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Refactor streaming's filtering logic & improve documentation (#26213)

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Emelia Smith 2023-07-27 15:38:18 +02:00 committed by GitHub
parent 1814990a3d
commit ddaf200c78
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1 changed files with 110 additions and 52 deletions
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162
streaming/index.js
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@ -622,29 +622,39 @@ const startServer = async () => {
log.verbose(req.requestId, `Starting stream from ${ids.join(', ')} for ${accountId}`);
// Currently message is of type string, soon it'll be Record<string, any>
const transmit = (event, payload) => {
// TODO: Replace "string"-based delete payloads with object payloads:
const encodedPayload = typeof payload === 'object' ? JSON.stringify(payload) : payload;
log.silly(req.requestId, `Transmitting for ${accountId}: ${event} ${encodedPayload}`);
output(event, encodedPayload);
};
// The listener used to process each message off the redis subscription,
// message here is an object with an `event` and `payload` property. Some
// events also include a queued_at value, but this is being removed shortly.
const listener = message => {
const { event, payload, queued_at } = message;
const { event, payload } = message;
const transmit = (payload) => {
const now = new Date().getTime();
const delta = now - queued_at;
const encodedPayload = typeof payload === 'object' ? JSON.stringify(payload) : payload;
log.silly(req.requestId, `Transmitting for ${accountId}: ${event} ${encodedPayload} Delay: ${delta}ms`);
output(event, encodedPayload);
};
// Only messages that may require filtering are statuses, since notifications
// are already personalized and deletes do not matter
if (!needsFiltering || event !== 'update') {
transmit(payload);
// Streaming only needs to apply filtering to some channels and only to
// some events. This is because majority of the filtering happens on the
// Ruby on Rails side when producing the event for streaming.
//
// The only events that require filtering from the streaming server are
// `update` and `status.update`, all other events are transmitted to the
// client as soon as they're received (pass-through).
//
// The channels that need filtering are determined in the function
// `channelNameToIds` defined below:
if (!needsFiltering || (event !== 'update' && event !== 'status.update')) {
transmit(event, payload);
return;
}
const targetAccountIds = [payload.account.id].concat(payload.mentions.map(item => item.id));
const accountDomain = payload.account.acct.split('@')[1];
// The rest of the logic from here on in this function is to handle
// filtering of statuses:
// Filter based on language:
if (Array.isArray(req.chosenLanguages) && payload.language !== null && req.chosenLanguages.indexOf(payload.language) === -1) {
log.silly(req.requestId, `Message ${payload.id} filtered by language (${payload.language})`);
return;
@ -652,11 +662,16 @@ const startServer = async () => {
// When the account is not logged in, it is not necessary to confirm the block or mute
if (!req.accountId) {
transmit(payload);
transmit(event, payload);
return;
}
pgPool.connect((err, client, done) => {
// Filter based on domain blocks, blocks, mutes, or custom filters:
const targetAccountIds = [payload.account.id].concat(payload.mentions.map(item => item.id));
const accountDomain = payload.account.acct.split('@')[1];
// TODO: Move this logic out of the message handling loop
pgPool.connect((err, client, releasePgConnection) => {
if (err) {
log.error(err);
return;
@ -683,28 +698,45 @@ const startServer = async () => {
}
Promise.all(queries).then(values => {
done();
releasePgConnection();
// Handling blocks & mutes and domain blocks: If one of those applies,
// then we don't transmit the payload of the event to the client
if (values[0].rows.length > 0 || (accountDomain && values[1].rows.length > 0)) {
return;
}
if (!payload.filtered && !req.cachedFilters) {
// If the payload already contains the `filtered` property, it means
// that filtering has been applied on the ruby on rails side, as
// such, we don't need to construct or apply the filters in streaming:
if (Object.prototype.hasOwnProperty.call(payload, "filtered")) {
transmit(event, payload);
return;
}
// Handling for constructing the custom filters and caching them on the request
