Rename Dns prefetching files to Predictor files...

chrome/browser/net/dns_host_info.cc

Index: chrome/browser/net/dns_host_info.cc
===================================================================
--- chrome/browser/net/dns_host_info.cc	(revision 50915)
+++ chrome/browser/net/dns_host_info.cc	(working copy)
@@ -1,439 +0,0 @@
-// 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.
-
-#include "chrome/browser/net/dns_host_info.h"
-
-#include <math.h>
-
-#include <algorithm>
-#include <string>
-
-#include "base/field_trial.h"
-#include "base/format_macros.h"
-#include "base/histogram.h"
-#include "base/logging.h"
-#include "base/string_util.h"
-
-using base::Time;
-using base::TimeDelta;
-using base::TimeTicks;
-
-namespace chrome_browser_net {
-
-static bool detailed_logging_enabled = false;
-
-// Use command line switch to enable detailed logging.
-void EnablePredictorDetailedLog(bool enable) {
-  detailed_logging_enabled = enable;
-}
-
-// static
-int UrlInfo::sequence_counter = 1;
-
-
-bool UrlInfo::NeedsDnsUpdate() {
-  switch (state_) {
-    case PENDING:  // Just now created info.
-      return true;
-
-    case QUEUED:  // In queue.
-    case ASSIGNED:  // It's being resolved.
-    case ASSIGNED_BUT_MARKED:  // It's being resolved.
-      return false;  // We're already working on it
-
-    case NO_SUCH_NAME:  // Lookup failed.
-    case FOUND:  // Lookup succeeded.
-      return !IsStillCached();  // See if DNS cache expired.
-
-    default:
-      NOTREACHED();
-      return false;
-  }
-}
-
-const TimeDelta UrlInfo::kNullDuration(TimeDelta::FromMilliseconds(-1));
-
-// Common low end TTL for sites is 5 minutes.  However, DNS servers give us
-// the remaining time, not the original 5 minutes.  Hence it doesn't much matter
-// whether we found something in the local cache, or an ISP cache, it will
-// on average be 2.5 minutes before it expires.  We could try to model this with
-// 180 seconds, but simpler is just to do the lookups all the time (wasting
-// OS calls(?)), and let that OS cache decide what to do (with TTL in hand).
-// We use a small time to help get some duplicate suppression, in case a page
-// has a TON of copies of the same domain name, so that we don't thrash the OS
-// to death.  Hopefully it is small enough that we're not hurting our cache hit
-// rate (i.e., we could always ask the OS).
-TimeDelta UrlInfo::kCacheExpirationDuration(TimeDelta::FromSeconds(5));
-
-const TimeDelta UrlInfo::kMaxNonNetworkDnsLookupDuration(
-    TimeDelta::FromMilliseconds(15));
-
-// Used by test ONLY.  The value is otherwise constant.
-void UrlInfo::set_cache_expiration(TimeDelta time) {
-  kCacheExpirationDuration = time;
-}
-
-void UrlInfo::SetQueuedState(ResolutionMotivation motivation) {
-  DCHECK(PENDING == state_ || FOUND == state_ || NO_SUCH_NAME == state_);
-  old_prequeue_state_ = state_;
-  state_ = QUEUED;
-  queue_duration_ = resolve_duration_ = kNullDuration;
-  SetMotivation(motivation);
-  GetDuration();  // Set time_
-  DLogResultsStats("DNS Prefetch in queue");
-}
-
-void UrlInfo::SetAssignedState() {
-  DCHECK(QUEUED == state_);
-  state_ = ASSIGNED;
-  queue_duration_ = GetDuration();
-  DLogResultsStats("DNS Prefetch assigned");
-  UMA_HISTOGRAM_TIMES("DNS.PrefetchQueue", queue_duration_);
-}
-
-void UrlInfo::RemoveFromQueue() {
-  DCHECK(ASSIGNED == state_);
-  state_ = old_prequeue_state_;
-  DLogResultsStats("DNS Prefetch reset to prequeue");
-  static const TimeDelta kBoundary = TimeDelta::FromSeconds(2);
-  if (queue_duration_ > kBoundary) {
-    UMA_HISTOGRAM_MEDIUM_TIMES("DNS.QueueRecycledDeltaOver2",
-                               queue_duration_ - kBoundary);
-    return;
-  }
-  // Make a custom linear histogram for the region from 0 to boundary.
