"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ServerCapabilities = exports.Topology = void 0;
const Denque = require("denque");
const timers_1 = require("timers");
const util_1 = require("util");
const bson_1 = require("../bson");
const connection_string_1 = require("../connection_string");
const constants_1 = require("../constants");
const error_1 = require("../error");
const mongo_types_1 = require("../mongo_types");
const read_preference_1 = require("../read_preference");
const utils_1 = require("../utils");
const common_1 = require("./common");
const events_1 = require("./events");
const server_1 = require("./server");
const server_description_1 = require("./server_description");
const server_selection_1 = require("./server_selection");
const srv_polling_1 = require("./srv_polling");
const topology_description_1 = require("./topology_description");
// Global state
let globalTopologyCounter = 0;
const stateTransition = (0, utils_1.makeStateMachine)({
[common_1.STATE_CLOSED]: [common_1.STATE_CLOSED, common_1.STATE_CONNECTING],
[common_1.STATE_CONNECTING]: [common_1.STATE_CONNECTING, common_1.STATE_CLOSING, common_1.STATE_CONNECTED, common_1.STATE_CLOSED],
[common_1.STATE_CONNECTED]: [common_1.STATE_CONNECTED, common_1.STATE_CLOSING, common_1.STATE_CLOSED],
[common_1.STATE_CLOSING]: [common_1.STATE_CLOSING, common_1.STATE_CLOSED]
});
/** @internal */
const kCancelled = Symbol('cancelled');
/** @internal */
const kWaitQueue = Symbol('waitQueue');
/**
* A container of server instances representing a connection to a MongoDB topology.
* @internal
*/
class Topology extends mongo_types_1.TypedEventEmitter {
/**
* @param seedlist - a list of HostAddress instances to connect to
*/
constructor(seeds, options) {
var _a;
super();
// Legacy CSFLE support
this.bson = Object.create(null);
this.bson.serialize = bson_1.serialize;
this.bson.deserialize = bson_1.deserialize;
// Options should only be undefined in tests, MongoClient will always have defined options
options = options !== null && options !== void 0 ? options : {
hosts: [utils_1.HostAddress.fromString('localhost:27017')],
...Object.fromEntries(connection_string_1.DEFAULT_OPTIONS.entries()),
...Object.fromEntries(connection_string_1.FEATURE_FLAGS.entries())
};
if (typeof seeds === 'string') {
seeds = [utils_1.HostAddress.fromString(seeds)];
}
else if (!Array.isArray(seeds)) {
seeds = [seeds];
}
const seedlist = [];
for (const seed of seeds) {
if (typeof seed === 'string') {
seedlist.push(utils_1.HostAddress.fromString(seed));
}
else if (seed instanceof utils_1.HostAddress) {
seedlist.push(seed);
}
else {
// FIXME(NODE-3483): May need to be a MongoParseError
throw new error_1.MongoRuntimeError(`Topology cannot be constructed from ${JSON.stringify(seed)}`);
}
}
const topologyType = topologyTypeFromOptions(options);
const topologyId = globalTopologyCounter++;
const selectedHosts = options.srvMaxHosts == null ||
options.srvMaxHosts === 0 ||
options.srvMaxHosts >= seedlist.length
? seedlist
: (0, utils_1.shuffle)(seedlist, options.srvMaxHosts);
const serverDescriptions = new Map();
for (const hostAddress of selectedHosts) {
serverDescriptions.set(hostAddress.toString(), new server_description_1.ServerDescription(hostAddress));
}
this[kWaitQueue] = new Denque();
this.s = {
// the id of this topology
id: topologyId,
// passed in options
options,
// initial seedlist of servers to connect to
seedlist,
// initial state
state: common_1.STATE_CLOSED,
// the topology description
description: new topology_description_1.TopologyDescription(topologyType, serverDescriptions, options.replicaSet, undefined, undefined, undefined, options),
