/
topology_description.ts
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/
topology_description.ts
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import { ServerDescription } from './server_description';
import * as WIRE_CONSTANTS from '../cmap/wire_protocol/constants';
import { TopologyType, ServerType } from './common';
import type { ObjectId, Document } from '../bson';
import type { SrvPollingEvent } from './srv_polling';
import { MongoError, MongoDriverError } from '../error';
// constants related to compatibility checks
const MIN_SUPPORTED_SERVER_VERSION = WIRE_CONSTANTS.MIN_SUPPORTED_SERVER_VERSION;
const MAX_SUPPORTED_SERVER_VERSION = WIRE_CONSTANTS.MAX_SUPPORTED_SERVER_VERSION;
const MIN_SUPPORTED_WIRE_VERSION = WIRE_CONSTANTS.MIN_SUPPORTED_WIRE_VERSION;
const MAX_SUPPORTED_WIRE_VERSION = WIRE_CONSTANTS.MAX_SUPPORTED_WIRE_VERSION;
const MONGOS_OR_UNKNOWN = new Set<ServerType>([ServerType.Mongos, ServerType.Unknown]);
const MONGOS_OR_STANDALONE = new Set<ServerType>([ServerType.Mongos, ServerType.Standalone]);
const NON_PRIMARY_RS_MEMBERS = new Set<ServerType>([
ServerType.RSSecondary,
ServerType.RSArbiter,
ServerType.RSOther
]);
/** @public */
export interface TopologyDescriptionOptions {
heartbeatFrequencyMS?: number;
localThresholdMS?: number;
}
/**
* Representation of a deployment of servers
* @public
*/
export class TopologyDescription {
type: TopologyType;
setName?: string;
maxSetVersion?: number;
maxElectionId?: ObjectId;
servers: Map<string, ServerDescription>;
stale: boolean;
compatible: boolean;
compatibilityError?: string;
logicalSessionTimeoutMinutes?: number;
heartbeatFrequencyMS: number;
localThresholdMS: number;
commonWireVersion?: number;
/**
* Create a TopologyDescription
*/
constructor(
topologyType: TopologyType,
serverDescriptions?: Map<string, ServerDescription>,
setName?: string,
maxSetVersion?: number,
maxElectionId?: ObjectId,
commonWireVersion?: number,
options?: TopologyDescriptionOptions
) {
options = options ?? {};
// TODO: consider assigning all these values to a temporary value `s` which
// we use `Object.freeze` on, ensuring the internal state of this type
// is immutable.
this.type = topologyType ?? TopologyType.Unknown;
this.servers = serverDescriptions ?? new Map();
this.stale = false;
this.compatible = true;
this.heartbeatFrequencyMS = options.heartbeatFrequencyMS ?? 0;
this.localThresholdMS = options.localThresholdMS ?? 0;
if (setName) {
this.setName = setName;
}
if (maxSetVersion) {
this.maxSetVersion = maxSetVersion;
}
if (maxElectionId) {
this.maxElectionId = maxElectionId;
}
if (commonWireVersion) {
this.commonWireVersion = commonWireVersion;
}
// determine server compatibility
for (const serverDescription of this.servers.values()) {
if (serverDescription.type === ServerType.Unknown) continue;
if (serverDescription.minWireVersion > MAX_SUPPORTED_WIRE_VERSION) {
this.compatible = false;
this.compatibilityError = `Server at ${serverDescription.address} requires wire version ${serverDescription.minWireVersion}, but this version of the driver only supports up to ${MAX_SUPPORTED_WIRE_VERSION} (MongoDB ${MAX_SUPPORTED_SERVER_VERSION})`;
}
if (serverDescription.maxWireVersion < MIN_SUPPORTED_WIRE_VERSION) {
this.compatible = false;
this.compatibilityError = `Server at ${serverDescription.address} reports wire version ${serverDescription.maxWireVersion}, but this version of the driver requires at least ${MIN_SUPPORTED_WIRE_VERSION} (MongoDB ${MIN_SUPPORTED_SERVER_VERSION}).`;
break;
}
}
// Whenever a client updates the TopologyDescription from an ismaster response, it MUST set
// TopologyDescription.logicalSessionTimeoutMinutes to the smallest logicalSessionTimeoutMinutes
// value among ServerDescriptions of all data-bearing server types. If any have a null
// logicalSessionTimeoutMinutes, then TopologyDescription.logicalSessionTimeoutMinutes MUST be
// set to null.
