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only set new live key when creating a fragment after the txn succeeds

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when doing a limited sync, and a new fragment is created,
this._lastLiveKey is updated immediately. If the transaction
would then fail, the fragmentId in this._lastLiveKey was incremented
but the fragment wasn't written to the store, so if sync is resumed
and would subsequently succeed, fragmentIds would be assigned to events
that don't have a corresponding fragment in the timelineFragment store.

This would throw errors when trying to load the timeline,
breaking the whole app.

This changes SyncWriter to only update this._lastLiveKey in
the emit phase, when the transactions has been committed already.
This commit is contained in:
Bruno Windels 2020-01-04 20:06:49 +01:00
parent bdc2c3d9ad
commit 224d56698a
2 changed files with 15 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
src/matrix/room/room.js
View file

@ -22,19 +22,20 @@ export default class Room extends EventEmitter {
async persistSync(roomResponse, membership, txn) {
const summaryChanged = this._summary.applySync(roomResponse, membership, txn);
const newTimelineEntries = await this._syncWriter.writeSync(roomResponse, txn);
const {entries, newLiveKey} = await this._syncWriter.writeSync(roomResponse, txn);
let removedPendingEvents;
if (roomResponse.timeline && roomResponse.timeline.events) {
removedPendingEvents = this._sendQueue.removeRemoteEchos(roomResponse.timeline.events, txn);
}
return {summaryChanged, newTimelineEntries, removedPendingEvents};
return {summaryChanged, newTimelineEntries: entries, newLiveKey, removedPendingEvents};
}
emitSync({summaryChanged, newTimelineEntries, removedPendingEvents}) {
emitSync({summaryChanged, newTimelineEntries, newLiveKey, removedPendingEvents}) {
if (summaryChanged) {
this.emit("change");
this._emitCollectionChange(this);
}
this._syncWriter.setKeyOnCompleted(newLiveKey);
if (this._timeline) {
this._timeline.appendLiveEntries(newTimelineEntries);
}

24
src/matrix/room/timeline/persistence/SyncWriter.js
View file

@ -84,23 +84,23 @@ export default class SyncWriter {
async writeSync(roomResponse, txn) {
const entries = [];
const timeline = roomResponse.timeline;
if (!this._lastLiveKey) {
let currentKey = this._lastLiveKey;
if (!currentKey) {
// means we haven't synced this room yet (just joined or did initial sync)
// as this is probably a limited sync, prev_batch should be there
// (but don't fail if it isn't, we won't be able to back-paginate though)
let liveFragment = await this._createLiveFragment(txn, timeline.prev_batch);
this._lastLiveKey = new EventKey(liveFragment.id, EventKey.defaultLiveKey.eventIndex);
currentKey = new EventKey(liveFragment.id, EventKey.defaultLiveKey.eventIndex);
entries.push(FragmentBoundaryEntry.start(liveFragment, this._fragmentIdComparer));
} else if (timeline.limited) {
// replace live fragment for limited sync, *only* if we had a live fragment already
const oldFragmentId = this._lastLiveKey.fragmentId;
this._lastLiveKey = this._lastLiveKey.nextFragmentKey();
const {oldFragment, newFragment} = await this._replaceLiveFragment(oldFragmentId, this._lastLiveKey.fragmentId, timeline.prev_batch, txn);
const oldFragmentId = currentKey.fragmentId;
currentKey = currentKey.nextFragmentKey();
const {oldFragment, newFragment} = await this._replaceLiveFragment(oldFragmentId, currentKey.fragmentId, timeline.prev_batch, txn);
entries.push(FragmentBoundaryEntry.end(oldFragment, this._fragmentIdComparer));
entries.push(FragmentBoundaryEntry.start(newFragment, this._fragmentIdComparer));
}
let currentKey = this._lastLiveKey;
if (timeline.events) {
const events = deduplicateEvents(timeline.events);
for(const event of events) {
@ -110,12 +110,6 @@ export default class SyncWriter {
entries.push(new EventEntry(entry, this._fragmentIdComparer));
}
}
// right thing to do? if the txn fails, not sure we'll continue anyways ...
// only advance the key once the transaction has succeeded
txn.complete().then(() => {
this._lastLiveKey = currentKey;
})
// persist state
const state = roomResponse.state;
if (state.events) {
@ -132,7 +126,11 @@ export default class SyncWriter {
}
}
return entries;
return {entries, newLiveKey: currentKey};
}
setKeyOnCompleted(newLiveKey) {
this._lastLiveKey = newLiveKey;
}
}