Merge pull request #538 from matrix-org/dbkr/reemit_use_fewer_closures

Make re-emitting events much more memory efficient

src/ReEmitter.js

@@ -0,0 +1,46 @@
+/*
+Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2017 Vector Creations Ltd
+Copyright 2017 New Vector 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.
+*/
+
+/**
+ * @module
+ */
+
+export default class Reemitter {
+    constructor(target) {
+        this.target = target;
+
+        // We keep one bound event handler for each event name so we know
+        // what event is arriving
+        this.boundHandlers = {};
+    }
+
+    _handleEvent(eventName, ...args) {
+        this.target.emit(eventName, ...args);
+    }
+
+    reEmit(source, eventNames) {
+        for (const eventName of eventNames) {
+            if (this.boundHandlers[eventName] === undefined) {
+                this.boundHandlers[eventName] = this._handleEvent.bind(this, eventName);
+            }
+            const boundHandler = this.boundHandlers[eventName];
+
+            source.on(eventName, boundHandler);
+        }
+    }
+}

src/client.js

@@ -40,7 +40,7 @@ const SyncApi = require("./sync");
 const MatrixBaseApis = require("./base-apis");
 const MatrixError = httpApi.MatrixError;
 
-import reEmit from './reemit';
+import ReEmitter from './ReEmitter';
 
 const SCROLLBACK_DELAY_MS = 3000;
 let CRYPTO_ENABLED = false;
@@ -115,6 +115,8 @@ try {
 function MatrixClient(opts) {
     MatrixBaseApis.call(this, opts);
 
+    this.reEmitter = new ReEmitter(this);
+
     this.store = opts.store || new StubStore();
 
     this.deviceId = opts.deviceId || null;
@@ -364,7 +366,7 @@ MatrixClient.prototype.initCrypto = async function() {
         this._cryptoStore,
     );
 
-    reEmit(this, crypto, [
+    this.reEmitter.reEmit(crypto, [
         "crypto.roomKeyRequest",
         "crypto.roomKeyRequestCancellation",
     ]);
@@ -3275,7 +3277,7 @@ function _PojoToMatrixEventMapper(client) {
     function mapper(plainOldJsObject) {
         const event = new MatrixEvent(plainOldJsObject);
         if (event.isEncrypted()) {
-            reEmit(client, event, [
+            client.reEmitter.reEmit(event, [
                 "Event.decrypted",
             ]);
             event.attemptDecryption(client._crypto);

src/models/room.js

@@ -27,7 +27,7 @@ const ContentRepo = require("../content-repo");
 const EventTimeline = require("./event-timeline");
 const EventTimelineSet = require("./event-timeline-set");
 
-import reEmit from '../reemit';
+import ReEmitter from '../ReEmitter';
 
 function synthesizeReceipt(userId, event, receiptType) {
     // console.log("synthesizing receipt for "+event.getId());
@@ -106,6 +106,8 @@ function Room(roomId, opts) {
     opts = opts || {};
     opts.pendingEventOrdering = opts.pendingEventOrdering || "chronological";
 
+    this.reEmitter = new ReEmitter(this);
+
     if (["chronological", "detached"].indexOf(opts.pendingEventOrdering) === -1) {
         throw new Error(
             "opts.pendingEventOrdering MUST be either 'chronological' or " +
@@ -153,7 +155,7 @@ function Room(roomId, opts) {
     // all our per-room timeline sets. the first one is the unfiltered ones;
     // the subsequent ones are the filtered ones in no particular order.
     this._timelineSets = [new EventTimelineSet(this, opts)];
-    reEmit(this, this.getUnfilteredTimelineSet(),
+    this.reEmitter.reEmit(this.getUnfilteredTimelineSet(),
            ["Room.timeline", "Room.timelineReset"]);
 
     this._fixUpLegacyTimelineFields();
@@ -490,7 +492,7 @@ Room.prototype.getOrCreateFilteredTimelineSet = function(filter) {
     }
     const opts = Object.assign({ filter: filter }, this._opts);
     const timelineSet = new EventTimelineSet(this, opts);
-    reEmit(this, timelineSet, ["Room.timeline", "Room.timelineReset"]);
+    this.reEmitter.reEmit(timelineSet, ["Room.timeline", "Room.timelineReset"]);
     this._filteredTimelineSets[filter.filterId] = timelineSet;
     this._timelineSets.push(timelineSet);
 

