mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-18 16:36:56 +03:00
Jacob Trimble
8835f7b898
If you attempt to load an asset and then the first load fails, then the second load will hang forever. This was caused by the second load trying to cancel the first, but the CancelableChain not handling this case. Closes #782 Change-Id: I79e201db44cbf47485e7221cc148bbfdde6276f7
124 lines
3.4 KiB
JavaScript
124 lines
3.4 KiB
JavaScript
/**
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* @license
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* Copyright 2016 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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goog.provide('shaka.util.CancelableChain');
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goog.require('goog.asserts');
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goog.require('shaka.util.Error');
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/**
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* A Promise-based abstraction that creates cancelable Promise chains.
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* When canceled, subsequent stages of the internal Promise chain will stop.
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* A canceled chain is rejected with a user-specified value.
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*
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* A CancelableChain only supports linear Promise chains. Chains which branch
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* (more than one then() handler chained to a particular stage) are not
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* supported. You will not be prevented from treating this as if branching
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* were supported, but everything will be serialized into a linear chain.
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* Be careful!
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*
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* @constructor
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* @struct
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*/
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shaka.util.CancelableChain = function() {
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/** @private {!Promise} */
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this.promise_ = Promise.resolve();
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/** @private {boolean} */
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this.final_ = false;
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/** @private {boolean} */
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this.complete_ = false;
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/** @private {boolean} */
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this.canceled_ = false;
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/** @private {shaka.util.Error} */
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this.rejectionValue_;
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/** @private {function()} */
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this.onCancelComplete_;
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/** @private {!Promise} */
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this.cancelPromise_ = new Promise(function(resolve) {
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this.onCancelComplete_ = resolve;
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}.bind(this));
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};
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/**
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* @param {function(*)} callback
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* @return {!shaka.util.CancelableChain} the chain itself.
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*/
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shaka.util.CancelableChain.prototype.then = function(callback) {
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goog.asserts.assert(!this.final_, 'Chain should not be final!');
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this.promise_ = this.promise_.then(callback).then(function(data) {
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if (this.canceled_) {
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this.onCancelComplete_();
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return Promise.reject(this.rejectionValue_);
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}
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return Promise.resolve(data);
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}.bind(this));
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return this;
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};
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/**
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* Finalize the chain.
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* Converts the chain into a simple Promise and stops accepting new stages.
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*
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* @return {!Promise}
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*/
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shaka.util.CancelableChain.prototype.finalize = function() {
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if (!this.final_) {
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this.promise_ = this.promise_.then(function(data) {
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this.complete_ = true;
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return Promise.resolve(data);
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}.bind(this), function(error) {
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this.complete_ = true;
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if (this.canceled_) {
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this.onCancelComplete_();
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return Promise.reject(this.rejectionValue_);
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}
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return Promise.reject(error);
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}.bind(this));
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}
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this.final_ = true;
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return this.promise_;
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};
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/**
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* Cancel the Promise chain and reject with the given value.
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*
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* @param {!shaka.util.Error} reason
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* @return {!Promise} resolved when the cancelation has been processed by the
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* the chain and no more stages will execute. Note that this may be before
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* the owner of the finalized chain has seen the rejection.
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*/
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shaka.util.CancelableChain.prototype.cancel = function(reason) {
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if (this.complete_) return Promise.resolve();
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this.canceled_ = true;
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this.rejectionValue_ = reason;
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return this.cancelPromise_;
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};
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