serverSelectionTimeoutMS: options.serverSelectionTimeoutMS,
heartbeatFrequencyMS: options.heartbeatFrequencyMS,
minHeartbeatFrequencyMS: options.minHeartbeatFrequencyMS,
// a map of server instances to normalized addresses
servers: new Map(),
credentials: options === null || options === void 0 ? void 0 : options.credentials,
clusterTime: undefined,
// timer management
connectionTimers: new Set(),
detectShardedTopology: ev => this.detectShardedTopology(ev),
detectSrvRecords: ev => this.detectSrvRecords(ev)
};
if (options.srvHost && !options.loadBalanced) {
this.s.srvPoller =
(_a = options.srvPoller) !== null && _a !== void 0 ? _a : new srv_polling_1.SrvPoller({
heartbeatFrequencyMS: this.s.heartbeatFrequencyMS,
srvHost: options.srvHost,
srvMaxHosts: options.srvMaxHosts,
srvServiceName: options.srvServiceName
});
this.on(Topology.TOPOLOGY_DESCRIPTION_CHANGED, this.s.detectShardedTopology);
}
}
detectShardedTopology(event) {
var _a, _b, _c;
const previousType = event.previousDescription.type;
const newType = event.newDescription.type;
const transitionToSharded = previousType !== common_1.TopologyType.Sharded && newType === common_1.TopologyType.Sharded;
const srvListeners = (_a = this.s.srvPoller) === null || _a === void 0 ? void 0 : _a.listeners(srv_polling_1.SrvPoller.SRV_RECORD_DISCOVERY);
const listeningToSrvPolling = !!(srvListeners === null || srvListeners === void 0 ? void 0 : srvListeners.includes(this.s.detectSrvRecords));
if (transitionToSharded && !listeningToSrvPolling) {
(_b = this.s.srvPoller) === null || _b === void 0 ? void 0 : _b.on(srv_polling_1.SrvPoller.SRV_RECORD_DISCOVERY, this.s.detectSrvRecords);
(_c = this.s.srvPoller) === null || _c === void 0 ? void 0 : _c.start();
}
}
detectSrvRecords(ev) {
const previousTopologyDescription = this.s.description;
this.s.description = this.s.description.updateFromSrvPollingEvent(ev, this.s.options.srvMaxHosts);
if (this.s.description === previousTopologyDescription) {
// Nothing changed, so return
return;
}
updateServers(this);
this.emit(Topology.TOPOLOGY_DESCRIPTION_CHANGED, new events_1.TopologyDescriptionChangedEvent(this.s.id, previousTopologyDescription, this.s.description));
}
/**
* @returns A `TopologyDescription` for this topology
*/
get description() {
return this.s.description;
}
get loadBalanced() {
return this.s.options.loadBalanced;
}
get capabilities() {
return new ServerCapabilities(this.lastHello());
}
connect(options, callback) {
var _a;
if (typeof options === 'function')
(callback = options), (options = {});
options = options !== null && options !== void 0 ? options : {};
if (this.s.state === common_1.STATE_CONNECTED) {
if (typeof callback === 'function') {
callback();
}
return;
}
stateTransition(this, common_1.STATE_CONNECTING);
// emit SDAM monitoring events
this.emit(Topology.TOPOLOGY_OPENING, new events_1.TopologyOpeningEvent(this.s.id));
// emit an event for the topology change
this.emit(Topology.TOPOLOGY_DESCRIPTION_CHANGED, new events_1.TopologyDescriptionChangedEvent(this.s.id, new topology_description_1.TopologyDescription(common_1.TopologyType.Unknown), // initial is always Unknown
this.s.description));
// connect all known servers, then attempt server selection to connect
const serverDescriptions = Array.from(this.s.description.servers.values());
this.s.servers = new Map(serverDescriptions.map(serverDescription => [
serverDescription.address,
createAndConnectServer(this, serverDescription)
]));
// In load balancer mode we need to fake a server description getting
// emitted from the monitor, since the monitor doesn't exist.
