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import { type Document, Long } from '../bson';
import { connect, makeConnection, makeSocket, performInitialHandshake } from '../cmap/connect';
import type { Connection, ConnectionOptions } from '../cmap/connection';
import { getFAASEnv } from '../cmap/handshake/client_metadata';
import { LEGACY_HELLO_COMMAND } from '../constants';
import { MongoError, MongoErrorLabel, MongoNetworkTimeoutError } from '../error';
import { MongoLoggableComponent } from '../mongo_logger';
import { CancellationToken, TypedEventEmitter } from '../mongo_types';
import {
calculateDurationInMs,
type Callback,
type EventEmitterWithState,
makeStateMachine,
noop,
now,
ns
} from '../utils';
import { ServerType, STATE_CLOSED, STATE_CLOSING } from './common';
import {
ServerHeartbeatFailedEvent,
ServerHeartbeatStartedEvent,
ServerHeartbeatSucceededEvent
} from './events';
import { Server } from './server';
import type { TopologyVersion } from './server_description';
const STATE_IDLE = 'idle';
const STATE_MONITORING = 'monitoring';
const stateTransition = makeStateMachine({
[STATE_CLOSING]: [STATE_CLOSING, STATE_IDLE, STATE_CLOSED],
[STATE_CLOSED]: [STATE_CLOSED, STATE_MONITORING],
[STATE_IDLE]: [STATE_IDLE, STATE_MONITORING, STATE_CLOSING],
[STATE_MONITORING]: [STATE_MONITORING, STATE_IDLE, STATE_CLOSING]
});
const INVALID_REQUEST_CHECK_STATES = new Set([STATE_CLOSING, STATE_CLOSED, STATE_MONITORING]);
function isInCloseState(monitor: Monitor) {
return monitor.s.state === STATE_CLOSED || monitor.s.state === STATE_CLOSING;
}
/** @public */
export const ServerMonitoringMode = Object.freeze({
auto: 'auto',
poll: 'poll',
stream: 'stream'
} as const);
/** @public */
export type ServerMonitoringMode = (typeof ServerMonitoringMode)[keyof typeof ServerMonitoringMode];
/** @internal */
export interface MonitorPrivate {
state: string;
}
/** @public */
export interface MonitorOptions
extends Omit<ConnectionOptions, 'id' | 'generation' | 'hostAddress'> {
connectTimeoutMS: number;
heartbeatFrequencyMS: number;
minHeartbeatFrequencyMS: number;
serverMonitoringMode: ServerMonitoringMode;
}
/** @public */
export type MonitorEvents = {
serverHeartbeatStarted(event: ServerHeartbeatStartedEvent): void;
serverHeartbeatSucceeded(event: ServerHeartbeatSucceededEvent): void;
serverHeartbeatFailed(event: ServerHeartbeatFailedEvent): void;
resetServer(error?: MongoError): void;
resetConnectionPool(): void;
close(): void;
} & EventEmitterWithState;
/** @internal */
export class Monitor extends TypedEventEmitter<MonitorEvents> {
/** @internal */
s: MonitorPrivate;
address: string;
options: Readonly<
Pick<
MonitorOptions,
| 'connectTimeoutMS'
| 'heartbeatFrequencyMS'
| 'minHeartbeatFrequencyMS'
| 'serverMonitoringMode'
>
>;
connectOptions: ConnectionOptions;
isRunningInFaasEnv: boolean;
server: Server;
connection: Connection | null;
cancellationToken: CancellationToken;
/** @internal */
monitorId?: MonitorInterval;
rttPinger?: RTTPinger;
/** @internal */
override component = MongoLoggableComponent.TOPOLOGY;
/** @internal */
private rttSampler: RTTSampler;
constructor(server: Server, options: MonitorOptions) {
super();
this.on('error', noop);
this.server = server;
this.connection = null;
this.cancellationToken = new CancellationToken();
this.cancellationToken.setMaxListeners(Infinity);
this.monitorId = undefined;
this.s = {
state: STATE_CLOSED
};
this.address = server.description.address;
this.options = Object.freeze({
connectTimeoutMS: options.connectTimeoutMS ?? 10000,
heartbeatFrequencyMS: options.heartbeatFrequencyMS ?? 10000,
minHeartbeatFrequencyMS: options.minHeartbeatFrequencyMS ?? 500,
serverMonitoringMode: options.serverMonitoringMode
});
this.isRunningInFaasEnv = getFAASEnv() != null;
this.mongoLogger = this.server.topology.client?.mongoLogger;
this.rttSampler = new RTTSampler(10);
const cancellationToken = this.cancellationToken;
// TODO: refactor this to pull it directly from the pool, requires new ConnectionPool integration
const connectOptions = {
id: '<monitor>' as const,
generation: server.pool.generation,
cancellationToken,
