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platform_browser.ts
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platform_browser.ts
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/**
* @license
* Copyright 2019 Google LLC. All Rights Reserved.
* 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 '../flags';
import {env} from '../environment';
import {BrowserIndexedDB, BrowserIndexedDBManager} from '../io/indexed_db';
import {BrowserLocalStorage, BrowserLocalStorageManager} from '../io/local_storage';
import {ModelStoreManagerRegistry} from '../io/model_management';
import {Platform} from './platform';
export class PlatformBrowser implements Platform {
// According to the spec, the built-in encoder can do only UTF-8 encoding.
// https://developer.mozilla.org/en-US/docs/Web/API/TextEncoder/TextEncoder
private textEncoder: TextEncoder;
// For setTimeoutCustom
private readonly messageName = 'setTimeoutCustom';
private functionRefs: Function[] = [];
private handledMessageCount = 0;
private hasEventListener = false;
fetch(path: string, init?: RequestInit): Promise<Response> {
return fetch(path, init);
}
now(): number {
return performance.now();
}
encode(text: string, encoding: string): Uint8Array {
if (encoding !== 'utf-8' && encoding !== 'utf8') {
throw new Error(
`Browser's encoder only supports utf-8, but got ${encoding}`);
}
if (this.textEncoder == null) {
this.textEncoder = new TextEncoder();
}
return this.textEncoder.encode(text);
}
decode(bytes: Uint8Array, encoding: string): string {
return new TextDecoder(encoding).decode(bytes);
}
// If the setTimeout nesting level is greater than 5 and timeout is less
// than 4ms, timeout will be clamped to 4ms, which hurts the perf.
// Interleaving window.postMessage and setTimeout will trick the browser and
// avoid the clamp.
setTimeoutCustom(functionRef: Function, delay: number): void {
if (typeof window === 'undefined' ||
!env().getBool('USE_SETTIMEOUTCUSTOM')) {
setTimeout(functionRef, delay);
return;
}
this.functionRefs.push(functionRef);
setTimeout(() => {
window.postMessage(
{name: this.messageName, index: this.functionRefs.length - 1}, '*');
}, delay);
if (!this.hasEventListener) {
this.hasEventListener = true;
window.addEventListener('message', (event: MessageEvent) => {
if (event.source === window && event.data.name === this.messageName) {
event.stopPropagation();
const functionRef = this.functionRefs[event.data.index];
functionRef();
this.handledMessageCount++;
if (this.handledMessageCount === this.functionRefs.length) {
this.functionRefs = [];
this.handledMessageCount = 0;
}
}
}, true);
}
}
isTypedArray(a: unknown): a is Uint8Array | Float32Array | Int32Array
| Uint8ClampedArray {
return a instanceof Float32Array || a instanceof Int32Array ||
a instanceof Uint8Array || a instanceof Uint8ClampedArray;
}
}
if (env().get('IS_BROWSER')) {
env().setPlatform('browser', new PlatformBrowser());
// Register LocalStorage IOHandler
try {
ModelStoreManagerRegistry.registerManager(
BrowserLocalStorage.URL_SCHEME, new BrowserLocalStorageManager());
} catch (err) {
}
// Register IndexedDB IOHandler
try {
ModelStoreManagerRegistry.registerManager(
BrowserIndexedDB.URL_SCHEME, new BrowserIndexedDBManager());
} catch (err) {
}
}