lazy load runtime metrics only when needed

packages/dd-trace/src/runtime_metrics/index.js

@@ -0,0 +1,34 @@
+'use strict'
+
+let runtimeMetrics
+
+const noop = runtimeMetrics = {
+  stop () {},
+  track () {},
+  boolean () {},
+  histogram () {},
+  count () {},
+  gauge () {},
+  increment () {},
+  decrement () {}
+}
+
+module.exports = {
+  start (config) {
+    if (!config?.runtimeMetrics) return
+
+    runtimeMetrics = require('./runtime_metrics')
+
+    Object.setPrototypeOf(module.exports, runtimeMetrics)
+
+    runtimeMetrics.start(config)
+  },
+
+  stop () {
+    runtimeMetrics.stop()
+
+    Object.setPrototypeOf(module.exports, runtimeMetrics = noop)
+  }
+}
+
+Object.setPrototypeOf(module.exports, noop)

packages/dd-trace/src/runtime_metrics.js → packages/dd-trace/src/runtime_metrics/runtime_metrics.js

@@ -4,12 +4,12 @@
 
 const v8 = require('v8')
 const os = require('os')
-const { DogStatsDClient } = require('./dogstatsd')
-const log = require('./log')
-const Histogram = require('./histogram')
+const { DogStatsDClient } = require('../dogstatsd')
+const log = require('../log')
+const Histogram = require('../histogram')
 const { performance, PerformanceObserver } = require('perf_hooks')
 
-const { NODE_MAJOR, NODE_MINOR } = require('../../../version')
+const { NODE_MAJOR, NODE_MINOR } = require('../../../../version')
 const INTERVAL = 10 * 1000
 
 // Node >=16 has PerformanceObserver with `gc` type, but <16.7 had a critical bug.

packages/dd-trace/test/runtime_metrics.spec.js

@@ -9,6 +9,101 @@ const isWindows = os.platform() === 'win32'
 
 const suiteDescribe = isWindows ? describe.skip : describe
 
+suiteDescribe('runtimeMetrics (proxy)', () => {
+  let runtimeMetrics
+  let proxy
+
+  beforeEach(() => {
+    runtimeMetrics = sinon.spy({
+      start () {},
+      stop () {},
+      track () {},
+      boolean () {},
+      histogram () {},
+      count () {},
+      gauge () {},
+      increment () {},
+      decrement () {}
+    })
+
+    proxy = proxyquire('../src/runtime_metrics', {
+      './runtime_metrics': runtimeMetrics
+    })
+  })
+
+  it('should be noop when disabled', () => {
+    proxy.start()
+    proxy.track()
+    proxy.boolean()
+    proxy.histogram()
+    proxy.count()
+    proxy.gauge()
+    proxy.increment()
+    proxy.decrement()
+    proxy.stop()
+
+    expect(runtimeMetrics.start).to.not.have.been.called
+    expect(runtimeMetrics.track).to.not.have.been.called
+    expect(runtimeMetrics.boolean).to.not.have.been.called
+    expect(runtimeMetrics.histogram).to.not.have.been.called
+    expect(runtimeMetrics.count).to.not.have.been.called
+    expect(runtimeMetrics.gauge).to.not.have.been.called
+    expect(runtimeMetrics.increment).to.not.have.been.called
+    expect(runtimeMetrics.decrement).to.not.have.been.called
+    expect(runtimeMetrics.stop).to.not.have.been.called
+  })
+
+  it('should proxy when enabled', () => {
+    const config = { runtimeMetrics: true }
+
+    proxy.start(config)
+    proxy.track()
+    proxy.boolean()
+    proxy.histogram()
+    proxy.count()
+    proxy.gauge()
+    proxy.increment()
+    proxy.decrement()
+    proxy.stop()
+
+    expect(runtimeMetrics.start).to.have.been.calledWith(config)
+    expect(runtimeMetrics.track).to.have.been.called
+    expect(runtimeMetrics.boolean).to.have.been.called
+    expect(runtimeMetrics.histogram).to.have.been.called
+    expect(runtimeMetrics.count).to.have.been.called
+    expect(runtimeMetrics.gauge).to.have.been.called
+    expect(runtimeMetrics.increment).to.have.been.called
+    expect(runtimeMetrics.decrement).to.have.been.called
+    expect(runtimeMetrics.stop).to.have.been.called
+  })
+
+  it('should be noop when disabled after being enabled', () => {
+    const config = { runtimeMetrics: true }
+
+    proxy.start(config)
+    proxy.stop()
+    proxy.start()
+    proxy.track()
+    proxy.boolean()
+    proxy.histogram()
+    proxy.count()
+    proxy.gauge()
+    proxy.increment()
+    proxy.decrement()
+    proxy.stop()
+
+    expect(runtimeMetrics.start).to.have.been.calledOnce
+    expect(runtimeMetrics.track).to.not.have.been.called
+    expect(runtimeMetrics.boolean).to.not.have.been.called
+    expect(runtimeMetrics.histogram).to.not.have.been.called
+    expect(runtimeMetrics.count).to.not.have.been.called
+    expect(runtimeMetrics.gauge).to.not.have.been.called
+    expect(runtimeMetrics.increment).to.not.have.been.called
+    expect(runtimeMetrics.decrement).to.not.have.been.called
+    expect(runtimeMetrics.stop).to.have.been.calledOnce
+  })
+})
+
 suiteDescribe('runtimeMetrics', () => {
   let runtimeMetrics
   let config
@@ -31,8 +126,8 @@ suiteDescribe('runtimeMetrics', () => {
       flush: sinon.spy()
     }
 
-    runtimeMetrics = proxyquire('../src/runtime_metrics', {
-      './dogstatsd': {
+    runtimeMetrics = proxyquire('../src/runtime_metrics/runtime_metrics', {
+      '../dogstatsd': {
         DogStatsDClient: Client
       }
     })
@@ -301,8 +396,8 @@ suiteDescribe('runtimeMetrics', () => {
 
     describe('without native runtimeMetrics', () => {
       beforeEach(() => {
-        runtimeMetrics = proxyquire('../src/runtime_metrics', {
-          './dogstatsd': Client,
+        runtimeMetrics = proxyquire('../src/runtime_metrics/runtime_metrics', {
+          '../dogstatsd': Client,
           'node-gyp-build': sinon.stub().returns(null)
         })
       })