From 5cafb92fee993353eeaf083bb6056c1d34fd3c4e Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Wed, 27 Feb 2019 19:27:45 +0100
Subject: [PATCH] emit after txn has been committed

to keep txn open for as short as possible,
and avoid any errors caused as part of emit aborting txn
---
 doc/TODO.md             |  2 +-
 src/matrix/room/room.js |  6 +++++-
 src/matrix/sync.js      | 17 ++++++++++++-----
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/doc/TODO.md b/doc/TODO.md
index 0a6b3420..3d098995 100644
--- a/doc/TODO.md
+++ b/doc/TODO.md
@@ -21,7 +21,7 @@
  - DONE: build a very basic interface with
  	- DONE: a start/stop sync button
  	- DONE: a room list sorted alphabetically
- - do some preprocessing on sync response which can then be used by persister, summary, timeline
+ - DONE: do some preprocessing on sync response which can then be used by persister, summary, timeline
  - support timeline
  	- clicking on a room list, you see messages (userId -> body)
  - send messages
diff --git a/src/matrix/room/room.js b/src/matrix/room/room.js
index 8ec39974..5b5923b6 100644
--- a/src/matrix/room/room.js
+++ b/src/matrix/room/room.js
@@ -12,9 +12,13 @@ export default class Room extends EventEmitter {
         this._emitCollectionChange = emitCollectionChange;
 	}
 
-	async applySync(roomResponse, membership, txn) {
+    persistSync(roomResponse, membership, txn) {
 		const changed = this._summary.applySync(roomResponse, membership, txn);
 		this._persister.persistSync(roomResponse, txn);
+        return changed;
+    }
+
+    emitSync(changed) {
         if (changed) {
             this.emit("change");
             (this._emitCollectionChange)(this);
diff --git a/src/matrix/sync.js b/src/matrix/sync.js
index 7f44d0a5..aae1fa0a 100644
--- a/src/matrix/sync.js
+++ b/src/matrix/sync.js
@@ -76,10 +76,11 @@ export default class Sync extends EventEmitter {
 			storeNames.roomTimeline,
 			storeNames.roomState,
 		]);
-		try {
-			this._session.applySync(syncToken, response.account_data, syncTxn);
-			// to_device
-			// presence
+        const roomChanges = [];
+        try {
+            this._session.applySync(syncToken, response.account_data, syncTxn);
+            // to_device
+            // presence
 			if (response.rooms) {
 				parseRooms(response.rooms, (roomId, roomResponse, membership) => {
 					let room = this._session.rooms.get(roomId);
@@ -87,7 +88,8 @@ export default class Sync extends EventEmitter {
 						room = this._session.createRoom(roomId);
 					}
 					console.log(` * applying sync response to room ${roomId} ...`);
-					room.applySync(roomResponse, membership, syncTxn);
+					const changes = room.persistSync(roomResponse, membership, syncTxn);
+                    roomChanges.push({room, changes});
 				});
 			}
 		} catch(err) {
@@ -104,6 +106,11 @@ export default class Sync extends EventEmitter {
 		} catch (err) {
 			throw new StorageError("unable to commit sync tranaction", err);
 		}
+        // emit room related events after txn has been closed
+        for(let {room, changes} of roomChanges) {
+            room.emitSync(changes);
+        }
+
 		return syncToken;
 	}