Pagination should only cancel _different_ pending "request result promises"

[jandppw]

Pagination.renderArray should not blindly cancel pending requests, but only if they are different from a new request.

We have code that "guards" remote requests against requesting the same information more than once concurrently (https://code.google.com/p/ppwcode/source/browse/javascript/util/oddsAndEnds/trunk/src/oddsAndEnds/promise/Arbiter.js). When "data" is asked, we check whether the "request" is the same or not, and if it is, and the request is still pending, we return the same Promise. That original Promise will later resolve for all callers of that "data".

That is just one example of sensibly returning the same Promise for different calls of a store.query.

This cannot be used with Pagination however, because Pagination (line 365 - 369) will blindly cancel a previous request, if it is not fulfilled yet, on refresh. The solution is to replace

if(this._topLevelRequest) {
  // Cancel previous async request that didn't finish
  this._topLevelRequest.cancel();
  delete this._topLevelRequest;
}

with

if(this._topLevelRequest && this._topLevelRequest !== results){
  // Cancel previous async request that didn't finish
  this._topLevelRequest.cancel();
  delete this._topLevelRequest;
}

This seems better in all cases.

[jandppw]

https://code.google.com/p/ppwcode/source/browse/javascript/util/oddsAndEnds/trunk/src/oddsAndEnds/promise/Arbiter.js is changed to work around this with a reference counter, but the proposed change still seems something Pagination should do to me.

[kfranqueiro]

Thanks for the suggestion; I've incorporated it.