// TODO: Move this logic out of the message handling lifecycle
if (!req.cachedFilters) {
const filterRows = values[accountDomain ? 2 : 1].rows;
req.cachedFilters = filterRows.reduce((cache, row) => {
if (cache[row.id]) {
cache[row.id].keywords.push([row.keyword, row.whole_word]);
req.cachedFilters = filterRows.reduce((cache, filter) => {
if (cache[filter.id]) {
cache[filter.id].keywords.push([filter.keyword, filter.whole_word]);
} else {
cache[row.id] = {
keywords: [[row.keyword, row.whole_word]],
expires_at: row.expires_at,
repr: {
id: row.id,
title: row.title,
context: row.context,
expires_at: row.expires_at,
filter_action: ['warn', 'hide'][row.filter_action],
cache[filter.id] = {
keywords: [[filter.keyword, filter.whole_word]],
expires_at: filter.expires_at,
filter: {
id: filter.id,
title: filter.title,
context: filter.context,
expires_at: filter.expires_at,
// filter.filter_action is the value from the
// custom_filters.action database column, it is an integer
// representing a value in an enum defined by Ruby on Rails:
//
// enum { warn: 0, hide: 1 }
filter_action: ['warn', 'hide'][filter.filter_action],
},
};
}
@ -712,6 +744,10 @@ const startServer = async () => {
return cache;
}, {});
// Construct the regular expressions for the custom filters: This
// needs to be done in a separate loop as the database returns one
// filterRow per keyword, so we need all the keywords before
// constructing the regular expression
Object.keys(req.cachedFilters).forEach((key) => {
req.cachedFilters[key].regexp = new RegExp(req.cachedFilters[key].keywords.map(([keyword, whole_word]) => {
let expr = keyword.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
@ -731,34 +767,56 @@ const startServer = async () => {
});
}
// Check filters
if (req.cachedFilters && !payload.filtered) {
const mutatedPayload = { ...payload };
// Apply cachedFilters against the payload, constructing a
// `filter_results` array of FilterResult entities
if (req.cachedFilters) {
const status = payload;
const searchContent = ([status.spoiler_text || '', status.content].concat((status.poll && status.poll.options) ? status.poll.options.map(option => option.title) : [])).concat(status.media_attachments.map(att => att.description)).join('\n\n').replace(/<br\s*\/?>/g, '\n').replace(/<\/p><p>/g, '\n\n');
const searchIndex = JSDOM.fragment(searchContent).textContent;
// TODO: Calculate searchableContent in Ruby on Rails:
const searchableContent = ([status.spoiler_text || '', status.content].concat((status.poll && status.poll.options) ? status.poll.options.map(option => option.title) : [])).concat(status.media_attachments.map(att => att.description)).join('\n\n').replace(/<br\s*\/?>/g, '\n').replace(/<\/p><p>/g, '\n\n');
const searchableTextContent = JSDOM.fragment(searchableContent).textContent;
const now = new Date();
mutatedPayload.filtered = [];
Object.values(req.cachedFilters).forEach((cachedFilter) => {
if ((cachedFilter.expires_at === null || cachedFilter.expires_at > now)) {
const keyword_matches = searchIndex.match(cachedFilter.regexp);
if (keyword_matches) {
mutatedPayload.filtered.push({
filter: cachedFilter.repr,
keyword_matches,
});
}
const filter_results = Object.values(req.cachedFilters).reduce((results, cachedFilter) => {
// Check the filter hasn't expired before applying:
if (cachedFilter.expires_at !== null && cachedFilter.expires_at < now) {
return;
}
});
transmit(mutatedPayload);
// Just in-case JSDOM fails to find textContent in searchableContent
if (!searchableTextContent) {
return;
}
const keyword_matches = searchableTextContent.match(cachedFilter.regexp);
if (keyword_matches) {
// results is an Array of FilterResult; status_matches is always
// null as we only are only applying the keyword-based custom
// filters, not the status-based custom filters.
// https://docs.joinmastodon.org/entities/FilterResult/
results.push({
filter: cachedFilter.filter,
keyword_matches,
status_matches: null
});
}
}, []);
// Send the payload + the FilterResults as the `filtered` property
// to the streaming connection. To reach this code, the `event` must
// have been either `update` or `status.update`, meaning the
// `payload` is a Status entity, which has a `filtered` property:
//
// filtered: https://docs.joinmastodon.org/entities/Status/#filtered
transmit(event, {
...payload,
filtered: filter_results
});
} else {
transmit(payload);
transmit(event, payload);
}
}).catch(err => {
releasePgConnection();
log.error(err);
done();
});
});
};