496466 - empty autocomplete results should be cached

Status: RESOLVED WORKSFORME

(Toolkit :: Form Manager, defect)

Description

[Justin Dolske [:Dolske]]

sayrer noticed that every keypress on a Gmail search field was generating a console warning about an inefficient query. There are a few things going on here, but the interesting part for this bug is that each invocation off form history's AutoCompleteSearch() had a null previousResult, so a new query was being performed.

Looks like something is broken, we should be getting an empty (but non-null!) previousResult so that we don't his the DB with each keystroke. nsIAutoCompleteResult seems to have some support for a RESULT_NOMATCH result, but who knows if this old code is working.

Comment 1

[[e-mail]]

This bug may have been copied from XPFE:
// check the many criteria for failure
if (aStatus == Components.interfaces.nsIAutoCompleteStatus.failed ||
    aStatus == Components.interfaces.nsIAutoCompleteStatus.ignored ||
    aStatus == Components.interfaces.nsIAutoCompleteStatus.noMatch ||
    aResults == null ||
    aResults.items.Count() == 0 ||
    aResults.searchString != this.currentSearchString)
{
  this.mLastResults[aSessionName] = null;
Thus forgetting that we "succesfully" found zero results.

Comment 2

[[e-mail]]

This is the equivalent toolkit code in nsAutoCompleteController.cpp:
PRUint16 searchResult;
result->GetSearchResult(&searchResult);
if (searchResult != nsIAutoCompleteResult::RESULT_SUCCESS &&
    searchResult != nsIAutoCompleteResult::RESULT_SUCCESS_ONGOING)
  result = nsnull;

Comment 3

[Matthew N. [:MattN]]

The lines causing this behavior are in nsAutoCompleteController.cpp where results would be cleared if there were no matches from the previous search:

257   if (mRowCount == 0)
258     // XXX Handle the case where we have no results because of an ignored prefix.
259     // This is just a hack. I have no idea what I'm doing. Hewitt, fix this the right
260     // way when you get a chance. -dwh
261     ClearResults();

I will properly fix (what I believe is) the "ignored prefix" issue in bug 497541 which will fix this.

Comment 4

[Matthew N. [:MattN]]

Fixed in bug 497541 on trunk: 
http://hg.mozilla.org/mozilla-central/rev/47bfcd275ede