-  const size_t kBucketCount = 52;
-  static scoped_refptr<Histogram> histogram = LinearHistogram::FactoryGet(
-      "DNS.QueueRecycledUnder2", TimeDelta(), kBoundary, kBucketCount,
-      Histogram::kUmaTargetedHistogramFlag);
-  histogram->AddTime(queue_duration_);
-}
-
-void UrlInfo::SetPendingDeleteState() {
-  DCHECK(ASSIGNED == state_  || ASSIGNED_BUT_MARKED == state_);
-  state_ = ASSIGNED_BUT_MARKED;
-}
-
-void UrlInfo::SetFoundState() {
-  DCHECK(ASSIGNED == state_);
-  state_ = FOUND;
-  resolve_duration_ = GetDuration();
-  if (kMaxNonNetworkDnsLookupDuration <= resolve_duration_) {
-    UMA_HISTOGRAM_CUSTOM_TIMES("DNS.PrefetchResolution", resolve_duration_,
-        kMaxNonNetworkDnsLookupDuration, TimeDelta::FromMinutes(15), 100);
-
-    static bool use_ipv6_histogram(FieldTrialList::Find("IPv6_Probe") &&
-        !FieldTrialList::Find("IPv6_Probe")->group_name().empty());
-    if (use_ipv6_histogram) {
-      UMA_HISTOGRAM_CUSTOM_TIMES(
-          FieldTrial::MakeName("DNS.PrefetchResolution", "IPv6_Probe"),
-          resolve_duration_, kMaxNonNetworkDnsLookupDuration,
-          TimeDelta::FromMinutes(15), 100);
-    }
-
-    // Record potential beneficial time, and maybe we'll get a cache hit.
-    // We keep the maximum, as the warming we did earlier may still be
-    // helping with a cache upstream in DNS resolution.
-    benefits_remaining_ = std::max(resolve_duration_, benefits_remaining_);
-  }
-  sequence_number_ = sequence_counter++;
-  DLogResultsStats("DNS PrefetchFound");
-}
-
-void UrlInfo::SetNoSuchNameState() {
-  DCHECK(ASSIGNED == state_);
-  state_ = NO_SUCH_NAME;
-  resolve_duration_ = GetDuration();
-  if (kMaxNonNetworkDnsLookupDuration <= resolve_duration_) {
-    DHISTOGRAM_TIMES("DNS.PrefetchNotFoundName", resolve_duration_);
-    // Record potential beneficial time, and maybe we'll get a cache hit.
-    benefits_remaining_ = std::max(resolve_duration_, benefits_remaining_);
-  }
-  sequence_number_ = sequence_counter++;
-  DLogResultsStats("DNS PrefetchNotFound");
-}
-
-void UrlInfo::SetStartedState() {
-  DCHECK(PENDING == state_);
-  state_ = STARTED;
-  queue_duration_ = resolve_duration_ = TimeDelta();  // 0ms.
-  SetMotivation(NO_PREFETCH_MOTIVATION);
-  GetDuration();  // Set time.
-}
-
-void UrlInfo::SetFinishedState(bool was_resolved) {
-  DCHECK(STARTED == state_);
-  state_ = was_resolved ? FINISHED : FINISHED_UNRESOLVED;
-  resolve_duration_ = GetDuration();
-  // TODO(jar): Sequence number should be incremented in prefetched HostInfo.
-  DLogResultsStats("DNS HTTP Finished");
-}
-
-void UrlInfo::SetUrl(const GURL& url) {
-  if (url_.is_empty())  // Not yet initialized.
-    url_ = url;
-  else
-    DCHECK_EQ(url_, url);
-}
-
-// IsStillCached() guesses if the DNS cache still has IP data,
-// or at least remembers results about "not finding host."
-bool UrlInfo::IsStillCached() const {
-  DCHECK(FOUND == state_ || NO_SUCH_NAME == state_);
-
-  // Default MS OS does not cache failures. Hence we could return false almost
-  // all the time for that case.  However, we'd never try again to prefetch
-  // the value if we returned false that way.  Hence we'll just let the lookup
-  // time out the same way as FOUND case.
-
-  if (sequence_counter - sequence_number_ > kMaxGuaranteedDnsCacheSize)
-    return false;
-
-  TimeDelta time_since_resolution = TimeTicks::Now() - time_;
-
-  return time_since_resolution < kCacheExpirationDuration;
-}
-
-// Compare the actual navigation DNS latency found in navigation_info, to the
-// previously prefetched info.
-DnsBenefit UrlInfo::AccruePrefetchBenefits(UrlInfo* navigation_info) {
-  DCHECK(FINISHED == navigation_info->state_ ||
-         FINISHED_UNRESOLVED == navigation_info->state_);
-  DCHECK(navigation_info->url() == url_);
-
-  if ((0 == benefits_remaining_.InMilliseconds()) ||
-      (FOUND != state_ && NO_SUCH_NAME != state_)) {
-    if (FINISHED == navigation_info->state_)
-      UMA_HISTOGRAM_LONG_TIMES("DNS.IndependentNavigation",
-                               navigation_info->resolve_duration_);
-    else
-      UMA_HISTOGRAM_LONG_TIMES("DNS.IndependentFailedNavigation",
-                               navigation_info->resolve_duration_);
-    return PREFETCH_NO_BENEFIT;
-  }
-
-  TimeDelta benefit = benefits_remaining_ - navigation_info->resolve_duration_;
-  navigation_info->benefits_remaining_ = benefits_remaining_;
-  benefits_remaining_ = TimeDelta();  // We used up all our benefits here.
