[MULTI_THREAD] Fix potential leak when cleaning now inexistant Period

This is a fix for a small-scale leak happening in cases where we would
be unlucky with timings on a live content in a "multithreading" mode.

It was seen while investigating all possibilities for the issue reported
by #1643, though it has an extremely low chance to actually be linked to
that issue.

This fix is about the handling of `Init`'s `"periodStreamCleaning"`
event handling.

That event allows to clean-up resources that have previously been
allocated for a specific Period in a content: track handling, boundaries
checking etc.

Previously, only in "multithreading" mode, we checked that the Period of
a `"PeriodStreamCleaning"` event was found in the Manifest before
bubbling the event up to the `API` (the RxPlayer module).

That step was unnecessary (only the `id` property of a `Period` is
needed when cleaning up) and more importantly the check could fail in
a situation where the `Period` has since been removed from a dynamic
Manifest (e.g. after playing an old `Period` which has been loaded locally
but which now does not exist anymore in the Manifest).

The only issue I can think of with that for now are relatively-low memory
leaks (which will be collected once stopping/switching content). Still.

src/main_thread/api/public_api.ts

@@ -2849,12 +2849,12 @@ class Player extends EventEmitter<IPublicAPIEvent> {
    */
   private _priv_onPeriodStreamCleared(
     contentInfos: IPublicApiContentInfos,
-    value: { type: IBufferType; period: IPeriodMetadata },
+    value: { type: IBufferType; periodId: string },
   ): void {
     if (contentInfos.contentId !== this._priv_contentInfos?.contentId) {
       return; // Event for another content
     }
-    const { type, period } = value;
+    const { type, periodId } = value;
     const tracksStore = contentInfos.tracksStore;
 
     // Clean-up track choices from TracksStore
@@ -2863,7 +2863,7 @@ class Player extends EventEmitter<IPublicAPIEvent> {
       case "text":
       case "video":
         if (!isNullOrUndefined(tracksStore)) {
-          tracksStore.removeTrackReference(type, period);
+          tracksStore.removeTrackReference(type, periodId);
         }
         break;
     }
@@ -2872,23 +2872,23 @@ class Player extends EventEmitter<IPublicAPIEvent> {
     const { activeAdaptations, activeRepresentations } = contentInfos;
     if (
       !isNullOrUndefined(activeAdaptations) &&
-      !isNullOrUndefined(activeAdaptations[period.id])
+      !isNullOrUndefined(activeAdaptations[periodId])
     ) {
-      const activePeriodAdaptations = activeAdaptations[period.id];
+      const activePeriodAdaptations = activeAdaptations[periodId];
       delete activePeriodAdaptations[type];
       if (Object.keys(activePeriodAdaptations).length === 0) {
-        delete activeAdaptations[period.id];
+        delete activeAdaptations[periodId];
       }
     }
 
     if (
       !isNullOrUndefined(activeRepresentations) &&
-      !isNullOrUndefined(activeRepresentations[period.id])
+      !isNullOrUndefined(activeRepresentations[periodId])
     ) {
-      const activePeriodRepresentations = activeRepresentations[period.id];
+      const activePeriodRepresentations = activeRepresentations[periodId];
       delete activePeriodRepresentations[type];
       if (Object.keys(activePeriodRepresentations).length === 0) {
-        delete activeRepresentations[period.id];
+        delete activeRepresentations[periodId];
       }
     }
   }

src/main_thread/init/media_source_content_initializer.ts

@@ -917,7 +917,10 @@ export default class MediaSourceContentInitializer extends ContentInitializer {
           if (cancelSignal.isCancelled()) {
             return; // Previous call has stopped streams due to a side-effect
           }
-          self.trigger("periodStreamCleared", value);
+          self.trigger("periodStreamCleared", {
+            type: value.type,
+            periodId: value.period.id,
+          });
         },
 
         bitrateEstimateChange: (value) => {

src/main_thread/init/multi_thread_content_initializer.ts

@@ -969,15 +969,8 @@ export default class MultiThreadContentInitializer extends ContentInitializer {
           ) {
             return;
           }
-          const period = arrayFind(
-            this._currentContentInfo.manifest.periods,
-            (p) => p.id === msgData.value.periodId,
-          );
-          if (period === undefined) {
-            return;
-          }
           this.trigger("periodStreamCleared", {
-            period,
+            periodId: msgData.value.periodId,
             type: msgData.value.bufferType,
           });
           break;

src/main_thread/init/types.ts

@@ -192,12 +192,13 @@ export interface IContentInitializerEvents {
      */
     type: IBufferType;
     /**
-     * The `Period` linked to the `PeriodStream` we just removed.
+     * The `id` property of the `Period` linked to the `PeriodStream` we just
+     * removed.
      *
      * The combination of this and `Period` should give you enough information
      * about which `PeriodStream` has been removed.
      */
-    period: IPeriodMetadata;
+    periodId: string;
   };
   /** Emitted when a new `Adaptation` is being considered. */
   adaptationChange: IAdaptationChangeEventPayload;

src/main_thread/tracks_store/tracks_store.ts

@@ -496,15 +496,22 @@ export default class TracksStore extends EventEmitter<ITracksStoreEvents> {
    * Remove shared reference to choose an "audio", "video" or "text" Adaptation
    * for a Period.
    * @param {string} bufferType - The concerned buffer type
-   * @param {Period} period - The concerned Period.
+   * @param {string} periodId - The concerned Period's `id`.
    */
   public removeTrackReference(
     bufferType: "audio" | "text" | "video",
-    period: IPeriodMetadata,
+    periodId: string,
   ): void {
-    const periodIndex = findPeriodIndex(this._storedPeriodInfo, period);
+    let periodIndex;
+    for (let i = 0; i < this._storedPeriodInfo.length; i++) {
+      const periodI = this._storedPeriodInfo[i];
+      if (periodI.period.id === periodId) {
+        periodIndex = i;
+        break;
+      }
+    }
     if (periodIndex === undefined) {
-      log.warn(`TS: ${bufferType} not found for period`, period.start);
+      log.warn(`TS: ${bufferType} not found for period`, periodId);
       return;
     }
 
@@ -513,7 +520,7 @@ export default class TracksStore extends EventEmitter<ITracksStoreEvents> {
     if (choiceItem?.dispatcher === null) {
       log.warn(
         `TS: TrackDispatcher already removed for ${bufferType} ` +
-          `and Period ${period.start}`,
+          `and Period ${periodId}`,
       );
       return;
     }
@@ -1378,26 +1385,6 @@ export default class TracksStore extends EventEmitter<ITracksStoreEvents> {
   }
 }
 
-/**
- * Returns the index of the given `period` in the given `periods`
- * Array.
- * Returns `undefined` if that `period` is not found.
- * @param {Object} periods
- * @param {Object} period
- * @returns {number|undefined}
- */
-function findPeriodIndex(
-  periods: ITSPeriodObject[],
-  period: IPeriodMetadata,
-): number | undefined {
-  for (let i = 0; i < periods.length; i++) {
-    const periodI = periods[i];
-    if (periodI.period.id === period.id) {
-      return i;
-    }
-  }
-}
-
 /**
  * Returns element in the given `periods` Array that corresponds to the
  * `period` given.