if (this.s.options.loadBalanced) {
for (const description of serverDescriptions) {
const newDescription = new server_description_1.ServerDescription(description.hostAddress, undefined, {
loadBalanced: this.s.options.loadBalanced
});
this.serverUpdateHandler(newDescription);
}
}
const exitWithError = (error) => callback ? callback(error) : this.emit(Topology.ERROR, error);
const readPreference = (_a = options.readPreference) !== null && _a !== void 0 ? _a : read_preference_1.ReadPreference.primary;
this.selectServer((0, server_selection_1.readPreferenceServerSelector)(readPreference), options, (err, server) => {
if (err) {
return this.close({ force: false }, () => exitWithError(err));
}
// TODO: NODE-2471
const skipPingOnConnect = this.s.options[Symbol.for('@@mdb.skipPingOnConnect')] === true;
if (!skipPingOnConnect && server && this.s.credentials) {
server.command((0, utils_1.ns)('admin.$cmd'), { ping: 1 }, {}, err => {
if (err) {
return exitWithError(err);
}
stateTransition(this, common_1.STATE_CONNECTED);
this.emit(Topology.OPEN, this);
this.emit(Topology.CONNECT, this);
callback === null || callback === void 0 ? void 0 : callback(undefined, this);
});
return;
}
stateTransition(this, common_1.STATE_CONNECTED);
this.emit(Topology.OPEN, this);
this.emit(Topology.CONNECT, this);
callback === null || callback === void 0 ? void 0 : callback(undefined, this);
});
}
close(options, callback) {
if (typeof options === 'function') {
callback = options;
options = {};
}
if (typeof options === 'boolean') {
options = { force: options };
}
options = options !== null && options !== void 0 ? options : {};
if (this.s.state === common_1.STATE_CLOSED || this.s.state === common_1.STATE_CLOSING) {
return callback === null || callback === void 0 ? void 0 : callback();
}
const destroyedServers = Array.from(this.s.servers.values(), server => {
return (0, util_1.promisify)(destroyServer)(server, this, options);
});
Promise.all(destroyedServers)
.then(() => {
this.s.servers.clear();
stateTransition(this, common_1.STATE_CLOSING);
drainWaitQueue(this[kWaitQueue], new error_1.MongoTopologyClosedError());
(0, common_1.drainTimerQueue)(this.s.connectionTimers);
if (this.s.srvPoller) {
this.s.srvPoller.stop();
this.s.srvPoller.removeListener(srv_polling_1.SrvPoller.SRV_RECORD_DISCOVERY, this.s.detectSrvRecords);
}
this.removeListener(Topology.TOPOLOGY_DESCRIPTION_CHANGED, this.s.detectShardedTopology);
stateTransition(this, common_1.STATE_CLOSED);
// emit an event for close
this.emit(Topology.TOPOLOGY_CLOSED, new events_1.TopologyClosedEvent(this.s.id));
})
.finally(() => callback === null || callback === void 0 ? void 0 : callback());
}
/**
* Selects a server according to the selection predicate provided
*
* @param selector - An optional selector to select servers by, defaults to a random selection within a latency window
* @param options - Optional settings related to server selection
* @param callback - The callback used to indicate success or failure
* @returns An instance of a `Server` meeting the criteria of the predicate provided
*/
selectServer(selector, options, callback) {
let serverSelector;
if (typeof selector !== 'function') {
if (typeof selector === 'string') {
serverSelector = (0, server_selection_1.readPreferenceServerSelector)(read_preference_1.ReadPreference.fromString(selector));
}
else {
let readPreference;
if (selector instanceof read_preference_1.ReadPreference) {
readPreference = selector;
}
else {
read_preference_1.ReadPreference.translate(options);
readPreference = options.readPreference || read_preference_1.ReadPreference.primary;
}
serverSelector = (0, server_selection_1.readPreferenceServerSelector)(readPreference);
}
}
else {
serverSelector = selector;
}
options = Object.assign({}, { serverSelectionTimeoutMS: this.s.serverSelectionTimeoutMS }, options);
const isSharded = this.description.type === common_1.TopologyType.Sharded;
const session = options.session;
const transaction = session && session.transaction;
if (isSharded && transaction && transaction.server) {
callback(undefined, transaction.server);
return;
}
const waitQueueMember = {
serverSelector,
transaction,
callback
};
const serverSelectionTimeoutMS = options.serverSelectionTimeoutMS;
if (serverSelectionTimeoutMS) {
