matrix-js-sdk/src/store/indexeddb-local-backend.js

/*
Copyright 2017 Vector Creations Ltd

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import q from "q";
import User from "../models/user";
import {MatrixEvent} from "../models/event";
import SyncAccumulator from "../sync-accumulator";
import utils from "../utils";

const VERSION = 1;

function createDatabase(db) {
    // Make user store, clobber based on user ID. (userId property of User objects)
    db.createObjectStore("users", { keyPath: ["userId"] });

    // Make account data store, clobber based on event type.
    // (event.type property of MatrixEvent objects)
    db.createObjectStore("accountData", { keyPath: ["type"] });

    // Make /sync store (sync tokens, room data, etc), always clobber (const key).
    db.createObjectStore("sync", { keyPath: ["clobber"] });
}

/**
 * Helper method to collect results from a Cursor and promiseify it.
 * @param {ObjectStore|Index} store The store to perform openCursor on.
 * @param {IDBKeyRange=} keyRange Optional key range to apply on the cursor.
 * @param {Function} resultMapper A function which is repeatedly called with a
 * Cursor.
 * Return the data you want to keep.
 * @return {Promise<T[]>} Resolves to an array of whatever you returned from
 * resultMapper.
 */
function selectQuery(store, keyRange, resultMapper) {
    const query = store.openCursor(keyRange);
    return q.Promise((resolve, reject) => { /*eslint new-cap: 0*/
        const results = [];
        query.onerror = (event) => {
            reject(new Error("Query failed: " + event.target.errorCode));
        };
        // collect results
        query.onsuccess = (event) => {
            const cursor = event.target.result;
            if (!cursor) {
                resolve(results);
                return; // end of results
            }
            results.push(resultMapper(cursor));
            cursor.continue();
        };
    });
}

function promiseifyTxn(txn) {
    return new q.Promise((resolve, reject) => {
        txn.oncomplete = function(event) {
            resolve(event);
        };
        txn.onerror = function(event) {
            reject(event);
        };
    });
}

function promiseifyRequest(req) {
    return new q.Promise((resolve, reject) => {
        req.onsuccess = function(event) {
            resolve(event);
        };
        req.onerror = function(event) {
            reject(event);
        };
    });
}

/**
 * Does the actual reading from and writing to the indexeddb
 *
 * Construct a new Indexed Database store backend. This requires a call to
 * <code>connect()</code> before this store can be used.
 * @constructor
 * @param {Object} indexedDBInterface The Indexed DB interface e.g
 * <code>window.indexedDB</code>
 * @param {string=} dbName Optional database name. The same name must be used
 * to open the same database.
 */
const LocalIndexedDBStoreBackend = function LocalIndexedDBStoreBackend(
    indexedDBInterface, dbName,
) {
    this.indexedDB = indexedDBInterface;
    this._dbName = "matrix-js-sdk:" + (dbName || "default");
    this.db = null;
    this._syncAccumulator = new SyncAccumulator();

    // Records the last-modified-time of each user at the last point we saved
    // the database, such that we can derive the set if users that have been
    // modified since we last saved.
    this._userModifiedMap = {
        // user_id : timestamp
    };
};


LocalIndexedDBStoreBackend.prototype = {
    /**
     * Attempt to connect to the database. This can fail if the user does not
     * grant permission.
     * @return {Promise} Resolves if successfully connected.
     */
    connect: function() {
        if (this.db) {
            return q();
        }
        const req = this.indexedDB.open(this._dbName, VERSION);
        req.onupgradeneeded = (ev) => {
            const db = ev.target.result;
            const oldVersion = ev.oldVersion;
            if (oldVersion < 1) { // The database did not previously exist.
                createDatabase(db);
            }
            // Expand as needed.
        };

        return promiseifyRequest(req).then((ev) => {
            this.db = ev.target.result;

            // add a poorly-named listener for when deleteDatabase is called
            // so we can close our db connections.
            this.db.onversionchange = () => {
                this.db.close();
            };
        });
    },

    /**
     * Clear the entire database. This should be used when logging out of a client
     * to prevent mixing data between accounts.
     * @return {Promise} Resolved when the database is cleared.
     */
    clearDatabase: function() {
        console.log("Removing indexeddb instance: ", this._dbName);
        return promiseifyRequest(this.indexedDB.deleteDatabase(this._dbName));
    },

