storage/mozIStorageAggregateFunction.idl
author Ralph Giles <giles@mozilla.com>
Tue, 31 Jan 2017 17:24:17 -0800
changeset 360930 931cbdebf471a80bddf8d834093c5ea6601e87c5
parent 264219 ad01543457e739b4eee7a245e16734a3ecfd10ad
permissions -rw-r--r--
Bug 1333931 - Handle nullptr TextTrack objects in sorting. r=kinetik Check for nullptr arguments passed to CompareTextTracks. Based on Ben Kelly's analysis this can happen if the cycle collector has cleared a TextTrack pointer while comparision is still happening, perhaps in a queued event task. This change makes nullptr sort to the end, and adds a MOZ_DIAGNOSTIC_ASSERT for trying to get the position of a nullptr track should someone add another call at a later date.

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

interface mozIStorageConnection;
interface mozIStorageValueArray;
interface nsIArray;
interface nsIVariant;

/**
 * mozIStorageAggregateFunction represents aggregate SQL function.
 * Common examples of aggregate functions are SUM() and COUNT().
 *
 * An aggregate function calculates one result for a given set of data, where
 * a set of data is a group of tuples. There can be one group
 * per request or many of them, if GROUP BY clause is used or not.
 */
[scriptable, uuid(763217b7-3123-11da-918d-000347412e16)]
interface mozIStorageAggregateFunction : nsISupports {
  /**
   * onStep is called when next value should be passed to
   * a custom function.
   * 
   * @param aFunctionArguments    The arguments passed in to the function
   */
  void onStep(in mozIStorageValueArray aFunctionArguments);

  /**
   * Called when all tuples in a group have been processed and the engine
   * needs the aggregate function's value.
   *
   * @returns aggregate result as Variant.
   */
  nsIVariant onFinal();
};