365 lines
12 KiB
JavaScript
365 lines
12 KiB
JavaScript
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'use strict';
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const ServerType = require('./server_description').ServerType;
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const ServerDescription = require('./server_description').ServerDescription;
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const ReadPreference = require('../topologies/read_preference');
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// contstants related to compatability checks
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const MIN_SUPPORTED_SERVER_VERSION = '2.6';
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const MIN_SUPPORTED_WIRE_VERSION = 2;
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const MAX_SUPPORTED_WIRE_VERSION = 5;
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// An enumeration of topology types we know about
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const TopologyType = {
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Single: 'Single',
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ReplicaSetNoPrimary: 'ReplicaSetNoPrimary',
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ReplicaSetWithPrimary: 'ReplicaSetWithPrimary',
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Sharded: 'Sharded',
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Unknown: 'Unknown'
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};
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// Representation of a deployment of servers
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class TopologyDescription {
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/**
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* Create a TopologyDescription
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*
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* @param {string} topologyType
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* @param {Map<string, ServerDescription>} serverDescriptions the a map of address to ServerDescription
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* @param {string} setName
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* @param {number} maxSetVersion
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* @param {ObjectId} maxElectionId
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*/
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constructor(topologyType, serverDescriptions, setName, maxSetVersion, maxElectionId, options) {
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options = options || {};
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// TODO: consider assigning all these values to a temporary value `s` which
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// we use `Object.freeze` on, ensuring the internal state of this type
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// is immutable.
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this.type = topologyType || TopologyType.Unknown;
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this.setName = setName || null;
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this.maxSetVersion = maxSetVersion || null;
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this.maxElectionId = maxElectionId || null;
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this.servers = serverDescriptions || new Map();
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this.stale = false;
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this.compatible = true;
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this.compatibilityError = null;
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this.logicalSessionTimeoutMinutes = null;
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this.heartbeatFrequencyMS = options.heartbeatFrequencyMS || 0;
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this.localThresholdMS = options.localThresholdMS || 0;
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this.options = options;
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// determine server compatibility
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for (const serverDescription of this.servers.values()) {
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if (serverDescription.minWireVersion > MAX_SUPPORTED_WIRE_VERSION) {
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this.compatible = false;
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this.compatibilityError = `Server at ${serverDescription.address} requires wire version ${
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serverDescription.minWireVersion
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}, but this version of the driver only supports up to ${MAX_SUPPORTED_WIRE_VERSION}.`;
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}
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if (serverDescription.maxWireVersion < MIN_SUPPORTED_WIRE_VERSION) {
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this.compatible = false;
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this.compatibilityError = `Server at ${serverDescription.address} reports wire version ${
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serverDescription.maxWireVersion
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}, but this version of the driver requires at least ${MIN_SUPPORTED_WIRE_VERSION} (MongoDB ${MIN_SUPPORTED_SERVER_VERSION}).`;
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break;
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}
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}
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// Whenever a client updates the TopologyDescription from an ismaster response, it MUST set
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// TopologyDescription.logicalSessionTimeoutMinutes to the smallest logicalSessionTimeoutMinutes
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// value among ServerDescriptions of all data-bearing server types. If any have a null
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// logicalSessionTimeoutMinutes, then TopologyDescription.logicalSessionTimeoutMinutes MUST be
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// set to null.