-
-  navigation_info->motivation_ = motivation_;
-  if (LEARNED_REFERAL_MOTIVATED == motivation_ ||
-      STATIC_REFERAL_MOTIVATED == motivation_)
-    navigation_info->referring_url_ = referring_url_;
-
-  if (navigation_info->resolve_duration_ > kMaxNonNetworkDnsLookupDuration) {
-    // Our precache effort didn't help since HTTP stack hit the network.
-    UMA_HISTOGRAM_LONG_TIMES("DNS.PrefetchCacheEvictionL", resolve_duration_);
-    DLogResultsStats("DNS PrefetchCacheEviction");
-    return PREFETCH_CACHE_EVICTION;
-  }
-
-  if (NO_SUCH_NAME == state_) {
-    UMA_HISTOGRAM_LONG_TIMES("DNS.PrefetchNegativeHitL", benefit);
-    DLogResultsStats("DNS PrefetchNegativeHit");
-    return PREFETCH_NAME_NONEXISTANT;
-  }
-
-  DCHECK_EQ(FOUND, state_);
-  if (LEARNED_REFERAL_MOTIVATED == motivation_ ||
-      STATIC_REFERAL_MOTIVATED == motivation_) {
-    UMA_HISTOGRAM_TIMES("DNS.PrefetchReferredPositiveHit", benefit);
-    DLogResultsStats("DNS PrefetchReferredPositiveHit");
-  } else {
-    UMA_HISTOGRAM_LONG_TIMES("DNS.PrefetchPositiveHitL", benefit);
-    DLogResultsStats("DNS PrefetchPositiveHit");
-  }
-  return PREFETCH_NAME_FOUND;
-}
-
-void UrlInfo::DLogResultsStats(const char* message) const {
-  if (!detailed_logging_enabled)
-    return;
-  DLOG(INFO) << "\t" << message <<  "\tq="
-      << queue_duration().InMilliseconds() << "ms,\tr="
-      << resolve_duration().InMilliseconds() << "ms\tp="
-      << benefits_remaining_.InMilliseconds() << "ms\tseq="
-      << sequence_number_
-      << "\t" << url_.spec();
-}
-
-//------------------------------------------------------------------------------
-// This last section supports HTML output, such as seen in about:dns.
-//------------------------------------------------------------------------------
-
-// Preclude any possibility of Java Script or markup in the text, by only
-// allowing alphanumerics, '.', '-', ':', and whitespace.
-static std::string RemoveJs(const std::string& text) {
-  std::string output(text);
-  size_t length = output.length();
-  for (size_t i = 0; i < length; i++) {
-    char next = output[i];
-    if (isalnum(next) || isspace(next) || strchr(".-:/", next) != NULL)
-      continue;
-    output[i] = '?';
-  }
-  return output;
-}
-
-class MinMaxAverage {
- public:
-  MinMaxAverage()
-    : sum_(0), square_sum_(0), count_(0),
-      minimum_(kint64max), maximum_(kint64min) {
-  }
-
-  // Return values for use in printf formatted as "%d"
-  int sample(int64 value) {
-    sum_ += value;
-    square_sum_ += value * value;
-    count_++;
-    minimum_ = std::min(minimum_, value);
-    maximum_ = std::max(maximum_, value);
-    return static_cast<int>(value);
-  }
-  int minimum() const { return static_cast<int>(minimum_);    }
-  int maximum() const { return static_cast<int>(maximum_);    }
-  int average() const { return static_cast<int>(sum_/count_); }
-  int     sum() const { return static_cast<int>(sum_);        }
-
-  int standard_deviation() const {
-    double average = static_cast<float>(sum_) / count_;
-    double variance = static_cast<float>(square_sum_)/count_
-                      - average * average;
-    return static_cast<int>(floor(sqrt(variance) + .5));
-  }
-
- private:
-  int64 sum_;
-  int64 square_sum_;
-  int count_;
-  int64 minimum_;
-  int64 maximum_;
-
-  // DISALLOW_COPY_AND_ASSIGN(MinMaxAverage);
-};
-
-static std::string HoursMinutesSeconds(int seconds) {
-  std::string result;
-  int print_seconds = seconds % 60;
-  int minutes = seconds / 60;
-  int print_minutes = minutes % 60;
-  int print_hours = minutes/60;
-  if (print_hours)
-    StringAppendF(&result, "%.2d:",  print_hours);
-  if (print_hours || print_minutes)
-    StringAppendF(&result, "%2.2d:",  print_minutes);
-  StringAppendF(&result, "%2.2d",  print_seconds);
-  return result;
-}
-
-// static
