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refactor pickServerCandidates into statefull class

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so we don't need to iterate over all members for every permalink
This commit is contained in:
Bruno Windels 2019-02-21 15:36:37 +01:00
parent a26b62ef94
commit c2791b9470
1 changed files with 203 additions and 102 deletions
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305
src/matrix-to.js
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@ -25,17 +25,211 @@ export const baseUrl = `https://${host}`;
// to add to permalinks. The servers are appended as ?via=example.org
const MAX_SERVER_CANDIDATES = 3;
export function makeEventPermalink(roomId, eventId) {
const permalinkBase = `${baseUrl}/#/${roomId}/${eventId}`;
// If the roomId isn't actually a room ID, don't try to list the servers.
// Aliases are already routable, and don't need extra information.
if (roomId[0] !== '!') return permalinkBase;
// Permalinks can have servers appended to them so that the user
// receiving them can have a fighting chance at joining the room.
// These servers are called "candidates" at this point because
// it is unclear whether they are going to be useful to actually
// join in the future.
//
// We pick 3 servers based on the following criteria:
//
// Server 1: The highest power level user in the room, provided
// they are at least PL 50. We don't calculate "what is a moderator"
// here because it is less relevant for the vast majority of rooms.
// We also want to ensure that we get an admin or high-ranking mod
// as they are less likely to leave the room. If no user happens
// to meet this criteria, we'll pick the most popular server in the
// room.
//
// Server 2: The next most popular server in the room (in user
// distribution). This cannot be the same as Server 1. If no other
// servers are available then we'll only return Server 1.
//
// Server 3: The next most popular server by user distribution. This
// has the same rules as Server 2, with the added exception that it
// must be unique from Server 1 and 2.
const serverCandidates = pickServerCandidates(roomId);
return `${permalinkBase}${encodeServerCandidates(serverCandidates)}`;
// Rationale for popular servers: It's hard to get rid of people when
// they keep flocking in from a particular server. Sure, the server could
// be ACL'd in the future or for some reason be evicted from the room
// however an event like that is unlikely the larger the room gets. If
// the server is ACL'd at the time of generating the link however, we
// shouldn't pick them. We also don't pick IP addresses.
// Note: we don't pick the server the room was created on because the
// homeserver should already be using that server as a last ditch attempt
// and there's less of a guarantee that the server is a resident server.
// Instead, we actively figure out which servers are likely to be residents
// in the future and try to use those.
// Note: Users receiving permalinks that happen to have all 3 potential
// servers fail them (in terms of joining) are somewhat expected to hunt
// down the person who gave them the link to ask for a participating server.
// The receiving user can then manually append the known-good server to
// the list and magically have the link work.
export class RoomPermaLinkCreator {
constructor(room) {
this._room = room;
this._highestPlUserId = null;
this._populationMap = null;
this._bannedHostsRegexps = null;
this._allowedHostsRegexps = null;
this._serverCandidates = null;
this.onPowerlevel = this.onPowerlevel.bind(this);
this.onMembership = this.onMembership.bind(this);
this.onRoomState = this.onRoomState.bind(this);
}
load() {
this._updateAllowedServers();
this._updatePopulationMap();
this._updateServerCandidates();
}
start() {
this.load();
this._room.on("RoomMember.membership", this.onMembership);
this._room.on("RoomMember.powerLevel", this.onPowerlevel);
this._room.on("RoomState.events", this.onRoomState);
}
stop() {
this._room.off("RoomMember.membership", this.onMembership);
this._room.off("RoomMember.powerLevel", this.onPowerlevel);
this._room.off("RoomState.events", this.onRoomState);
}
forEvent(eventId) {
const roomId = this._room.roomId;
const permalinkBase = `${baseUrl}/#/${roomId}/${eventId}`;
// If the roomId isn't actually a room ID, don't try to list the servers.
