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Diffstat (limited to '')
| -rw-r--r-- | services/settings/IDBHelpers.jsm | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/services/settings/IDBHelpers.jsm b/services/settings/IDBHelpers.jsm new file mode 100644 index 0000000000..0a0e26636d --- /dev/null +++ b/services/settings/IDBHelpers.jsm @@ -0,0 +1,214 @@ +/* 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/. */ + +var EXPORTED_SYMBOLS = ["IDBHelpers"]; + +const DB_NAME = "remote-settings"; +const DB_VERSION = 3; + +/** + * Wrap IndexedDB errors to catch them more easily. + */ +class IndexedDBError extends Error { + constructor(error, method = "", identifier = "") { + if (typeof error == "string") { + error = new Error(error); + } + super(`IndexedDB: ${identifier} ${method} ${error && error.message}`); + this.name = error.name; + this.stack = error.stack; + } +} + +class ShutdownError extends IndexedDBError { + constructor(error, method = "", identifier = "") { + super(error, method, identifier); + } +} + +// We batch operations in order to reduce round-trip latency to the IndexedDB +// database thread. The trade-offs are that the more records in the batch, the +// more time we spend on this thread in structured serialization, and the +// greater the chance to jank PBackground and this thread when the responses +// come back. The initial choice of 250 was made targeting 2-3ms on a fast +// machine and 10-15ms on a slow machine. +// Every chunk waits for success before starting the next, and +// the final chunk's completion will fire transaction.oncomplete . +function bulkOperationHelper( + store, + { reject, completion }, + operation, + list, + listIndex = 0 +) { + try { + const CHUNK_LENGTH = 250; + const max = Math.min(listIndex + CHUNK_LENGTH, list.length); + let request; + for (; listIndex < max; listIndex++) { + request = store[operation](list[listIndex]); + } + if (listIndex < list.length) { + // On error, `transaction.onerror` is called. + request.onsuccess = bulkOperationHelper.bind( + null, + store, + { reject, completion }, + operation, + list, + listIndex + ); + } else if (completion) { + completion(); + } + // otherwise, we're done, and the transaction will complete on its own. + } catch (e) { + // The executeIDB callsite has a try... catch, but it will not catch + // errors in subsequent bulkOperationHelper calls chained through + // request.onsuccess above. We do want to catch those, so we have to + // feed them through manually. We cannot use an async function with + // promises, because if we wait a microtask after onsuccess fires to + // put more requests on the transaction, the transaction will auto-commit + // before we can add more requests. + reject(e); + } +} + +/** + * Helper to wrap some IDBObjectStore operations into a promise. + * + * @param {IDBDatabase} db + * @param {String|String[]} storeNames - either a string or an array of strings. + * @param {String} mode + * @param {function} callback + * @param {String} description of the operation for error handling purposes. + */ +function executeIDB(db, storeNames, mode, callback, desc) { + if (!Array.isArray(storeNames)) { + storeNames = [storeNames]; + } + const transaction = db.transaction(storeNames, mode); + let promise = new Promise((resolve, reject) => { + let stores = storeNames.map(name => transaction.objectStore(name)); + let result; + let rejectWrapper = e => { + reject(new IndexedDBError(e, desc || "execute()", storeNames.join(", "))); + try { + transaction.abort(); + } catch (ex) { + console.error(ex); + } + }; + // Add all the handlers before using the stores. + transaction.onerror = event => + reject(new IndexedDBError(event.target.error, desc || "execute()")); + transaction.onabort = event => + reject( + new IndexedDBError( + event.target.error || transaction.error || "IDBTransaction aborted", + desc || "execute()" + ) + ); + transaction.oncomplete = event => resolve(result); + // Simplify access to a single datastore: + if (stores.length == 1) { + stores = stores[0]; + } + try { + // Although this looks sync, once the callback places requests + // on the datastore, it can independently keep the transaction alive and + // keep adding requests. Even once we exit this try.. catch, we may + // therefore experience errors which should abort the transaction. + // This is why we pass the rejection handler - then the consumer can + // continue to ensure that errors are handled appropriately. + // In theory, exceptions thrown from onsuccess handlers should also + // cause IndexedDB to abort the transaction, so this is a belt-and-braces + // approach. + result = callback(stores, rejectWrapper); + } catch (e) { + rejectWrapper(e); + } + }); + return { promise, transaction }; +} + +/** + * Helper to wrap indexedDB.open() into a promise. + */ +async function openIDB(allowUpgrades = true) { + return new Promise((resolve, reject) => { + const request = indexedDB.open(DB_NAME, DB_VERSION); + request.onupgradeneeded = event => { + if (!allowUpgrades) { + reject( + new Error( + `IndexedDB: Error accessing ${DB_NAME} IDB at version ${DB_VERSION}` + ) + ); + return; + } + // When an upgrade is needed, a transaction is started. + const transaction = event.target.transaction; + transaction.onabort = event => { + const error = + event.target.error || + transaction.error || + new DOMException("The operation has been aborted", "AbortError"); + reject(new IndexedDBError(error, "open()")); + }; + + const db = event.target.result; + db.onerror = event => reject(new IndexedDBError(event.target.error)); + + if (event.oldVersion < 1) { + // Records store + const recordsStore = db.createObjectStore("records", { + keyPath: ["_cid", "id"], + }); + // An index to obtain all the records in a collection. + recordsStore.createIndex("cid", "_cid"); + // Last modified field + recordsStore.createIndex("last_modified", ["_cid", "last_modified"]); + // Timestamps store + db.createObjectStore("timestamps", { + keyPath: "cid", + }); + } + if (event.oldVersion < 2) { + // Collections store + db.createObjectStore("collections", { + keyPath: "cid", + }); + } + if (event.oldVersion < 3) { + // Attachment store + db.createObjectStore("attachments", { + keyPath: ["cid", "attachmentId"], + }); + } + }; + request.onerror = event => reject(new IndexedDBError(event.target.error)); + request.onsuccess = event => { + const db = event.target.result; + resolve(db); + }; + }); +} + +function destroyIDB() { + const request = indexedDB.deleteDatabase(DB_NAME); + return new Promise((resolve, reject) => { + request.onerror = event => reject(new IndexedDBError(event.target.error)); + request.onsuccess = () => resolve(); + }); +} + +var IDBHelpers = { + bulkOperationHelper, + executeIDB, + openIDB, + destroyIDB, + IndexedDBError, + ShutdownError, +}; |