waitQueueMember.timer = (0, timers_1.setTimeout)(() => {
waitQueueMember[kCancelled] = true;
waitQueueMember.timer = undefined;
const timeoutError = new error_1.MongoServerSelectionError(`Server selection timed out after ${serverSelectionTimeoutMS} ms`, this.description);
waitQueueMember.callback(timeoutError);
}, serverSelectionTimeoutMS);
}
this[kWaitQueue].push(waitQueueMember);
processWaitQueue(this);
}
// Sessions related methods
/**
* @returns Whether the topology should initiate selection to determine session support
*/
shouldCheckForSessionSupport() {
if (this.description.type === common_1.TopologyType.Single) {
return !this.description.hasKnownServers;
}
return !this.description.hasDataBearingServers;
}
/**
* @returns Whether sessions are supported on the current topology
*/
hasSessionSupport() {
return this.loadBalanced || this.description.logicalSessionTimeoutMinutes != null;
}
/**
* Update the internal TopologyDescription with a ServerDescription
*
* @param serverDescription - The server to update in the internal list of server descriptions
*/
serverUpdateHandler(serverDescription) {
if (!this.s.description.hasServer(serverDescription.address)) {
return;
}
// ignore this server update if its from an outdated topologyVersion
if (isStaleServerDescription(this.s.description, serverDescription)) {
return;
}
// these will be used for monitoring events later
const previousTopologyDescription = this.s.description;
const previousServerDescription = this.s.description.servers.get(serverDescription.address);
if (!previousServerDescription) {
return;
}
// Driver Sessions Spec: "Whenever a driver receives a cluster time from
// a server it MUST compare it to the current highest seen cluster time
// for the deployment. If the new cluster time is higher than the
// highest seen cluster time it MUST become the new highest seen cluster
// time. Two cluster times are compared using only the BsonTimestamp
// value of the clusterTime embedded field."
const clusterTime = serverDescription.$clusterTime;
if (clusterTime) {
(0, common_1._advanceClusterTime)(this, clusterTime);
}
// If we already know all the information contained in this updated description, then
// we don't need to emit SDAM events, but still need to update the description, in order
// to keep client-tracked attributes like last update time and round trip time up to date
const equalDescriptions = previousServerDescription && previousServerDescription.equals(serverDescription);
// first update the TopologyDescription
this.s.description = this.s.description.update(serverDescription);
if (this.s.description.compatibilityError) {
this.emit(Topology.ERROR, new error_1.MongoCompatibilityError(this.s.description.compatibilityError));
return;
}
// emit monitoring events for this change
if (!equalDescriptions) {
const newDescription = this.s.description.servers.get(serverDescription.address);
if (newDescription) {
this.emit(Topology.SERVER_DESCRIPTION_CHANGED, new events_1.ServerDescriptionChangedEvent(this.s.id, serverDescription.address, previousServerDescription, newDescription));
}
}
// update server list from updated descriptions
updateServers(this, serverDescription);
// attempt to resolve any outstanding server selection attempts
if (this[kWaitQueue].length > 0) {
processWaitQueue(this);
}
if (!equalDescriptions) {
this.emit(Topology.TOPOLOGY_DESCRIPTION_CHANGED, new events_1.TopologyDescriptionChangedEvent(this.s.id, previousTopologyDescription, this.s.description));
}
}
auth(credentials, callback) {
if (typeof credentials === 'function')
(callback = credentials), (credentials = undefined);
if (typeof callback === 'function')
callback(undefined, true);
}
get clientMetadata() {
return this.s.options.metadata;
}
isConnected() {
return this.s.state === common_1.STATE_CONNECTED;
}
isDestroyed() {
return this.s.state === common_1.STATE_CLOSED;
}
/**
* @deprecated This function is deprecated and will be removed in the next major version.
*/
unref() {
(0, utils_1.emitWarning)('`unref` is a noop and will be removed in the next major version');
}
// NOTE: There are many places in code where we explicitly check the last hello
// to do feature support detection. This should be done any other way, but for
// now we will just return the first hello seen, which should suffice.
