Adds speculative prefetching of resources.

chrome/browser/predictors/resource_prefetch_common.h

 // 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.
 
 #ifndef CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_
 
 #include "base/time.h"
 #include "googleurl/src/gurl.h"
 
@@ skipping 22 matching lines @@
   int render_process_id;
   int render_view_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. It is
+// useful for running experiments.
+struct ResourcePrefetchPredictorConfig {
+  // Initializes the config with default values.
+  ResourcePrefetchPredictorConfig();
+
+  // If a navigation hasn't seen a load complete event in this much time, it
+  // is considered abandoned.
+  int max_navigation_lifetime_seconds;  // Default 60

[dominich, 2012/07/23 16:04:41]

i don't think you should put the defaults here. Anyone interested can look at
the .cc file, and this just makes it more likely to get out of date comments.

[Shishir, 2012/08/01 22:35:24]

Done.

+  // Size of LRU caches for the Url data.

[dominich, 2012/07/23 16:04:41]

nit: URL

[Shishir, 2012/08/01 22:35:24]

Done.

+  size_t max_urls_to_track;  // Default 500
+  // The number of times, we should have seen a visit to this Url in history

[dominich, 2012/07/23 16:04:41]

nit: URL

[Shishir, 2012/08/01 22:35:24]

Done.

+  // to start tracking it. This is to ensure we dont bother with oneoff
+  // entries.
+  int min_url_visit_count;  // Default 3
+  // The maximum number of resources to store per entry.
+  int max_resources_per_entry;  // Default 50
+  // The number of consecutive misses after we stop tracking a resource Url.

[dominich, 2012/07/23 16:04:41]

nit: URL

[Shishir, 2012/08/01 22:35:24]

Done.

+  int max_consecutive_misses;  // Default 3
+
+  // The number of resources we should report accuracy stats on.
+  int num_resources_assumed_prefetched;  // Default 25
+
+  // The minimum confidence (accuracy of hits) required for a resource to be
+  // prefetched.
+  float min_resource_confidence_to_trigger_prefetch;  // Default 0.8
+  // The minimum number of times we must have a url on record to prefetch it.
+  float min_resource_hits_to_trigger_prefetch;  // Default 4

[dominich, 2012/07/23 16:04:41]

why is this float?

[Shishir, 2012/08/01 22:35:24]

Changed to int

+
+  // Maximum number of prefetches that can be inflight for a single navigation.
+  size_t max_prefetches_inflight_per_navigation;  // Default 24
+  // Maximum number of prefetches that can be inflight for a host for a single
+  // navigation.
+  int max_prefetches_inflight_per_host_per_navigation;  // Default 3

[dominich, 2012/07/23 16:04:41]

inconsistency: Both are max prefetches in-flight, but one is size_t and one is
int.

[Shishir, 2012/08/01 22:35:24]

Its just the way they are used. One was used in comparing vector size, not the
other. Changing all size_t to int for consistency.

+};
+
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_