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httpMetrics.ts
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httpMetrics.ts
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'use strict'
import * as shimmer from 'shimmer'
import Debug from 'debug'
import Configuration from '../configuration'
import { MetricInterface } from '../features/metrics'
import { ServiceManager } from '../serviceManager'
import Meter from '../utils/metrics/meter'
import Histogram from '../utils/metrics/histogram'
import * as requireMiddle from 'require-in-the-middle'
import {
MetricService,
InternalMetric,
MetricType,
Metric
} from '../services/metrics'
export class HttpMetricsConfig {
http: boolean
}
export default class HttpMetrics implements MetricInterface {
private defaultConf: HttpMetricsConfig = {
http: true
}
private metrics: Map<string, any> = new Map<string, any>()
private logger: any = Debug('axm:features:metrics:http')
private metricService: MetricService | undefined
private modules: any = {}
private hooks
init (config?: HttpMetricsConfig | boolean) {
if (config === false) return
if (config === undefined) {
config = this.defaultConf
}
if (typeof config !== 'object') {
config = this.defaultConf
}
this.logger('init')
Configuration.configureModule({
latency: true
})
this.metricService = ServiceManager.get('metrics')
if (this.metricService === undefined) return this.logger(`Failed to load metric service`)
this.logger('hooking to require')
this.hookRequire()
}
private registerHttpMetric () {
if (this.metricService === undefined) return this.logger(`Failed to load metric service`)
const histogram = new Histogram()
const p50: InternalMetric = {
name: `HTTP Mean Latency`,
id: 'internal/http/builtin/latency/p50',
type: MetricType.histogram,
historic: true,
implementation: histogram,
unit: 'ms',
handler: () => {
const percentiles = histogram.percentiles([ 0.5 ])
return percentiles[0.5]
}
}
const p95: InternalMetric = {
name: `HTTP P95 Latency`,
id: 'internal/http/builtin/latency/p95',
type: MetricType.histogram,
historic: true,
implementation: histogram,
handler: () => {
const percentiles = histogram.percentiles([ 0.95 ])
return percentiles[0.95]
},
unit: 'ms'
}
const meter: Metric = {
name: 'HTTP',
historic: true,
id: 'internal/http/builtin/reqs',
unit: 'req/min'
}
this.metricService.registerMetric(p50)
this.metricService.registerMetric(p95)
this.metrics.set('http.latency', histogram)
this.metrics.set('http.meter', this.metricService.meter(meter))
}
private registerHttpsMetric () {
if (this.metricService === undefined) return this.logger(`Failed to load metric service`)
const histogram = new Histogram()
const p50: InternalMetric = {
name: `HTTPS Mean Latency`,
id: 'internal/https/builtin/latency/p50',
type: MetricType.histogram,
historic: true,
implementation: histogram,
unit: 'ms',
handler: () => {
const percentiles = histogram.percentiles([ 0.5 ])
return percentiles[0.5]
}
}
const p95: InternalMetric = {
name: `HTTPS P95 Latency`,
id: 'internal/https/builtin/latency/p95',
type: MetricType.histogram,
historic: true,
implementation: histogram,
handler: () => {
const percentiles = histogram.percentiles([ 0.95 ])
return percentiles[0.95]
},
unit: 'ms'
}
const meter: Metric = {
name: 'HTTPS',
historic: true,
id: 'internal/https/builtin/reqs',
unit: 'req/min'
}
this.metricService.registerMetric(p50)
this.metricService.registerMetric(p95)
this.metrics.set('https.latency', histogram)
this.metrics.set('https.meter', this.metricService.meter(meter))
}
destroy () {
if (this.modules.http !== undefined) {
this.logger('unwraping http module')
shimmer.unwrap(this.modules.http, 'emit')
this.modules.http = undefined
}
if (this.modules.https !== undefined) {
this.logger('unwraping https module')
shimmer.unwrap(this.modules.https, 'emit')
this.modules.https = undefined
}
if (this.hooks) {
this.hooks.unhook()
}
this.logger('destroy')
}
/**
* Hook the http emit event emitter to be able to track response latency / request count
*/
private hookHttp (nodule: any, name: string) {
if (nodule.Server === undefined || nodule.Server.prototype === undefined) return
if (this.modules[name] !== undefined) return this.logger(`Module ${name} already hooked`)
this.logger(`Hooking to ${name} module`)
this.modules[name] = nodule.Server.prototype
// register the metrics
if (name === 'http') {
this.registerHttpMetric()
} else if (name === 'https') {
this.registerHttpsMetric()
}
const self = this
// wrap the emitter
shimmer.wrap(nodule.Server.prototype, 'emit', (original: Function) => {
return function (event: string, req: any, res: any) {
// only handle http request
if (event !== 'request') return original.apply(this, arguments)
const meter: Meter | undefined = self.metrics.get(`${name}.meter`)
if (meter !== undefined) {
meter.mark()
}
const latency: Histogram | undefined = self.metrics.get(`${name}.latency`)
if (latency === undefined) return original.apply(this, arguments)
if (res === undefined || res === null) return original.apply(this, arguments)
const startTime = Date.now()
// wait for the response to set the metrics
res.once('finish', _ => {
latency.update(Date.now() - startTime)
})
return original.apply(this, arguments)
}
})
}
private hookRequire () {
this.hooks = requireMiddle(['http', 'https'], (exports, name) => {
this.hookHttp(exports, name)
return exports
})
}
}