this.logicalSessionTimeoutMinutes = undefined;
for (const [, server] of this.servers) {
if (server.isReadable) {
if (server.logicalSessionTimeoutMinutes == null) {
// If any of the servers have a null logicalSessionsTimeout, then the whole topology does
this.logicalSessionTimeoutMinutes = undefined;
break;
}
if (this.logicalSessionTimeoutMinutes == null) {
// First server with a non null logicalSessionsTimeout
this.logicalSessionTimeoutMinutes = server.logicalSessionTimeoutMinutes;
continue;
}
// Always select the smaller of the:
// current server logicalSessionsTimeout and the topologies logicalSessionsTimeout
this.logicalSessionTimeoutMinutes = Math.min(
this.logicalSessionTimeoutMinutes,
server.logicalSessionTimeoutMinutes
);
}
}
}
/**
* Returns a new TopologyDescription based on the SrvPollingEvent
* @internal
*/
updateFromSrvPollingEvent(ev: SrvPollingEvent): TopologyDescription {
const newAddresses = ev.addresses();
const serverDescriptions = new Map(this.servers);
for (const address of this.servers.keys()) {
if (newAddresses.has(address)) {
newAddresses.delete(address);
} else {
serverDescriptions.delete(address);
}
}
if (serverDescriptions.size === this.servers.size && newAddresses.size === 0) {
return this;
}
for (const [address, host] of newAddresses) {
serverDescriptions.set(address, new ServerDescription(host));
}
return new TopologyDescription(
this.type,
serverDescriptions,
this.setName,
this.maxSetVersion,
this.maxElectionId,
this.commonWireVersion,
{ heartbeatFrequencyMS: this.heartbeatFrequencyMS, localThresholdMS: this.localThresholdMS }
);
}
/**
* Returns a copy of this description updated with a given ServerDescription
* @internal
*/
update(serverDescription: ServerDescription): TopologyDescription {
const address = serverDescription.address;
// potentially mutated values
let { type: topologyType, setName, maxSetVersion, maxElectionId, commonWireVersion } = this;
if (serverDescription.setName && setName && serverDescription.setName !== setName) {
serverDescription = new ServerDescription(address, undefined);
}
const serverType = serverDescription.type;
const serverDescriptions = new Map(this.servers);
// update common wire version
if (serverDescription.maxWireVersion !== 0) {
if (commonWireVersion == null) {
commonWireVersion = serverDescription.maxWireVersion;
} else {
commonWireVersion = Math.min(commonWireVersion, serverDescription.maxWireVersion);
}
}
// update the actual server description
serverDescriptions.set(address, serverDescription);
if (topologyType === TopologyType.Single) {
// once we are defined as single, that never changes
return new TopologyDescription(
TopologyType.Single,
serverDescriptions,
setName,
maxSetVersion,
maxElectionId,
commonWireVersion,
{ heartbeatFrequencyMS: this.heartbeatFrequencyMS, localThresholdMS: this.localThresholdMS }
);
}
if (topologyType === TopologyType.Unknown) {
if (serverType === ServerType.Standalone && this.servers.size !== 1) {
serverDescriptions.delete(address);
} else {
topologyType = topologyTypeForServerType(serverType);
}
}
if (topologyType === TopologyType.Sharded) {
if (!MONGOS_OR_UNKNOWN.has(serverType)) {
serverDescriptions.delete(address);
}
}
if (topologyType === TopologyType.ReplicaSetNoPrimary) {
if (MONGOS_OR_STANDALONE.has(serverType)) {
serverDescriptions.delete(address);
}
if (serverType === ServerType.RSPrimary) {
const result = updateRsFromPrimary(
serverDescriptions,
serverDescription,
setName,
maxSetVersion,
maxElectionId
);
topologyType = result[0];
setName = result[1];
maxSetVersion = result[2];
maxElectionId = result[3];
} else if (NON_PRIMARY_RS_MEMBERS.has(serverType)) {
const result = updateRsNoPrimaryFromMember(serverDescriptions, serverDescription, setName);
topologyType = result[0];
setName = result[1];
}
}
if (topologyType === TopologyType.ReplicaSetWithPrimary) {
if (MONGOS_OR_STANDALONE.has(serverType)) {
serverDescriptions.delete(address);
topologyType = checkHasPrimary(serverDescriptions);
} else if (serverType === ServerType.RSPrimary) {
const result = updateRsFromPrimary(
serverDescriptions,
serverDescription,
setName,
maxSetVersion,
maxElectionId
);
topologyType = result[0];
setName = result[1];
maxSetVersion = result[2];
maxElectionId = result[3];
} else if (NON_PRIMARY_RS_MEMBERS.has(serverType)) {
topologyType = updateRsWithPrimaryFromMember(
serverDescriptions,
serverDescription,
setName
);
} else {
topologyType = checkHasPrimary(serverDescriptions);
}
}
return new TopologyDescription(
topologyType,
serverDescriptions,
setName,
maxSetVersion,
maxElectionId,
commonWireVersion,
{ heartbeatFrequencyMS: this.heartbeatFrequencyMS, localThresholdMS: this.localThresholdMS }
);
}
get error(): MongoError | undefined {
const descriptionsWithError = Array.from(this.servers.values()).filter(
(sd: ServerDescription) => sd.error
);
if (descriptionsWithError.length > 0) {
return descriptionsWithError[0].error;
}
}
/**
* Determines if the topology description has any known servers
*/
get hasKnownServers(): boolean {
return Array.from(this.servers.values()).some(
(sd: ServerDescription) => sd.type !== ServerType.Unknown
);
}
/**
* Determines if this topology description has a data-bearing server available.
