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/**
* Copyright 2017 Google Inc. 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 {assert} from '../util/assert.js';
import {isErrorLike} from '../util/ErrorLike.js';
import {CDPSession} from './Connection.js';
import {getReadableAsBuffer, getReadableFromProtocolStream} from './util.js';
/**
* @public
*/
export interface TracingOptions {
path?: string;
screenshots?: boolean;
categories?: string[];
}
/**
* The Tracing class exposes the tracing audit interface.
* @remarks
* You can use `tracing.start` and `tracing.stop` to create a trace file
* which can be opened in Chrome DevTools or {@link https://chromedevtools.github.io/timeline-viewer/ | timeline viewer}.
*
* @example
*
* ```ts
* await page.tracing.start({path: 'trace.json'});
* await page.goto('https://www.google.com');
* await page.tracing.stop();
* ```
*
* @public
*/
export class Tracing {
#client: CDPSession;
#recording = false;
#path?: string;
/**
* @internal
*/
constructor(client: CDPSession) {
this.#client = client;
}
/**
* Starts a trace for the current page.
* @remarks
* Only one trace can be active at a time per browser.
*
* @param options - Optional `TracingOptions`.
*/
async start(options: TracingOptions = {}): Promise<void> {
assert(
!this.#recording,
'Cannot start recording trace while already recording trace.'
);
const defaultCategories = [
'-*',
'devtools.timeline',
'v8.execute',
'disabled-by-default-devtools.timeline',
'disabled-by-default-devtools.timeline.frame',
'toplevel',
'blink.console',
'blink.user_timing',
'latencyInfo',
'disabled-by-default-devtools.timeline.stack',
'disabled-by-default-v8.cpu_profiler',
];
const {path, screenshots = false, categories = defaultCategories} = options;
if (screenshots) {
categories.push('disabled-by-default-devtools.screenshot');
}
const excludedCategories = categories
.filter(cat => {
return cat.startsWith('-');
})
.map(cat => {
return cat.slice(1);
});
const includedCategories = categories.filter(cat => {
return !cat.startsWith('-');
});
this.#path = path;
this.#recording = true;
await this.#client.send('Tracing.start', {
transferMode: 'ReturnAsStream',
traceConfig: {
excludedCategories,
includedCategories,
},
});
}
/**
* Stops a trace started with the `start` method.
* @returns Promise which resolves to buffer with trace data.
*/
async stop(): Promise<Buffer | undefined> {
let resolve: (value: Buffer | undefined) => void;
let reject: (err: Error) => void;
const contentPromise = new Promise<Buffer | undefined>((x, y) => {
resolve = x;
reject = y;
});
this.#client.once('Tracing.tracingComplete', async event => {
try {
const readable = await getReadableFromProtocolStream(
this.#client,
event.stream
);
const buffer = await getReadableAsBuffer(readable, this.#path);
resolve(buffer ?? undefined);
} catch (error) {
if (isErrorLike(error)) {
reject(error);
} else {
reject(new Error(`Unknown error: ${error}`));
}
}
});
await this.#client.send('Tracing.end');
this.#recording = false;
return contentPromise;
}
}
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