Jean-Baptiste Queru | d56b88a | 2012-11-07 07:48:57 -0800 | [diff] [blame] | 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 | package com.android.volley; |
| 18 | |
Jean-Baptiste Queru | e48f443 | 2012-11-07 07:54:36 -0800 | [diff] [blame] | 19 | import java.util.Collections; |
| 20 | import java.util.Map; |
| 21 | |
Jean-Baptiste Queru | d56b88a | 2012-11-07 07:48:57 -0800 | [diff] [blame] | 22 | /** |
| 23 | * An interface for a cache keyed by a String with a byte array as data. |
| 24 | */ |
| 25 | public interface Cache { |
| 26 | /** |
| 27 | * Retrieves an entry from the cache. |
| 28 | * @param key Cache key |
| 29 | * @return An {@link Entry} or null in the event of a cache miss |
| 30 | */ |
| 31 | public Entry get(String key); |
| 32 | |
| 33 | /** |
| 34 | * Adds or replaces an entry to the cache. |
| 35 | * @param key Cache key |
| 36 | * @param entry Data to store and metadata for cache coherency, TTL, etc. |
| 37 | */ |
| 38 | public void put(String key, Entry entry); |
| 39 | |
| 40 | /** |
| 41 | * Performs any potentially long-running actions needed to initialize the cache; |
| 42 | * will be called from a worker thread. |
| 43 | */ |
| 44 | public void initialize(); |
| 45 | |
| 46 | /** |
| 47 | * Invalidates an entry in the cache. |
| 48 | * @param key Cache key |
| 49 | * @param fullExpire True to fully expire the entry, false to soft expire |
| 50 | */ |
| 51 | public void invalidate(String key, boolean fullExpire); |
| 52 | |
| 53 | /** |
| 54 | * Removes an entry from the cache. |
| 55 | * @param key Cache key |
| 56 | */ |
| 57 | public void remove(String key); |
| 58 | |
| 59 | /** |
| 60 | * Empties the cache. |
| 61 | */ |
| 62 | public void clear(); |
| 63 | |
| 64 | /** |
| 65 | * Data and metadata for an entry returned by the cache. |
| 66 | */ |
| 67 | public static class Entry { |
| 68 | /** The data returned from cache. */ |
| 69 | public byte[] data; |
| 70 | |
| 71 | /** ETag for cache coherency. */ |
| 72 | public String etag; |
| 73 | |
| 74 | /** Date of this response as reported by the server. */ |
| 75 | public long serverDate; |
| 76 | |
| 77 | /** TTL for this record. */ |
| 78 | public long ttl; |
| 79 | |
| 80 | /** Soft TTL for this record. */ |
| 81 | public long softTtl; |
| 82 | |
Jean-Baptiste Queru | e48f443 | 2012-11-07 07:54:36 -0800 | [diff] [blame] | 83 | /** Immutable response headers as received from server; must be non-null. */ |
| 84 | public Map<String, String> responseHeaders = Collections.emptyMap(); |
| 85 | |
Jean-Baptiste Queru | d56b88a | 2012-11-07 07:48:57 -0800 | [diff] [blame] | 86 | /** True if the entry is expired. */ |
| 87 | public boolean isExpired() { |
| 88 | return this.ttl < System.currentTimeMillis(); |
| 89 | } |
| 90 | |
| 91 | /** True if a refresh is needed from the original data source. */ |
| 92 | public boolean refreshNeeded() { |
| 93 | return this.softTtl < System.currentTimeMillis(); |
| 94 | } |
| 95 | } |
| 96 | |
| 97 | } |