declare module 'perf_hooks' {
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import { AsyncResource } from 'async_hooks';
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interface PerformanceEntry {
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/**
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* The total number of milliseconds elapsed for this entry.
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* This value will not be meaningful for all Performance Entry types.
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*/
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readonly duration: number;
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/**
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* The name of the performance entry.
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*/
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readonly name: string;
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/**
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* The high resolution millisecond timestamp marking the starting time of the Performance Entry.
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*/
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readonly startTime: number;
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/**
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* The type of the performance entry.
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* Currently it may be one of: 'node', 'mark', 'measure', 'gc', or 'function'.
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*/
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readonly entryType: string;
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/**
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* When performanceEntry.entryType is equal to 'gc', the performance.kind property identifies
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* the type of garbage collection operation that occurred.
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* The value may be one of perf_hooks.constants.
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*/
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readonly kind?: number;
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}
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interface PerformanceNodeTiming extends PerformanceEntry {
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/**
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* The high resolution millisecond timestamp at which the Node.js process completed bootstrap.
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* If bootstrapping has not yet finished, the property has the value of -1.
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*/
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readonly bootstrapComplete: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js process completed bootstrapping.
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* If bootstrapping has not yet finished, the property has the value of -1.
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*/
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readonly environment: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js environment was initialized.
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*/
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readonly idleTime: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js event loop exited.
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* If the event loop has not yet exited, the property has the value of -1.
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* It can only have a value of not -1 in a handler of the 'exit' event.
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*/
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readonly loopExit: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js event loop started.
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* If the event loop has not yet started (e.g., in the first tick of the main script), the property has the value of -1.
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*/
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readonly loopStart: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js process was initialized.
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*/
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readonly nodeStart: number;
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/**
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* The high resolution millisecond timestamp at which the V8 platform was initialized.
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*/
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readonly v8Start: number;
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}
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interface EventLoopUtilization {
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idle: number;
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active: number;
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utilization: number;
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}
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interface Performance {
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/**
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* If name is not provided, removes all PerformanceMark objects from the Performance Timeline.
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* If name is provided, removes only the named mark.
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* @param name
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*/
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clearMarks(name?: string): void;
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/**
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* Creates a new PerformanceMark entry in the Performance Timeline.
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* A PerformanceMark is a subclass of PerformanceEntry whose performanceEntry.entryType is always 'mark',
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* and whose performanceEntry.duration is always 0.
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* Performance marks are used to mark specific significant moments in the Performance Timeline.
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* @param name
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*/
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mark(name?: string): void;
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/**
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* Creates a new PerformanceMeasure entry in the Performance Timeline.
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* A PerformanceMeasure is a subclass of PerformanceEntry whose performanceEntry.entryType is always 'measure',
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* and whose performanceEntry.duration measures the number of milliseconds elapsed since startMark and endMark.
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*
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* The startMark argument may identify any existing PerformanceMark in the the Performance Timeline, or may identify
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* any of the timestamp properties provided by the PerformanceNodeTiming class. If the named startMark does not exist,
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* then startMark is set to timeOrigin by default.
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*
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* The endMark argument must identify any existing PerformanceMark in the the Performance Timeline or any of the timestamp
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* properties provided by the PerformanceNodeTiming class. If the named endMark does not exist, an error will be thrown.
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* @param name
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* @param startMark
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* @param endMark
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*/
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measure(name: string, startMark: string, endMark: string): void;
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/**
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* An instance of the PerformanceNodeTiming class that provides performance metrics for specific Node.js operational milestones.
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*/
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readonly nodeTiming: PerformanceNodeTiming;
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/**
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* @return the current high resolution millisecond timestamp
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*/
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now(): number;
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/**
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* The timeOrigin specifies the high resolution millisecond timestamp from which all performance metric durations are measured.
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*/
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readonly timeOrigin: number;
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/**
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* Wraps a function within a new function that measures the running time of the wrapped function.
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* A PerformanceObserver must be subscribed to the 'function' event type in order for the timing details to be accessed.
