✨[RUMF-373] Add View load duration and load type

packages/rum/src/trackPageActivities.ts

@@ -0,0 +1,148 @@
+import { monitor, Observable } from '@datadog/browser-core'
+import { LifeCycle, LifeCycleEventType, Subscription } from './lifeCycle'
+
+// Delay to wait for a page activity to validate the tracking process
+export const PAGE_ACTIVITY_VALIDATION_DELAY = 100
+// Delay to wait after a page activity to end the tracking process
+export const PAGE_ACTIVITY_END_DELAY = 100
+// Maximum duration of the tracking process
+export const PAGE_ACTIVITY_MAX_DURATION = 10_000
+
+export interface PageActivityEvent {
+  isBusy: boolean
+}
+
+export function waitIdlePageActivity(
+  lifeCycle: LifeCycle,
+  completionCallback: (hadActivity: boolean, endTime: number) => void
+): { stop(): void } {
+  const { observable: pageActivitiesObservable, stop: stopPageActivitiesTracking } = trackPageActivities(lifeCycle)
+
+  const { stop: stopWaitPageActivitiesCompletion } = waitPageActivitiesCompletion(
+    pageActivitiesObservable,
+    stopPageActivitiesTracking,
+    completionCallback
+  )
+
+  function stop() {
+    stopWaitPageActivitiesCompletion()
+    stopPageActivitiesTracking()
+  }
+
+  return { stop }
+}
+
+// Automatic user action collection lifecycle overview:
+//                      (Start new trackPageActivities)
+//              .-------------------'--------------------.
+//              v                                        v
+//     [Wait for a page activity ]          [Wait for a maximum duration]
+//     [timeout: VALIDATION_DELAY]          [  timeout: MAX_DURATION    ]
+//          /                  \                           |
+//         v                    v                          |
+//  [No page activity]   [Page activity]                   |
+//         |                   |,----------------------.   |
+//         v                   v                       |   |
+//     (Discard)     [Wait for a page activity]        |   |
+//                   [   timeout: END_DELAY   ]        |   |
+//                       /                \            |   |
+//                      v                  v           |   |
+//             [No page activity]    [Page activity]   |   |
+//                      |                 |            |   |
+//                      |                 '------------'   |
+//                      '-----------. ,--------------------'
+//                                   v
+//                                 (End)
+//
+// Note: because MAX_DURATION > VALIDATION_DELAY, we are sure that if the process is still alive
+// after MAX_DURATION, it has been validated.
+export function trackPageActivities(lifeCycle: LifeCycle): { observable: Observable<PageActivityEvent>; stop(): void } {
+  const observable = new Observable<PageActivityEvent>()
+  const subscriptions: Subscription[] = []
+  let firstRequestId: undefined | number
+  let pendingRequestsCount = 0
+
+  subscriptions.push(lifeCycle.subscribe(LifeCycleEventType.DOM_MUTATED, () => notifyPageActivity()))
+
+  subscriptions.push(
+    lifeCycle.subscribe(LifeCycleEventType.PERFORMANCE_ENTRY_COLLECTED, (entry) => {
+      if (entry.entryType !== 'resource') {
+        return
+      }
+
+      notifyPageActivity()
+    })
+  )
+
+  subscriptions.push(
+    lifeCycle.subscribe(LifeCycleEventType.REQUEST_STARTED, (startEvent) => {
+      if (firstRequestId === undefined) {
+        firstRequestId = startEvent.requestId
+      }
+
+      pendingRequestsCount += 1
+      notifyPageActivity()
+    })
+  )
+
+  subscriptions.push(
+    lifeCycle.subscribe(LifeCycleEventType.REQUEST_COMPLETED, (request) => {
+      // If the request started before the tracking start, ignore it
+      if (firstRequestId === undefined || request.requestId < firstRequestId) {
+        return
+      }
+      pendingRequestsCount -= 1
+      notifyPageActivity()
+    })
+  )
+
+  function notifyPageActivity() {
+    observable.notify({ isBusy: pendingRequestsCount > 0 })
+  }
+
+  return {
+    observable,
+    stop() {
+      subscriptions.forEach((s) => s.unsubscribe())
+    },
+  }
+}
+
+export function waitPageActivitiesCompletion(
+  pageActivitiesObservable: Observable<PageActivityEvent>,
+  stopPageActivitiesTracking: () => void,
+  completionCallback: (hadActivity: boolean, endTime: number) => void
+): { stop(): void } {
+  let idleTimeoutId: ReturnType<typeof setTimeout>
+  let hasCompleted = false
+
+  const validationTimeoutId = setTimeout(monitor(() => complete(false, 0)), PAGE_ACTIVITY_VALIDATION_DELAY)
+  const maxDurationTimeoutId = setTimeout(monitor(() => complete(true, performance.now())), PAGE_ACTIVITY_MAX_DURATION)
+
+  pageActivitiesObservable.subscribe(({ isBusy }) => {
+    clearTimeout(validationTimeoutId)
+    clearTimeout(idleTimeoutId)
+    const lastChangeTime = performance.now()
+    if (!isBusy) {
+      idleTimeoutId = setTimeout(monitor(() => complete(true, lastChangeTime)), PAGE_ACTIVITY_END_DELAY)
+    }
+  })
+
+  function stop() {
+    hasCompleted = true
+    clearTimeout(validationTimeoutId)
+    clearTimeout(idleTimeoutId)
+    clearTimeout(maxDurationTimeoutId)
+    stopPageActivitiesTracking()
+  }
+
+  function complete(hadActivity: boolean, endTime: number) {
+    if (hasCompleted) {
+      return
+    }
+    stop()
+    completionCallback(hadActivity, endTime)
+  }
+
+  return { stop }
+}