Adding knobs on HQP provider.

chrome/browser/history/scored_history_match.cc

Index: chrome/browser/history/scored_history_match.cc
diff --git a/chrome/browser/history/scored_history_match.cc b/chrome/browser/history/scored_history_match.cc
index 1f1184c859273b31a94a901238661ce72bd018d8..1b9a33a8963361b18370c8067b9a724fd09a419e 100644
--- a/chrome/browser/history/scored_history_match.cc
+++ b/chrome/browser/history/scored_history_match.cc
@@ -14,6 +14,8 @@
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/autocomplete/history_url_provider.h"
@@ -61,6 +63,9 @@ ScoredHistoryMatch::ScoredHistoryMatch(
       can_inline_(false) {
   Init();
 
+  // Initialize the HQP scoring params.
+  InitializeHQPExperimentalParams();

[Mark P, 2015/02/11 21:57:29]

This new location for initializing the parameters does not help.  This class
gets constructed each time we want to score a URL; you're still calling the
initialization functions thousands of times on each keystroke.

It would make more sense to make your variables static and initialize them once
by calling your init function within the main Init().

[Ashok vardhan, 2015/02/12 19:56:31]

I see. Got your point. Thought my parsing was the problem for each URL, but
didn't notice this. Fixed it.

+
   GURL gurl = row.url();
   if (!gurl.is_valid())
     return;
@@ -154,7 +159,8 @@ ScoredHistoryMatch::ScoredHistoryMatch(
       terms.size(), url, terms_to_word_starts_offsets, word_starts);
   const float frequency_score = GetFrequency(
       now, (history_client && history_client->IsBookmarked(gurl)), visits);
-  raw_score_ = GetFinalRelevancyScore(topicality_score, frequency_score);
+  raw_score_ = GetFinalRelevancyScore(topicality_score, frequency_score,
+                                      hqp_relevance_buckets_);
   raw_score_ =
       (raw_score_ <= kint32max) ? static_cast<int>(raw_score_) : kint32max;
 
@@ -438,7 +444,15 @@ float ScoredHistoryMatch::GetTopicalityScore(
   // TODO(mpearson): If there are multiple terms, consider taking the
   // geometric mean of per-term scores rather than the arithmetic mean.
 
-  return topicality_score / num_terms;
+  float final_topicality_score = topicality_score / num_terms;
+
+  // Demote all the URLs if the topicality score is less than threshold.
+  if (hqp_experimental_scoring_enabled_ &&
+      (final_topicality_score < topicality_threshold_)) {
+    return 0.0;
+  }
+
+  return final_topicality_score;
 }
 
 // static
@@ -542,8 +556,10 @@ float ScoredHistoryMatch::GetFrequency(const base::Time& now,
 }
 