hostAddress: server.description.hostAddress,
...options,
// force BSON serialization options
raw: false,
useBigInt64: false,
promoteLongs: true,
promoteValues: true,
promoteBuffers: true
};
// ensure no authentication is used for monitoring
delete connectOptions.credentials;
if (connectOptions.autoEncrypter) {
delete connectOptions.autoEncrypter;
}
this.connectOptions = Object.freeze(connectOptions);
}
connect(): void {
if (this.s.state !== STATE_CLOSED) {
return;
}
// start
const heartbeatFrequencyMS = this.options.heartbeatFrequencyMS;
const minHeartbeatFrequencyMS = this.options.minHeartbeatFrequencyMS;
this.monitorId = new MonitorInterval(monitorServer(this), {
heartbeatFrequencyMS: heartbeatFrequencyMS,
minHeartbeatFrequencyMS: minHeartbeatFrequencyMS,
immediate: true
});
}
requestCheck(): void {
if (INVALID_REQUEST_CHECK_STATES.has(this.s.state)) {
return;
}
this.monitorId?.wake();
}
reset(): void {
const topologyVersion = this.server.description.topologyVersion;
if (isInCloseState(this) || topologyVersion == null) {
return;
}
stateTransition(this, STATE_CLOSING);
resetMonitorState(this);
// restart monitor
stateTransition(this, STATE_IDLE);
// restart monitoring
const heartbeatFrequencyMS = this.options.heartbeatFrequencyMS;
const minHeartbeatFrequencyMS = this.options.minHeartbeatFrequencyMS;
this.monitorId = new MonitorInterval(monitorServer(this), {
heartbeatFrequencyMS: heartbeatFrequencyMS,
minHeartbeatFrequencyMS: minHeartbeatFrequencyMS
});
}
close(): void {
if (isInCloseState(this)) {
return;
}
stateTransition(this, STATE_CLOSING);
resetMonitorState(this);
// close monitor
this.emit('close');
stateTransition(this, STATE_CLOSED);
}
get roundTripTime(): number {
return this.rttSampler.average();
}
get minRoundTripTime(): number {
return this.rttSampler.min();
}
get latestRtt(): number | null {
return this.rttSampler.last;
}
addRttSample(rtt: number) {
this.rttSampler.addSample(rtt);
}
clearRttSamples() {
this.rttSampler.clear();
}
}
function resetMonitorState(monitor: Monitor) {
monitor.monitorId?.stop();
monitor.monitorId = undefined;
monitor.rttPinger?.close();
monitor.rttPinger = undefined;
monitor.cancellationToken.emit('cancel');
monitor.connection?.destroy();
monitor.connection = null;
monitor.clearRttSamples();
}
function useStreamingProtocol(monitor: Monitor, topologyVersion: TopologyVersion | null): boolean {
// If we have no topology version we always poll no matter
// what the user provided, since the server does not support
// the streaming protocol.
if (topologyVersion == null) return false;
const serverMonitoringMode = monitor.options.serverMonitoringMode;
if (serverMonitoringMode === ServerMonitoringMode.poll) return false;
if (serverMonitoringMode === ServerMonitoringMode.stream) return true;
// If we are in auto mode, we need to figure out if we're in a FaaS
// environment or not and choose the appropriate mode.
if (monitor.isRunningInFaasEnv) return false;
return true;
}
function checkServer(monitor: Monitor, callback: Callback<Document | null>) {
let start: number;
let awaited: boolean;
const topologyVersion = monitor.server.description.topologyVersion;
const isAwaitable = useStreamingProtocol(monitor, topologyVersion);
monitor.emitAndLogHeartbeat(
Server.SERVER_HEARTBEAT_STARTED,
monitor.server.topology.s.id,
undefined,
new ServerHeartbeatStartedEvent(monitor.address, isAwaitable)
);
function onHeartbeatFailed(err: Error) {
monitor.connection?.destroy();
monitor.connection = null;
monitor.emitAndLogHeartbeat(
Server.SERVER_HEARTBEAT_FAILED,
monitor.server.topology.s.id,
undefined,
new ServerHeartbeatFailedEvent(monitor.address, calculateDurationInMs(start), err, awaited)
);
const error = !(err instanceof MongoError)
? new MongoError(MongoError.buildErrorMessage(err), { cause: err })
: err;
error.addErrorLabel(MongoErrorLabel.ResetPool);
if (error instanceof MongoNetworkTimeoutError) {
error.addErrorLabel(MongoErrorLabel.InterruptInUseConnections);
}
monitor.emit('resetServer', error);
callback(err);
}
function onHeartbeatSucceeded(hello: Document) {
if (!('isWritablePrimary' in hello)) {
// Provide hello-style response document.
