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AsyncStore.ts
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AsyncStore.ts
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// Copyright (C) 2022 reallyread.it, inc.
//
// This file is part of Readup.
//
// Readup is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License version 3 as published by the Free Software Foundation.
//
// Readup is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License version 3 along with Foobar. If not, see <https://www.gnu.org/licenses/>.
export type ChromeStorageArea = 'local' | 'managed' | 'session' | 'sync';
const promisify = (storage: chrome.storage.StorageArea) =>
chrome.runtime.getManifest().manifest_version > 2
? // MV3 supports Promises natively
{
get: storage.get.bind(storage),
set: storage.set.bind(storage),
remove: storage.remove.bind(storage),
}
: // MV2 must use callbacks: convert to Promises
{
get: (keys?: string | string[] | { [key: string]: any }) =>
new Promise((resolve, reject) =>
storage.get(keys, (itemsObject) => {
if (chrome.runtime.lastError) {
reject(chrome.runtime.lastError);
} else {
resolve(itemsObject);
}
})
),
set: (items: { [key: string]: any }) =>
new Promise<void>((resolve, reject) =>
storage.set(items, () => {
if (chrome.runtime.lastError) {
reject(chrome.runtime.lastError);
} else {
resolve();
}
})
),
remove: (keys: string | string[]) =>
new Promise<void>((resolve, reject) =>
storage.remove(keys, () => {
if (chrome.runtime.lastError) {
reject(chrome.runtime.lastError);
} else {
resolve();
}
})
),
};
// https://developer.chrome.com/docs/extensions/reference/storage/#property-local
// https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime/lastError
async function checkStorage(type: ChromeStorageArea = 'local') {
// Test whether storing something doesn't raise an exception.
var storage = promisify(chrome.storage[type]),
x = '__storage_test__';
await storage.set({ [x]: x });
await storage.remove(x);
return true;
}
type ChromeStorageEvent = { [key: string]: chrome.storage.StorageChange };
/**
* Stores a single value, backed by either web localStorage or sessionStorage.
* Usage: `const store = await new AsyncStore<T>().initialized
*/
export default abstract class AsyncStore<T> {
// Fallback memory
private _fallbackMemoryValue: T;
// Internal storage interface, starting with fallback memory accessors
private _storage: {
read: () => Promise<T>;
write: (value: T) => Promise<void>;
} = {
read: async () => {
if (!this._isInitialized)
console.warn(
'AsyncStore read happened before it was fully initialized.'
);
return this._fallbackMemoryValue;
},
write: async (value: T) => {
if (!this._isInitialized)
console.warn(
'AsyncStore write happened before it was fully initialized.'
);
const oldValue = this._fallbackMemoryValue;
this._fallbackMemoryValue = value;
// Emalate a ChromeStorageEvent
this._onStorageChanged(
{ [this._key]: { oldValue, newValue: value } },
'local'
);
},
};
private _isInitialized = false;
private _key: string;
private _storageType: ChromeStorageArea;
private _onStorageChanged = (
changes: ChromeStorageEvent,
areaName: ChromeStorageArea
) => {
if (areaName !== this._storageType) {
// Skip events that did not happen in the area of this AsyncStore.
return;
}
const changeForKey = Object.entries(changes).find(([changedKey, _]) => {
if (changedKey === this._key) {
return true;
}
return false;
});
if (changeForKey) {
const [, { oldValue, newValue }] = changeForKey;
this._eventListeners.forEach((listener) =>
listener(oldValue as T, newValue as T)
);
}
};
private _eventListeners: ((oldValue: T, newValue: T) => void)[] = [];
private readonly _defaultValue: T;
constructor(
key: string,
defaultValue: T,
storageType: ChromeStorageArea = 'local'
) {
this._defaultValue = defaultValue;
this._key = key;
this._storageType = storageType;
// Initialize the storage to its default value
if (this._fallbackMemoryValue == null) {
this._fallbackMemoryValue = this._defaultValue;
}
// Asynchronously upgrade to a chrome.storage store
// This is an alternative for having to asynchronously initialize
// the store by any consumer, but it might lead to some weird race conditions.
// See the fallback store read/write warnings above.
checkStorage(storageType)
.then(async () => {
// use storage
let storage = promisify(chrome.storage[storageType]);
// Overwrite internal storage accessors
this._storage = {
// PROXY EXT TODO: should we parse JSON here?
read: async () => (await storage.get(key))[key] as T,
write: async (value: T) => await storage.set({ [key]: value }),
};
const currentValue = await this._read();
// Reset the value in case it's uninitialized
if (currentValue == null) {
await this.clear();
}
this._isInitialized = true;
})
.catch((e) => {
console.warn("Can't load chrome.storage: ", e);
this._isInitialized = true;
});
}
/**
* Asynchronously wait for chrome.storage quality checking before initializing it.
* @deprecated
*/
public async initialized(): Promise<AsyncStore<T>> {
const key = this._key;
const storageType = this._storageType;
// check if storage is available
if (await checkStorage(storageType)) {
// use storage
let storage = promisify(chrome.storage[storageType]);
this._storage = {
// PROXY EXT TODO: should we parse JSON here?
read: async () => (await storage.get(key))[key] as T,
write: async (value: T) => await storage.set({ [key]: value }),
};
// reset the storage in case it's uninitialized/corrupted
// JSON.parse can throw an exception
try {
if ((await this._read()) == null) {
await this.clear();
}
} catch (ex) {
await this.clear();
}
} else {
// leave memory store in place
}
return this;
}
protected async _read() {
return await this._storage.read();
}
protected async _write(value: T) {
await this._storage.write(value);
}
public async clear() {
await this._write(this._defaultValue);
}
public addEventListener(listener: (oldValue: T, newValue: T) => void) {
if (this._eventListeners.length === 0) {
chrome.storage.onChanged.addListener(this._onStorageChanged);
}
this._eventListeners.push(listener);
}
public removeEventListener(listener: (oldValue: T, newValue: T) => void) {
this._eventListeners.splice(
this._eventListeners.findIndex(
(thisListener) => thisListener === listener
),
1
);
if (this._eventListeners.length === 0) {
chrome.storage.onChanged.removeListener(this._onStorageChanged);
}
}
}