143 lines
4.1 KiB
JavaScript
143 lines
4.1 KiB
JavaScript
// Copyright 2011 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* @fileoverview Provides a convenient API for data persistence with expiration.
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*
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*/
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goog.provide('goog.storage.ExpiringStorage');
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goog.require('goog.storage.RichStorage');
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goog.require('goog.storage.RichStorage.Wrapper');
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goog.require('goog.storage.mechanism.Mechanism');
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/**
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* Provides a storage with expirning keys.
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*
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* @param {!goog.storage.mechanism.Mechanism} mechanism The underlying
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* storage mechanism.
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* @constructor
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* @extends {goog.storage.RichStorage}
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*/
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goog.storage.ExpiringStorage = function(mechanism) {
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goog.base(this, mechanism);
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};
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goog.inherits(goog.storage.ExpiringStorage, goog.storage.RichStorage);
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/**
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* Metadata key under which the expiration time is stored.
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*
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* @type {string}
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* @protected
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*/
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goog.storage.ExpiringStorage.EXPIRATION_TIME_KEY = 'expiration';
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/**
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* Metadata key under which the creation time is stored.
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*
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* @type {string}
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* @protected
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*/
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goog.storage.ExpiringStorage.CREATION_TIME_KEY = 'creation';
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/**
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* Returns the wrapper creation time.
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*
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* @param {!Object} wrapper The wrapper.
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* @return {number|undefined} Wrapper creation time.
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*/
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goog.storage.ExpiringStorage.getCreationTime = function(wrapper) {
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return wrapper[goog.storage.ExpiringStorage.CREATION_TIME_KEY];
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};
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/**
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* Returns the wrapper expiration time.
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*
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* @param {!Object} wrapper The wrapper.
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* @return {number|undefined} Wrapper expiration time.
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*/
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goog.storage.ExpiringStorage.getExpirationTime = function(wrapper) {
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return wrapper[goog.storage.ExpiringStorage.EXPIRATION_TIME_KEY];
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};
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/**
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* Checks if the data item has expired.
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*
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* @param {!Object} wrapper The wrapper.
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* @return {boolean} True if the item has expired.
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*/
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goog.storage.ExpiringStorage.isExpired = function(wrapper) {
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var creation = goog.storage.ExpiringStorage.getCreationTime(wrapper);
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var expiration = goog.storage.ExpiringStorage.getExpirationTime(wrapper);
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return !!expiration && expiration < goog.now() ||
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!!creation && creation > goog.now();
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};
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/**
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* Set an item in the storage.
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*
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* @param {string} key The key to set.
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* @param {*} value The value to serialize to a string and save.
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* @param {number=} opt_expiration The number of miliseconds since epoch
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* (as in goog.now()) when the value is to expire. If the expiration
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* time is not provided, the value will persist as long as possible.
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* @override
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*/
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goog.storage.ExpiringStorage.prototype.set = function(
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key, value, opt_expiration) {
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var wrapper = goog.storage.RichStorage.Wrapper.wrapIfNecessary(value);
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if (wrapper) {
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if (opt_expiration) {
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if (opt_expiration < goog.now()) {
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goog.storage.ExpiringStorage.prototype.remove.call(this, key);
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return;
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}
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wrapper[goog.storage.ExpiringStorage.EXPIRATION_TIME_KEY] =
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opt_expiration;
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}
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wrapper[goog.storage.ExpiringStorage.CREATION_TIME_KEY] = goog.now();
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}
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goog.base(this, 'set', key, wrapper);
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};
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/**
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* Get an item wrapper (the item and its metadata) from the storage.
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*
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* @param {string} key The key to get.
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* @param {boolean=} opt_expired If true, return expired wrappers as well.
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* @return {(!Object|undefined)} The wrapper, or undefined if not found.
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* @override
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*/
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goog.storage.ExpiringStorage.prototype.getWrapper = function(key, opt_expired) {
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var wrapper = goog.base(this, 'getWrapper', key);
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if (!wrapper) {
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return undefined;
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}
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if (!opt_expired && goog.storage.ExpiringStorage.isExpired(wrapper)) {
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goog.storage.ExpiringStorage.prototype.remove.call(this, key);
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return undefined;
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}
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return wrapper;
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};
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