hello.isWritablePrimary = hello[LEGACY_HELLO_COMMAND];
}
// NOTE: here we use the latestRtt as this measurement corresponds with the value
// obtained for this successful heartbeat, if there is no latestRtt, then we calculate the
// duration
const duration =
isAwaitable && monitor.rttPinger
? (monitor.rttPinger.latestRtt ?? calculateDurationInMs(start))
: calculateDurationInMs(start);
monitor.addRttSample(duration);
monitor.emitAndLogHeartbeat(
Server.SERVER_HEARTBEAT_SUCCEEDED,
monitor.server.topology.s.id,
hello.connectionId,
new ServerHeartbeatSucceededEvent(monitor.address, duration, hello, isAwaitable)
);
if (isAwaitable) {
// If we are using the streaming protocol then we immediately issue another 'started'
// event, otherwise the "check" is complete and return to the main monitor loop
monitor.emitAndLogHeartbeat(
Server.SERVER_HEARTBEAT_STARTED,
monitor.server.topology.s.id,
undefined,
new ServerHeartbeatStartedEvent(monitor.address, true)
);
// We have not actually sent an outgoing handshake, but when we get the next response we
// want the duration to reflect the time since we last heard from the server
start = now();
} else {
monitor.rttPinger?.close();
monitor.rttPinger = undefined;
callback(undefined, hello);
}
}
const { connection } = monitor;
if (connection && !connection.closed) {
const { serverApi, helloOk } = connection;
const connectTimeoutMS = monitor.options.connectTimeoutMS;
const maxAwaitTimeMS = monitor.options.heartbeatFrequencyMS;
const cmd = {
[serverApi?.version || helloOk ? 'hello' : LEGACY_HELLO_COMMAND]: 1,
...(isAwaitable && topologyVersion
? { maxAwaitTimeMS, topologyVersion: makeTopologyVersion(topologyVersion) }
: {})
};
const options = isAwaitable
? {
socketTimeoutMS: connectTimeoutMS ? connectTimeoutMS + maxAwaitTimeMS : 0,
exhaustAllowed: true
}
: { socketTimeoutMS: connectTimeoutMS };
if (isAwaitable && monitor.rttPinger == null) {
monitor.rttPinger = new RTTPinger(monitor);
}
// Record new start time before sending handshake
start = now();
if (isAwaitable) {
awaited = true;
return connection.exhaustCommand(ns('admin.$cmd'), cmd, options, (error, hello) => {
if (error) return onHeartbeatFailed(error);
return onHeartbeatSucceeded(hello);
});
}
awaited = false;
connection
.command(ns('admin.$cmd'), cmd, options)
.then(onHeartbeatSucceeded, onHeartbeatFailed);
return;
}
// connecting does an implicit `hello`
(async () => {
const socket = await makeSocket(monitor.connectOptions);
const connection = makeConnection(monitor.connectOptions, socket);
// The start time is after socket creation but before the handshake
start = now();
try {
await performInitialHandshake(connection, monitor.connectOptions);
return connection;
} catch (error) {
connection.destroy();
throw error;
}
})().then(
connection => {
if (isInCloseState(monitor)) {
connection.destroy();
return;
}
const duration = calculateDurationInMs(start);
monitor.addRttSample(duration);
monitor.connection = connection;
monitor.emitAndLogHeartbeat(
Server.SERVER_HEARTBEAT_SUCCEEDED,
monitor.server.topology.s.id,
connection.hello?.connectionId,
new ServerHeartbeatSucceededEvent(
monitor.address,
duration,
connection.hello,
useStreamingProtocol(monitor, connection.hello?.topologyVersion)
)
);
callback(undefined, connection.hello);
},
error => {
monitor.connection = null;
awaited = false;
onHeartbeatFailed(error);
}
);
}
function monitorServer(monitor: Monitor) {
return (callback: Callback) => {
Iif (monitor.s.state === STATE_MONITORING) {
process.nextTick(callback);
return;
}
stateTransition(monitor, STATE_MONITORING);
function done() {
if (!isInCloseState(monitor)) {
stateTransition(monitor, STATE_IDLE);
}
callback();
}
checkServer(monitor, (err, hello) => {
if (err) {
// otherwise an error occurred on initial discovery, also bail
