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Fix handling of duplicate and out-of-order notifications in WebUI (#19693)

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* Fix handling of duplicate notifications from streaming server

* Fix handling of duplicate and out-of-order notifications when polling/expanding

Fixes #19615
This commit is contained in:
Claire 2022-11-04 00:14:39 +01:00 • committed by GitHub
commit 7c8e2b9859
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1 changed files with 68 additions and 17 deletions
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85
app/javascript/mastodon/reducers/notifications.js
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@ -58,6 +58,11 @@ const notificationToMap = notification => ImmutableMap({
const normalizeNotification = (state, notification, usePendingItems) => {
const top = state.get('top');
// Under currently unknown conditions, the client may receive duplicates from the server
if (state.get('pendingItems').some((item) => item?.get('id') === notification.id) || state.get('items').some((item) => item?.get('id') === notification.id)) {
return state;
}
if (usePendingItems || !state.get('pendingItems').isEmpty()) {
return state.update('pendingItems', list => list.unshift(notificationToMap(notification))).update('unread', unread => unread + 1);
}
@ -77,28 +82,74 @@ const normalizeNotification = (state, notification, usePendingItems) => {
});
};
const expandNormalizedNotifications = (state, notifications, next, isLoadingRecent, usePendingItems) => {
const lastReadId = state.get('lastReadId');
let items = ImmutableList();
const expandNormalizedNotifications = (state, notifications, next, isLoadingMore, isLoadingRecent, usePendingItems) => {
// This method is pretty tricky because:
// - existing notifications might be out of order
// - the existing notifications may have gaps, most often explicitly noted with a `null` item
// - ideally, we don't want it to reorder existing items
// - `notifications` may include items that are already included
// - this function can be called either to fill in a gap, or load newer items
notifications.forEach((n, i) => {
items = items.set(i, notificationToMap(n));
});
const lastReadId = state.get('lastReadId');
const newItems = ImmutableList(notifications.map(notificationToMap));
return state.withMutations(mutable => {
if (!items.isEmpty()) {
if (!newItems.isEmpty()) {
usePendingItems = isLoadingRecent && (usePendingItems || !mutable.get('pendingItems').isEmpty());
mutable.update(usePendingItems ? 'pendingItems' : 'items', list => {
const lastIndex = 1 + list.findLastIndex(
item => item !== null && (compareId(item.get('id'), items.last().get('id')) > 0 || item.get('id') === items.last().get('id')),
);
mutable.update(usePendingItems ? 'pendingItems' : 'items', oldItems => {
// If called to poll *new* notifications, we just need to add them on top without duplicates
if (isLoadingRecent) {
const idsToCheck = oldItems.map(item => item?.get('id')).toSet();
const insertedItems = newItems.filterNot(item => idsToCheck.includes(item.get('id')));
return insertedItems.concat(oldItems);
}
const firstIndex = 1 + list.take(lastIndex).findLastIndex(
item => item !== null && compareId(item.get('id'), items.first().get('id')) > 0,
);
// If called to expand more (presumably older than any known to the WebUI), we just have to
// add them to the bottom without duplicates
if (isLoadingMore) {
const idsToCheck = oldItems.map(item => item?.get('id')).toSet();
const insertedItems = newItems.filterNot(item => idsToCheck.includes(item.get('id')));
return oldItems.concat(insertedItems);
}
return list.take(firstIndex).concat(items, list.skip(lastIndex));
// Now this gets tricky, as we don't necessarily know for sure where the gap to fill is,
// and some items in the timeline may not be properly ordered.
// However, we know that `newItems.last()` is the oldest item that was requested and that
// there is no “hole” between `newItems.last()` and `newItems.first()`.
// First, find the furthest (if properly sorted, oldest) item in the notifications that is
// newer than the oldest fetched one, as it's most likely that it delimits the gap.
// Start the gap *after* that item.
const lastIndex = oldItems.findLastIndex(item => item !== null && compareId(item.get('id'), newItems.last().get('id')) >= 0) + 1;
// Then, try to find the furthest (if properly sorted, oldest) item in the notifications that
// is newer than the most recent fetched one, as it delimits a section comprised of only
// items older or within `newItems` (or that were deleted from the server, so should be removed
// anyway).
// Stop the gap *after* that item.
const firstIndex = oldItems.take(lastIndex).findLastIndex(item => item !== null && compareId(item.get('id'), newItems.first().get('id')) > 0) + 1;
// At this point:
// - no `oldItems` after `firstIndex` is newer than any of the `newItems`
// - all `oldItems` after `lastIndex` are older than every of the `newItems`
// - it is possible for items in the replaced slice to be older than every `newItems`
// - it is possible for items before `firstIndex` to be in the `newItems` range
// Therefore:
// - to avoid losing items, items from the replaced slice that are older than `newItems`
// should be added in the back.
// - to avoid duplicates, `newItems` should be checked the first `firstIndex` items of
// `oldItems`
const idsToCheck = oldItems.take(firstIndex).map(item => item?.get('id')).toSet();
const insertedItems = newItems.filterNot(item => idsToCheck.includes(item.get('id')));
const olderItems = oldItems.slice(firstIndex, lastIndex).filter(item => item !== null && compareId(item.get('id'), newItems.last().get('id')) < 0);
return oldItems.take(firstIndex).concat(
insertedItems,
olderItems,
oldItems.skip(lastIndex),
);
});
}
@ -109,7 +160,7 @@ const expandNormalizedNotifications = (state, notifications, next, isLoadingRece
if (shouldCountUnreadNotifications(state)) {
mutable.set('unread', mutable.get('pendingItems').count(item => item !== null) + mutable.get('items').count(item => item && compareId(item.get('id'), lastReadId) > 0));
} else {
const mostRecent = items.find(item => item !== null);
const mostRecent = newItems.find(item => item !== null);
if (mostRecent && compareId(lastReadId, mostRecent.get('id')) < 0) {
mutable.set('lastReadId', mostRecent.get('id'));
}
@ -224,7 +275,7 @@ export default function notifications(state = initialState, action) {
case NOTIFICATIONS_UPDATE:
return normalizeNotification(state, action.notification, action.usePendingItems);
case NOTIFICATIONS_EXPAND_SUCCESS:
return expandNormalizedNotifications(state, action.notifications, action.next, action.isLoadingRecent, action.usePendingItems);
return expandNormalizedNotifications(state, action.notifications, action.next, action.isLoadingMore, action.isLoadingRecent, action.usePendingItems);
case ACCOUNT_BLOCK_SUCCESS:
return filterNotifications(state, [action.relationship.id]);
case ACCOUNT_MUTE_SUCCESS: