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whippy-edition/app/javascript/mastodon/actions/timelines.js
Matt Panaro 31f7c3fc5d Summary: fix slowness due to layout thrashing when reloading a large … (#12661)
* Summary: fix slowness due to layout thrashing when reloading a large set of status updates

in order to limit the maximum size of a status in a list view (e.g. the home timeline), so as to avoid having to scroll all the way through an abnormally large status update (see https://github.com/tootsuite/mastodon/pull/8205), the following steps are taken:
•the element containing the status is rendered in the browser
•its height is calculated, to determine if it exceeds the maximum height threshold.
Unfortunately for performance, these steps are carried out in the componentDidMount(/Update) method, which also performs style modifications on the element.  The combination of  height request and style modification during javascript evaluation in the browser leads to layout-thrashing, where the elements are repeatedly re-laid-out (see https://developers.google.com/web/fundamentals/performance/rendering/avoid-large-complex-layouts-and-layout-thrashing & https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Performance_best_practices_for_Firefox_fe_engineers).
The solution implemented here is to memoize the collapsed state in Redux the first time the status is seen (e.g. when fetched as part of a small batch, to populate the home timeline) , so that on subsequent re-renders, the value can be queried, rather than recalculated.  This strategy is derived from https://github.com/tootsuite/mastodon/pull/4439 & https://github.com/tootsuite/mastodon/pull/4909, and should resolve https://github.com/tootsuite/mastodon/issues/12455.

Andrew Lin (https://github.com/onethreeseven) is thanked for his assistance in root cause analysis and solution brainstorming

* remove getSnapshotBeforeUpdate from status

* remove componentWillUnmount from status

* persist last-intersected status update and restore when ScrollableList is restored

e.g. when navigating from home-timeline to a status conversational  thread and <Back again

* cache currently-viewing status id to avoid calling redux with identical value

* refactor collapse toggle to pass explicit boolean
2019-12-29 05:39:48 +01:00

183 lines
6.2 KiB
JavaScript

import { importFetchedStatus, importFetchedStatuses } from './importer';
import api, { getLinks } from 'mastodon/api';
import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
import compareId from 'mastodon/compare_id';
import { usePendingItems as preferPendingItems } from 'mastodon/initial_state';
export const TIMELINE_UPDATE = 'TIMELINE_UPDATE';
export const TIMELINE_DELETE = 'TIMELINE_DELETE';
export const TIMELINE_CLEAR = 'TIMELINE_CLEAR';
export const TIMELINE_EXPAND_REQUEST = 'TIMELINE_EXPAND_REQUEST';
export const TIMELINE_EXPAND_SUCCESS = 'TIMELINE_EXPAND_SUCCESS';
export const TIMELINE_EXPAND_FAIL = 'TIMELINE_EXPAND_FAIL';
export const TIMELINE_SCROLL_TOP = 'TIMELINE_SCROLL_TOP';
export const TIMELINE_LOAD_PENDING = 'TIMELINE_LOAD_PENDING';
export const TIMELINE_DISCONNECT = 'TIMELINE_DISCONNECT';
export const TIMELINE_CONNECT = 'TIMELINE_CONNECT';
export const CURRENTLY_VIEWING = 'CURRENTLY_VIEWING';
export const updateCurrentlyViewing = (timeline, id) => ({
type: CURRENTLY_VIEWING,
timeline,
id,
});
export const loadPending = timeline => ({
type: TIMELINE_LOAD_PENDING,
timeline,
});
export function updateTimeline(timeline, status, accept) {
return dispatch => {
if (typeof accept === 'function' && !accept(status)) {
return;
}
dispatch(importFetchedStatus(status));
dispatch({
type: TIMELINE_UPDATE,
timeline,
status,
usePendingItems: preferPendingItems,
});
};
};
export function deleteFromTimelines(id) {
return (dispatch, getState) => {
const accountId = getState().getIn(['statuses', id, 'account']);
const references = getState().get('statuses').filter(status => status.get('reblog') === id).map(status => [status.get('id'), status.get('account')]);
const reblogOf = getState().getIn(['statuses', id, 'reblog'], null);
dispatch({
type: TIMELINE_DELETE,
id,
accountId,
references,
reblogOf,
});
};
};
export function clearTimeline(timeline) {
return (dispatch) => {
dispatch({ type: TIMELINE_CLEAR, timeline });
};
};
const noOp = () => {};
const parseTags = (tags = {}, mode) => {
return (tags[mode] || []).map((tag) => {
return tag.value;
});
};
export function expandTimeline(timelineId, path, params = {}, done = noOp) {
return (dispatch, getState) => {
const timeline = getState().getIn(['timelines', timelineId], ImmutableMap());
const isLoadingMore = !!params.max_id;
if (timeline.get('isLoading')) {
done();
return;
}
if (!params.max_id && !params.pinned && (timeline.get('items', ImmutableList()).size + timeline.get('pendingItems', ImmutableList()).size) > 0) {
const a = timeline.getIn(['pendingItems', 0]);
const b = timeline.getIn(['items', 0]);
if (a && b && compareId(a, b) > 0) {
params.since_id = a;
} else {
params.since_id = b || a;
}
}
const isLoadingRecent = !!params.since_id;
dispatch(expandTimelineRequest(timelineId, isLoadingMore));
api(getState).get(path, { params }).then(response => {
const next = getLinks(response).refs.find(link => link.rel === 'next');
dispatch(importFetchedStatuses(response.data));
dispatch(expandTimelineSuccess(timelineId, response.data, next ? next.uri : null, response.status === 206, isLoadingRecent, isLoadingMore, isLoadingRecent && preferPendingItems));
done();
}).catch(error => {
dispatch(expandTimelineFail(timelineId, error, isLoadingMore));
done();
});
};
};
export const expandHomeTimeline = ({ maxId } = {}, done = noOp) => expandTimeline('home', '/api/v1/timelines/home', { max_id: maxId }, done);
export const expandPublicTimeline = ({ maxId, onlyMedia } = {}, done = noOp) => expandTimeline(`public${onlyMedia ? ':media' : ''}`, '/api/v1/timelines/public', { max_id: maxId, only_media: !!onlyMedia }, done);
export const expandCommunityTimeline = ({ maxId, onlyMedia } = {}, done = noOp) => expandTimeline(`community${onlyMedia ? ':media' : ''}`, '/api/v1/timelines/public', { local: true, max_id: maxId, only_media: !!onlyMedia }, done);
export const expandAccountTimeline = (accountId, { maxId, withReplies } = {}) => expandTimeline(`account:${accountId}${withReplies ? ':with_replies' : ''}`, `/api/v1/accounts/${accountId}/statuses`, { exclude_replies: !withReplies, max_id: maxId });
export const expandAccountFeaturedTimeline = accountId => expandTimeline(`account:${accountId}:pinned`, `/api/v1/accounts/${accountId}/statuses`, { pinned: true });
export const expandAccountMediaTimeline = (accountId, { maxId } = {}) => expandTimeline(`account:${accountId}:media`, `/api/v1/accounts/${accountId}/statuses`, { max_id: maxId, only_media: true, limit: 40 });
export const expandListTimeline = (id, { maxId } = {}, done = noOp) => expandTimeline(`list:${id}`, `/api/v1/timelines/list/${id}`, { max_id: maxId }, done);
export const expandHashtagTimeline = (hashtag, { maxId, tags } = {}, done = noOp) => {
return expandTimeline(`hashtag:${hashtag}`, `/api/v1/timelines/tag/${hashtag}`, {
max_id: maxId,
any: parseTags(tags, 'any'),
all: parseTags(tags, 'all'),
none: parseTags(tags, 'none'),
}, done);
};
export function expandTimelineRequest(timeline, isLoadingMore) {
return {
type: TIMELINE_EXPAND_REQUEST,
timeline,
skipLoading: !isLoadingMore,
};
};
export function expandTimelineSuccess(timeline, statuses, next, partial, isLoadingRecent, isLoadingMore, usePendingItems) {
return {
type: TIMELINE_EXPAND_SUCCESS,
timeline,
statuses,
next,
partial,
isLoadingRecent,
usePendingItems,
skipLoading: !isLoadingMore,
};
};
export function expandTimelineFail(timeline, error, isLoadingMore) {
return {
type: TIMELINE_EXPAND_FAIL,
timeline,
error,
skipLoading: !isLoadingMore,
};
};
export function scrollTopTimeline(timeline, top) {
return {
type: TIMELINE_SCROLL_TOP,
timeline,
top,
};
};
export function connectTimeline(timeline) {
return {
type: TIMELINE_CONNECT,
timeline,
};
};
export const disconnectTimeline = timeline => ({
type: TIMELINE_DISCONNECT,
timeline,
usePendingItems: preferPendingItems,
});