Merge pull request #1684 from matrix-org/gsouquet/cache-decrypt

spec/integ/megolm-integ.spec.js

@@ -484,8 +484,9 @@ describe("megolm", function() {
             return aliceTestClient.flushSync().then(() => {
                 return aliceTestClient.flushSync();
             });
-        }).then(function() {
+        }).then(async function() {
             const room = aliceTestClient.client.getRoom(ROOM_ID);
+            await room.decryptCriticalEvents();
             const event = room.getLiveTimeline().getEvents()[0];
             expect(event.getContent().body).toEqual('42');
         });
@@ -933,8 +934,9 @@ describe("megolm", function() {
 
             aliceTestClient.httpBackend.when("GET", "/sync").respond(200, syncResponse);
             return aliceTestClient.flushSync();
-        }).then(function() {
+        }).then(async function() {
             const room = aliceTestClient.client.getRoom(ROOM_ID);
+            await room.decryptCriticalEvents();
             const event = room.getLiveTimeline().getEvents()[0];
             expect(event.getContent().body).toEqual('42');
 

spec/test-utils.js

@@ -212,10 +212,12 @@ MockStorageApi.prototype = {
  * @returns {Promise} promise which resolves (to `event`) when the event has been decrypted
  */
 export function awaitDecryption(event) {
-    if (!event.isBeingDecrypted()) {
+    // An event is not always decrypted ahead of time
-        return Promise.resolve(event);
+    // getClearContent is a good signal to know whether an event has been decrypted
-    }
+    // already
-
+    if (event.getClearContent() !== null) {
+        return event;
+    } else {
         logger.log(`${Date.now()} event ${event.getId()} is being decrypted; waiting`);
 
         return new Promise((resolve, reject) => {
@@ -225,6 +227,7 @@ export function awaitDecryption(event) {
             });
         });
     }
+}
 
 
 export function HttpResponse(

src/client.js

@@ -5554,8 +5554,9 @@ function _resolve(callback, resolve, res) {
     resolve(res);
 }
 
-function _PojoToMatrixEventMapper(client, options) {
+function _PojoToMatrixEventMapper(client, options = {}) {
-    const preventReEmit = Boolean(options && options.preventReEmit);
+    const preventReEmit = Boolean(options.preventReEmit);
+    const decrypt = options.decrypt !== false;
     function mapper(plainOldJsObject) {
         const event = new MatrixEvent(plainOldJsObject);
         if (event.isEncrypted()) {
@@ -5564,8 +5565,10 @@ function _PojoToMatrixEventMapper(client, options) {
                     "Event.decrypted",
                 ]);
             }
+            if (decrypt) {
                 event.attemptDecryption(client._crypto);
             }
+        }
         if (!preventReEmit) {
             client.reEmitter.reEmit(event, ["Event.replaced"]);
         }
@@ -5577,6 +5580,7 @@ function _PojoToMatrixEventMapper(client, options) {
 /**
  * @param {object} [options]
  * @param {bool} options.preventReEmit don't reemit events emitted on an event mapped by this mapper on the client
+ * @param {bool} options.decrypt decrypt event proactively
  * @return {Function}
  */
 MatrixClient.prototype.getEventMapper = function(options = undefined) {

src/crypto/algorithms/megolm.js

@@ -1692,7 +1692,7 @@ MegolmDecryption.prototype._retryDecryption = async function(senderKey, sessionI
 
     await Promise.all([...pending].map(async (ev) => {
         try {
-            await ev.attemptDecryption(this._crypto, true);
+            await ev.attemptDecryption(this._crypto, { isRetry: true });
         } catch (e) {
             // don't die if something goes wrong
         }

src/models/event.js

@@ -399,6 +399,12 @@ utils.extend(MatrixEvent.prototype, {
             this._clearEvent.content.msgtype === "m.bad.encrypted";
     },
 
+    shouldAttemptDecryption: function() {
+        return this.isEncrypted()
+            && !this.isBeingDecrypted()
+            && this.getClearContent() === null;
+    },
+
     /**
      * Start the process of trying to decrypt this event.
      *
@@ -407,12 +413,22 @@ utils.extend(MatrixEvent.prototype, {
      * @internal
      *
      * @param {module:crypto} crypto crypto module
-     * @param {bool} isRetry True if this is a retry (enables more logging)
+     * @param {object} options
+     * @param {bool} options.isRetry True if this is a retry (enables more logging)
+     * @param {bool} options.emit Emits "event.decrypted" if set to true
      *
      * @returns {Promise} promise which resolves (to undefined) when the decryption
      * attempt is completed.
      */
-    attemptDecryption: async function(crypto, isRetry) {
+    attemptDecryption: async function(crypto, options = {}) {
+        // For backwards compatibility purposes
+        // The function signature used to be attemptDecryption(crypto, isRetry)
+        if (typeof options === "boolean") {
+            options = {
+                isRetry: options,
+            };
+        }
+
         // start with a couple of sanity checks.
         if (!this.isEncrypted()) {
             throw new Error("Attempt to decrypt event which isn't encrypted");
@@ -442,7 +458,7 @@ utils.extend(MatrixEvent.prototype, {
             return this._decryptionPromise;
         }
 
-        this._decryptionPromise = this._decryptionLoop(crypto, isRetry);
+        this._decryptionPromise = this._decryptionLoop(crypto, options);
         return this._decryptionPromise;
     },
 
@@ -487,7 +503,7 @@ utils.extend(MatrixEvent.prototype, {
         return recipients;
     },
 
-    _decryptionLoop: async function(crypto, isRetry) {
+    _decryptionLoop: async function(crypto, options = {}) {
         // make sure that this method never runs completely synchronously.
         // (doing so would mean that we would clear _decryptionPromise *before*
         // it is set in attemptDecryption - and hence end up with a stuck
@@ -504,7 +520,7 @@ utils.extend(MatrixEvent.prototype, {
                     res = this._badEncryptedMessage("Encryption not enabled");
                 } else {
                     res = await crypto.decryptEvent(this);
-                    if (isRetry) {
+                    if (options.isRetry === true) {
                         logger.info(`Decrypted event on retry (id=${this.getId()})`);
                     }
                 }
@@ -512,7 +528,7 @@ utils.extend(MatrixEvent.prototype, {
                 if (e.name !== "DecryptionError") {
                     // not a decryption error: log the whole exception as an error
                     // (and don't bother with a retry)
-                    const re = isRetry ? 're' : '';
+                    const re = options.isRetry ? 're' : '';
                     logger.error(
                         `Error ${re}decrypting event ` +
                         `(id=${this.getId()}): ${e.stack || e}`,
@@ -578,7 +594,9 @@ utils.extend(MatrixEvent.prototype, {
             // pick up the wrong contents.
             this.setPushActions(null);
 
+            if (options.emit !== false) {
                 this.emit("Event.decrypted", this, err);
+            }
 
             return;
         }

src/models/room.js

@@ -228,6 +228,51 @@ function pendingEventsKey(roomId) {
 
 utils.inherits(Room, EventEmitter);
 
+
+/**
+ * Bulk decrypt critical events in a room
+ *
+ * Critical events represents the minimal set of events to decrypt
+ * for a typical UI to function properly
+ *
+ * - Last event of every room (to generate likely message preview)
+ * - All events up to the read receipt (to calculate an accurate notification count)
+ *
+ * @returns {Promise} Signals when all events have been decrypted
+ */
+Room.prototype.decryptCriticalEvents = function() {
+    const readReceiptEventId = this.getEventReadUpTo(this._client.getUserId(), true);
+    const events = this.getLiveTimeline().getEvents();
+    const readReceiptTimelineIndex = events.findIndex(matrixEvent => {
+        return matrixEvent.event.event_id === readReceiptEventId;
+    });
+
+    const decryptionPromises = events
+        .slice(readReceiptTimelineIndex)
+        .filter(event => event.shouldAttemptDecryption())
+        .reverse()
+        .map(event => event.attemptDecryption(this._client._crypto, { isRetry: true }));
+
+    return Promise.allSettled(decryptionPromises);
+};
+
+/**
+ * Bulk decrypt events in a room
+ *
+ * @returns {Promise} Signals when all events have been decrypted
+ */
+Room.prototype.decryptAllEvents = function() {
+    const decryptionPromises = this
+        .getUnfilteredTimelineSet()
+        .getLiveTimeline()
+        .getEvents()
+        .filter(event => event.shouldAttemptDecryption())
+        .reverse()
+        .map(event => event.attemptDecryption(this._client._crypto, { isRetry: true }));
+
+    return Promise.allSettled(decryptionPromises);
+};
+
 /**
  * Gets the version of the room
  * @returns {string} The version of the room, or null if it could not be determined

src/sync.js

@@ -1158,10 +1158,15 @@ SyncApi.prototype._processSyncResponse = async function(
     await utils.promiseMapSeries(joinRooms, async function(joinObj) {
         const room = joinObj.room;
         const stateEvents = self._mapSyncEventsFormat(joinObj.state, room);
-        const timelineEvents = self._mapSyncEventsFormat(joinObj.timeline, room);
+        // Prevent events from being decrypted ahead of time
+        // this helps large account to speed up faster
+        // room::decryptCriticalEvent is in charge of decrypting all the events
+        // required for a client to function properly
+        const timelineEvents = self._mapSyncEventsFormat(joinObj.timeline, room, false);
         const ephemeralEvents = self._mapSyncEventsFormat(joinObj.ephemeral);
         const accountDataEvents = self._mapSyncEventsFormat(joinObj.account_data);
 
+        const encrypted = client.isRoomEncrypted(room.roomId);
         // we do this first so it's correct when any of the events fire
         if (joinObj.unread_notifications) {
             room.setUnreadNotificationCount(
@@ -1172,7 +1177,6 @@ SyncApi.prototype._processSyncResponse = async function(
             // bother setting it here. We trust our calculations better than the
             // server's for this case, and therefore will assume that our non-zero
             // count is accurate.
-            const encrypted = client.isRoomEncrypted(room.roomId);
             if (!encrypted
                 || (encrypted && room.getUnreadNotificationCount('highlight') <= 0)) {
                 room.setUnreadNotificationCount(
@@ -1294,6 +1298,11 @@ SyncApi.prototype._processSyncResponse = async function(
         });
 
         room.updateMyMembership("join");
+
+        // Decrypt only the last message in all rooms to make sure we can generate a preview
+        // And decrypt all events after the recorded read receipt to ensure an accurate
+        // notification count
+        room.decryptCriticalEvents();
     });
 
     // Handle leaves (e.g. kicked rooms)
@@ -1516,13 +1525,14 @@ SyncApi.prototype._mapSyncResponseToRoomArray = function(obj) {
 /**
  * @param {Object} obj
  * @param {Room} room
+ * @param {bool} decrypt
  * @return {MatrixEvent[]}
  */
-SyncApi.prototype._mapSyncEventsFormat = function(obj, room) {
+SyncApi.prototype._mapSyncEventsFormat = function(obj, room, decrypt = true) {
     if (!obj || !utils.isArray(obj.events)) {
         return [];
     }
-    const mapper = this.client.getEventMapper();
+    const mapper = this.client.getEventMapper({ decrypt });
     return obj.events.map(function(e) {
         if (room) {
             e.room_id = room.roomId;