// Aliases are already routable, and don't need extra information.
if (roomId[0] !== '!') return permalinkBase;
return `${permalinkBase}${encodeServerCandidates(this._serverCandidates)}`;
}
forRoom() {
const roomId = this._room.roomId;
const permalinkBase = `${baseUrl}/#/${roomId}`;
return `${permalinkBase}${encodeServerCandidates(this._serverCandidates)}`;
}
onRoomState(event) {
if (event.getType() === "m.room.server_acl") {
this._updateAllowedServers();
this._updatePopulationMap();
this._updateServerCandidates();
}
}
onMembership(evt, member, oldMembership) {
const userId = member.userId;
const membership = member.membership;
const serverName = getServerName(userId);
const hasJoined = oldMembership !== "join" && membership === "join";
const hasLeft = oldMembership === "join" && membership !== "join";
if (hasLeft) {
this._populationMap[serverName]--;
} else if (hasJoined) {
this._populationMap[serverName]++;
}
this._updateHighestPlUser();
this._updateServerCandidates();
}
onPowerlevel() {
this._updateHighestPlUser();
this._updateServerCandidates();
}
_updateHighestPlUser() {
const plEvent = this._room.currentState.getStateEvents("m.room.power_levels", "");
const content = plEvent.getContent();
if (content) {
const users = content.users;
if (users) {
const entries = Object.entries(users);
const allowedEntries = entries.filter(([userId]) => {
const member = this._room.getMember(userId);
if (!member || member.membership !== "join") {
return false;
}
const serverName = getServerName(userId);
return !isHostnameIpAddress(serverName) &&
!isHostInRegex(serverName, this._bannedHostsRegexps) &&
isHostInRegex(serverName, this._allowedHostsRegexps);
});
const maxEntry = allowedEntries.reduce((max, entry) => {
return (entry[1] > max[1]) ? entry : max;
}, [null, 0]);
const [userId, powerLevel] = maxEntry;
// object wasn't empty, and max entry wasn't a demotion from the default
if (userId !== null && powerLevel > (content.users_default || 0)) {
this._highestPlUserId = userId;
return;
}
}
}
this._highestPlUserId = null;
}
_updateAllowedServers() {
const bannedHostsRegexps = [];
let allowedHostsRegexps = [new RegExp(".*")]; // default allow everyone
if (this._room.currentState) {
const aclEvent = this._room.currentState.getStateEvents("m.room.server_acl", "");
if (aclEvent && aclEvent.getContent()) {
const getRegex = (hostname) => new RegExp("^" + utils.globToRegexp(hostname, false) + "$");
const denied = aclEvent.getContent().deny || [];
denied.forEach(h => bannedHostsRegexps.push(getRegex(h)));
const allowed = aclEvent.getContent().allow || [];
allowedHostsRegexps = []; // we don't want to use the default rule here
allowed.forEach(h => allowedHostsRegexps.push(getRegex(h)));
}
}
this._bannedHostsRegexps = bannedHostsRegexps;
this._allowedHostsRegexps = allowedHostsRegexps;
}
_updatePopulationMap() {
const populationMap: {[server:string]:number} = {};
for (const member of this._room.getJoinedMembers()) {
const serverName = getServerName(member.userId);
if (!populationMap[serverName]) {
populationMap[serverName] = 0;
}
populationMap[serverName]++;
}
this._populationMap = populationMap;
}
_updateServerCandidates() {
let candidates = [];
if (this._highestPlUserId) {
candidates.push(getServerName(this._highestPlUserId));
}
const serversByPopulation = Object.keys(this._populationMap)
.sort((a, b) => this._populationMap[b] - this._populationMap[a])
.filter(a => !candidates.includes(a) && !isHostnameIpAddress(a)
&& !isHostInRegex(a, this._bannedHostsRegexps) && isHostInRegex(a, this._allowedHostsRegexps));
const remainingServers = serversByPopulation.slice(0, MAX_SERVER_CANDIDATES - candidates.length);
candidates = candidates.concat(remainingServers);
this._serverCandidates = candidates;
}
}
export function makeUserPermalink(userId) {
return `${baseUrl}/#/${userId}`;
}
@ -60,101 +254,8 @@ export function encodeServerCandidates(candidates) {
return `?via=${candidates.map(c => encodeURIComponent(c)).join("&via=")}`;
}
export function pickServerCandidates(roomId) {
const client = MatrixClientPeg.get();
const room = client.getRoom(roomId);
if (!room) return [];
// Permalinks can have servers appended to them so that the user
// receiving them can have a fighting chance at joining the room.
