84 lines
1.9 KiB
TypeScript
84 lines
1.9 KiB
TypeScript
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import { randomBytes } from 'crypto'
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import { SpanId } from './shared'
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import { report } from './report'
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const NUM_OF_MICROSEC_IN_SEC = BigInt('1000')
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const getId = () => randomBytes(8).toString('hex')
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export enum SpanStatus {
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Started,
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Stopped,
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}
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export class Span {
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name: string
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id: SpanId
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parentId?: SpanId
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duration: number | null
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attrs: { [key: string]: any }
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status: SpanStatus
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_start: bigint
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constructor(name: string, parentId?: SpanId, attrs?: Object) {
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this.name = name
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this.parentId = parentId
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this.duration = null
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this.attrs = attrs ? { ...attrs } : {}
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this.status = SpanStatus.Started
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this.id = getId()
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this._start = process.hrtime.bigint()
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}
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// Durations are reported as microseconds. This gives 1000x the precision
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// of something like Date.now(), which reports in milliseconds.
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// Additionally, ~285 years can be safely represented as microseconds as
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// a float64 in both JSON and JavaScript.
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stop() {
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const end: bigint = process.hrtime.bigint()
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const duration = (end - this._start) / NUM_OF_MICROSEC_IN_SEC
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this.status = SpanStatus.Stopped
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if (duration > Number.MAX_SAFE_INTEGER) {
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throw new Error(`Duration is too long to express as float64: ${duration}`)
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}
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const timestamp = this._start / NUM_OF_MICROSEC_IN_SEC
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report(
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this.name,
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Number(duration),
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Number(timestamp),
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this.id,
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this.parentId,
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this.attrs
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)
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}
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traceChild(name: string, attrs?: Object) {
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return new Span(name, this.id, attrs)
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}
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setAttribute(key: string, value: any) {
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this.attrs[key] = value
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}
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traceFn(fn: any) {
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try {
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return fn()
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} finally {
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this.stop()
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}
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}
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async traceAsyncFn(fn: any) {
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try {
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return await fn()
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} finally {
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this.stop()
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}
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}
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}
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export const trace = (name: string, parentId?: SpanId, attrs?: Object) => {
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return new Span(name, parentId, attrs)
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}
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