From bafe9c06d448ff5fdc0ceef480819fb27be64eeb Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Tue, 4 Apr 2017 16:25:58 +0100
Subject: [PATCH] Move more functionality to the indexeddb backend

Now the backend drives the sync accumulator as well. Also moves
the backend out to a separate file.
---
 src/store/indexeddb-local-backend.js | 316 +++++++++++++++++++++++++++
 src/store/indexeddb.js               | 285 +-----------------------
 2 files changed, 323 insertions(+), 278 deletions(-)
 create mode 100644 src/store/indexeddb-local-backend.js

diff --git a/src/store/indexeddb-local-backend.js b/src/store/indexeddb-local-backend.js
new file mode 100644
index 000000000..a6a99ab62
--- /dev/null
+++ b/src/store/indexeddb-local-backend.js
@@ -0,0 +1,316 @@
+/*
+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;
diff --git a/src/store/indexeddb.js b/src/store/indexeddb.js
index 51989d299..507c54b4d 100644
--- a/src/store/indexeddb.js
+++ b/src/store/indexeddb.js
@@ -13,22 +13,17 @@ 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.
 */
-"use strict";
 
 import q from "q";
 import {MatrixInMemoryStore} from "./memory";
-import User from "../models/user";
-import {MatrixEvent} from "../models/event";
 import utils from "../utils";
-import SyncAccumulator from "../sync-accumulator";
+import LocalIndexedDBStoreBackend from "./indexeddb-local-backend.js";
 
 /**
  * This is an internal module. See {@link IndexedDBStore} for the public class.
  * @module store/indexeddb
  */
 
-const VERSION = 1;
-
 // If this value is too small we'll be writing very often which will cause
 // noticable stop-the-world pauses. If this value is too big we'll be writing
 // so infrequently that the /sync size gets bigger on reload. Writing more
@@ -36,174 +31,6 @@ const VERSION = 1;
 // response is persisted each time.
 const WRITE_DELAY_MS = 1000 * 60 * 5; // once every 5 minutes
 
-/**
- * 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 IndexedDBStoreBackend = function IndexedDBStoreBackend(indexedDBInterface,
-                                                             dbName) {
-    this.indexedDB = indexedDBInterface;
-    this._dbName = "matrix-js-sdk:" + (dbName || "default");
-    this.db = null;
-};
-
-
-IndexedDBStoreBackend.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));
-    },
-
-    /**
-     * 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));
-                }
-                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] : {});
-            });
-        });
-    },
-};
 
 /**
  * Construct a new Indexed Database store, which extends MatrixInMemoryStore.
@@ -217,9 +44,7 @@ IndexedDBStoreBackend.prototype = {
  * the data is eagerly fetched when <code>startup()</code> is called.
  * <pre>
  * let opts = { localStorage: window.localStorage };
- * let store = new IndexedDBStore(
- *     new IndexedDBStoreBackend(window.indexedDB), syncAccumulator, opts
- * );
+ * let store = new IndexedDBStore();
  * await store.startup(); // load from indexed db
  * let client = sdk.createClient({
  *     store: store,
@@ -250,15 +75,9 @@ const IndexedDBStore = function IndexedDBStore(opts) {
         throw new Error('Missing required option: indexedDB');
     }
 
-    this.backend = new IndexedDBStoreBackend(opts.indexedDB, opts.dbName);
+    this.backend = new LocalIndexedDBStoreBackend(opts.indexedDB, opts.dbName);
     this.startedUp = false;
     this._syncTs = Date.now(); // updated when writes to the database are performed
-
-    // internal structs to determine deltas for syncs to the database.
-    this._userModifiedMap = {
-        // user_id : timestamp
-    };
-    this._syncAccumulator = new SyncAccumulator();
 };
 utils.inherits(IndexedDBStore, MatrixInMemoryStore);
 
@@ -282,7 +101,6 @@ IndexedDBStore.prototype.startup = function() {
             " -- Reticulating splines...",
         );
         users.forEach((u) => {
-            this._userModifiedMap[u.userId] = u.getLastModifiedTime();
             this.storeUser(u);
         });
         this._syncTs = Date.now(); // pretend we've written so we don't rewrite
@@ -303,11 +121,7 @@ IndexedDBStore.prototype.startup = function() {
  * is no saved sync data.
  */
 IndexedDBStore.prototype.getSavedSync = function() {
-    const data = this._syncAccumulator.getJSON();
-    if (!data.nextBatch) return q(null);
-    // 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));
+    return this.backend.getSavedSync();
 };
 
 /**
@@ -331,99 +145,14 @@ IndexedDBStore.prototype.deleteAllData = function() {
 IndexedDBStore.prototype.save = function() {
     const now = Date.now();
     if (now - this._syncTs > WRITE_DELAY_MS) {
-        return this._syncToDatabase().catch((err) => {console.error("sync fail:", err);});
+        this._syncTs = Date.now(); // set now to guard against multi-writes
+        return this.backend.syncToDatabase(this.getUsers()).catch((err) => {console.error("sync fail:", err);});
     }
     return q();
 };
 
 IndexedDBStore.prototype.setSyncData = function(syncData) {
-    this._syncAccumulator.accumulate(syncData);
+    this.backend.setSyncData(syncData);
 };
 
-IndexedDBStore.prototype._syncToDatabase = function() {
-    this._syncTs = Date.now(); // set now to guard against multi-writes
-
-    // work out changed users (this doesn't handle deletions but you
-    // can't 'delete' users as they are just presence events).
-    const changedUsers = this.getUsers().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.backend.persistUsers(changedUsers),
-        this.backend.persistAccountData(syncData.accountData),
-        this.backend.persistSyncData(syncData.nextBatch, syncData.roomsData),
-    ]);
-};
-
-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);
-        };
-    });
-}
-
 module.exports.IndexedDBStore = IndexedDBStore;
-module.exports.IndexedDBStoreBackend = IndexedDBStoreBackend;