1 /* 2 * Copyright 2015 Google LLC 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.google.cloud; 18 19 /** 20 * Implementation of this interface can persist their state and restore from it. 21 * 22 * <p>A typical capture usage: 23 * 24 * <pre>{@code 25 * X restorableObj; // X instanceof Restorable<X> 26 * RestorableState<X> state = restorableObj.capture(); 27 * .. persist state 28 * }</pre> 29 * 30 * <p>A typical restore usage: 31 * 32 * <pre>{@code 33 * RestorableState<X> state = ... // read from persistence 34 * X restorableObj = state.restore(); 35 * ... 36 * }</pre> 37 * 38 * @param <T> the restorable object's type 39 */ 40 public interface Restorable<T extends Restorable<T>> { 41 42 /** 43 * Captures the state of this object. 44 * 45 * @return a {@link RestorableState} instance that contains the state for this object and can 46 * restore it afterwards. 47 */ capture()48 RestorableState<T> capture(); 49 } 50