/*! @license * Shaka Player * Copyright 2016 Google LLC * SPDX-License-Identifier: Apache-2.0 */goog.provide('shaka.util.AbortableOperation');goog.require('shaka.util.Error');goog.require('shaka.util.PublicPromise');/** * A utility to wrap abortable operations. Note that these are not cancelable. * Cancelation implies undoing what has been done so far, whereas aborting only * means that further work is stopped. * * @implements {shaka.extern.IAbortableOperation.<T>} * @template T * @export */shaka.util.AbortableOperation = class { /** * @param {!Promise.<T>} promise * A Promise which represents the underlying operation. It is resolved when * the operation is complete, and rejected if the operation fails or is * aborted. Aborted operations should be rejected with a shaka.util.Error * object using the error code OPERATION_ABORTED. * @param {function():!Promise} onAbort * Will be called by this object to abort the underlying operation. * This is not cancelation, and will not necessarily result in any work * being undone. abort() should return a Promise which is resolved when the * underlying operation has been aborted. The returned Promise should never * be rejected. */ constructor(promise, onAbort) { /** @const {!Promise.<T>} */ this.promise = promise; /** @private {function():!Promise} */ this.onAbort_ = onAbort; /** @private {boolean} */ this.aborted_ = false; } /** * @param {!shaka.util.Error} error * @return {!shaka.util.AbortableOperation} An operation which has already * failed with the error given by the caller. * @export */ static failed(error) { return new shaka.util.AbortableOperation( Promise.reject(error), () => Promise.resolve()); } /** * @return {!shaka.util.AbortableOperation} An operation which has already * failed with the error OPERATION_ABORTED. * @export */ static aborted() { const p = Promise.reject(shaka.util.AbortableOperation.abortError()); // Silence uncaught rejection errors, which may otherwise occur any place // we don't explicitly handle aborted operations. p.catch(() => {}); return new shaka.util.AbortableOperation(p, () => Promise.resolve()); } /** @return {!shaka.util.Error} */ static abortError() { return new shaka.util.Error( shaka.util.Error.Severity.CRITICAL, shaka.util.Error.Category.PLAYER, shaka.util.Error.Code.OPERATION_ABORTED); } /** * @param {U} value * @return {!shaka.util.AbortableOperation.<U>} An operation which has already * completed with the given value. * @template U * @export */ static completed(value) { return new shaka.util.AbortableOperation( Promise.resolve(value), () => Promise.resolve()); } /** * @param {!Promise.<U>} promise * @return {!shaka.util.AbortableOperation.<U>} An operation which cannot be * aborted. It will be completed when the given Promise is resolved, or * will be failed when the given Promise is rejected. * @template U * @export */ static notAbortable(promise) { return new shaka.util.AbortableOperation( promise, // abort() here will return a Promise which is resolved when the input // promise either resolves or fails. () => promise.catch(() => {})); } /** * @override * @export */ abort() { this.aborted_ = true; return this.onAbort_(); } /** * @param {!Array.<!shaka.util.AbortableOperation>} operations * @return {!shaka.util.AbortableOperation} An operation which is resolved * when all operations are successful and fails when any operation fails. * For this operation, abort() aborts all given operations. * @export */ static all(operations) { return new shaka.util.AbortableOperation( Promise.all(operations.map((op) => op.promise)), () => Promise.all(operations.map((op) => op.abort()))); } /** * @override * @export */ finally(onFinal) { this.promise.then((value) => onFinal(true), (e) => onFinal(false)); return this; } /** * @param {(undefined| * function(T):U| * function(T):!Promise.<U>| * function(T):!shaka.util.AbortableOperation.<U>)} onSuccess * A callback to be invoked after this operation is complete, to chain to * another operation. The callback can return a plain value, a Promise to * an asynchronous value, or another AbortableOperation. * @param {function(*)=} onError * An optional callback to be invoked if this operation fails, to perform * some cleanup or error handling. Analogous to the second parameter of * Promise.prototype.then. * @return {!shaka.util.AbortableOperation.<U>} An operation which is resolved * when this operation and the operation started by the callback are both * complete. * @template U * @export */ chain(onSuccess, onError) { const newPromise = new shaka.util.PublicPromise(); const abortError = shaka.util.AbortableOperation.abortError(); // If called before "this" completes, just abort "this". let abort = () => { newPromise.reject(abortError); return this.abort(); }; const makeCallback = (isSuccess) => { return (value) => { if (this.aborted_ && isSuccess) { // If "this" is not abortable(), or if abort() is called after "this" // is complete but before the next stage in the chain begins, we // should stop right away. newPromise.reject(abortError); return; } const cb = isSuccess ? onSuccess : onError; if (!cb) { // No callback? Pass it along. const next = isSuccess ? newPromise.resolve : newPromise.reject; next(value); return; } // Call the callback, interpret the return value, set the Promise state, // and get the next abort function. abort = shaka.util.AbortableOperation.wrapChainCallback_( cb, value, newPromise); }; }; this.promise.then(makeCallback(true), makeCallback(false)); return new shaka.util.AbortableOperation( newPromise, // By creating a closure around abort(), we can update the value of // abort() at various stages. () => abort()); } /** * @param {(function(T):U| * function(T):!Promise.<U>| * function(T):!shaka.util.AbortableOperation.<U>| * function(*))} callback * A callback to be invoked with the given value. * @param {T} value * @param {!shaka.util.PublicPromise} newPromise The promise for the next * stage in the chain. * @return {function():!Promise} The next abort() function for the chain. * @private * @template T, U */ static wrapChainCallback_(callback, value, newPromise) { try { const ret = callback(value); if (ret && ret.promise && ret.abort) { // This is an abortable operation, with its own abort() method. // After this point, abort() should abort the operation from the // callback, and the new promise should be tied to the promise // from the callback's operation. newPromise.resolve(ret.promise); // This used to say "return ret.abort;", but it caused subtle issues by // unbinding part of the abort chain. There is now a test to ensure // that we don't call abort with the wrong "this". return () => ret.abort(); } else { // This is a Promise or a plain value, and this step cannot be aborted. newPromise.resolve(ret); // Abort is complete when the returned value/Promise is resolved or // fails, but never fails itself nor returns a value. return () => Promise.resolve(ret).then(() => {}, () => {}); } } catch (exception) { // The callback threw an exception or error. Reject the new Promise and // resolve any future abort call right away. newPromise.reject(exception); return () => Promise.resolve(); } }};/** * @const {!Promise.<T>} * @exportInterface */// eslint-disable-next-line no-restricted-syntaxshaka.util.AbortableOperation.prototype.promise;