001/** 002 * Copyright (c) 2008-2009 Apple Inc. All rights reserved. 003 * Copyright (C) 2012 FuseSource, Inc. 004 * http://fusesource.com 005 * 006 * Licensed under the Apache License, Version 2.0 (the "License"); 007 * you may not use this file except in compliance with the License. 008 * You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019package org.fusesource.hawtdispatch; 020 021/** 022 * <p> 023 * The EventAggregator interface is used by the {@link CustomDispatchSource} objects to handle 024 * coalescing data before passing it to the application. Implementations of this class should 025 * be stateless to remain thread-safe. You can also use one of several built in implementations: 026 * </p> 027 * 028 * <ul> 029 * <li>{@link EventAggregators#INTEGER_ADD}</li> 030 * <li>{@link EventAggregators#INTEGER_OR}</li> 031 * <li>{@link EventAggregators#LONG_ADD}</li> 032 * <li>{@link EventAggregators#LONG_OR}</li> 033 * </ul> 034 * 035 * @author <a href="http://hiramchirino.com">Hiram Chirino</a> 036 */ 037public interface EventAggregator<Event, MergedEvent> { 038 039 /** 040 * <p> 041 * Merge the given event with the previous event values. 042 * </p> 043 * 044 * @param previous may be null 045 * @param event the value that should be merged 046 * @return a newly merged result 047 */ 048 public MergedEvent mergeEvent(MergedEvent previous, Event event); 049 050 /** 051 * <p> 052 * Merge the given events with the previous event values. 053 * </p> 054 * 055 * @param previous the value of previous merges 056 * @param events the value of more merges 057 * @return a newly merged result 058 */ 059 public MergedEvent mergeEvents(MergedEvent previous, MergedEvent events); 060 061}