fix(preload): Wait for drm keys when preloading (#7698)

Closes #7520

Author: theodab

lib/media/drm_engine.js

@@ -9,6 +9,7 @@ goog.provide('shaka.media.DrmEngine');
 goog.require('goog.asserts');
 goog.require('shaka.log');
 goog.require('shaka.net.NetworkingEngine');
+goog.require('shaka.util.ArrayUtils');
 goog.require('shaka.util.BufferUtils');
 goog.require('shaka.util.Destroyer');
 goog.require('shaka.util.DrmUtils');
@@ -67,12 +68,18 @@ shaka.media.DrmEngine = class {
      */
     this.activeSessions_ = new Map();
 
+    /** @private {!Array.<!shaka.net.NetworkingEngine.PendingRequest>} */
+    this.activeRequests_ = [];
+
     /**
      * @private {!Map<string,
      *           {initData: ?Uint8Array, initDataType: ?string}>}
      */
     this.storedPersistentSessions_ = new Map();
 
+    /** @private {boolean} */
+    this.hasInitData_ = false;
+
     /** @private {!shaka.util.PublicPromise} */
     this.allSessionsLoaded_ = new shaka.util.PublicPromise();
 
@@ -706,6 +713,7 @@ shaka.media.DrmEngine = class {
 
       // Reset the promise for the next sessions to come if key needs aren't
       // satisfied with persistent sessions
+      this.hasInitData_ = false;
       this.allSessionsLoaded_ = new shaka.util.PublicPromise();
       this.allSessionsLoaded_.catch(() => {});
     }
@@ -767,11 +775,16 @@ shaka.media.DrmEngine = class {
       }
     }
 
+    // Mark that there is init data, so that the preloader will know to wait
+    // for sessions to be loaded.
+    this.hasInitData_ = true;
+
     // If there are pre-existing sessions that have all been loaded
     // then reset the allSessionsLoaded_ promise, which can now be
     // used to wait for new sesssions to be loaded
     if (this.activeSessions_.size > 0 && this.areAllSessionsLoaded_()) {
       this.allSessionsLoaded_.resolve();
+      this.hasInitData_ = false;
       this.allSessionsLoaded_ = new shaka.util.PublicPromise();
       this.allSessionsLoaded_.catch(() => {});
     }
@@ -1387,6 +1400,14 @@ shaka.media.DrmEngine = class {
             this.video_.paused && !this.initialRequestsSent_);
   }
 
+  /** @return {!Promise} */
+  async waitForActiveRequests() {
+    if (this.hasInitData_) {
+      await this.allSessionsLoaded_;
+      await Promise.all(this.activeRequests_.map((req) => req.promise));
+    }
+  }
+
   /**
    * Sends a license request.
    * @param {!MediaKeyMessageEvent} event
@@ -1446,7 +1467,9 @@ shaka.media.DrmEngine = class {
     try {
       const req = this.playerInterface_.netEngine.request(
           requestType, request, {isPreload: this.isPreload_()});
+      this.activeRequests_.push(req);
       response = await req.promise;
+      shaka.util.ArrayUtils.remove(this.activeRequests_, req);
     } catch (error) {
       if (this.destroyer_.destroyed()) {
         return;

lib/media/preload_manager.js

@@ -398,7 +398,13 @@ shaka.media.PreloadManager = class extends shaka.util.FakeEventTarget {
         await this.initializeDrmInner_();
         this.throwIfDestroyed_();
 
-        await this.chooseInitialVariantInner_();
+        await this.chooseInitialVariantAndPrefetchInner_();
+        this.throwIfDestroyed_();
+
+        // We don't need the drm keys to load completely for the initial variant
+        // to be chosen, but we won't mark the load as a success until it has
+        // been loaded. So wait for it here, not inside initializeDrmInner_.
+        await this.drmEngine_.waitForActiveRequests();
         this.throwIfDestroyed_();
 
         this.successPromise_.resolve();
@@ -610,12 +616,12 @@ shaka.media.PreloadManager = class extends shaka.util.FakeEventTarget {
 
   /**
    * Performs a final filtering of the manifest, and chooses the initial
-   * variant.
+   * variant. Also prefetches segments.
    *
    * @return {!Promise}
    * @private
    */
-  async chooseInitialVariantInner_() {
+  async chooseInitialVariantAndPrefetchInner_() {
     goog.asserts.assert(
         this.manifest_, 'The manifest should already be parsed.');
 

test/test/util/fake_drm_engine.js

@@ -46,6 +46,10 @@ shaka.test.FakeDrmEngine = class {
       this.offlineSessions_.push('session-' + num);
     });
 
+    /** @type {!jasmine.Spy} */
+    this.waitForActiveRequests = jasmine.createSpy('waitForActiveRequests');
+    this.waitForActiveRequests.and.returnValue(Promise.resolve());
+
     /** @type {!jasmine.Spy} */
     this.getExpiration = jasmine.createSpy('getExpiration');
     this.getExpiration.and.returnValue(Infinity);