Rename Dns prefetching files to Predictor files...

chrome/browser/net/dns_host_info.h

-// Copyright (c) 2006-2010 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.
-
-// A UrlInfo object is used to store prediction related information about a host
-// port and scheme triplet.  When performing DNS pre-resolution of the host/port
-// pair, its state is monitored as it is resolved.
-// It includes progress, from placement in the Predictor's queue, to resolution
-// by the DNS service as either FOUND or NO_SUCH_NAME.  Each instance may also
-// hold records of previous resolution times, which might later be shown to be
-// savings relative to resolution time during a navigation.
-// UrlInfo objects are also used to describe frames, and additional instances
-// may describe associated subresources, for future speculative connections to
-// those expected subresources.
-
-#ifndef CHROME_BROWSER_NET_DNS_HOST_INFO_H_
-#define CHROME_BROWSER_NET_DNS_HOST_INFO_H_
-
-#include <string>
-#include <vector>
-
-#include "base/time.h"
-#include "googleurl/src/gurl.h"
-#include "net/base/host_port_pair.h"
-
-namespace chrome_browser_net {
-
-// Use command line switch to enable detailed logging.
-void EnablePredictorDetailedLog(bool enable);
-
-enum DnsBenefit {
-  PREFETCH_NO_BENEFIT,  // Prefetch never hit the network. Name was pre-cached.
-  PREFETCH_CACHE_EVICTION,  // Prefetch used network, but so did HTTP stack.
-  PREFETCH_NAME_NONEXISTANT,  // Valuable prefetch of "name not found" was used.
-  PREFETCH_NAME_FOUND,  // Valuable prefetch was used.
-  PREFETCH_OBLIVIOUS  // No prefetch attempt was even made.
-};
-
-class UrlInfo {
- public:
-  // Reasons for a domain to be resolved.
-  enum ResolutionMotivation {
-    MOUSE_OVER_MOTIVATED,  // Mouse-over link induced resolution.
-    PAGE_SCAN_MOTIVATED,   // Scan of rendered page induced resolution.
-    UNIT_TEST_MOTIVATED,
-    LINKED_MAX_MOTIVATED,    // enum demarkation above motivation from links.
-    OMNIBOX_MOTIVATED,       // Omni-box suggested resolving this.
-    STARTUP_LIST_MOTIVATED,  // Startup list caused this resolution.
-
-    NO_PREFETCH_MOTIVATION,  // Browser navigation info (not prefetch related).
-
-    // The following involve predictive prefetching, triggered by a navigation.
-    // The referrinrg_url_ is also set when these are used.
-    // TODO(jar): Support STATIC_REFERAL_MOTIVATED API and integration.
-    STATIC_REFERAL_MOTIVATED,  // External database suggested this resolution.
-    LEARNED_REFERAL_MOTIVATED,  // Prior navigation taught us this resolution.
-  };
-
-  enum DnsProcessingState {
-      // When processed by our prefetching system, the states are:
-      PENDING,       // Constructor has completed.
-      QUEUED,        // In name queue but not yet being resolved.
-      ASSIGNED,      // Being resolved (or being reset to earlier state)
-      ASSIGNED_BUT_MARKED,  // Needs to be deleted as soon as it's resolved.
-      FOUND,         // DNS resolution completed.
-      NO_SUCH_NAME,  // DNS resolution completed.
-      // When processed by the network stack during navigation, the states are:
-      STARTED,               // Resolution has begun for a navigation.
-      FINISHED,              // Resolution has completed for a navigation.
-      FINISHED_UNRESOLVED};  // No resolution found, so navigation will fail.
-  static const base::TimeDelta kMaxNonNetworkDnsLookupDuration;
-  // The number of OS cache entries we can guarantee(?) before cache eviction
-  // might likely take place.
-  static const int kMaxGuaranteedDnsCacheSize = 50;
-
-  typedef std::vector<UrlInfo> DnsInfoTable;
-
-  static const base::TimeDelta kNullDuration;
-
-  // UrlInfo are usually made by the default constructor during
-  // initializing of the Predictor's map (of info for Hostnames).
