Use thread-sync monotonic timestamp

.eslintrc.js

@@ -328,6 +328,11 @@ module.exports = {
     "prefer-template": "off",
     "no-restricted-properties": [
       "error",
+      {
+        "object": "performance",
+        "property": "now",
+        "message": "Avoid using `performance.now` directly as timestamps may be different in the worker and the main thread. Please use the `getMonotonicTimeStamp` util instead.",
+      },
       {
         "object": "window",
         "message": "`window` doesn't work in Node.JS and only works when JavaScript is running in the main thread. Please import `globalScope` instead.",

src/core/adaptive/buffer_based_chooser.ts

@@ -16,6 +16,7 @@
 
 import log from "../../log";
 import arrayFindIndex from "../../utils/array_find_index";
+import getMonotonicTimeStamp from "../../utils/monotonic_timestamp";
 import getBufferLevels from "./utils/get_buffer_levels";
 import {
   IRepresentationMaintainabilityScore,
@@ -94,8 +95,8 @@ export default class BufferBasedChooser {
   private _currentEstimate: number | undefined;
 
   /**
-   * Laast timestamp, in terms of `performance.now`, at which the current
-   * quality was seen as too high by this algorithm.
+   * Laast monotonically-raising timestamp, at which the current quality was
+   * seen as too high by this algorithm.
    * Begins at `undefined`.
    */
   private _lastUnsuitableQualityTimestamp: number | undefined;
@@ -166,7 +167,7 @@ export default class BufferBasedChooser {
       bufferGap :
       0;
 
-    const now = performance.now();
+    const now = getMonotonicTimeStamp();
 
     if (
       actualBufferGap < bufferLevels[currentBitrateIndex] ||

src/core/adaptive/guess_based_chooser.ts

@@ -17,6 +17,7 @@
 import log from "../../log";
 import { Representation } from "../../manifest";
 import arrayFindIndex from "../../utils/array_find_index";
+import getMonotonicTimeStamp from "../../utils/monotonic_timestamp";
 import { estimateRequestBandwidth } from "./network_analyzer";
 import LastEstimateStorage, {
   ABRAlgorithmType,
@@ -146,7 +147,7 @@ export default class GuessBasedChooser {
     if (shouldStopGuess) {
       // Block guesses for a time
       this._consecutiveWrongGuesses++;
-      this._blockGuessesUntil = performance.now() +
+      this._blockGuessesUntil = getMonotonicTimeStamp() +
         Math.min(this._consecutiveWrongGuesses * 15000, 120000);
       return getPreviousRepresentation(representations, currentRepresentation);
     } else if (scoreData === undefined) {
@@ -177,7 +178,7 @@ export default class GuessBasedChooser {
     { score, confidenceLevel } : IRepresentationMaintainabilityScore
   ) : boolean {
     return isFinite(bufferGap) && bufferGap >= 2.5 &&
-           performance.now() > this._blockGuessesUntil &&
+           getMonotonicTimeStamp() > this._blockGuessesUntil &&
            confidenceLevel === ScoreConfidenceLevel.HIGH &&
            score / speed > 1.01;
   }
@@ -207,7 +208,7 @@ export default class GuessBasedChooser {
       return req.content.representation.id === lastGuess.id;
     });
 
-    const now = performance.now();
+    const now = getMonotonicTimeStamp();
     for (const req of guessedRepresentationRequests) {
       const requestElapsedTime = now - req.requestTimestamp;
       if (req.content.segment.isInit) {

src/core/adaptive/network_analyzer.ts

@@ -18,6 +18,7 @@ import config from "../../config";
 import log from "../../log";
 import { Representation } from "../../manifest";
 import arrayFind from "../../utils/array_find";
+import getMonotonicTimeStamp from "../../utils/monotonic_timestamp";
 import {
   IRepresentationEstimatorPlaybackObservation,
 } from "./adaptive_representation_selector";
@@ -160,7 +161,7 @@ function estimateStarvationModeBitrate(
   }
 
   const concernedRequest = concernedRequests[0];
-  const now = performance.now();
+  const now = getMonotonicTimeStamp();
 
   let minimumRequestTime = concernedRequest.content.segment.duration * 1.5;
   minimumRequestTime = Math.min(minimumRequestTime, 3000);
@@ -243,7 +244,7 @@ function shouldDirectlySwitchToLowBitrate(
     return true;
   }
 
