xhr-msstream-loader.js

/*
 * Copyright (C) 2016 Bilibili. All Rights Reserved.
 *
 * @author zheng qian <xqq@xqq.im>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import Log from '../utils/logger.js';
import {BaseLoader, LoaderStatus, LoaderErrors} from './loader.js';
import {RuntimeException} from '../utils/exception.js';

/* Notice: ms-stream may cause IE/Edge browser crash if seek too frequently!!!
 * The browser may crash in wininet.dll. Disable for now.
 *
 * For IE11/Edge browser by microsoft which supports `xhr.responseType = 'ms-stream'`
 * Notice that ms-stream API sucks. The buffer is always expanding along with downloading.
 *
 * We need to abort the xhr if buffer size exceeded limit size (e.g. 16 MiB), then do reconnect.
 * in order to release previous ArrayBuffer to avoid memory leak
 *
 * Otherwise, the ArrayBuffer will increase to a terrible size that equals final file size.
 */
class MSStreamLoader extends BaseLoader {

    static isSupported() {
        try {
            if (typeof self.MSStream === 'undefined' || typeof self.MSStreamReader === 'undefined') {
                return false;
            }

            let xhr = new XMLHttpRequest();
            xhr.open('GET', 'https://example.com', true);
            xhr.responseType = 'ms-stream';
            return (xhr.responseType === 'ms-stream');
        } catch (e) {
            Log.w('MSStreamLoader', e.message);
            return false;
        }
    }

    constructor(seekHandler, config) {
        super('xhr-msstream-loader');
        this.TAG = 'MSStreamLoader';

        this._seekHandler = seekHandler;
        this._config = config;
        this._needStash = true;

        this._xhr = null;
        this._reader = null;  // MSStreamReader

        this._totalRange = null;
        this._currentRange = null;

        this._currentRequestURL = null;
        this._currentRedirectedURL = null;

        this._contentLength = null;
        this._receivedLength = 0;

        this._bufferLimit = 16 * 1024 * 1024;  // 16MB
        this._lastTimeBufferSize = 0;
        this._isReconnecting = false;
    }

    destroy() {
        if (this.isWorking()) {
            this.abort();
        }
        if (this._reader) {
            this._reader.onprogress = null;
            this._reader.onload = null;
            this._reader.onerror = null;
            this._reader = null;
        }
        if (this._xhr) {
            this._xhr.onreadystatechange = null;
            this._xhr = null;
        }
        super.destroy();
    }

    open(dataSource, range) {
        this._internalOpen(dataSource, range, false);
    }

    _internalOpen(dataSource, range, isSubrange) {
        this._dataSource = dataSource;

        if (!isSubrange) {
            this._totalRange = range;
        } else {
            this._currentRange = range;
        }

        let sourceURL = dataSource.url;
        if (this._config.reuseRedirectedURL) {
            if (this._currentRedirectedURL != undefined) {
                sourceURL = this._currentRedirectedURL;
            } else if (dataSource.redirectedURL != undefined) {
                sourceURL = dataSource.redirectedURL;
            }
        }

        let seekConfig = this._seekHandler.getConfig(sourceURL, range);
        this._currentRequestURL = seekConfig.url;

        let reader = this._reader = new self.MSStreamReader();
        reader.onprogress = this._msrOnProgress.bind(this);
        reader.onload = this._msrOnLoad.bind(this);
        reader.onerror = this._msrOnError.bind(this);

        let xhr = this._xhr = new XMLHttpRequest();
        xhr.open('GET', seekConfig.url, true);
        xhr.responseType = 'ms-stream';
        xhr.onreadystatechange = this._xhrOnReadyStateChange.bind(this);
        xhr.onerror = this._xhrOnError.bind(this);

        if (dataSource.withCredentials) {
            xhr.withCredentials = true;
        }

        if (typeof seekConfig.headers === 'object') {
            let headers = seekConfig.headers;

            for (let key in headers) {
                if (headers.hasOwnProperty(key)) {
                    xhr.setRequestHeader(key, headers[key]);
                }
            }
        }

        // add additional headers
        if (typeof this._config.headers === 'object') {
            let headers = this._config.headers;

            for (let key in headers) {
                if (headers.hasOwnProperty(key)) {
                    xhr.setRequestHeader(key, headers[key]);
                }
            }
        }

        if (this._isReconnecting) {
            this._isReconnecting = false;
        } else {
            this._status = LoaderStatus.kConnecting;
        }
        xhr.send();
    }

    abort() {
        this._internalAbort();
        this._status = LoaderStatus.kComplete;
    }