-void UrlInfo::GetHtmlTable(const DnsInfoTable host_infos,
-                               const char* description,
-                               const bool brief,
-                               std::string* output) {
-  if (0 == host_infos.size())
-    return;
-  output->append(description);
-  StringAppendF(output, "%" PRIuS " %s", host_infos.size(),
-                (1 == host_infos.size()) ? "hostname" : "hostnames");
-
-  if (brief) {
-    output->append("<br><br>");
-    return;
-  }
-
-  const char* row_format = "<tr align=right><td>%s</td>"
-                           "<td>%d</td><td>%d</td><td>%s</td><td>%s</td></tr>";
-
-  output->append("<br><table border=1>");
-  StringAppendF(output,
-      "<tr><th>%s</th><th>%s</th><th>%s</th><th>%s</th><th>%s</th></tr>",
-      "Host name", "Applicable Prefetch<br>Time (ms)",
-      "Recent Resolution<br>Time(ms)", "How long ago<br>(HH:MM:SS)",
-      "Motivation");
-
-  // Print bulk of table, and gather stats at same time.
-  MinMaxAverage queue, resolve, preresolve, when;
-  TimeTicks current_time = TimeTicks::Now();
-  for (DnsInfoTable::const_iterator it(host_infos.begin());
-       it != host_infos.end(); it++) {
-    queue.sample((it->queue_duration_.InMilliseconds()));
-    StringAppendF(output, row_format,
-                  RemoveJs(it->url_.spec()).c_str(),
-                  preresolve.sample((it->benefits_remaining_.InMilliseconds())),
-                  resolve.sample((it->resolve_duration_.InMilliseconds())),
-                  HoursMinutesSeconds(when.sample(
-                      (current_time - it->time_).InSeconds())).c_str(),
-                  it->GetAsciiMotivation().c_str());
-  }
-  // Write min, max, and average summary lines.
-  if (host_infos.size() > 2) {
-    output->append("<B>");
-    StringAppendF(output, row_format,
-                  "<b>---minimum---</b>",
-                  preresolve.minimum(), resolve.minimum(),
-                  HoursMinutesSeconds(when.minimum()).c_str(), "");
-    StringAppendF(output, row_format,
-                  "<b>---average---</b>",
-                  preresolve.average(), resolve.average(),
-                  HoursMinutesSeconds(when.average()).c_str(), "");
-    StringAppendF(output, row_format,
-                  "<b>standard deviation</b>",
-                  preresolve.standard_deviation(),
-                  resolve.standard_deviation(), "n/a", "");
-    StringAppendF(output, row_format,
-                  "<b>---maximum---</b>",
-                  preresolve.maximum(), resolve.maximum(),
-                  HoursMinutesSeconds(when.maximum()).c_str(), "");
-    StringAppendF(output, row_format,
-                  "<b>-----SUM-----</b>",
-                  preresolve.sum(), resolve.sum(), "n/a", "");
-  }
-  output->append("</table>");
-
-#ifdef DEBUG
-  StringAppendF(output,
-                "Prefetch Queue Durations: min=%d, avg=%d, max=%d<br><br>",
-                queue.minimum(), queue.average(), queue.maximum());
-#endif
-
-  output->append("<br>");
-}
-
-void UrlInfo::SetMotivation(ResolutionMotivation motivation) {
-  motivation_ = motivation;
-  if (motivation < LINKED_MAX_MOTIVATED)
-    was_linked_ = true;
-}
-
-std::string UrlInfo::GetAsciiMotivation() const {
-  switch (motivation_) {
-    case MOUSE_OVER_MOTIVATED:
-      return "[mouse-over]";
-
-    case PAGE_SCAN_MOTIVATED:
-      return "[page scan]";
-
-    case OMNIBOX_MOTIVATED:
-      return "[omnibox]";
-
-    case STARTUP_LIST_MOTIVATED:
-      return "[startup list]";
-
-    case NO_PREFETCH_MOTIVATION:
-      return "n/a";
-
-    case STATIC_REFERAL_MOTIVATED:
-      return RemoveJs(referring_url_.spec()) + "*";
-
-    case LEARNED_REFERAL_MOTIVATED:
-      return RemoveJs(referring_url_.spec());
-
-    default:
-      return "";
-  }
-}
-
-}  // namespace chrome_browser_net