-  const now = performance.now();
+  const now = getMonotonicTimeStamp();
   const lastProgressEvent = nextRequest.progress.length > 0 ?
     nextRequest.progress[nextRequest.progress.length - 1] :
     undefined;

src/core/adaptive/utils/pending_requests_store.ts

@@ -103,7 +103,10 @@ export interface IPendingRequestStoreProgress {
   id: string;
   /** Current downloaded size, in bytes. */
   size : number;
-  /** Value of `performance.now` at the time this progression report was available. */
+  /**
+   * Value of the monotonically-raising timestamp at the time this progression
+   * report was available.
+   */
   timestamp : number;
   /**
    * Total size of the segment to download (including already-loaded data),
@@ -121,7 +124,7 @@ export interface IPendingRequestStoreBegin {
    * should have this `id` at the same time.
    */
   id: string;
-  /** Value of `performance.now` at the time the request began.  */
+  /** Value of the monotonically-raising timestamp at the time the request began.  */
   requestTimestamp: number;
   /** Context associated to the segment. */
   content: IRequestInfoContent;
@@ -131,7 +134,10 @@ export interface IPendingRequestStoreBegin {
 export interface IRequestInfo {
   /** Information on the current progress made by this request. */
   progress: IPendingRequestStoreProgress[];
-  /** `Performance.now()` corresponding to the time at which the request began. */
+  /**
+   * Monotonically-raising timestamp corresponding to the time at which the
+   * request began.
+   */
   requestTimestamp: number;
   /** Context associated to the segment. */
   content: IRequestInfoContent;

src/core/api/debug/buffer_size_graph.ts

@@ -1,3 +1,5 @@
+import getMonotonicTimeStamp from "../../../utils/monotonic_timestamp";
+
 /**
  * Maximum history of the buffer size that will be displayed, in milliseconds.
  * For example, a value of `3000` indicates that we will just show at most the
@@ -30,7 +32,7 @@ export default class BufferSizeGraph {
   }
 
   public pushBufferSize(bufferSize : number) : void {
-    const now = performance.now();
+    const now = getMonotonicTimeStamp();
     this._history.push({ timestamp: now, bufferSize });
     if (this._history.length > 0) {
       const minimumTime = now - TIME_SAMPLES_MS;

src/core/api/playback_observer.ts

@@ -16,6 +16,7 @@
 
 import config from "../../config";
 import log from "../../log";
+import getMonotonicTimeStamp from "../../utils/monotonic_timestamp";
 import noop from "../../utils/noop";
 import objectAssign from "../../utils/object_assign";
 import { getRange } from "../../utils/ranges";
@@ -455,7 +456,10 @@ export interface IRebufferingStatus {
   reason : "seeking" | // Building buffer after seeking
            "not-ready" | // Building buffer after low readyState
            "buffering"; // Other cases
-  /** `performance.now` at the time the rebuffering happened. */
+  /**
+   * Monotonically-raising timestamp at the time the rebuffering happened on the
+   * main thread.
+   */
   timestamp : number;
   /**
    * Position, in seconds, at which data is awaited.
@@ -471,7 +475,10 @@ export interface IRebufferingStatus {
  * an unknown reason.
  */
 export interface IFreezingStatus {
-  /** `performance.now` at the time the freezing started to be detected. */
+  /**
+   * Monotonically-raising timestamp at the time the freezing started to be
+   * detected.
+   */
   timestamp : number;
 }
 
@@ -834,7 +841,7 @@ function getRebufferingStatus(
                position: rebufferEndPosition };
     }
     return { reason,
-             timestamp: performance.now(),
+             timestamp: getMonotonicTimeStamp(),
              position: rebufferEndPosition };
   }
   return null;
@@ -875,7 +882,7 @@ function getFreezingStatus(
          currentInfo.readyState >= 1 &&
          currentInfo.playbackRate !== 0 &&
          currentInfo.position === prevObservation.position ?
-           { timestamp: performance.now() } :
+           { timestamp: getMonotonicTimeStamp() } :
            null;
 }
 