lastHello() {
const serverDescriptions = Array.from(this.description.servers.values());
if (serverDescriptions.length === 0)
return {};
const sd = serverDescriptions.filter((sd) => sd.type !== common_1.ServerType.Unknown)[0];
const result = sd || { maxWireVersion: this.description.commonWireVersion };
return result;
}
get commonWireVersion() {
return this.description.commonWireVersion;
}
get logicalSessionTimeoutMinutes() {
return this.description.logicalSessionTimeoutMinutes;
}
get clusterTime() {
return this.s.clusterTime;
}
set clusterTime(clusterTime) {
this.s.clusterTime = clusterTime;
}
}
exports.Topology = Topology;
/** @event */
Topology.SERVER_OPENING = constants_1.SERVER_OPENING;
/** @event */
Topology.SERVER_CLOSED = constants_1.SERVER_CLOSED;
/** @event */
Topology.SERVER_DESCRIPTION_CHANGED = constants_1.SERVER_DESCRIPTION_CHANGED;
/** @event */
Topology.TOPOLOGY_OPENING = constants_1.TOPOLOGY_OPENING;
/** @event */
Topology.TOPOLOGY_CLOSED = constants_1.TOPOLOGY_CLOSED;
/** @event */
Topology.TOPOLOGY_DESCRIPTION_CHANGED = constants_1.TOPOLOGY_DESCRIPTION_CHANGED;
/** @event */
Topology.ERROR = constants_1.ERROR;
/** @event */
Topology.OPEN = constants_1.OPEN;
/** @event */
Topology.CONNECT = constants_1.CONNECT;
/** @event */
Topology.CLOSE = constants_1.CLOSE;
/** @event */
Topology.TIMEOUT = constants_1.TIMEOUT;
/** Destroys a server, and removes all event listeners from the instance */
function destroyServer(server, topology, options, callback) {
options = options !== null && options !== void 0 ? options : {};
for (const event of constants_1.LOCAL_SERVER_EVENTS) {
server.removeAllListeners(event);
}
server.destroy(options, () => {
topology.emit(Topology.SERVER_CLOSED, new events_1.ServerClosedEvent(topology.s.id, server.description.address));
for (const event of constants_1.SERVER_RELAY_EVENTS) {
server.removeAllListeners(event);
}
if (typeof callback === 'function') {
callback();
}
});
}
/** Predicts the TopologyType from options */
function topologyTypeFromOptions(options) {
if (options === null || options === void 0 ? void 0 : options.directConnection) {
return common_1.TopologyType.Single;
}
if (options === null || options === void 0 ? void 0 : options.replicaSet) {
return common_1.TopologyType.ReplicaSetNoPrimary;
}
if (options === null || options === void 0 ? void 0 : options.loadBalanced) {
return common_1.TopologyType.LoadBalanced;
}
return common_1.TopologyType.Unknown;
}
/**
* Creates new server instances and attempts to connect them
*
* @param topology - The topology that this server belongs to
* @param serverDescription - The description for the server to initialize and connect to
*/
function createAndConnectServer(topology, serverDescription) {
topology.emit(Topology.SERVER_OPENING, new events_1.ServerOpeningEvent(topology.s.id, serverDescription.address));
const server = new server_1.Server(topology, serverDescription, topology.s.options);
for (const event of constants_1.SERVER_RELAY_EVENTS) {
server.on(event, (e) => topology.emit(event, e));
}
server.on(server_1.Server.DESCRIPTION_RECEIVED, description => topology.serverUpdateHandler(description));
server.connect();
return server;
}
/**
* @param topology - Topology to update.
* @param incomingServerDescription - New server description.
*/
function updateServers(topology, incomingServerDescription) {
// update the internal server's description
if (incomingServerDescription && topology.s.servers.has(incomingServerDescription.address)) {
const server = topology.s.servers.get(incomingServerDescription.address);
if (server) {
server.s.description = incomingServerDescription;
if (incomingServerDescription.error instanceof error_1.MongoError &&
incomingServerDescription.error.hasErrorLabel(error_1.MongoErrorLabel.ResetPool)) {
server.s.pool.clear();
}
else if (incomingServerDescription.error == null) {
const newTopologyType = topology.s.description.type;
const shouldMarkPoolReady = incomingServerDescription.isDataBearing ||
(incomingServerDescription.type !== common_1.ServerType.Unknown &&
newTopologyType === common_1.TopologyType.Single);
if (shouldMarkPoolReady) {
server.s.pool.ready();
}
}
}
}
// add new servers for all descriptions we currently don't know about locally
for (const serverDescription of topology.description.servers.values()) {
if (!topology.s.servers.has(serverDescription.address)) {
const server = createAndConnectServer(topology, serverDescription);
