From 300529b7c571d430a3903a10b71c820de0e29734 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Thu, 1 Oct 2020 14:36:22 +0200
Subject: [PATCH] write sync token first

in case we get a TransactionInactiveError,
we have at least written the sync token
and won't repeat the same sync request
---
 src/matrix/Session.js | 11 ++++++-----
 src/matrix/Sync.js    |  2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/matrix/Session.js b/src/matrix/Session.js
index dbb95c24..3c2f0e8c 100644
--- a/src/matrix/Session.js
+++ b/src/matrix/Session.js
@@ -341,17 +341,18 @@ export class Session {
             deviceMessageDecryptionPending: false
         };
         const syncToken = syncResponse.next_batch;
-        const deviceOneTimeKeysCount = syncResponse.device_one_time_keys_count;
-
-        if (this._e2eeAccount && deviceOneTimeKeysCount) {
-            changes.e2eeAccountChanges = this._e2eeAccount.writeSync(deviceOneTimeKeysCount, txn);
-        }
         if (syncToken !== this.syncToken) {
             const syncInfo = {token: syncToken, filterId: syncFilterId};
             // don't modify `this` because transaction might still fail
             txn.session.set("sync", syncInfo);
             changes.syncInfo = syncInfo;
         }
+
+        const deviceOneTimeKeysCount = syncResponse.device_one_time_keys_count;
+        if (this._e2eeAccount && deviceOneTimeKeysCount) {
+            changes.e2eeAccountChanges = this._e2eeAccount.writeSync(deviceOneTimeKeysCount, txn);
+        }
+        
         if (this._deviceTracker) {
             const deviceLists = syncResponse.device_lists;
             if (deviceLists) {
diff --git a/src/matrix/Sync.js b/src/matrix/Sync.js
index ff41f9c1..889be6ad 100644
--- a/src/matrix/Sync.js
+++ b/src/matrix/Sync.js
@@ -186,12 +186,12 @@ export class Sync {
         let sessionChanges;
         const syncTxn = this._openSyncTxn();
         try {
+            sessionChanges = await this._session.writeSync(response, syncFilterId, syncTxn);
             await Promise.all(roomStates.map(async rs => {
                 console.log(` * applying sync response to room ${rs.room.id} ...`);
                 rs.changes = await rs.room.writeSync(
                     rs.roomResponse, isInitialSync, rs.preparation, syncTxn);
             }));
-            sessionChanges = await this._session.writeSync(response, syncFilterId, syncTxn);
         } catch(err) {
             // avoid corrupting state by only
             // storing the sync up till the point