chrome/browser/predictors/resource_prefetch_common.h

// 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_COMMON_H_
#define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_

#include <stddef.h>

#include "base/feature_list.h"
#include "base/time/time.h"
#include "components/sessions/core/session_id.h"
#include "url/gurl.h"

class Profile;

namespace content {
class WebContents;
}

namespace predictors {

extern const char kSpeculativeResourcePrefetchingFeatureName[];
extern const char kModeParamName[];
extern const char kLearningMode[];
extern const char kExternalPrefetchingMode[];
extern const char kPrefetchingMode[];
extern const char kEnableUrlLearningParamName[];
extern const char kEnableManifestsParamName[];
extern const char kEnableOriginLearningParamName[];
extern const base::Feature kSpeculativeResourcePrefetchingFeature;

struct ResourcePrefetchPredictorConfig;

// Returns true if prefetching is enabled. And will initilize the |config|
// fields to the appropritate values.
bool IsSpeculativeResourcePrefetchingEnabled(
    Profile* profile,
    ResourcePrefetchPredictorConfig* config);

// Represents the type of key based on which prefetch data is stored.
enum PrefetchKeyType {
  PREFETCH_KEY_TYPE_HOST,
  PREFETCH_KEY_TYPE_URL
};

// Indicates what caused the prefetch request.
enum class PrefetchOrigin { NAVIGATION, EXTERNAL };

// Represents a single navigation for a render frame.
struct NavigationID {
  NavigationID();
  explicit NavigationID(content::WebContents* web_contents);
  NavigationID(content::WebContents* web_contents,
               const GURL& main_frame_url,
               const base::TimeTicks& creation_time);
  NavigationID(const NavigationID& other);

  bool operator<(const NavigationID& rhs) const;
  bool operator==(const NavigationID& rhs) const;

  // Returns true iff the tab_id is valid and the Main frame URL is set.
  bool is_valid() const;

  SessionID::id_type tab_id;
  GURL main_frame_url;

  // NOTE: Even though we store the creation time here, it is not used during
  // comparison of two NavigationIDs because it cannot always be determined
  // correctly.
  base::TimeTicks creation_time;
};

// Represents the config for the resource prefetch prediction algorithm.
struct ResourcePrefetchPredictorConfig {
  // Initializes the config with default values.
  ResourcePrefetchPredictorConfig();
  ResourcePrefetchPredictorConfig(const ResourcePrefetchPredictorConfig& other);
  ~ResourcePrefetchPredictorConfig();

  // The mode the prefetcher is running in. Forms a bit map.
  enum Mode {
    LEARNING = 1 << 0,
    PREFETCHING_FOR_NAVIGATION = 1 << 2,  // Should also turn on LEARNING.
    PREFETCHING_FOR_EXTERNAL = 1 << 3     // Should also turn on LEARNING.
  };
  int mode;

  // Helpers to deal with mode.
  bool IsLearningEnabled() const;
  bool IsPrefetchingEnabledForSomeOrigin(Profile* profile) const;
  bool IsPrefetchingEnabledForOrigin(Profile* profile,
                                     PrefetchOrigin origin) const;

  bool IsLowConfidenceForTest() const;
  bool IsHighConfidenceForTest() const;
  bool IsMoreResourcesEnabledForTest() const;
  bool IsSmallDBEnabledForTest() const;

  // If a navigation hasn't seen a load complete event in this much time, it
  // is considered abandoned.
  size_t max_navigation_lifetime_seconds;

  // Size of LRU caches for the URL and host data.
  size_t max_urls_to_track;
  size_t max_hosts_to_track;

  // The number of times we should have seen a visit to this URL in history
  // to start tracking it. This is to ensure we don't bother with oneoff
  // entries. For hosts we track each one.
  size_t min_url_visit_count;

  // The maximum number of resources to store per entry.
  size_t max_resources_per_entry;
  // The maximum number of origins to store per entry.
  size_t max_origins_per_entry;
  // The number of consecutive misses after which we stop tracking a resource
  // URL.
  size_t max_consecutive_misses;
  // The number of consecutive misses after which we stop tracking a redirect
  // endpoint.
  size_t max_redirect_consecutive_misses;

  // The minimum confidence (accuracy of hits) required for a resource to be
  // prefetched.
  float min_resource_confidence_to_trigger_prefetch;
  // The minimum number of times we must have a URL on record to prefetch it.
  size_t min_resource_hits_to_trigger_prefetch;

  // Maximum number of prefetches that can be inflight for a single navigation.
  size_t max_prefetches_inflight_per_navigation;
  // Maximum number of prefetches that can be inflight for a host for a single
  // navigation.
  size_t max_prefetches_inflight_per_host_per_navigation;
  // True iff the predictor could use a url-based database.
  bool is_url_learning_enabled;
  // True iff the predictor could use manifests.
  bool is_manifests_enabled;
  // True iff origin-based learning is enabled.
  bool is_origin_learning_enabled;
};

}  // namespace predictors

#endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_