1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
// Copyright 2011 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Provides a convenient API for data persistence with expiration.
*
*/
goog.provide('goog.storage.ExpiringStorage');
goog.require('goog.storage.RichStorage');
/**
* Provides a storage with expiring keys.
*
* @param {!goog.storage.mechanism.Mechanism} mechanism The underlying
* storage mechanism.
* @constructor
* @struct
* @extends {goog.storage.RichStorage}
*/
goog.storage.ExpiringStorage = function(mechanism) {
goog.storage.ExpiringStorage.base(this, 'constructor', mechanism);
};
goog.inherits(goog.storage.ExpiringStorage, goog.storage.RichStorage);
/**
* Metadata key under which the expiration time is stored.
*
* @type {string}
* @protected
*/
goog.storage.ExpiringStorage.EXPIRATION_TIME_KEY = 'expiration';
/**
* Metadata key under which the creation time is stored.
*
* @type {string}
* @protected
*/
goog.storage.ExpiringStorage.CREATION_TIME_KEY = 'creation';
/**
* Returns the wrapper creation time.
*
* @param {!Object} wrapper The wrapper.
* @return {number|undefined} Wrapper creation time.
*/
goog.storage.ExpiringStorage.getCreationTime = function(wrapper) {
return wrapper[goog.storage.ExpiringStorage.CREATION_TIME_KEY];
};
/**
* Returns the wrapper expiration time.
*
* @param {!Object} wrapper The wrapper.
* @return {number|undefined} Wrapper expiration time.
*/
goog.storage.ExpiringStorage.getExpirationTime = function(wrapper) {
return wrapper[goog.storage.ExpiringStorage.EXPIRATION_TIME_KEY];
};
/**
* Checks if the data item has expired.
*
* @param {!Object} wrapper The wrapper.
* @return {boolean} True if the item has expired.
*/
goog.storage.ExpiringStorage.isExpired = function(wrapper) {
var creation = goog.storage.ExpiringStorage.getCreationTime(wrapper);
var expiration = goog.storage.ExpiringStorage.getExpirationTime(wrapper);
return !!expiration && expiration < goog.now() ||
!!creation && creation > goog.now();
};
/**
* Set an item in the storage.
*
* @param {string} key The key to set.
* @param {*} value The value to serialize to a string and save.
* @param {number=} opt_expiration The number of miliseconds since epoch
* (as in goog.now()) when the value is to expire. If the expiration
* time is not provided, the value will persist as long as possible.
* @override
*/
goog.storage.ExpiringStorage.prototype.set = function(
key, value, opt_expiration) {
var wrapper = goog.storage.RichStorage.Wrapper.wrapIfNecessary(value);
if (wrapper) {
if (opt_expiration) {
if (opt_expiration < goog.now()) {
goog.storage.ExpiringStorage.prototype.remove.call(this, key);
return;
}
wrapper[goog.storage.ExpiringStorage.EXPIRATION_TIME_KEY] =
opt_expiration;
}
wrapper[goog.storage.ExpiringStorage.CREATION_TIME_KEY] = goog.now();
}
goog.storage.ExpiringStorage.base(this, 'set', key, wrapper);
};
/**
* Get an item wrapper (the item and its metadata) from the storage.
*
* @param {string} key The key to get.
* @param {boolean=} opt_expired If true, return expired wrappers as well.
* @return {(!Object|undefined)} The wrapper, or undefined if not found.
* @override
*/
goog.storage.ExpiringStorage.prototype.getWrapper = function(key, opt_expired) {
var wrapper = goog.storage.ExpiringStorage.base(this, 'getWrapper', key);
if (!wrapper) {
return undefined;
}
if (!opt_expired && goog.storage.ExpiringStorage.isExpired(wrapper)) {
goog.storage.ExpiringStorage.prototype.remove.call(this, key);
return undefined;
}
return wrapper;
};
|