src/core/api/public_api.ts

@@ -89,6 +89,7 @@ import EventEmitter, {
 import idGenerator from "../../utils/id_generator";
 import isNullOrUndefined from "../../utils/is_null_or_undefined";
 import Logger from "../../utils/logger";
+import getMonotonicTimeStamp from "../../utils/monotonic_timestamp";
 import objectAssign from "../../utils/object_assign";
 import { getLeftSizeOfRange } from "../../utils/ranges";
 import createSharedReference, {
@@ -402,6 +403,8 @@ class Player extends EventEmitter<IPublicAPIEvent> {
         value: {
           wasmUrl: workerOptions.dashWasmUrl,
           logLevel: log.getLevel(),
+          date: Date.now(),
+          timestamp: getMonotonicTimeStamp(),
         },
       });
       log.addEventListener("onLogLevelChange", (logLevel) => {

src/core/fetchers/manifest/manifest_fetcher.ts

@@ -30,6 +30,7 @@ import {
 } from "../../../transports";
 import EventEmitter from "../../../utils/event_emitter";
 import isNullOrUndefined from "../../../utils/is_null_or_undefined";
+import getMonotonicTimeStamp from "../../../utils/monotonic_timestamp";
 import noop from "../../../utils/noop";
 import TaskCanceller from "../../../utils/task_canceller";
 import errorSelector from "../utils/error_selector";
@@ -282,7 +283,7 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
     parserOptions : IManifestFetcherParserOptions,
     requestUrl : string | undefined
   ) : Promise<IManifestFetcherParsedResult> {
-    const parsingTimeStart = performance.now();
+    const parsingTimeStart = getMonotonicTimeStamp();
     const cancelSignal = this._canceller.signal;
     const trigger = this.trigger.bind(this);
     const { sendingTime, receivedTime } = loaded;
@@ -361,7 +362,7 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
       warnings: IPlayerError[]
     ) : IManifestFetcherParsedResult {
       onWarnings(warnings);
-      const parsingTime = performance.now() - parsingTimeStart;
+      const parsingTime = getMonotonicTimeStamp() - parsingTimeStart;
       log.info(`MF: Manifest parsed in ${parsingTime}ms`);
 
       return { manifest,
@@ -435,7 +436,7 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
     /** Time elapsed since the beginning of the Manifest request, in milliseconds. */
     const timeSinceRequest = sendingTime === undefined ?
       0 :
-      performance.now() - sendingTime;
+      getMonotonicTimeStamp() - sendingTime;
 
     /** Minimum update delay we should not go below, in milliseconds. */
     const minInterval = Math.max(this._settings.minimumManifestUpdateInterval -
@@ -458,7 +459,7 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
       // (to avoid asking for it too often).
       const timeSinceLastRefresh = sendingTime === undefined ?
                                      0 :
-                                     performance.now() - sendingTime;
+                                     getMonotonicTimeStamp() - sendingTime;
       const _minInterval = Math.max(this._settings.minimumManifestUpdateInterval -
                                       timeSinceLastRefresh,
                                     0);
@@ -598,7 +599,7 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
         const { manifest: newManifest,
                 sendingTime: newSendingTime,
                 parsingTime } = res;
-        const updateTimeStart = performance.now();
+        const updateTimeStart = getMonotonicTimeStamp();
 
         if (fullRefresh) {
           manifest.replace(newManifest);
@@ -615,8 +616,8 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
             // The value allows to set a delay relatively to the last Manifest refresh
             // (to avoid asking for it too often).
             const timeSinceLastRefresh = newSendingTime === undefined ?
-                                           0 :
-                                           performance.now() - newSendingTime;
+              0 :
+              getMonotonicTimeStamp() - newSendingTime;
             const _minInterval = Math.max(this._settings.minimumManifestUpdateInterval -
                                             timeSinceLastRefresh,
                                           0);
@@ -635,7 +636,7 @@ export default class ManifestFetcher extends EventEmitter<IManifestFetcherEvent>
             return;
           }
         }
-        const updatingTime = performance.now() - updateTimeStart;
+        const updatingTime = getMonotonicTimeStamp() - updateTimeStart;
         this._recursivelyRefreshManifest(manifest, { sendingTime: newSendingTime,
                                                      parsingTime,
                                                      updatingTime });
@@ -670,11 +671,11 @@ interface IManifestFetcherParsedResult {
   /** The resulting Manifest */
   manifest : Manifest;
   /**
-   * The time (`performance.now()`) at which the request was started (at which
+   * Monotonically-raising timestamp at which the request was started (at which
    * the JavaScript call was done).
    */
   sendingTime? : number | undefined;
-  /** The time (`performance.now()`) at which the request was fully received. */
+  /** Monotonically-raising timestamp at which the request was fully received. */
   receivedTime? : number | undefined;
   /* The time taken to parse the Manifest through the corresponding parse function. */
   parsingTime? : number | undefined;
@@ -689,8 +690,8 @@ interface IManifestFetcherResponse {
 
