Omnibox - HistoryQuick Provider - Don't Run Duplicate Searches

components/omnibox/browser/url_index_private_data.cc

Index: components/omnibox/browser/url_index_private_data.cc
diff --git a/components/omnibox/browser/url_index_private_data.cc b/components/omnibox/browser/url_index_private_data.cc
index b9f2a93ea945bc2e73e33afdb396d0bd0ef8a975..f5612576bed7a5ef7f71a0d6bb52894fb987264c 100644
--- a/components/omnibox/browser/url_index_private_data.cc
+++ b/components/omnibox/browser/url_index_private_data.cc
@@ -10,6 +10,7 @@
 #include <iterator>
 #include <limits>
 #include <numeric>
+#include <set>
 #include <string>
 #include <vector>
 
@@ -173,6 +174,9 @@ ScoredHistoryMatches URLIndexPrivateData::HistoryItemsForTerms(
   ResetSearchTermCache();
 
   bool history_ids_were_trimmed = false;
+  // A set containing the list of words extracted from each search string,
+  // used to prevent running duplicate searches.
+  std::set<String16Vector> search_string_words;
   for (const base::string16& search_string : search_strings) {
     // The search string we receive may contain escaped characters. For reducing
     // the index we need individual, lower-cased words, ignoring escapings. For
@@ -192,6 +196,10 @@ ScoredHistoryMatches URLIndexPrivateData::HistoryItemsForTerms(
         String16VectorFromString16(lower_unescaped_string, false, nullptr));
     if (lower_words.empty())
       continue;
+    // If we've already searched for this list of words, don't do it again.
+    if (search_string_words.find(lower_words) != search_string_words.end())

[Peter Kasting, 2017/05/05 23:07:34]

Nit: Or base::ContainsKey(search_string_words, lower_words)

(You may or may not find this easier to read)

[Mark P, 2017/05/08 22:46:19]

Left as-is.  I find the current code a bit more readable.  It also better fits
local style (see lines 1211, 1267, and 1270 for examples).

+      continue;
+    search_string_words.insert(lower_words);
 
     HistoryIDVector history_ids = HistoryIDsFromWords(lower_words);
     history_ids_were_trimmed |= TrimHistoryIdsPool(&history_ids);