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