Support both preconnection, and pre-resolution for subresources...

chrome/browser/net/url_info.cc

 // 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/url_info.h"
 
 #include <math.h>
 
 #include <algorithm>
 #include <string>
@@ skipping 113 matching lines @@
         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.
@@ skipping 55 matching lines @@
   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,
+void UrlInfo::GetHtmlTable(const UrlInfoTable 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>"
+      "<tr><th>Host name</th>"
+      "<th>How long ago<br>(HH:MM:SS)</th>"
+      "<th>Motivation</th>"
+      "</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");
+  const char* row_format = "<tr align=right><td>%s</td>"  // Host name.
+                           "<td>%s</td>"                  // How long ago.
+                           "<td>%s</td>"                  // Motivation.
+                           "</tr>";
 
   // Print bulk of table, and gather stats at same time.
-  MinMaxAverage queue, resolve, preresolve, when;
+  MinMaxAverage queue, when;
   TimeTicks current_time = TimeTicks::Now();
-  for (DnsInfoTable::const_iterator it(host_infos.begin());
+  for (UrlInfoTable::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>");
 }
@@ skipping 26 matching lines @@
 
     case LEARNED_REFERAL_MOTIVATED:
       return RemoveJs(referring_url_.spec());
 
     default:
       return "";
   }
 }
 
 }  // namespace chrome_browser_net