Add a PrefetchList to Prerender Local Predictor, to emulate how effective

chrome/browser/prerender/prerender_field_trial.cc

 // Copyright (c) 2012 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/prerender/prerender_field_trial.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 36 matching lines @@
 const char kPrerenderPrefetchKeyName[] = "PrerenderPrefetch";
 const char kPrerenderQueryPrerenderServiceKeyName[] =
     "PrerenderQueryPrerenderService";
 const char kPrerenderQueryPrerenderServiceCurrentURLKeyName[] =
     "PrerenderQueryPrerenderServiceCurrentURL";
 const char kPrerenderQueryPrerenderServiceCandidateURLsKeyName[] =
     "PrerenderQueryPrerenderServiceCandidateURLs";
 const char kPrerenderServiceBehaviorIDKeyName[] = "PrerenderServiceBehaviorID";
 const char kPrerenderServiceFetchTimeoutKeyName[] =
     "PrerenderServiceFetchTimeoutMs";
+const char kPrefetchListTimeoutKeyName[] = "PrefetchListTimeoutSeconds";
 const char kPrerenderTTLKeyName[] = "PrerenderTTLSeconds";
 const char kPrerenderPriorityHalfLifeTimeKeyName[] =
     "PrerenderPriorityHalfLifeTimeSeconds";
 const char kMaxConcurrentPrerenderKeyName[] = "MaxConcurrentPrerenders";
 const char kMaxLaunchPrerenderKeyName[] = "MaxLaunchPrerenders";
 const char kSkipFragment[] = "SkipFragment";
 const char kSkipHTTPS[] = "SkipHTTPS";
 const char kSkipWhitelist[] = "SkipWhitelist";
 const char kSkipServiceWhitelist[] = "SkipServiceWhitelist";
 const char kSkipLoggedIn[] = "SkipLoggedIn";
 const char kSkipDefaultNoPrerender[] = "SkipDefaultNoPrerender";
 const char kPrerenderServiceURLPrefixParameterName[] =
     "PrerenderServiceURLPrefix";
 const char kDefaultPrerenderServiceURLPrefix[] =
     "https://clients4.google.com/prerenderservice/?q=";
 const int kMinPrerenderServiceTimeoutMs = 1;
 const int kMaxPrerenderServiceTimeoutMs = 10000;
 const int kDefaultPrerenderServiceTimeoutMs = 1000;
+const int kMinPrefetchListTimeoutSeconds = 1;
+const int kMaxPrefetchListTimeoutSeconds = 1800;
+const int kDefaultPrefetchListTimeoutSeconds = 300;
 const char kSkipPrerenderLocalCanadidates[] = "SkipPrerenderLocalCandidates";
 const char kSkipPrerenderServiceCanadidates[] =
     "SkipPrerenderServiceCandidates";
 const char kDisableSessionStorageNamespaceMerging[] =
     "DisableSessionStorageNamespaceMerging";
 const char kPrerenderCookieStore[] = "PrerenderCookieStore";
 
 void SetupPrerenderFieldTrial() {
   const FieldTrial::Probability divisor = 1000;
 
@@ skipping 290 matching lines @@
 int GetPrerenderServiceFetchTimeoutMs() {
   int result;
   StringToInt(GetLocalPredictorSpecValue(kPrerenderServiceFetchTimeoutKeyName),
               &result);
   // If the value is outside the valid range, use the default value.
   return (result < kMinPrerenderServiceTimeoutMs ||
           result > kMaxPrerenderServiceTimeoutMs) ?
       kDefaultPrerenderServiceTimeoutMs : result;
 }
 
+int GetPrerenderPrefetchListTimeoutSeconds() {
+  int result;
+  StringToInt(GetLocalPredictorSpecValue(kPrefetchListTimeoutKeyName), &result);

[davidben, 2014/08/05 18:51:12]

Nit: Check for StringToInt returning false here, so we're not reading an
uninitialized value if that fails.

[tburkard, 2014/08/05 20:05:54]

See comment in base/strings/string_number_conversions.h
StringToInt will always set result to something, the return value only indicates
if it was a "perfect" conversion or not.

So result will always have a defined value, and the check afterwards will ensure
it is in the correct range.

+  // If the value is outside the valid range, use the default value.
+  return (result < kMinPrefetchListTimeoutSeconds ||
+          result > kMaxPrefetchListTimeoutSeconds) ?
+      kDefaultPrefetchListTimeoutSeconds : result;
+}
+
 int GetLocalPredictorTTLSeconds() {
   int ttl;
   StringToInt(GetLocalPredictorSpecValue(kPrerenderTTLKeyName), &ttl);
   // If the value is outside of 10s or 600s, use a default value of 180s.
   return (ttl < 10 || ttl > 600) ? 180 : ttl;
 }
 
 int GetLocalPredictorPrerenderPriorityHalfLifeTimeSeconds() {
   int half_life_time;
   StringToInt(GetLocalPredictorSpecValue(kPrerenderPriorityHalfLifeTimeKeyName),
@@ skipping 56 matching lines @@
   return GetLocalPredictorSpecValue(kDisableSessionStorageNamespaceMerging) !=
       kDisabledGroup;
 }
 
 bool IsPrerenderCookieStoreEnabled() {
   return GetLocalPredictorSpecValue(kPrerenderCookieStore) != kDisabledGroup &&
       FieldTrialList::FindFullName(kPrerenderCookieStore) != kDisabledGroup;
 }
 
 }  // namespace prerender