-  UrlInfo()
-      : state_(PENDING),
-        old_prequeue_state_(state_),
-        resolve_duration_(kNullDuration),
-        queue_duration_(kNullDuration),
-        benefits_remaining_(),
-        sequence_number_(0),
-        motivation_(NO_PREFETCH_MOTIVATION),
-        was_linked_(false) {
-  }
-
-  ~UrlInfo() {}
-
-  // NeedDnsUpdate decides, based on our internal info,
-  // if it would be valuable to attempt to update (prefectch)
-  // DNS data for hostname.  This decision is based
-  // on how recently we've done DNS prefetching for hostname.
-  bool NeedsDnsUpdate();
-
-  static void set_cache_expiration(base::TimeDelta time);
-
-  // The prefetching lifecycle.
-  void SetQueuedState(ResolutionMotivation motivation);
-  void SetAssignedState();
-  void RemoveFromQueue();
-  void SetPendingDeleteState();
-  void SetFoundState();
-  void SetNoSuchNameState();
-  // The actual browsing resolution lifecycle.
-  void SetStartedState();
-  void SetFinishedState(bool was_resolved);
-
-  // Finish initialization. Must only be called once.
-  void SetUrl(const GURL& url);
-
-  bool was_linked() const { return was_linked_; }
-
-  GURL referring_url() const { return referring_url_; }
-  void SetReferringHostname(const GURL& url) {
-    referring_url_ = url;
-  }
-
-  bool was_found() const { return FOUND == state_; }
-  bool was_nonexistant() const { return NO_SUCH_NAME == state_; }
-  bool is_assigned() const {
-    return ASSIGNED == state_ || ASSIGNED_BUT_MARKED == state_;
-  }
-  bool is_marked_to_delete() const { return ASSIGNED_BUT_MARKED == state_; }
-  const GURL url() const { return url_; }
-
-  bool HasUrl(const GURL& url) const {
-    return url_ == url;
-  }
-
-  base::TimeDelta resolve_duration() const { return resolve_duration_;}
-  base::TimeDelta queue_duration() const { return queue_duration_;}
-  base::TimeDelta benefits_remaining() const { return benefits_remaining_; }
-
-  DnsBenefit AccruePrefetchBenefits(UrlInfo* navigation_info);
-
-  void DLogResultsStats(const char* message) const;
-
-  static void GetHtmlTable(const DnsInfoTable host_infos,
-                           const char* description,
-                           const bool brief,
-                           std::string* output);
-
- private:
-  base::TimeDelta GetDuration() {
-    base::TimeTicks old_time = time_;
-    time_ = base::TimeTicks::Now();
-    return time_ - old_time;
-  }
-
-  // IsStillCached() guesses if the DNS cache still has IP data.
-  bool IsStillCached() const;
-
-  // Record why we created, or have updated (reqested pre-resolution) of this
-  // instance.
-  void SetMotivation(ResolutionMotivation motivation);
-
-  // Helper function for about:dns printing.
-  std::string GetAsciiMotivation() const;
-
-  // The next declaration is non-const to facilitate testing.
-  static base::TimeDelta kCacheExpirationDuration;
-
-  // The current state of this instance.
-  DnsProcessingState state_;
-
-  // Record the state prior to going to a queued state, in case we have to back
-  // out of the queue.
-  DnsProcessingState old_prequeue_state_;
-
-  GURL url_;  // Host, port and scheme for this info.
-
-  // When was last state changed (usually lookup completed).
-  base::TimeTicks time_;
-  // Time needed for DNS to resolve.
-  base::TimeDelta resolve_duration_;
-  // Time spent in queue.
-  base::TimeDelta queue_duration_;
-  // Unused potential benefits of a prefetch.
-  base::TimeDelta benefits_remaining_;
-
-  int sequence_number_;  // Used to calculate potential of cache eviction.
-  static int sequence_counter;  // Used to allocate sequence_number_'s.
-
-  // Motivation for creation of this instance.
-  ResolutionMotivation motivation_;
-
-  // Record if the motivation for prefetching was ever a page-link-scan.
-  bool was_linked_;
-
-  // If this instance holds data about a navigation, we store the referrer.
-  // If this instance hold data about a prefetch, and the prefetch was
-  // instigated by a referrer, we store it here (for use in about:dns).
-  GURL referring_url_;
-
-  // We put these objects into a std::map, and hence we
-  // need some "evil" constructors.
-  // DISALLOW_COPY_AND_ASSIGN(UrlInfo);
-};
-
-}  // namespace chrome_browser_net
-
-#endif  // CHROME_BROWSER_NET_DNS_HOST_INFO_H_