if (monitor.server.description.type === ServerType.Unknown) {
return done();
}
}
// if the check indicates streaming is supported, immediately reschedule monitoring
if (useStreamingProtocol(monitor, hello?.topologyVersion)) {
setTimeout(() => {
if (!isInCloseState(monitor)) {
monitor.monitorId?.wake();
}
}, 0);
}
done();
});
};
}
function makeTopologyVersion(tv: TopologyVersion) {
return {
processId: tv.processId,
// tests mock counter as just number, but in a real situation counter should always be a Long
// TODO(NODE-2674): Preserve int64 sent from MongoDB
counter: Long.isLong(tv.counter) ? tv.counter : Long.fromNumber(tv.counter)
};
}
/** @internal */
export interface RTTPingerOptions extends ConnectionOptions {
heartbeatFrequencyMS: number;
}
/** @internal */
export class RTTPinger {
connection?: Connection;
/** @internal */
cancellationToken: CancellationToken;
/** @internal */
monitorId: NodeJS.Timeout;
/** @internal */
monitor: Monitor;
closed: boolean;
/** @internal */
latestRtt?: number;
constructor(monitor: Monitor) {
this.connection = undefined;
this.cancellationToken = monitor.cancellationToken;
this.closed = false;
this.monitor = monitor;
this.latestRtt = monitor.latestRtt ?? undefined;
const heartbeatFrequencyMS = monitor.options.heartbeatFrequencyMS;
this.monitorId = setTimeout(() => this.measureRoundTripTime(), heartbeatFrequencyMS);
}
get roundTripTime(): number {
return this.monitor.roundTripTime;
}
get minRoundTripTime(): number {
return this.monitor.minRoundTripTime;
}
close(): void {
this.closed = true;
clearTimeout(this.monitorId);
this.connection?.destroy();
this.connection = undefined;
}
private measureAndReschedule(start: number, conn?: Connection) {
if (this.closed) {
conn?.destroy();
return;
}
if (this.connection == null) {
this.connection = conn;
}
this.latestRtt = calculateDurationInMs(start);
this.monitorId = setTimeout(
() => this.measureRoundTripTime(),
this.monitor.options.heartbeatFrequencyMS
);
}
private measureRoundTripTime() {
const start = now();
Iif (this.closed) {
return;
}
const connection = this.connection;
if (connection == null) {
connect(this.monitor.connectOptions).then(
connection => {
this.measureAndReschedule(start, connection);
},
() => {
this.connection = undefined;
}
);
return;
}
const commandName =
connection.serverApi?.version || connection.helloOk ? 'hello' : LEGACY_HELLO_COMMAND;
connection.command(ns('admin.$cmd'), { [commandName]: 1 }, undefined).then(
() => this.measureAndReschedule(start),
() => {
this.connection?.destroy();
this.connection = undefined;
return;
}
);
}
}
/**
* @internal
*/
export interface MonitorIntervalOptions {
/** The interval to execute a method on */
heartbeatFrequencyMS: number;
/** A minimum interval that must elapse before the method is called */
minHeartbeatFrequencyMS: number;
/** Whether the method should be called immediately when the interval is started */
immediate: boolean;
}
/**
* @internal
*/
export class MonitorInterval {
fn: (callback: Callback) => void;
timerId: NodeJS.Timeout | undefined;
lastExecutionEnded: number;
isExpeditedCallToFnScheduled = false;
stopped = false;
isExecutionInProgress = false;
hasExecutedOnce = false;
heartbeatFrequencyMS: number;
minHeartbeatFrequencyMS: number;
constructor(fn: (callback: Callback) => void, options: Partial<MonitorIntervalOptions> = {}) {
this.fn = fn;
this.lastExecutionEnded = -Infinity;
this.heartbeatFrequencyMS = options.heartbeatFrequencyMS ?? 1000;
this.minHeartbeatFrequencyMS = options.minHeartbeatFrequencyMS ?? 500;
if (options.immediate) {
this._executeAndReschedule();
} else {
this._reschedule(undefined);
}
}
wake() {
const currentTime = now();
const timeSinceLastCall = currentTime - this.lastExecutionEnded;
// TODO(NODE-4674): Add error handling and logging to the monitor