src/reemit.js

@@ -1,44 +0,0 @@
-/*
-Copyright 2015, 2016 OpenMarket Ltd
-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.
-*/
-
-/**
- * @module
- */
-
-/**
- * re-emit events raised by one EventEmitter from another
- *
- * @param {external:EventEmitter} reEmitEntity
- *     entity from which we want events to be emitted
- * @param {external:EventEmitter} emittableEntity
- *     entity from which events are currently emitted
- * @param {Array<string>} eventNames
- *     list of events to be reemitted
- */
-export default function reEmit(reEmitEntity, emittableEntity, eventNames) {
-    for (const eventName of eventNames) {
-        // setup a listener on the entity (the Room, User, etc) for this event
-        emittableEntity.on(eventName, function(...args) {
-            // take the args from the listener and reuse them, adding the
-            // event name to the arg list so it works with .emit()
-            // Transformation Example:
-            // listener on "foo" => function(a,b) { ... }
-            // Re-emit on "thing" => thing.emit("foo", a, b)
-            reEmitEntity.emit(eventName, ...args);
-        });
-    }
-}

src/sync.js

@@ -32,8 +32,6 @@ const utils = require("./utils");
 const Filter = require("./filter");
 const EventTimeline = require("./models/event-timeline");
 
-import reEmit from './reemit';
-
 const DEBUG = true;
 
 // /sync requests allow you to set a timeout= but the request may continue
@@ -100,7 +98,7 @@ function SyncApi(client, opts) {
     this._failedSyncCount = 0; // Number of consecutive failed /sync requests
 
     if (client.getNotifTimelineSet()) {
-        reEmit(client, client.getNotifTimelineSet(),
+        client.reEmitter.reEmit(client.getNotifTimelineSet(),
                ["Room.timeline", "Room.timelineReset"]);
     }
 }
@@ -115,7 +113,7 @@ SyncApi.prototype.createRoom = function(roomId) {
         pendingEventOrdering: this.opts.pendingEventOrdering,
         timelineSupport: client.timelineSupport,
     });
-    reEmit(client, room, ["Room.name", "Room.timeline", "Room.redaction",
+    client.reEmitter.reEmit(room, ["Room.name", "Room.timeline", "Room.redaction",
                           "Room.receipt", "Room.tags",
                           "Room.timelineReset",
                           "Room.localEchoUpdated",
@@ -132,7 +130,7 @@ SyncApi.prototype.createRoom = function(roomId) {
 SyncApi.prototype.createGroup = function(groupId) {
     const client = this.client;
     const group = new Group(groupId);
-    reEmit(client, group, ["Group.profile", "Group.myMembership"]);
+    client.reEmitter.reEmit(group, ["Group.profile", "Group.myMembership"]);
     return group;
 };
 
@@ -145,13 +143,13 @@ SyncApi.prototype._registerStateListeners = function(room) {
     // we need to also re-emit room state and room member events, so hook it up
     // to the client now. We need to add a listener for RoomState.members in
     // order to hook them correctly. (TODO: find a better way?)
-    reEmit(client, room.currentState, [
+    client.reEmitter.reEmit(room.currentState, [
         "RoomState.events", "RoomState.members", "RoomState.newMember",
     ]);
     room.currentState.on("RoomState.newMember", function(event, state, member) {
         member.user = client.getUser(member.userId);
-        reEmit(
-            client, member,
+        client.reEmitter.reEmit(
+            member,
             [
                 "RoomMember.name", "RoomMember.typing", "RoomMember.powerLevel",
                 "RoomMember.membership",
@@ -1337,7 +1335,7 @@ SyncApi.prototype._onOnline = function() {
 
 function createNewUser(client, userId) {
     const user = new User(userId);
-    reEmit(client, user, [
+    client.reEmitter.reEmit(user, [
         "User.avatarUrl", "User.displayName", "User.presence",
         "User.currentlyActive", "User.lastPresenceTs",
     ]);