1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 18 package android.filterfw.core; 19 20 import java.util.Set; 21 22 import android.filterfw.core.Filter; 23 import android.filterfw.core.Scheduler; 24 25 /** 26 * @hide 27 */ 28 public class RoundRobinScheduler extends Scheduler { 29 30 private int mLastPos = -1; 31 32 public RoundRobinScheduler(FilterGraph graph) { 33 super(graph); 34 } 35 36 @Override 37 public void reset() { 38 mLastPos = -1; 39 } 40 41 @Override 42 public Filter scheduleNextNode() { 43 Set<Filter> all_filters = getGraph().getFilters(); 44 if (mLastPos >= all_filters.size()) mLastPos = -1; 45 int pos = 0; 46 Filter first = null; 47 int firstNdx = -1; 48 for (Filter filter : all_filters) { 49 if (filter.canProcess()) { 50 if (pos <= mLastPos) { 51 if (first == null) { 52 // store the first available filter 53 first = filter; 54 firstNdx = pos; 55 } 56 } else { 57 // return the next available filter since last 58 mLastPos = pos; 59 return filter; 60 } 61 } 62 pos ++; 63 } 64 // going around from the beginning 65 if (first != null ) { 66 mLastPos = firstNdx; 67 return first; 68 } 69 // if there is nothing to be scheduled, still keep the previous 70 // position. 71 return null; 72 } 73 } 74
