2 * Copyright (C) 2011 Apple Inc. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
26 var PersistentCache = {
27 contains: function(key) {
28 return key in localStorage;
32 var string = localStorage[key];
36 // FIXME: We could update the date stored with the value here to make this more of an MRU
37 // cache (instead of most-recently-stored), but that would result in extra disk access that
38 // might not be so great.
39 return JSON.parse(this._parseDateAndJSONFromString(string).json);
42 set: function(key, value) {
44 localStorage[key] = this._addDateToJSONString(JSON.stringify(value));
46 if (e.code !== 22) // QUOTA_EXCEEDED_ERR
49 // We've run out of space in localStorage. Let's just throw away everything and try
58 for (var key in localStorage) {
59 var date = this._parseDateAndJSONFromString(localStorage[key]).date;
60 if (now - date <= this._dataAgeLimitMS)
62 delete localStorage[key];
65 this.set(this._lastPruneDateKey, now);
68 _addDateToJSONString: function(jsonString) {
69 return Date.now() + this._dateAndJSONSeparator + jsonString;
72 _dataAgeLimitMS: 1000 * 60 * 60 * 24 * 1.1, // Just over one day
74 _dateAndJSONSeparator: ': ',
76 _emptyCache: function() {
77 for (var key in localStorage)
78 delete localStorage[key];
81 _parseDateAndJSONFromString: function(string) {
82 var separatorIndex = string.indexOf(this._dateAndJSONSeparator);
84 date: new Date(parseInt(string.substring(0, separatorIndex), 10)),
85 json: string.substring(separatorIndex + this._dateAndJSONSeparator.length),