if (timeSinceLastCall < 0) {
return this._executeAndReschedule();
}
if (this.isExecutionInProgress) {
return;
}
// debounce multiple calls to wake within the `minInterval`
if (this.isExpeditedCallToFnScheduled) {
return;
}
// reschedule a call as soon as possible, ensuring the call never happens
// faster than the `minInterval`
if (timeSinceLastCall < this.minHeartbeatFrequencyMS) {
this.isExpeditedCallToFnScheduled = true;
this._reschedule(this.minHeartbeatFrequencyMS - timeSinceLastCall);
return;
}
this._executeAndReschedule();
}
stop() {
this.stopped = true;
if (this.timerId) {
clearTimeout(this.timerId);
this.timerId = undefined;
}
this.lastExecutionEnded = -Infinity;
this.isExpeditedCallToFnScheduled = false;
}
toString() {
return JSON.stringify(this);
}
toJSON() {
const currentTime = now();
const timeSinceLastCall = currentTime - this.lastExecutionEnded;
return {
timerId: this.timerId != null ? 'set' : 'cleared',
lastCallTime: this.lastExecutionEnded,
isExpeditedCheckScheduled: this.isExpeditedCallToFnScheduled,
stopped: this.stopped,
heartbeatFrequencyMS: this.heartbeatFrequencyMS,
minHeartbeatFrequencyMS: this.minHeartbeatFrequencyMS,
currentTime,
timeSinceLastCall
};
}
private _reschedule(ms?: number) {
if (this.stopped) return;
if (this.timerId) {
clearTimeout(this.timerId);
}
this.timerId = setTimeout(this._executeAndReschedule, ms || this.heartbeatFrequencyMS);
}
private _executeAndReschedule = () => {
Iif (this.stopped) return;
if (this.timerId) {
clearTimeout(this.timerId);
}
this.isExpeditedCallToFnScheduled = false;
this.isExecutionInProgress = true;
this.fn(() => {
this.lastExecutionEnded = now();
this.isExecutionInProgress = false;
this._reschedule(this.heartbeatFrequencyMS);
});
};
}
/** @internal
* This class implements the RTT sampling logic specified for [CSOT](https://github.com/mongodb/specifications/blob/bbb335e60cd7ea1e0f7cd9a9443cb95fc9d3b64d/source/client-side-operations-timeout/client-side-operations-timeout.md#drivers-use-minimum-rtt-to-short-circuit-operations)
*
* This is implemented as a [circular buffer](https://en.wikipedia.org/wiki/Circular_buffer) keeping
* the most recent `windowSize` samples
* */
export class RTTSampler {
/** Index of the next slot to be overwritten */
private writeIndex: number;
private length: number;
private rttSamples: Float64Array;
constructor(windowSize = 10) {
this.rttSamples = new Float64Array(windowSize);
this.length = 0;
this.writeIndex = 0;
}
/**
* Adds an rtt sample to the end of the circular buffer
* When `windowSize` samples have been collected, `addSample` overwrites the least recently added
* sample
*/
addSample(sample: number) {
this.rttSamples[this.writeIndex++] = sample;
if (this.length < this.rttSamples.length) {
this.length++;
}
this.writeIndex %= this.rttSamples.length;
}
/**
* When \< 2 samples have been collected, returns 0
* Otherwise computes the minimum value samples contained in the buffer
*/
min(): number {
if (this.length < 2) return 0;
let min = this.rttSamples[0];
for (let i = 1; i < this.length; i++) {
if (this.rttSamples[i] < min) min = this.rttSamples[i];
}
return min;
}
/**
* Returns mean of samples contained in the buffer
*/
average(): number {
Iif (this.length === 0) return 0;
let sum = 0;
for (let i = 0; i < this.length; i++) {
sum += this.rttSamples[i];
}
return sum / this.length;
}
/**
* Returns most recently inserted element in the buffer
* Returns null if the buffer is empty
* */
get last(): number | null {
if (this.length === 0) return null;
return this.rttSamples[this.writeIndex === 0 ? this.length - 1 : this.writeIndex - 1];
}
/**
* Clear the buffer
* NOTE: this does not overwrite the data held in the internal array, just the pointers into
* this array
*/
clear() {
this.length = 0;
this.writeIndex = 0;
}
}
|