 interface IManifestFetcherParserOptions {
   /**
-   * If set, offset to add to `performance.now()` to obtain the current
-   * server's time.
+   * If set, offset to add to the monotonically-raising timestamp to obtain the
+   * current server's time.
    */
   externalClockOffset? : number | undefined;
   /** The previous value of the Manifest (when updating). */

src/core/fetchers/segment/segment_fetcher.ts

@@ -38,6 +38,7 @@ import arrayIncludes from "../../../utils/array_includes";
 import idGenerator from "../../../utils/id_generator";
 import InitializationSegmentCache from "../../../utils/initialization_segment_cache";
 import isNullOrUndefined from "../../../utils/is_null_or_undefined";
+import getTimestamp from "../../../utils/monotonic_timestamp";
 import objectAssign from "../../../utils/object_assign";
 import {
   CancellationError,
@@ -179,7 +180,7 @@ export default function createSegmentFetcher<TLoadedFormat, TSegmentDataType>(
           lifecycleCallbacks.onProgress?.({ duration: info.duration,
                                             size: info.size,
                                             totalSize: info.totalSize,
-                                            timestamp: performance.now(),
+                                            timestamp: getTimestamp(),
                                             id: requestId });
         }
       },
@@ -205,7 +206,7 @@ export default function createSegmentFetcher<TLoadedFormat, TSegmentDataType>(
     }
 
     log.debug("SF: Beginning request", segmentIdString);
-    lifecycleCallbacks.onRequestBegin?.({ requestTimestamp: performance.now(),
+    lifecycleCallbacks.onRequestBegin?.({ requestTimestamp: getTimestamp(),
                                           id: requestId,
                                           content });
 

src/core/fetchers/utils/schedule_request.ts

@@ -24,6 +24,7 @@ import log from "../../../log";
 import { ICdnMetadata } from "../../../parsers/manifest";
 import cancellableSleep from "../../../utils/cancellable_sleep";
 import getFuzzedDelay from "../../../utils/get_fuzzed_delay";
+import getTimestamp from "../../../utils/monotonic_timestamp";
 import noop from "../../../utils/noop";
 import TaskCanceller, {
   CancellationSignal,
@@ -248,7 +249,7 @@ export async function scheduleRequestWithCdns<T>(
         const delay = Math.min(baseDelay * Math.pow(2, errorCounter - 1),
                                maxDelay);
         const fuzzedDelay = getFuzzedDelay(delay);
-        missedAttemptsObj.blockedUntil = performance.now() + fuzzedDelay;
+        missedAttemptsObj.blockedUntil = getTimestamp() + fuzzedDelay;
       }
 
       return retryWithNextCdn(error);
@@ -303,7 +304,7 @@ export async function scheduleRequestWithCdns<T>(
       return requestCdn(nextWantedCdn);
     }
 
-    const now = performance.now();
+    const now = getTimestamp();
     const blockedFor = nextCdnAttemptObj.blockedUntil - now;
     if (blockedFor <= 0) {
       return requestCdn(nextWantedCdn);
@@ -360,7 +361,7 @@ export async function scheduleRequestWithCdns<T>(
     if (missedAttempts.size === 0) {
       return sortedCdns[0];
     }
-    const now = performance.now();
+    const now = getTimestamp();
     return sortedCdns
       .filter(c =>  missedAttempts.get(c)?.isBlacklisted !== true)
       .reduce((
@@ -427,8 +428,8 @@ interface ICdnAttemptMetadata {
    */
   errorCounter : number;
   /**
-   * Timestamp, in terms of `performance.now()`, until which it should be
-   * forbidden to request this CDN.
+   * Monotonically-raising timestamp, until which it should be forbidden to
+   * request this CDN.
    * Enforcing this delay allows to prevent making too much requests to a given
    * CDN.
    *