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* @param fn
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*/
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timerify<T extends (...optionalParams: any[]) => any>(fn: T): T;
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/**
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* eventLoopUtilization is similar to CPU utilization except that it is calculated using high precision wall-clock time.
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* It represents the percentage of time the event loop has spent outside the event loop's event provider (e.g. epoll_wait).
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* No other CPU idle time is taken into consideration.
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*
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* @param util1 The result of a previous call to eventLoopUtilization()
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* @param util2 The result of a previous call to eventLoopUtilization() prior to util1
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*/
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eventLoopUtilization(util1?: EventLoopUtilization, util2?: EventLoopUtilization): EventLoopUtilization;
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}
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interface PerformanceObserverEntryList {
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/**
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* @return a list of PerformanceEntry objects in chronological order with respect to performanceEntry.startTime.
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*/
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getEntries(): PerformanceEntry[];
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/**
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* @return a list of PerformanceEntry objects in chronological order with respect to performanceEntry.startTime
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* whose performanceEntry.name is equal to name, and optionally, whose performanceEntry.entryType is equal to type.
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*/
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getEntriesByName(name: string, type?: string): PerformanceEntry[];
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/**
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* @return Returns a list of PerformanceEntry objects in chronological order with respect to performanceEntry.startTime
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* whose performanceEntry.entryType is equal to type.
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*/
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getEntriesByType(type: string): PerformanceEntry[];
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}
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type PerformanceObserverCallback = (list: PerformanceObserverEntryList, observer: PerformanceObserver) => void;
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class PerformanceObserver extends AsyncResource {
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constructor(callback: PerformanceObserverCallback);
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/**
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* Disconnects the PerformanceObserver instance from all notifications.
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*/
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disconnect(): void;
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/**
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* Subscribes the PerformanceObserver instance to notifications of new PerformanceEntry instances identified by options.entryTypes.
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* When options.buffered is false, the callback will be invoked once for every PerformanceEntry instance.
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* Property buffered defaults to false.
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* @param options
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*/
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observe(options: { entryTypes: ReadonlyArray<string>, buffered?: boolean }): void;
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}
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namespace constants {
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const NODE_PERFORMANCE_GC_MAJOR: number;
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const NODE_PERFORMANCE_GC_MINOR: number;
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const NODE_PERFORMANCE_GC_INCREMENTAL: number;
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const NODE_PERFORMANCE_GC_WEAKCB: number;
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}
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const performance: Performance;
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interface EventLoopMonitorOptions {
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/**
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* The sampling rate in milliseconds.
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* Must be greater than zero.
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* @default 10
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*/
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resolution?: number;
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}
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interface EventLoopDelayMonitor {
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/**
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* Enables the event loop delay sample timer. Returns `true` if the timer was started, `false` if it was already started.
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*/
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enable(): boolean;
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/**
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* Disables the event loop delay sample timer. Returns `true` if the timer was stopped, `false` if it was already stopped.
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*/
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disable(): boolean;
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/**
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* Resets the collected histogram data.
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*/
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reset(): void;
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/**
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* Returns the value at the given percentile.
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* @param percentile A percentile value between 1 and 100.
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*/
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percentile(percentile: number): number;
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/**
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* A `Map` object detailing the accumulated percentile distribution.
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*/
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readonly percentiles: Map<number, number>;
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/**
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* The number of times the event loop delay exceeded the maximum 1 hour eventloop delay threshold.
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*/
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readonly exceeds: number;
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/**
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* The minimum recorded event loop delay.
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*/
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readonly min: number;
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/**
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* The maximum recorded event loop delay.
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*/
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readonly max: number;
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/**
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* The mean of the recorded event loop delays.
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*/
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readonly mean: number;
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/**
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* The standard deviation of the recorded event loop delays.
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*/
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readonly stddev: number;
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}
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function monitorEventLoopDelay(options?: EventLoopMonitorOptions): EventLoopDelayMonitor;
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}
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