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const readableServers = Array.from(this.servers.values()).filter(s => s.isReadable);
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this.logicalSessionTimeoutMinutes = readableServers.reduce((result, server) => {
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if (server.logicalSessionTimeoutMinutes == null) return null;
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if (result == null) return server.logicalSessionTimeoutMinutes;
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return Math.min(result, server.logicalSessionTimeoutMinutes);
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}, null);
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}
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/**
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* @returns The minimum reported wire version of all known servers
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*/
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get commonWireVersion() {
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return Array.from(this.servers.values())
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.filter(server => server.type !== ServerType.Unknown)
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.reduce(
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(min, server) =>
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min == null ? server.maxWireVersion : Math.min(min, server.maxWireVersion),
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null
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);
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}
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/**
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* Returns a copy of this description updated with a given ServerDescription
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*
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* @param {ServerDescription} serverDescription
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*/
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update(serverDescription) {
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const address = serverDescription.address;
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// NOTE: there are a number of prime targets for refactoring here
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// once we support destructuring assignments
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// potentially mutated values
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let topologyType = this.type;
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let setName = this.setName;
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let maxSetVersion = this.maxSetVersion;
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let maxElectionId = this.maxElectionId;
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const serverType = serverDescription.type;
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let serverDescriptions = new Map(this.servers);
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// update the actual server description
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serverDescriptions.set(address, serverDescription);
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if (topologyType === TopologyType.Single) {
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// once we are defined as single, that never changes
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return new TopologyDescription(
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TopologyType.Single,
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serverDescriptions,
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setName,
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maxSetVersion,
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maxElectionId,
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this.options
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);
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}
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if (topologyType === TopologyType.Unknown) {
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if (serverType === ServerType.Standalone) {
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serverDescriptions.delete(address);
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} else {
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topologyType = topologyTypeForServerType(serverType);
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}
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}
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if (topologyType === TopologyType.Sharded) {
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if ([ServerType.Mongos, ServerType.Unknown].indexOf(serverType) === -1) {
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serverDescriptions.delete(address);
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}
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}
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if (topologyType === TopologyType.ReplicaSetNoPrimary) {
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if ([ServerType.Mongos, ServerType.Unknown].indexOf(serverType) >= 0) {
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serverDescriptions.delete(address);
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}
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if (serverType === ServerType.RSPrimary) {
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const result = updateRsFromPrimary(
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serverDescriptions,
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setName,
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serverDescription,
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maxSetVersion,
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maxElectionId
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);
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(topologyType = result[0]),
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(setName = result[1]),
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(maxSetVersion = result[2]),
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(maxElectionId = result[3]);
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} else if (
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[ServerType.RSSecondary, ServerType.RSArbiter, ServerType.RSOther].indexOf(serverType) >= 0
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) {
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const result = updateRsNoPrimaryFromMember(serverDescriptions, setName, serverDescription);
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(topologyType = result[0]), (setName = result[1]);
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}
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}
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if (topologyType === TopologyType.ReplicaSetWithPrimary) {
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if ([ServerType.Standalone, ServerType.Mongos].indexOf(serverType) >= 0) {
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serverDescriptions.delete(address);
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topologyType = checkHasPrimary(serverDescriptions);
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} else if (serverType === ServerType.RSPrimary) {
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const result = updateRsFromPrimary(
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serverDescriptions,
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setName,
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serverDescription,
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maxSetVersion,
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maxElectionId
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);
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(topologyType = result[0]),
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(setName = result[1]),
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(maxSetVersion = result[2]),
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(maxElectionId = result[3]);
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} else if (
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[ServerType.RSSecondary, ServerType.RSArbiter, ServerType.RSOther].indexOf(serverType) >= 0
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) {
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topologyType = updateRsWithPrimaryFromMember(
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serverDescriptions,
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setName,
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serverDescription
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);
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} else {
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topologyType = checkHasPrimary(serverDescriptions);
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}
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}
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return new TopologyDescription(
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topologyType,
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serverDescriptions,
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setName,
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maxSetVersion,
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maxElectionId,
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this.options
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);
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}
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/**
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* Determines if the topology has a readable server available. See the table in the
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* following section for behaviour rules.
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*
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* @param {ReadPreference} [readPreference] An optional read preference for determining if a readable server is present
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* @return {Boolean} Whether there is a readable server in this topology
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*/
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hasReadableServer(/* readPreference */) {
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// To be implemented when server selection is implemented
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}
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/**
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* Determines if the topology has a writable server available. See the table in the
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* following section for behaviour rules.