    _internalAbort() {
        if (this._reader) {
            if (this._reader.readyState === 1) {  // LOADING
                this._reader.abort();
            }
            this._reader.onprogress = null;
            this._reader.onload = null;
            this._reader.onerror = null;
            this._reader = null;
        }
        if (this._xhr) {
            this._xhr.abort();
            this._xhr.onreadystatechange = null;
            this._xhr = null;
        }
    }

    _xhrOnReadyStateChange(e) {
        let xhr = e.target;

        if (xhr.readyState === 2) {  // HEADERS_RECEIVED
            if (xhr.status >= 200 && xhr.status <= 299) {
                this._status = LoaderStatus.kBuffering;

                if (xhr.responseURL != undefined) {
                    let redirectedURL = this._seekHandler.removeURLParameters(xhr.responseURL);
                    if (xhr.responseURL !== this._currentRequestURL && redirectedURL !== this._currentRedirectedURL) {
                        this._currentRedirectedURL = redirectedURL;
                        if (this._onURLRedirect) {
                            this._onURLRedirect(redirectedURL);
                        }
                    }
                }

                let lengthHeader = xhr.getResponseHeader('Content-Length');
                if (lengthHeader != null && this._contentLength == null) {
                    let length = parseInt(lengthHeader);
                    if (length > 0) {
                        this._contentLength = length;
                        if (this._onContentLengthKnown) {
                            this._onContentLengthKnown(this._contentLength);
                        }
                    }
                }
            } else {
                this._status = LoaderStatus.kError;
                if (this._onError) {
                    this._onError(LoaderErrors.HTTP_STATUS_CODE_INVALID, {code: xhr.status, msg: xhr.statusText});
                } else {
                    throw new RuntimeException('MSStreamLoader: Http code invalid, ' + xhr.status + ' ' + xhr.statusText);
                }
            }
        } else if (xhr.readyState === 3) {  // LOADING
            if (xhr.status >= 200 && xhr.status <= 299) {
                this._status = LoaderStatus.kBuffering;

                let msstream = xhr.response;
                this._reader.readAsArrayBuffer(msstream);
            }
        }
    }

    _xhrOnError(e) {
        this._status = LoaderStatus.kError;
        let type = LoaderErrors.EXCEPTION;
        let info = {code: -1, msg: e.constructor.name + ' ' + e.type};

        if (this._onError) {
            this._onError(type, info);
        } else {
            throw new RuntimeException(info.msg);
        }
    }

    _msrOnProgress(e) {
        let reader = e.target;
        let bigbuffer = reader.result;
        if (bigbuffer == null) {  // result may be null, workaround for buggy M$
            this._doReconnectIfNeeded();
            return;
        }

        let slice = bigbuffer.slice(this._lastTimeBufferSize);
        this._lastTimeBufferSize = bigbuffer.byteLength;
        let byteStart = this._totalRange.from + this._receivedLength;
        this._receivedLength += slice.byteLength;

        if (this._onDataArrival) {
            this._onDataArrival(slice, byteStart, this._receivedLength);
        }

        if (bigbuffer.byteLength >= this._bufferLimit) {
            Log.v(this.TAG, `MSStream buffer exceeded max size near ${byteStart + slice.byteLength}, reconnecting...`);
            this._doReconnectIfNeeded();
        }
    }

    _doReconnectIfNeeded() {
        if (this._contentLength == null || this._receivedLength < this._contentLength) {
            this._isReconnecting = true;
            this._lastTimeBufferSize = 0;
            this._internalAbort();

            let range = {
                from: this._totalRange.from + this._receivedLength,
                to: -1
            };
            this._internalOpen(this._dataSource, range, true);
        }
    }

    _msrOnLoad(e) {  // actually it is onComplete event
        this._status = LoaderStatus.kComplete;
        if (this._onComplete) {
            this._onComplete(this._totalRange.from, this._totalRange.from + this._receivedLength - 1);
        }
    }

    _msrOnError(e) {
        this._status = LoaderStatus.kError;
        let type = 0;
        let info = null;

        if (this._contentLength && this._receivedLength < this._contentLength) {
            type = LoaderErrors.EARLY_EOF;
            info = {code: -1, msg: 'MSStream meet Early-Eof'};
        } else {
            type = LoaderErrors.EARLY_EOF;
            info = {code: -1, msg: e.constructor.name + ' ' + e.type};
        }

        if (this._onError) {
            this._onError(type, info);
        } else {
            throw new RuntimeException(info.msg);
        }
    }
}

export default MSStreamLoader;