Source: lib/util/destroyer.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.util.Destroyer');
  9. goog.require('shaka.util.Error');
  10. goog.require('shaka.util.PublicPromise');
  13. /**
  14.  * @summary
  15.  * A utility class to help work with |shaka.util.IDestroyable| objects.
  16.  *
  17.  * @final
  18.  */
  19. shaka.util.Destroyer = class {
  20.   /**
  21.    * @param {function():!Promise} callback
  22.    *    A callback to destroy an object. This callback will only be called once
  23.    *    regardless of how many times |destroy| is called.
  24.    */
  25.   constructor(callback) {
  26.     /** @private {boolean} */
  27.     this.destroyed_ = false;
  29.     /** @private {!shaka.util.PublicPromise} */
  30.     this.waitOnDestroy_ = new shaka.util.PublicPromise();
  32.     /** @private {function():!Promise} */
  33.     this.onDestroy_ = callback;
  34.   }
  36.   /**
  37.    * Check if |destroy| has been called. This returning |true| does not mean
  38.    * that the promise returned by |destroy| has resolved yet.
  39.    *
  40.    * @return {boolean}
  41.    * @final
  42.    */
  43.   destroyed() {
  44.     return this.destroyed_;
  45.   }
  47.   /**
  48.    * Request that the destroy callback be called. Will return a promise that
  49.    * will resolve once the callback terminates. The promise will never be
  50.    * rejected.
  51.    *
  52.    * @return {!Promise}
  53.    * @final
  54.    */
  55.   destroy() {
  56.     if (this.destroyed_) {
  57.       return this.waitOnDestroy_;
  58.     }
  60.     // We have started destroying this object, so we should never get here
  61.     // again.
  62.     this.destroyed_ = true;
  64.     return this.onDestroy_().then(
  65.         () => { this.waitOnDestroy_.resolve(); },
  66.         () => { this.waitOnDestroy_.resolve(); });
  67.   }
  69.   /**
  70.    * Checks if the object is destroyed and throws an error if it is.
  71.    * @param {*=} error The inner error, if any.
  72.    */
  73.   ensureNotDestroyed(error) {
  74.     if (this.destroyed_) {
  75.       if (error instanceof shaka.util.Error &&
  76.           error.code == shaka.util.Error.Code.OBJECT_DESTROYED) {
  77.         throw error;
  78.       }
  79.       throw shaka.util.Destroyer.destroyedError(error);
  80.     }
  81.   }
  83.   /**
  84.    * @param {*=} error The inner error, if any.
  85.    * @return {!shaka.util.Error}
  86.    */
  87.   static destroyedError(error) {
  88.     return new shaka.util.Error(
  89.         shaka.util.Error.Severity.CRITICAL,
  90.         shaka.util.Error.Category.PLAYER,
  91.         shaka.util.Error.Code.OBJECT_DESTROYED,
  92.         error);
  93.   }
  94. };