 // static
-float ScoredHistoryMatch::GetFinalRelevancyScore(float topicality_score,
-                                                 float frequency_score) {
+float ScoredHistoryMatch::GetFinalRelevancyScore(
+    float topicality_score,
+    float frequency_score,
+    std::vector<ScoreMaxRelevance>& hqp_relevance_buckets) {
   if (topicality_score == 0)
     return 0;
   // Here's how to interpret intermediate_score: Suppose the omnibox
@@ -559,29 +575,91 @@ float ScoredHistoryMatch::GetFinalRelevancyScore(float topicality_score,
   // - a typed visit once a week -> 11.77
   // - a typed visit every three days -> 14.12
   // - at least ten typed visits today -> 20.0 (maximum score)
-  const float intermediate_score = topicality_score * frequency_score;
+  //
   // The below code maps intermediate_score to the range [0, 1399].
+  // For example:
+  // HQP default scoring buckets: "1.5:600,12.0:1300,20.0:1399"
+  // We will linearly interpolate the scores between:
+  //      0 to 1.5    --> 400 to 600
+  //    1.5 to 12.0   --> 600 to 1300
+  //    12.0 to 20.0  --> 1300 to 1399
+  //       >= 20.0    --> 1399
+  //
   // The score maxes out at 1400 (i.e., cannot beat a good inline result).
-  if (intermediate_score <= 1) {
-    // Linearly extrapolate between 0 and 1.5 so 0 has a score of 400
-    // and 1.5 has a score of 600.
-    const float slope = (600 - 400) / (1.5f - 0.0f);
-    return 400 + slope * intermediate_score;
+  //
+  // If experimental scoring is enabled, then the score buckets will be like:
+  // HQP experimental scoring buckets: "1.5:600,5.0:900,12.0:1100,20.0:1300"
+  const float intermediate_score = topicality_score * frequency_score;
+
+  double base_intermediate_score = 0.0;
+  int base_hqp_score = 400;
+  double max_intermediate_score = base_intermediate_score;
+  int max_hqp_score = base_hqp_score;
+
+  // Find the threshold where intermediate score is greater than bucket.
+  for (size_t i = 0; i < hqp_relevance_buckets.size(); ++i) {
+    ScoreMaxRelevance hqp_bucket = hqp_relevance_buckets[i];
+    max_intermediate_score = hqp_bucket.first;
+    max_hqp_score = hqp_bucket.second;
+    if (intermediate_score <= max_intermediate_score) {
+      const float slope = (
+          (max_hqp_score - base_hqp_score) /
+          (max_intermediate_score - base_intermediate_score));
+      const int final_hqp_score = (base_hqp_score +
+                                   (slope * (intermediate_score -
+                                             base_intermediate_score)));
+      return std::min(final_hqp_score, max_hqp_score);
+    }
+    base_intermediate_score = max_intermediate_score;
+    base_hqp_score = max_hqp_score;
   }
-  if (intermediate_score <= 12.0) {
-    // Linearly extrapolate up to 12 so 12 has a score of 1300.
-    const float slope = (1300 - 600) / (12.0f - 1.5f);
-    return 600 + slope * (intermediate_score - 1.5);
+  // It will reach this stage when the score is > highest bucket score or
+  // when buckets are not specified. Return max_hqp_score.
+  return max_hqp_score;
+}
+
+void ScoredHistoryMatch::InitializeHQPExperimentalParams() {
+  // Initialize the hqp experiment params.
+  hqp_experimental_scoring_enabled_ = false;
+  topicality_threshold_ = -1;
+  // These are default HQP scoring params.
+  // See GetFinalRelevancyScore() for details.
+  std::string hqp_relevance_buckets_str = "1.5:600,12.0:1300,20.0:1399";
+
+  // Fetch the experiment params if they are any.
+  hqp_experimental_scoring_enabled_ =
+    OmniboxFieldTrial::HQPExperimentalScoringEnabled();
+
+  if (hqp_experimental_scoring_enabled_) {
+    // Add the topicality threshold from experiment params.
+    float hqp_experimental_topicality_threhold =
+      OmniboxFieldTrial::HQPExperimentalTopicalityThreshold();
+    if (hqp_experimental_topicality_threhold > 0)
+      topicality_threshold_ = hqp_experimental_topicality_threhold;
+
+    // Add the HQP experimental scoring buckets.
+    std::string hqp_experimental_scoring_buckets =
+      OmniboxFieldTrial::HQPExperimentalScoringBuckets();
+    if (!hqp_experimental_scoring_buckets.empty())
+      hqp_relevance_buckets_str = hqp_experimental_scoring_buckets;
+  }
+
+  // Parse the hqp_relevance_buckets_str string once and store them in vector
+  // which is easy to access.
+  base::StringPairs kv_pairs;
+  if (base::SplitStringIntoKeyValuePairs(hqp_relevance_buckets_str,
+                                         ':', ',', &kv_pairs)) {
+    for (base::StringPairs::const_iterator it = kv_pairs.begin();
+         it != kv_pairs.end(); ++it) {
+      ScoreMaxRelevance bucket;
+      base::StringToDouble(it->first, &bucket.first);
+      base::StringToInt(it->second, &bucket.second);
+      hqp_relevance_buckets_.push_back(bucket);
+    }
   }
-  // Linearly extrapolate so a score of 20 (or more) has a score of 1399.
-  // (Scores above 20 are possible for URLs that have multiple term hits
-  // in the URL and/or title and that are visited practically all
-  // the time using typed visits.  We don't attempt to distinguish
-  // between these very good results.)
-  const float slope = (1399 - 1300) / (20.0f - 12.0f);
-  return std::min(1399.0, 1300 + slope * (intermediate_score - 12.0));
 }
 
+// static
 void ScoredHistoryMatch::Init() {
   if (initialized_)
     return;
@@ -602,6 +680,7 @@ void ScoredHistoryMatch::Init() {
   bookmark_value_ = OmniboxFieldTrial::HQPBookmarkValue();
   allow_tld_matches_ = OmniboxFieldTrial::HQPAllowMatchInTLDValue();
   allow_scheme_matches_ = OmniboxFieldTrial::HQPAllowMatchInSchemeValue();
+
   initialized_ = true;
 }