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+/* 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/. */
+
+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();
+ });
+}
+
+export var IDBHelpers = {
+ bulkOperationHelper,
+ executeIDB,
+ openIDB,
+ destroyIDB,
+ IndexedDBError,
+ ShutdownError,
+};