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*
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* @return {Boolean} Whether there is a writable server in this topology
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*/
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hasWritableServer() {
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return this.hasReadableServer(ReadPreference.primary);
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}
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/**
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* Determines if the topology has a definition for the provided address
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*
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* @param {String} address
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* @return {Boolean} Whether the topology knows about this server
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*/
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hasServer(address) {
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return this.servers.has(address);
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}
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}
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function topologyTypeForServerType(serverType) {
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if (serverType === ServerType.Mongos) return TopologyType.Sharded;
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if (serverType === ServerType.RSPrimary) return TopologyType.ReplicaSetWithPrimary;
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return TopologyType.ReplicaSetNoPrimary;
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}
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function updateRsFromPrimary(
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serverDescriptions,
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setName,
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serverDescription,
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maxSetVersion,
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maxElectionId
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) {
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setName = setName || serverDescription.setName;
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if (setName !== serverDescription.setName) {
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serverDescriptions.delete(serverDescription.address);
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return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
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}
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const electionIdOID = serverDescription.electionId ? serverDescription.electionId.$oid : null;
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const maxElectionIdOID = maxElectionId ? maxElectionId.$oid : null;
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if (serverDescription.setVersion != null && electionIdOID != null) {
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if (maxSetVersion != null && maxElectionIdOID != null) {
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if (maxSetVersion > serverDescription.setVersion || maxElectionIdOID > electionIdOID) {
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// this primary is stale, we must remove it
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serverDescriptions.set(
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serverDescription.address,
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new ServerDescription(serverDescription.address)
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);
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return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
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}
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}
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maxElectionId = serverDescription.electionId;
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}
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if (
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serverDescription.setVersion != null &&
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(maxSetVersion == null || serverDescription.setVersion > maxSetVersion)
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) {
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maxSetVersion = serverDescription.setVersion;
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}
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// We've heard from the primary. Is it the same primary as before?
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for (const address of serverDescriptions.keys()) {
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const server = serverDescriptions.get(address);
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if (server.type === ServerType.RSPrimary && server.address !== serverDescription.address) {
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// Reset old primary's type to Unknown.
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serverDescriptions.set(address, new ServerDescription(server.address));
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// There can only be one primary
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break;
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}
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}
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// Discover new hosts from this primary's response.
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serverDescription.allHosts.forEach(address => {
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if (!serverDescriptions.has(address)) {
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serverDescriptions.set(address, new ServerDescription(address));
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}
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});
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// Remove hosts not in the response.
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const currentAddresses = Array.from(serverDescriptions.keys());
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const responseAddresses = serverDescription.allHosts;
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currentAddresses.filter(addr => responseAddresses.indexOf(addr) === -1).forEach(address => {
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serverDescriptions.delete(address);
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});
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return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
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}
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function updateRsWithPrimaryFromMember(serverDescriptions, setName, serverDescription) {
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if (setName == null) {
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throw new TypeError('setName is required');
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}
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if (
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setName !== serverDescription.setName ||
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(serverDescription.me && serverDescription.address !== serverDescription.me)
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) {
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serverDescriptions.delete(serverDescription.address);
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}
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return checkHasPrimary(serverDescriptions);
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}
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function updateRsNoPrimaryFromMember(serverDescriptions, setName, serverDescription) {
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let topologyType = TopologyType.ReplicaSetNoPrimary;
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setName = setName || serverDescription.setName;
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if (setName !== serverDescription.setName) {
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serverDescriptions.delete(serverDescription.address);
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return [topologyType, setName];
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}
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serverDescription.allHosts.forEach(address => {
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if (!serverDescriptions.has(address)) {
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serverDescriptions.set(address, new ServerDescription(address));
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}
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});
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if (serverDescription.me && serverDescription.address !== serverDescription.me) {
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serverDescriptions.delete(serverDescription.address);
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}
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return [topologyType, setName];
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}
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function checkHasPrimary(serverDescriptions) {
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for (const addr of serverDescriptions.keys()) {
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if (serverDescriptions.get(addr).type === ServerType.RSPrimary) {
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return TopologyType.ReplicaSetWithPrimary;
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}
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}
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return TopologyType.ReplicaSetNoPrimary;
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}
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module.exports = {
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TopologyType,
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TopologyDescription
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};
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