PrefetchData& data,
+                                 ResourcePrefetcher::RequestVector* requests);
+
+  // Starts prefetching if it is enabled and prefetching data exists for the
+  // NavigationID either at the URL or at the host level.
+  void StartPrefetching(const NavigationID& navigation_id);
+
+  // Stops prefetching that may be in progress corresponding to |navigation_id|.
+  void StopPrefetching(const NavigationID& navigation_id);
+
+  // Starts initialization by posting a task to the DB thread to read the
+  // predictor database.
+  void StartInitialization();
+
+  // Callback for task to read predictor database. Takes ownership of
+  // |url_data_map| and |host_data_map|.
+  void CreateCaches(scoped_ptr<PrefetchDataMap> url_data_map,
+                    scoped_ptr<PrefetchDataMap> host_data_map);
+
+  // Called during initialization when history is read and the predictor
+  // database has been read.
+  void OnHistoryAndCacheLoaded();
+
+  // Removes data for navigations where the onload never fired. Will cleanup
+  // inflight_navigations_ and results_map_.
+  void CleanupAbandonedNavigations(const NavigationID& navigation_id);
+
+  // Deletes all URLs from the predictor database, the caches and removes all
+  // inflight navigations.
+  void DeleteAllUrls();
+
+  // Deletes data for the input |urls| and their corresponding hosts from the
+  // predictor database and caches.
+  void DeleteUrls(const history::URLRows& urls);
+
+  // Callback for GetUrlVisitCountTask.
+  void OnVisitCountLookup(size_t visit_count,
+                          const NavigationID& navigation_id,
+                          const std::vector<URLRequestSummary>& requests);
+
+  // Removes the oldest entry in the input |data_map|, also deleting it from the
+  // predictor database.
+  void RemoveOldestEntryInPrefetchDataMap(PrefetchKeyType key_type,
+                                          PrefetchDataMap* data_map);
+
+  // Merges resources in |new_resources| into the |data_map| and correspondingly
+  // updates the predictor database.
+  void LearnNavigation(const std::string& key,
+                       PrefetchKeyType key_type,
+                       const std::vector<URLRequestSummary>& new_resources,
+                       size_t max_data_map_size,
+                       PrefetchDataMap* data_map);
+
+  // Reports accuracy by comparing prefetched resources with resources that are
+  // actually used by the page.
+  void ReportAccuracyStats(PrefetchKeyType key_type,
+                           const std::vector<URLRequestSummary>& actual,
+                           ResourcePrefetcher::RequestVector* prefetched) const;
+
+  // Reports predicted accuracy i.e. by comparing resources that are actually
+  // used by the page with those that may have been prefetched.
+  void ReportPredictedAccuracyStats(
+      PrefetchKeyType key_type,
+      const std::vector<URLRequestSummary>& actual,
+      const ResourcePrefetcher::RequestVector& predicted) const;
+  void ReportPredictedAccuracyStatsHelper(
+      PrefetchKeyType key_type,
+      const ResourcePrefetcher::RequestVector& predicted,
+      const std::map<GURL, bool>& actual,
+      size_t total_resources_fetched_from_network,
+      size_t max_assumed_prefetched) const;
+
+  // Used for testing to inject mock tables.
+  void set_mock_tables(scoped_refptr<ResourcePrefetchPredictorTables> tables) {
+    tables_ = tables;
+  }
+
+  Profile* const profile_;
+  ResourcePrefetchPredictorConfig const config_;
+  InitializationState initialization_state_;
+  scoped_refptr<ResourcePrefetchPredictorTables> tables_;
+  scoped_refptr<ResourcePrefetcherManager> prefetch_manager_;
+  content::NotificationRegistrar notification_registrar_;
+  base::CancelableTaskTracker history_lookup_consumer_;
+
+  // Map of all the navigations in flight to their resource requests.
+  NavigationMap inflight_navigations_;
+
+  // Copy of the data in the predictor tables.
+  scoped_ptr<PrefetchDataMap> url_table_cache_;
+  scoped_ptr<PrefetchDataMap> host_table_cache_;
+
+  ResultsMap results_map_;
+  STLValueDeleter<ResultsMap> results_map_deleter_;
+
+  DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictor);
+};
+
+}  // namespace predictors
+
+#endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_H_