1 /* 2 * Copyright (C) 2016 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 package com.android.ahat.heapdump; 18 19 /** 20 * An interface for instances/sites/heaps/etc in a heap dump that can be 21 * related to corresponding instances/sites/heaps/etc in a second heap dump 22 * when the two heap dumps have been diffed. 23 */ 24 public interface Diffable<T> { 25 /** 26 * Returns the object in the other heap dump that corresponds to this object. 27 * When two heap dumps are diffed, diffable objects from the first heap dump 28 * will be matched to "baseline" objects from the second heap dump, and 29 * diffable objects from the second heap dump will be matched to "baseline" 30 * objects from the first heap dump. 31 * 32 * @return the matched object from the other heap dump 33 */ getBaseline()34 T getBaseline(); 35 36 /** 37 * Returns true if this is a placeholder object. 38 * A placeholder object is used to indicate there is some object in the 39 * baseline heap dump that is not in this heap dump. In that case, we create 40 * a dummy place holder object in this heap dump as an indicator of the 41 * object removed from the baseline heap dump. 42 * 43 * @return true if the object is a placeholder 44 */ isPlaceHolder()45 boolean isPlaceHolder(); 46 } 47 48