// These servers are called "candidates" at this point because
// it is unclear whether they are going to be useful to actually
// join in the future.
//
// We pick 3 servers based on the following criteria:
//
// Server 1: The highest power level user in the room, provided
// they are at least PL 50. We don't calculate "what is a moderator"
// here because it is less relevant for the vast majority of rooms.
// We also want to ensure that we get an admin or high-ranking mod
// as they are less likely to leave the room. If no user happens
// to meet this criteria, we'll pick the most popular server in the
// room.
//
// Server 2: The next most popular server in the room (in user
// distribution). This cannot be the same as Server 1. If no other
// servers are available then we'll only return Server 1.
//
// Server 3: The next most popular server by user distribution. This
// has the same rules as Server 2, with the added exception that it
// must be unique from Server 1 and 2.
// Rationale for popular servers: It's hard to get rid of people when
// they keep flocking in from a particular server. Sure, the server could
// be ACL'd in the future or for some reason be evicted from the room
// however an event like that is unlikely the larger the room gets. If
// the server is ACL'd at the time of generating the link however, we
// shouldn't pick them. We also don't pick IP addresses.
// Note: we don't pick the server the room was created on because the
// homeserver should already be using that server as a last ditch attempt
// and there's less of a guarantee that the server is a resident server.
// Instead, we actively figure out which servers are likely to be residents
// in the future and try to use those.
// Note: Users receiving permalinks that happen to have all 3 potential
// servers fail them (in terms of joining) are somewhat expected to hunt
// down the person who gave them the link to ask for a participating server.
// The receiving user can then manually append the known-good server to
// the list and magically have the link work.
const bannedHostsRegexps = [];
let allowedHostsRegexps = [new RegExp(".*")]; // default allow everyone
if (room.currentState) {
const aclEvent = room.currentState.getStateEvents("m.room.server_acl", "");
if (aclEvent && aclEvent.getContent()) {
const getRegex = (hostname) => new RegExp("^" + utils.globToRegexp(hostname, false) + "$");
const denied = aclEvent.getContent().deny || [];
denied.forEach(h => bannedHostsRegexps.push(getRegex(h)));
const allowed = aclEvent.getContent().allow || [];
allowedHostsRegexps = []; // we don't want to use the default rule here
allowed.forEach(h => allowedHostsRegexps.push(getRegex(h)));
}
}
const populationMap: {[server:string]:number} = {};
const highestPlUser = {userId: null, powerLevel: 0, serverName: null};
for (const member of room.getJoinedMembers()) {
const serverName = member.userId.split(":").splice(1).join(":");
if (member.powerLevel > highestPlUser.powerLevel && !isHostnameIpAddress(serverName)
&& !isHostInRegex(serverName, bannedHostsRegexps) && isHostInRegex(serverName, allowedHostsRegexps)) {
highestPlUser.userId = member.userId;
highestPlUser.powerLevel = member.powerLevel;
highestPlUser.serverName = serverName;
}
if (!populationMap[serverName]) populationMap[serverName] = 0;
populationMap[serverName]++;
}
const candidates = [];
if (highestPlUser.powerLevel >= 50) candidates.push(highestPlUser.serverName);
const beforePopulation = candidates.length;
const serversByPopulation = Object.keys(populationMap)
.sort((a, b) => populationMap[b] - populationMap[a])
.filter(a => !candidates.includes(a) && !isHostnameIpAddress(a)
&& !isHostInRegex(a, bannedHostsRegexps) && isHostInRegex(a, allowedHostsRegexps));
for (let i = beforePopulation; i < MAX_SERVER_CANDIDATES; i++) {
const idx = i - beforePopulation;
if (idx >= serversByPopulation.length) break;
candidates.push(serversByPopulation[idx]);
}
return candidates;
function getServerName(userId) {
return userId.split(":").splice(1).join(":");
}
function getHostnameFromMatrixDomain(domain) {