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Ensure we always have receipts for users we've seen

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This adds additional receipt storage to so that we can handle cases where the
receipts and events lists get out of sync. If we ever find a user who previously
had a receipt but momentarily no longer does, we recover their previous receipt
and go with that until we hear something new.

Part of https://github.com/vector-im/riot-web/issues/9745
This commit is contained in:
J. Ryan Stinnett 2019-06-03 13:28:31 +01:00
parent f8eb449dd7
commit 4cea2f0af1
1 changed files with 40 additions and 0 deletions
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40
src/components/structures/MessagePanel.js
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@ -115,6 +115,18 @@ module.exports = React.createClass({
// to manage its animations
this._readReceiptMap = {};
// Track read receipts by user ID. For each user ID we've ever shown a
// a read receipt for, we store an object:
// {
// lastShownEventId,
// receipt,
// }
// so that we can always keep receipts displayed by reverting back to
// the last shown event for that user ID when needed. This may feel like
// it duplicates the receipt storage in the room, but at this layer, we
// are tracking _shown_ event IDs, which the JS SDK knows nothing about.
this._readReceiptsByUserId = {};
// Remember the read marker ghost node so we can do the cleanup that
// Velocity requires
this._readMarkerGhostNode = null;
@ -604,6 +616,7 @@ module.exports = React.createClass({
// they are folded into the receipts of the last shown event.
_getReadReceiptsByShownEvent: function() {
const receiptsByEvent = {};
const receiptsByUserId = {};
let lastShownEventId;
for (const event of this.props.events) {
@ -613,11 +626,38 @@ module.exports = React.createClass({
if (!lastShownEventId) {
continue;
}
const existingReceipts = receiptsByEvent[lastShownEventId] || [];
const newReceipts = this._getReadReceiptsForEvent(event);
receiptsByEvent[lastShownEventId] = existingReceipts.concat(newReceipts);
// Record these receipts along with their last shown event ID for
// each associated user ID.
for (const receipt of newReceipts) {
receiptsByUserId[receipt.userId] = {
lastShownEventId,
receipt,
};
}
}
// It's possible in some cases (for example, when a read receipt
// advances before we have paginated in the new event that it's marking
// received) that we can temporarily not have a matching event for
// someone which had one in the last. By looking through our previous
// mapping of receipts by user ID, we can cover recover any receipts
// that would have been lost by using the same event ID from last time.
for (const userId in this._readReceiptsByUserId) {
if (receiptsByUserId[userId]) {
continue;
}
const { lastShownEventId, receipt } = this._readReceiptsByUserId[userId];
const existingReceipts = receiptsByEvent[lastShownEventId] || [];
receiptsByEvent[lastShownEventId] = existingReceipts.concat(receipt);
receiptsByUserId[userId] = { lastShownEventId, receipt };
}
this._readReceiptsByUserId = receiptsByUserId;
// After grouping receipts by shown events, do another pass to sort each
// receipt list.
for (const eventId in receiptsByEvent) {