Omnibox: Truncate HistoryContents Searches at 10k Characters

chrome/browser/autocomplete/history_contents_provider.cc

Index: chrome/browser/autocomplete/history_contents_provider.cc
diff --git a/chrome/browser/autocomplete/history_contents_provider.cc b/chrome/browser/autocomplete/history_contents_provider.cc
index 190d0a3afc85bbd3186f5ca0caeda03bd8bdfa81..5cafbcb07340288961d7db0f9ac73d324a691ab5 100644
--- a/chrome/browser/autocomplete/history_contents_provider.cc
+++ b/chrome/browser/autocomplete/history_contents_provider.cc
@@ -31,6 +31,15 @@ namespace {
 // time it will take.
 const int kDaysToSearch = 30;
 
+// The maximum number of characters used in a search for full text results.
+// This was chosen arbitrarily because omnibox results that come back too
+// late (after tens of seconds) aren't useful to the user so it's not
+// worth spending CPU time on them.  Furthermore, if a URL matches the
+// first 10k of characters the user typed (more likely pasted) into the
+// omnibox, it's likely it matches the rest; there's strongly diminished
+// returns for the ability to add additional search terms.
+const size_t kMaxCharactersToConsider = 10000u;

[Peter Kasting, 2013/04/17 22:34:57]

Even 10K seems like it will take a while.  What about truncating at like... 2K? 
I can't imagine there'd be a noticeable quality difference between the two.

[Mark P, 2013/04/17 22:58:22]

2k is also okay with me.  Done.

+
 }  // namespace
 
 HistoryContentsProvider::MatchReference::MatchReference(
@@ -139,7 +148,9 @@ void HistoryContentsProvider::Start(const AutocompleteInput& input,
       options.body_only = body_only_;
       options.SetRecentDayRange(kDaysToSearch);
       options.max_count = kMaxMatches;
-      history->QueryHistory(input.text(), options,
+      history->QueryHistory(
+          input.text().substr(0, kMaxCharactersToConsider),
+          options,
           &request_consumer_,
           base::Bind(&HistoryContentsProvider::QueryComplete,
                      base::Unretained(this)));