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declare module 'perf_hooks' {
import { AsyncResource } from 'async_hooks';
type EntryType = 'node' | 'mark' | 'measure' | 'gc' | 'function' | 'http2' | 'http';
interface PerformanceEntry {
/**
* The total number of milliseconds elapsed for this entry.
* This value will not be meaningful for all Performance Entry types.
*/
readonly duration: number;
/**
* The name of the performance entry.
*/
readonly name: string;
/**
* The high resolution millisecond timestamp marking the starting time of the Performance Entry.
*/
readonly startTime: number;
/**
* The type of the performance entry.
* Currently it may be one of: 'node', 'mark', 'measure', 'gc', or 'function'.
*/
readonly entryType: EntryType;
/**
* When `performanceEntry.entryType` is equal to 'gc', `the performance.kind` property identifies
* the type of garbage collection operation that occurred.
* See perf_hooks.constants for valid values.
*/
readonly kind?: number;
/**
* When `performanceEntry.entryType` is equal to 'gc', the `performance.flags`
* property contains additional information about garbage collection operation.
* See perf_hooks.constants for valid values.
*/
readonly flags?: number;
}
interface PerformanceNodeTiming extends PerformanceEntry {
/**
* The high resolution millisecond timestamp at which the Node.js process completed bootstrap.
*/
readonly bootstrapComplete: number;
/**
* The high resolution millisecond timestamp at which the Node.js process completed bootstrapping.
* If bootstrapping has not yet finished, the property has the value of -1.
*/
readonly environment: number;
/**
* The high resolution millisecond timestamp at which the Node.js environment was initialized.
*/
readonly idleTime: number;
/**
* The high resolution millisecond timestamp of the amount of time the event loop has been idle
* within the event loop's event provider (e.g. `epoll_wait`). This does not take CPU usage
* into consideration. If the event loop has not yet started (e.g., in the first tick of the main script),
* the property has the value of 0.
*/
readonly loopExit: number;
/**
* The high resolution millisecond timestamp at which the Node.js event loop started.
* 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.
*/
readonly loopStart: number;
/**
* The high resolution millisecond timestamp at which the V8 platform was initialized.
*/
readonly v8Start: number;
}
interface EventLoopUtilization {
idle: number;
active: number;
utilization: number;
}
interface Performance {
/**
* If name is not provided, removes all PerformanceMark objects from the Performance Timeline.
* If name is provided, removes only the named mark.
* @param name
*/
clearMarks(name?: string): void;
/**
* Creates a new PerformanceMark entry in the Performance Timeline.
* A PerformanceMark is a subclass of PerformanceEntry whose performanceEntry.entryType is always 'mark',
* and whose performanceEntry.duration is always 0.
* Performance marks are used to mark specific significant moments in the Performance Timeline.
* @param name
*/
mark(name?: string): void;
/**
* Creates a new PerformanceMeasure entry in the Performance Timeline.
* A PerformanceMeasure is a subclass of PerformanceEntry whose performanceEntry.entryType is always 'measure',
* and whose performanceEntry.duration measures the number of milliseconds elapsed since startMark and endMark.
*
* The startMark argument may identify any existing PerformanceMark in the the Performance Timeline, or may identify
* any of the timestamp properties provided by the PerformanceNodeTiming class. If the named startMark does not exist,
* then startMark is set to timeOrigin by default.
*
* The endMark argument must identify any existing PerformanceMark in the the Performance Timeline or any of the timestamp
* properties provided by the PerformanceNodeTiming class. If the named endMark does not exist, an error will be thrown.
* @param name
* @param startMark
* @param endMark
*/
measure(name: string, startMark: string, endMark: string): void;
/**
* An instance of the PerformanceNodeTiming class that provides performance metrics for specific Node.js operational milestones.
*/
readonly nodeTiming: PerformanceNodeTiming;
/**
* @return the current high resolution millisecond timestamp
*/
now(): number;
/**
* The timeOrigin specifies the high resolution millisecond timestamp from which all performance metric durations are measured.
*/
readonly timeOrigin: number;
/**
* Wraps a function within a new function that measures the running time of the wrapped function.
* A PerformanceObserver must be subscribed to the 'function' event type in order for the timing details to be accessed.
