8267fd8a52
The current `lastModified`-getter, which only contains a time-stamp, is a fairly crude way of detecting if the stored data has actually been changed. In particular, when the `getRawValue`-method is used, the `lastModified`-getter doesn't cope with data being modified from the "outside". To fix these issues[1], and to prevent any future bugs in this code, this patch introduces a new `AnnotationStorage.hash`-getter which computes a hash of the currently stored data. To simplify things this re-uses the existing `MurmurHash3_64`-implementation, which required moving that file into the `src/shared/`-folder, since its performance should be good enough here. --- [1] Given how the `AnnotationStorage.lastModified`-getter was used, this would have been limited to *printing* of forms.
144 lines
3.3 KiB
JavaScript
144 lines
3.3 KiB
JavaScript
/* Copyright 2020 Mozilla Foundation
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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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import { MurmurHash3_64 } from "../shared/murmurhash3.js";
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import { objectFromMap } from "../shared/util.js";
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/**
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* Key/value storage for annotation data in forms.
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*/
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class AnnotationStorage {
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constructor() {
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this._storage = new Map();
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this._modified = false;
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// Callbacks to signal when the modification state is set or reset.
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// This is used by the viewer to only bind on `beforeunload` if forms
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// are actually edited to prevent doing so unconditionally since that
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// can have undesirable effects.
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this.onSetModified = null;
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this.onResetModified = null;
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}
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/**
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* Get the value for a given key if it exists, or return the default value.
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*
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* @public
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* @memberof AnnotationStorage
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* @param {string} key
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* @param {Object} defaultValue
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* @returns {Object}
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*/
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getValue(key, defaultValue) {
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const value = this._storage.get(key);
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if (value === undefined) {
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return defaultValue;
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}
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return Object.assign(defaultValue, value);
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}
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/**
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* Get the value for a given key.
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*
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* @public
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* @memberof AnnotationStorage
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* @param {string} key
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* @returns {Object}
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*/
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getRawValue(key) {
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return this._storage.get(key);
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}
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/**
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* Set the value for a given key
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*
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* @public
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* @memberof AnnotationStorage
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* @param {string} key
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* @param {Object} value
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*/
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setValue(key, value) {
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const obj = this._storage.get(key);
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let modified = false;
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if (obj !== undefined) {
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for (const [entry, val] of Object.entries(value)) {
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if (obj[entry] !== val) {
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modified = true;
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obj[entry] = val;
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}
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}
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} else {
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modified = true;
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this._storage.set(key, value);
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}
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if (modified) {
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this._setModified();
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}
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}
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getAll() {
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return this._storage.size > 0 ? objectFromMap(this._storage) : null;
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}
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get size() {
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return this._storage.size;
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}
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/**
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* @private
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*/
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_setModified() {
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if (!this._modified) {
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this._modified = true;
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if (typeof this.onSetModified === "function") {
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this.onSetModified();
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}
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}
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}
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resetModified() {
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if (this._modified) {
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this._modified = false;
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if (typeof this.onResetModified === "function") {
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this.onResetModified();
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}
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}
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}
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/**
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* PLEASE NOTE: Only intended for usage within the API itself.
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* @ignore
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*/
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get serializable() {
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return this._storage.size > 0 ? this._storage : null;
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}
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/**
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* PLEASE NOTE: Only intended for usage within the API itself.
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* @ignore
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*/
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get hash() {
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const hash = new MurmurHash3_64();
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for (const [key, value] of this._storage) {
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hash.update(`${key}:${JSON.stringify(value)}`);
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}
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return hash.hexdigest();
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}
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}
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export { AnnotationStorage };
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