    /**
     * @param {boolean=} copy If false, the data returned is from internal
     * buffers and must not be muated. Otherwise, a copy is made before
     * returning such that the data can be safely mutated. Default: true.
     *
     * @return {Promise} Resolves with a sync response to restore the
     * client state to where it was at the last save, or null if there
     * is no saved sync data.
     */
    getSavedSync: function(copy) {
        if (copy === undefined) copy = true;

        const data = this._syncAccumulator.getJSON();
        if (!data.nextBatch) return q(null);
        if (copy) {
            // We must deep copy the stored data so that the /sync processing code doesn't
            // corrupt the internal state of the sync accumulator (it adds non-clonable keys)
            return q(utils.deepCopy(data));
        } else {
            return q(data);
        }
    },

    setSyncData: function(syncData) {
        this._syncAccumulator.accumulate(syncData);
    },

    syncToDatabase: function(users) {
        // work out changed users (this doesn't handle deletions but you
        // can't 'delete' users as they are just presence events).
        const changedUsers = users.filter((user) => {
            return this._userModifiedMap[user.userId] !== user.getLastModifiedTime();
        });
        changedUsers.forEach((u) => { // update times
            this._userModifiedMap[u.userId] = u.getLastModifiedTime();
        });

        const syncData = this._syncAccumulator.getJSON();

        return q.all([
            this._persistUsers(changedUsers),
            this._persistAccountData(syncData.accountData),
            this._persistSyncData(syncData.nextBatch, syncData.roomsData),
        ]);
    },

    /**
     * Persist rooms /sync data along with the next batch token.
     * @param {string} nextBatch The next_batch /sync value.
     * @param {Object} roomsData The 'rooms' /sync data from a SyncAccumulator
     * @return {Promise} Resolves if the data was persisted.
     */
    _persistSyncData: function(nextBatch, roomsData) {
        console.log("Persisting sync data up to ", nextBatch);
        return q.try(() => {
            const txn = this.db.transaction(["sync"], "readwrite");
            const store = txn.objectStore("sync");
            store.put({
                clobber: "-", // constant key so will always clobber
                nextBatch: nextBatch,
                roomsData: roomsData,
            }); // put == UPSERT
            return promiseifyTxn(txn);
        });
    },

    /**
     * Persist a list of account data events. Events with the same 'type' will
     * be replaced.
     * @param {Object[]} accountData An array of raw user-scoped account data events
     * @return {Promise} Resolves if the events were persisted.
     */
    _persistAccountData: function(accountData) {
        return q.try(() => {
            const txn = this.db.transaction(["accountData"], "readwrite");
            const store = txn.objectStore("accountData");
            for (let i = 0; i < accountData.length; i++) {
                store.put(accountData[i]); // put == UPSERT
            }
            return promiseifyTxn(txn);
        });
    },

    /**
     * Persist a list of User objects. Users with the same 'userId' will be
     * replaced.
     * @param {User[]} users An array of users
     * @return {Promise} Resolves if the users were persisted.
     */
    _persistUsers: function(users) {
        return q.try(() => {
            const txn = this.db.transaction(["users"], "readwrite");
            const store = txn.objectStore("users");
            for (let i = 0; i < users.length; i++) {
                store.put({
                    userId: users[i].userId,
                    event: (users[i].events.presence ?
                                users[i].events.presence.event :
                                null),
                }); // put == UPSERT
            }
            return promiseifyTxn(txn);
        });
    },

    /**
     * Load all the users from the database. This is not cached.
     * @return {Promise<User[]>} A list of users.
     */
    loadUsers: function() {
        return q.try(() => {
            const txn = this.db.transaction(["users"], "readonly");
            const store = txn.objectStore("users");
            return selectQuery(store, undefined, (cursor) => {
                const user = new User(cursor.value.userId);
                if (cursor.value.event) {
                    user.setPresenceEvent(new MatrixEvent(cursor.value.event));
                }
                this._userModifiedMap[user.userId] = user.getLastModifiedTime();
                return user;
            });
        });
    },

    /**
     * Load all the account data events from the database. This is not cached.
     * @return {Promise<Object[]>} A list of raw global account events.
     */
    loadAccountData: function() {
        return q.try(() => {
            const txn = this.db.transaction(["accountData"], "readonly");
            const store = txn.objectStore("accountData");
            return selectQuery(store, undefined, (cursor) => {
                return cursor.value;
            });
        });
    },

    /**
     * Load the sync data from the database.
     * @return {Promise<Object>} An object with "roomsData" and "nextBatch" keys.
     */
    loadSyncData: function() {
        return q.try(() => {
            const txn = this.db.transaction(["sync"], "readonly");
            const store = txn.objectStore("sync");
            return selectQuery(store, undefined, (cursor) => {
                return cursor.value;
            }).then((results) => {
                if (results.length > 1) {
                    console.warn("loadSyncData: More than 1 sync row found.");
                }
                return (results.length > 0 ? results[0] : {});
            });
        });
    },
};

export default LocalIndexedDBStoreBackend;