topology.s.servers.set(serverDescription.address, server);
}
}
// for all servers no longer known, remove their descriptions and destroy their instances
for (const entry of topology.s.servers) {
const serverAddress = entry[0];
if (topology.description.hasServer(serverAddress)) {
continue;
}
if (!topology.s.servers.has(serverAddress)) {
continue;
}
const server = topology.s.servers.get(serverAddress);
topology.s.servers.delete(serverAddress);
// prepare server for garbage collection
if (server) {
destroyServer(server, topology);
}
}
}
function drainWaitQueue(queue, err) {
while (queue.length) {
const waitQueueMember = queue.shift();
if (!waitQueueMember) {
continue;
}
if (waitQueueMember.timer) {
(0, timers_1.clearTimeout)(waitQueueMember.timer);
}
if (!waitQueueMember[kCancelled]) {
waitQueueMember.callback(err);
}
}
}
function processWaitQueue(topology) {
if (topology.s.state === common_1.STATE_CLOSED) {
drainWaitQueue(topology[kWaitQueue], new error_1.MongoTopologyClosedError());
return;
}
const isSharded = topology.description.type === common_1.TopologyType.Sharded;
const serverDescriptions = Array.from(topology.description.servers.values());
const membersToProcess = topology[kWaitQueue].length;
for (let i = 0; i < membersToProcess; ++i) {
const waitQueueMember = topology[kWaitQueue].shift();
if (!waitQueueMember) {
continue;
}
if (waitQueueMember[kCancelled]) {
continue;
}
let selectedDescriptions;
try {
const serverSelector = waitQueueMember.serverSelector;
selectedDescriptions = serverSelector
? serverSelector(topology.description, serverDescriptions)
: serverDescriptions;
}
catch (e) {
if (waitQueueMember.timer) {
(0, timers_1.clearTimeout)(waitQueueMember.timer);
}
waitQueueMember.callback(e);
continue;
}
let selectedServer;
if (selectedDescriptions.length === 0) {
topology[kWaitQueue].push(waitQueueMember);
continue;
}
else if (selectedDescriptions.length === 1) {
selectedServer = topology.s.servers.get(selectedDescriptions[0].address);
}
else {
const descriptions = (0, utils_1.shuffle)(selectedDescriptions, 2);
const server1 = topology.s.servers.get(descriptions[0].address);
const server2 = topology.s.servers.get(descriptions[1].address);
selectedServer =
server1 && server2 && server1.s.operationCount < server2.s.operationCount
? server1
: server2;
}
if (!selectedServer) {
waitQueueMember.callback(new error_1.MongoServerSelectionError('server selection returned a server description but the server was not found in the topology', topology.description));
return;
}
const transaction = waitQueueMember.transaction;
if (isSharded && transaction && transaction.isActive && selectedServer) {
transaction.pinServer(selectedServer);
}
if (waitQueueMember.timer) {
(0, timers_1.clearTimeout)(waitQueueMember.timer);
}
waitQueueMember.callback(undefined, selectedServer);
}
if (topology[kWaitQueue].length > 0) {
// ensure all server monitors attempt monitoring soon
for (const [, server] of topology.s.servers) {
process.nextTick(function scheduleServerCheck() {
return server.requestCheck();
});
}
}
}
function isStaleServerDescription(topologyDescription, incomingServerDescription) {
const currentServerDescription = topologyDescription.servers.get(incomingServerDescription.address);
const currentTopologyVersion = currentServerDescription === null || currentServerDescription === void 0 ? void 0 : currentServerDescription.topologyVersion;
return ((0, server_description_1.compareTopologyVersion)(currentTopologyVersion, incomingServerDescription.topologyVersion) > 0);
}
/** @public */
class ServerCapabilities {
constructor(hello) {
this.minWireVersion = hello.minWireVersion || 0;
this.maxWireVersion = hello.maxWireVersion || 0;
}
get hasAggregationCursor() {
return this.maxWireVersion >= 1;
}
get hasWriteCommands() {
return this.maxWireVersion >= 2;
}
get hasTextSearch() {
return this.minWireVersion >= 0;
}
get hasAuthCommands() {
return this.maxWireVersion >= 1;
}
get hasListCollectionsCommand() {
return this.maxWireVersion >= 3;
}
get hasListIndexesCommand() {
return this.maxWireVersion >= 3;
}
get supportsSnapshotReads() {
return this.maxWireVersion >= 13;
}
get commandsTakeWriteConcern() {
return this.maxWireVersion >= 5;
}
get commandsTakeCollation() {
return this.maxWireVersion >= 5;
}
}
exports.ServerCapabilities = ServerCapabilities;
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