* @param fn
*/
timerify<T extends (...optionalParams: any[]) => any>(fn: T): T;
/**
* eventLoopUtilization is similar to CPU utilization except that it is calculated using high precision wall-clock time.
* It represents the percentage of time the event loop has spent outside the event loop's event provider (e.g. epoll_wait).
* No other CPU idle time is taken into consideration.
*
* @param util1 The result of a previous call to eventLoopUtilization()
* @param util2 The result of a previous call to eventLoopUtilization() prior to util1
*/
eventLoopUtilization(util1?: EventLoopUtilization, util2?: EventLoopUtilization): EventLoopUtilization;
}
interface PerformanceObserverEntryList {
/**
* @return a list of PerformanceEntry objects in chronological order with respect to performanceEntry.startTime.
*/
getEntries(): PerformanceEntry[];
/**
* @return a list of PerformanceEntry objects in chronological order with respect to performanceEntry.startTime
* whose performanceEntry.name is equal to name, and optionally, whose performanceEntry.entryType is equal to type.
*/
getEntriesByName(name: string, type?: EntryType): PerformanceEntry[];
/**
* @return Returns a list of PerformanceEntry objects in chronological order with respect to performanceEntry.startTime
* whose performanceEntry.entryType is equal to type.
*/
getEntriesByType(type: EntryType): PerformanceEntry[];
}
type PerformanceObserverCallback = (list: PerformanceObserverEntryList, observer: PerformanceObserver) => void;
class PerformanceObserver extends AsyncResource {
constructor(callback: PerformanceObserverCallback);
/**
* Disconnects the PerformanceObserver instance from all notifications.
*/
disconnect(): void;
/**
* Subscribes the PerformanceObserver instance to notifications of new PerformanceEntry instances identified by options.entryTypes.
* When options.buffered is false, the callback will be invoked once for every PerformanceEntry instance.
* Property buffered defaults to false.
* @param options
*/
observe(options: { entryTypes: ReadonlyArray<EntryType>; buffered?: boolean }): void;
}
namespace constants {
const NODE_PERFORMANCE_GC_MAJOR: number;
const NODE_PERFORMANCE_GC_MINOR: number;
const NODE_PERFORMANCE_GC_INCREMENTAL: number;
const NODE_PERFORMANCE_GC_WEAKCB: number;
const NODE_PERFORMANCE_GC_FLAGS_NO: number;
const NODE_PERFORMANCE_GC_FLAGS_CONSTRUCT_RETAINED: number;
const NODE_PERFORMANCE_GC_FLAGS_FORCED: number;
const NODE_PERFORMANCE_GC_FLAGS_SYNCHRONOUS_PHANTOM_PROCESSING: number;
const NODE_PERFORMANCE_GC_FLAGS_ALL_AVAILABLE_GARBAGE: number;
const NODE_PERFORMANCE_GC_FLAGS_ALL_EXTERNAL_MEMORY: number;
const NODE_PERFORMANCE_GC_FLAGS_SCHEDULE_IDLE: number;
}
const performance: Performance;
interface EventLoopMonitorOptions {
/**
* The sampling rate in milliseconds.
* Must be greater than zero.
* @default 10
*/
resolution?: number;
}
interface EventLoopDelayMonitor {
/**
* Enables the event loop delay sample timer. Returns `true` if the timer was started, `false` if it was already started.
*/
enable(): boolean;
/**
* Disables the event loop delay sample timer. Returns `true` if the timer was stopped, `false` if it was already stopped.
*/
disable(): boolean;
/**
* Resets the collected histogram data.
*/
reset(): void;
/**
* Returns the value at the given percentile.
* @param percentile A percentile value between 1 and 100.
*/
percentile(percentile: number): number;
/**
* A `Map` object detailing the accumulated percentile distribution.
*/
readonly percentiles: Map<number, number>;
/**
* The number of times the event loop delay exceeded the maximum 1 hour eventloop delay threshold.
*/
readonly exceeds: number;
/**
* The minimum recorded event loop delay.
*/
readonly min: number;
/**
* The maximum recorded event loop delay.
*/
readonly max: number;
/**
* The mean of the recorded event loop delays.
*/
readonly mean: number;
/**
* The standard deviation of the recorded event loop delays.
*/
readonly stddev: number;
}
function monitorEventLoopDelay(options?: EventLoopMonitorOptions): EventLoopDelayMonitor;
}