*/
get hasDataBearingServers(): boolean {
return Array.from(this.servers.values()).some((sd: ServerDescription) => sd.isDataBearing);
}
/**
* Determines if the topology has a definition for the provided address
* @internal
*/
hasServer(address: string): boolean {
return this.servers.has(address);
}
}
function topologyTypeForServerType(serverType: ServerType): TopologyType {
switch (serverType) {
case ServerType.Standalone:
return TopologyType.Single;
case ServerType.Mongos:
return TopologyType.Sharded;
case ServerType.RSPrimary:
return TopologyType.ReplicaSetWithPrimary;
case ServerType.RSOther:
case ServerType.RSSecondary:
return TopologyType.ReplicaSetNoPrimary;
default:
return TopologyType.Unknown;
}
}
// TODO: improve these docs when ObjectId is properly typed
function compareObjectId(oid1: Document, oid2: Document): number {
if (oid1 == null) {
return -1;
}
if (oid2 == null) {
return 1;
}
if (oid1.id instanceof Buffer && oid2.id instanceof Buffer) {
const oid1Buffer = oid1.id;
const oid2Buffer = oid2.id;
return oid1Buffer.compare(oid2Buffer);
}
const oid1String = oid1.toString();
const oid2String = oid2.toString();
return oid1String.localeCompare(oid2String);
}
function updateRsFromPrimary(
serverDescriptions: Map<string, ServerDescription>,
serverDescription: ServerDescription,
setName?: string,
maxSetVersion?: number,
maxElectionId?: ObjectId
): [TopologyType, string?, number?, ObjectId?] {
setName = setName || serverDescription.setName;
if (setName !== serverDescription.setName) {
serverDescriptions.delete(serverDescription.address);
return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
}
const electionId = serverDescription.electionId ? serverDescription.electionId : null;
if (serverDescription.setVersion && electionId) {
if (maxSetVersion && maxElectionId) {
if (
maxSetVersion > serverDescription.setVersion ||
compareObjectId(maxElectionId, electionId) > 0
) {
// this primary is stale, we must remove it
serverDescriptions.set(
serverDescription.address,
new ServerDescription(serverDescription.address)
);
return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
}
}
maxElectionId = serverDescription.electionId;
}
if (
serverDescription.setVersion != null &&
(maxSetVersion == null || serverDescription.setVersion > maxSetVersion)
) {
maxSetVersion = serverDescription.setVersion;
}
// We've heard from the primary. Is it the same primary as before?
for (const [address, server] of serverDescriptions) {
if (server.type === ServerType.RSPrimary && server.address !== serverDescription.address) {
// Reset old primary's type to Unknown.
serverDescriptions.set(address, new ServerDescription(server.address));
// There can only be one primary
break;
}
}
// Discover new hosts from this primary's response.
serverDescription.allHosts.forEach((address: string) => {
if (!serverDescriptions.has(address)) {
serverDescriptions.set(address, new ServerDescription(address));
}
});
// Remove hosts not in the response.
const currentAddresses = Array.from(serverDescriptions.keys());
const responseAddresses = serverDescription.allHosts;
currentAddresses
.filter((addr: string) => responseAddresses.indexOf(addr) === -1)
.forEach((address: string) => {
serverDescriptions.delete(address);
});
return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
}
function updateRsWithPrimaryFromMember(
serverDescriptions: Map<string, ServerDescription>,
serverDescription: ServerDescription,
setName?: string
): TopologyType {
if (setName == null) {
// TODO(NODE-3483): should be an appropriate runtime error
throw new MongoDriverError('Argument "setName" is required if connected to a replica set');
}
if (
setName !== serverDescription.setName ||
(serverDescription.me && serverDescription.address !== serverDescription.me)
) {
serverDescriptions.delete(serverDescription.address);
}
return checkHasPrimary(serverDescriptions);
}
function updateRsNoPrimaryFromMember(
serverDescriptions: Map<string, ServerDescription>,
serverDescription: ServerDescription,
setName?: string
): [TopologyType, string?] {
const topologyType = TopologyType.ReplicaSetNoPrimary;
setName = setName || serverDescription.setName;
if (setName !== serverDescription.setName) {
serverDescriptions.delete(serverDescription.address);
return [topologyType, setName];
}
serverDescription.allHosts.forEach((address: string) => {
if (!serverDescriptions.has(address)) {
serverDescriptions.set(address, new ServerDescription(address));
}
});
if (serverDescription.me && serverDescription.address !== serverDescription.me) {
serverDescriptions.delete(serverDescription.address);
}
return [topologyType, setName];
}
function checkHasPrimary(serverDescriptions: Map<string, ServerDescription>): TopologyType {
for (const serverDescription of serverDescriptions.values()) {
if (serverDescription.type === ServerType.RSPrimary) {
return TopologyType.ReplicaSetWithPrimary;
}
}
return TopologyType.ReplicaSetNoPrimary;
}