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Diffstat (limited to '')
-rw-r--r-- | browser/components/newtab/lib/PersistentCache.sys.mjs | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/browser/components/newtab/lib/PersistentCache.sys.mjs b/browser/components/newtab/lib/PersistentCache.sys.mjs new file mode 100644 index 0000000000..1db9ca102e --- /dev/null +++ b/browser/components/newtab/lib/PersistentCache.sys.mjs @@ -0,0 +1,90 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/** + * A file (disk) based persistent cache of a JSON serializable object. + */ +export class PersistentCache { + /** + * Create a cache object based on a name. + * + * @param {string} name Name of the cache. It will be used to create the filename. + * @param {boolean} preload (optional). Whether the cache should be preloaded from file. Defaults to false. + */ + constructor(name, preload = false) { + this.name = name; + this._filename = `activity-stream.${name}.json`; + if (preload) { + this._load(); + } + } + + /** + * Set a value to be cached with the specified key. + * + * @param {string} key The cache key. + * @param {object} value The data to be cached. + */ + async set(key, value) { + const data = await this._load(); + data[key] = value; + await this._persist(data); + } + + /** + * Get a value from the cache. + * + * @param {string} key (optional) The cache key. If not provided, we return the full cache. + * @returns {object} The cached data. + */ + async get(key) { + const data = await this._load(); + return key ? data[key] : data; + } + + /** + * Load the cache into memory if it isn't already. + */ + _load() { + return ( + this._cache || + // eslint-disable-next-line no-async-promise-executor + (this._cache = new Promise(async (resolve, reject) => { + let filepath; + try { + filepath = PathUtils.join(PathUtils.localProfileDir, this._filename); + } catch (error) { + reject(error); + return; + } + + let data = {}; + try { + data = await IOUtils.readJSON(filepath); + } catch (error) { + if ( + // isInstance() is not available in node unit test. It should be safe to use instanceof as it's directly from IOUtils. + // eslint-disable-next-line mozilla/use-isInstance + !(error instanceof DOMException) || + error.name !== "NotFoundError" + ) { + console.error(`Failed to parse ${this._filename}:`, error.message); + } + } + + resolve(data); + })) + ); + } + + /** + * Persist the cache to file. + */ + async _persist(data) { + const filepath = PathUtils.join(PathUtils.localProfileDir, this._filename); + await IOUtils.writeJSON(filepath, data, { + tmpPath: `${filepath}.tmp`, + }); + } +} |